Biowin 6 Help Manual

Contents
Welcome to BioWin 3
Welcome ....................................................................................................................... 3
BioWin in Brief .............................................................................................................. 4
Limitations .................................................................................................................... 6

Help, Tutorials and Examples 7

Help and Manual........................................................................................................... 7
Welcome to the Online Help System for BioWin ............................................ 7
Using The BioWin Help System ........................................................................ 7
Context Sensitive Help in BioWin .................................................................. 12
About the Manual .......................................................................................... 13
How To Print The Manual .............................................................................. 14
BioWin Tutorials.......................................................................................................... 14
Learning Objectives ....................................................................................... 14
TUTORIAL 1 - BioWin Familiarization............................................................. 14
TUTORIAL 2A - Building a Configuration ........................................................ 21
TUTORIAL 2B - A Nutrient Removal Refresher .............................................. 30
TUTORIAL 3 - Nitrification Dynamics and Setting up Charts.......................... 33
TUTORIAL 4 – Secondary Clarifier Simulation................................................ 39
TUTORIAL 5 - Aeration System Simulation .................................................... 43
TUTORIAL 6 – Setting Up an SBR System ....................................................... 46
BioWin Examples ........................................................................................................ 55
Pre-Configured File Cabinet ........................................................................... 55

General Operation 57
Main Simulator Window ............................................................................................. 57
Main Window Menus .................................................................................... 58
Toolbars ......................................................................................................... 59
Main Window Summary Panes ...................................................................... 61
Main Window Status Bar ............................................................................... 62
Managing Other Windows ............................................................................. 64
Managing BioWin Projects.......................................................................................... 65
Specifying Project Model Parameter Values ................................................. 65
Setting Project Options .................................................................................. 66
Specifying Project Details .............................................................................. 80
Recording Project Notes ................................................................................ 81
Solids Retention Time Calculation ................................................................. 82
Hydraulic Retention Time Calculation ........................................................... 86

Biowin 6 Help Manual Contents • iii

 Specifying Project Liquid Temperature.......................................................... 90
Specifying Project Inlet Air Conditions .......................................................... 90
Specifying Project Blower Calculation Method ............................................. 91
Project Air Supply Groups/Blower Specifications ........................................ 103
Specifying Project Electricity Costs .............................................................. 107
Specifying Project Fuel/Chemical Costs ....................................................... 110
Specifying Project Combined Heat and Power Parameters ........................ 112
Specifying Project HVAC Power ................................................................... 113
Managing Data............................................................................................. 113
Alarms .......................................................................................................... 130
Opening Files from Previous Versions ......................................................... 135
Customizing BioWin .................................................................................................. 138
Customizing the Project Appearance .......................................................... 138
Customizing the Work Environment............................................................ 144
Chart Template Options............................................................................... 157
Useful BioWin Interface Tools and Techniques ........................................................ 161
Model Parameter Editors ............................................................................ 161
Itinerary Editors ........................................................................................... 165
Model Builder ........................................................................................................... 191
Managing Models ........................................................................................ 192
Entering Model Constants ........................................................................... 197
Entering Model Processes ........................................................................... 198
Entering Model Equations ........................................................................... 199
Cabinet Models provided with BioWin ........................................................ 206
Inert conversion Add-on .............................................................................. 206

Building Configurations 207

Using the Drawing Board .......................................................................................... 207
Place an Element on the Drawing Board ..................................................... 207
Selecting Multiple Elements on the Drawing Board .................................... 207
Rearranging and Moving Elements on the Drawing Board ......................... 208
Name an Element on the Drawing Board .................................................... 209
Copy Elements on the Drawing Board ......................................................... 209
Delete an Element from the Drawing Board ............................................... 209
Connect Elements with Pipes ...................................................................... 210
Undo Drawing Board Actions....................................................................... 211
Access Element Properties from the Drawing Board .................................. 211
Zoom In on a Drawing Board Area ............................................................... 211
Printing the Drawing Board ......................................................................... 212
Element Descriptions ................................................................................................ 213
Influents ....................................................................................................... 213
Effluents ....................................................................................................... 250
Model Builder Unit ...................................................................................... 257
Bioreactors ................................................................................................... 267
SBRs.............................................................................................................. 341
Granular Sludge Sequencing Tank ............................................................... 425
Thermal Hydrolysis Unit............................................................................... 440

iv • Contents Biowin 6 Help Manual

 Aerobic Digester .......................................................................................... 448
Anaerobic Digester ...................................................................................... 454
Pipes............................................................................................................. 467
Tanks ............................................................................................................ 472
Clarifiers ....................................................................................................... 483
Dewatering Unit........................................................................................... 513
Splitter ......................................................................................................... 518
Microscreen ................................................................................................. 522
Cyclone......................................................................................................... 526
ISS Cyclone ................................................................................................... 532
Mixers .......................................................................................................... 537
Plug Flow Channel........................................................................................ 541
Pumps .......................................................................................................... 545

Running Simulations 551

Running Simulations in BioWin ................................................................................. 551
Check Simulate Data .................................................................................... 551
Flow Balance ................................................................................................ 552
Steady State Balance ................................................................................... 552
Dynamic Simulation ..................................................................................... 554
Tips for Complex Systems ......................................................................................... 556
Stopping a Steady State Simulation ............................................................. 559

Data Output (charts, tables, reports) 561

BioWin Album ........................................................................................................... 561
Album Menus............................................................................................... 562
Album pages and panes ............................................................................... 562
Album Toolbar ............................................................................................. 568
Album Table Displays ................................................................................... 568
Element Info - Pre-defined Table in Album ................................................. 574
Drawing Board Table Displays ..................................................................... 577
Album Chart Sub-Menu ............................................................................... 578
Creating Charts & Adding Series .................................................................. 581
Series Available from the Album ................................................................. 582
Series Available from the Drawing Board .................................................... 624
Chart Formatting Procedures ...................................................................... 637
Series Formatting Procedures...................................................................... 682
BioWin Explorer ........................................................................................................ 722
Navigating in the Explorer ........................................................................... 723
Explorer Appearance ................................................................................... 724
Mass Balance Window .............................................................................................. 724
Rates Window ........................................................................................................... 727
Creating Project Reports ........................................................................................... 733
Creating a Word Report ............................................................................... 734
Creating an Excel™ Report ........................................................................... 735

Model Reference 753

Biowin 6 Help Manual Contents • v

 Biological/Chemical Models ..................................................................................... 753
Activated Sludge Processes ......................................................................... 753
Anaerobic Digestion Processes .................................................................... 785
Sulfur Modeling ........................................................................................... 803
Chemical Precipitation Reactions ............................................................................. 811
Chemical Phosphorus Removal with Iron Salts ........................................... 811
Chemical Phosphorus Removal with Aluminum Salts ................................. 815
Setting up Channels ..................................................................................... 818
Chemical Phosphorus Removal Example ..................................................... 819
Modeling Metal-Colloidal Coagulation Reactions ....................................... 823
Iron RedOx Reactions and Precipitation of Vivianite and FeS ..................... 828
Precipitation of Brushite, Hydroxy-Apatite and Struvite ............................. 831
Modeling of pH and Alkalinity .................................................................................. 833
General Parameters ..................................................................................... 843
Modeling of Industrial Components ......................................................................... 844
General Parameters .................................................................................................. 863
Aeration and Gas Transfer Model............................................................................. 864
Mass transfer Parameters ........................................................................... 864
Aeration Parameters.................................................................................... 865
Diffuser Parameters ..................................................................................... 867
Surface aerator Parameters......................................................................... 868
Further Reading: Gas-Liquid Mass Transfer Model ..................................... 868
Solid-Liquid Separation / Clarifier Models ................................................................ 885
Types of Models ........................................................................................... 885
Point Separation Models ............................................................................. 885
Ideal Separation Models .............................................................................. 886
Flux Based Models ....................................................................................... 887
References ................................................................................................... 897
Modeling Fixed Film Processes ................................................................................. 898
Introduction ................................................................................................. 898
Model usage ................................................................................................ 899
Model Formulation (Fixed Film Processes).................................................. 900
Model Calibration ........................................................................................ 902
References ................................................................................................... 903
Modeling Sidestream Treatment Processes ............................................................. 903
Introduction ................................................................................................. 904
Model Formulation (Sidestream Treatment Processes) .............................. 905
References ................................................................................................... 906
Modeling Granular Sludge Sequencing Tanks .......................................................... 907
Introduction ................................................................................................. 907
Model Description ....................................................................................... 908
References ................................................................................................... 914
Definition of Non-State Variables ............................................................................. 914
COD and BOD in BioWin ........................................................................................... 923
BOD Calculations in BioWin ......................................................................... 923

Power in BioWin 945

vi • Contents Biowin 6 Help Manual

 Entering Power and Power Calculations ................................................................... 945
Blower Power Parameters and Calculations................................................ 946
Mixing Power ............................................................................................... 958
Mechanical Power ....................................................................................... 959
Pumping Power............................................................................................ 960
Heating Power and Power Recovery ........................................................... 968
Surface Aeration Power ............................................................................... 991
S/L sep./Disinfection Power......................................................................... 994
Heating Ventilation and Cooling (HVAC) Power .......................................... 996
Displaying Power Demand and Energy Consumption .............................................. 996
Element Information.................................................................................... 997
Tables ........................................................................................................... 998
Charts .........................................................................................................1003

Operating Costs in BioWin 1019

Operating Costs ......................................................................................................1019
Power / Energy consumption ....................................................................1020
Chemicals ...................................................................................................1024
Fuel (Heating and/or Sale) .........................................................................1028
Sludge ........................................................................................................1033
Displaying Cost Information....................................................................................1034
Element Information..................................................................................1034
Tables .........................................................................................................1036
Charts .........................................................................................................1039

Glossary of Terms 1057

Index 1061

Biowin 6 Help Manual Contents • vii

Biowin 6 Help Manual Welcome to BioWin • 1
Welcome to BioWin

Welcome
Welcome to the latest version of BioWin - a comprehensive simulation tool for biological wastewater
treatment plant design, analysis and training. The package was developed with the primary objective of
providing a powerful tool to aid both the process designer and operators of these facilities.
For getting started, go to the BioWin Tutorials section of the “Help, Tutorials and Examples“ chapter. This set
of tutorials and case studies is designed as a training exercise in the application of BioWin. The primary
objective is to provide "how to…" training on using the BioWin software itself. The case studies are not
intended as a course in wastewater treatment process engineering. Nevertheless, several of the case studies
focus on process applications and identify interesting design and operating issues.
There are two places where you can find more BioWin examples:
• On the BioWin main window toolbar, at the end on the right, click on the arrow next to the icon that
looks like a filing cabinet. This brings down a list of pre-configured BioWin process files for a range of
system configurations.
• Select File|Open and browse to the BioWin Examples directory. The standard path is:
C:\Program Files\EnviroSim\BioWin X.X\Data\Examples (replace X.X with version number). These
systems are discussed in the BioWin Tutorials and BioWin Examples sections of the “Help, Tutorials
and Examples“ chapter.

Biowin 6 Help Manual Welcome to BioWin • 3

The BioWin wastewater treatment process simulator

BioWin in Brief
The user can define and analyze behavior of complex treatment plant configurations with single or multiple
wastewater inputs. An example of a plant configuration is shown below.
Most types of wastewater treatment systems can be configured in BioWin using the many process modules.
These include:
• A range of activated sludge bioreactor modules – suspended growth reactors (diffused air or surface
aeration), various SBRs, media reactors for IFAS and MBBR systems, variable volume reactors.
• Anaerobic and aerobic digesters.
• Various settling tank modules – primary, ideal and 1-D model settlers.
• Different input elements – wastewater influent (COD- or BOD-based), user-defined (state variable
concentrations), metal addition for chemical phosphorus precipitation (ferric or alum), methanol for
denitrification.
• Other process modules – holding tanks, equalization tanks, dewatering units, flow splitters and
combiners.
A crucial component of BioWin is the biological process model. The BioWin model is unique in that it merges
both activated sludge and anaerobic biological processes. Additionally, the model integrates pH and
chemical phosphorus precipitation processes.

4 • Welcome to BioWin Biowin 6 Help Manual

It’s easy to use. The program has the look and feel of the many other Windows applications. When it is
launched it comes up with the familiar interface and menu structure. Complex treatment plant schemes can
be configured rapidly through "drag and drop" mouse actions. Functions are selected from the pull-down
menus, using short cut keys, or by pointing the mouse and clicking on icons in the toolbar. The user can also
access many of the Windows functions usually embedded in a Windows application; for example, selecting
and configuring the printer setup. Context-sensitive Help is built into BioWin to provide on-line assistance,
particularly for new users.
Careful consideration has gone into the design of the package; for example, the hardware and software
platforms, the object-oriented software development system, the data structures, the user interface, and so
on. A primary aim has been the production of a package structured to allow on-going development in years
to come.
The BioWin simulator suite presently includes two modules:
• A steady state module for analyzing systems based on constant influent loading and/or flow
weighted averages of time-varying inputs. This unit is also very useful for mass balancing over
complex plant configurations.
• An interactive dynamic simulator where the user can operate and manipulate the treatment system
"on the fly". This module is ideal for training and for analyzing system response when subjected to
time-varying inputs or changes in operating strategy.

Biowin 6 Help Manual Welcome to BioWin • 5

Limitations
BioWin is a very powerful analysis tool. The program has been evaluated against an extensive data set and
has been demonstrated to provide accurate simulation results for a range of systems. Nevertheless, the user
is cautioned that BioWin is merely a tool.
BioWin incorporates several models. These necessarily are a simplification of reality and have limited ranges
of applicability. It is the responsibility of the user to carefully assess results generated by the program.

6 • Welcome to BioWin Biowin 6 Help Manual

Help, Tutorials and Examples

Help and Manual

Welcome to the Online Help System for BioWin

BioWin comes equipped with full featured, context-sensitive on-line help. The help features an
expanding/collapsing table of contents, a full multi-level keyword index, and a full text search. The on-line
help is built from the manual, so users will have a number of options available to them when it comes to
accessing information.
The help format used in BioWin is known as HTML help. This format commonly is used in Microsoft Office
applications, and will be familiar to most users. This format delivers the help system via a two-paned web
browser interface that displays the help system topic structure in the left pane and the selected topic in the
right pane. In this way, users can see where they are in the overall topic structure as they browse through
the help system. For more information on this style of help, please see the section entitled Using the BioWin
Help System.

Using The BioWin Help System

BioWin’s help system may be accessed with one of two methods:
• The main simulator window menu command Help|Contents and index;
• Clicking the Help Contents and Index button ( ) on the main toolbar of the main simulator
window.
When the help system is opened, you will see a two-paned window with the right pane showing the
contents of the currently selected topic (or a default start topic if one is not selected) and the left pane
showing the Contents, Index, Search, or Favorites tab, depending on which tab was active when the
help system was last exited. Note that the relative size of the panes can be changed by dragging the pane
dividing bar. The two-paned window is shown below.

Biowin 6 Help Manual Help, Tutorials and Examples • 7

The BioWin Help two-paned window

The buttons at the top of the two-paned window have the following functions:

Button Function

Hide / Show Used to toggle the left pane between hidden and
visible states.
Locate Clicking this button will display the contents tab in
the left pane and highlight the topic that you
currently are viewing. This button is useful for
locating related topics when using the Index or
Search tab.
Back Moves one topic back in your browse history.
Takes you to the last topic that you viewed.
Forward Moves one topic forward in your browse history.
Takes you to the previous topic you viewed.
Print A dialog box opens that allows you to choose
whether you want the current topic or the current
topic and all its sub-topics to be printed.

8 • Help, Tutorials and Examples Biowin 6 Help Manual

 Options Sets display options for your help system – it is
recommended that these options be left set to
their defaults.

Help Contents Tab

One advantage of the BioWin help is that when the Contents tab is selected, it is possible to view topics and
the help system outline structure simultaneously, as shown in the picture below.

The Help Contents Tab

You can expand and collapse levels of the help system outline by clicking on the book icons or titles of the
levels. If there is text associated with a level, it will be displayed in the right pane. When you locate the
topic you wish to view, click on it and the topic contents will be displayed in the right pane.

Help Search Tab

When the Search tab is selected, it is possible to view your search results and topics simultaneously, as
shown in the picture below.

Biowin 6 Help Manual Help, Tutorials and Examples • 9

The Help Search tab

To use the search utility, type in the keyword(s) or phrase that you are searching for, and click the List Topics
button. This will display the list of topics containing the keyword(s) or phrase that you searched for. To
view a topic, you can either double-click on the topic title, or click topic title and then click the Display
button, and the topic contents with your search term(s) highlighted will be displayed in the right pane.

Help Favorites Tab

Another feature of the BioWin help is the Favorites tab, shown below.

10 • Help, Tutorials and Examples Biowin 6 Help Manual

The Help Favorites tab

Once you have found a topic using the Contents or Search tabs, you can add it to a list of favorites so that
you can easily access it repeatedly. To do this,
1. Locate the topic that you want to add using the Contents or Search tab.
2. Click the Favorites tab.
3. The topic you currently are viewing will be displayed in the right pane, and at the bottom of the left
pane the topic title will be displayed in the Current topic box.
4. To add the current topic to your list of favorites, click the Add button.
5. The topic will be added to the Topics list in the left pane.
6. To view other topics in the Topics list, double-click the topic, or click the topic then click the Display
button.
7. To remove a topic from the list, click the topic title and then click the Remove button.

Popups and Jumps

In BioWin’s help topics, you may encounter text that is blue and underlined. This means that the text
represents a popup or hyperlink jump. If the text represents a popup, then clicking on the text will open a
small “popup” window. Popups usually are used for definitions, small pictures, etc. When you are done
viewing the contents of the popup, simply position your mouse cursor outside of the popup window and
click once, or press any key on your keyboard to close it.

Biowin 6 Help Manual Help, Tutorials and Examples • 11

If the text represents a hyperlink jump, clicking on that text will send you to another location in the help file
– usually a topic that contains material relevant to the text that denoted the jump. Note that when you do
this, the help engine tracks your position in the help system outline if you have the Contents tab selected so
you know your location in the help system hierarchy. To return to the topic that you jumped from, click the
Back button.

Context Sensitive Help in BioWin

Context sensitive help is an advance in help; it is a system that makes it easier for users to find help
immediately on topics that are relevant to the operations they are performing in BioWin.
When context sensitive help is called, the help system is opened with a topic that is related to the dialog box
or menu command that you want help on. From this topic it is easy to navigate to other related topics.
There are a number of ways that the utility of context sensitive help may be employed:

Context Sensitive Help on a Dialog Box

To get context sensitive help on a dialog box, press the F1 key on your keyboard. Certain dialog boxes have
red text at the bottom to remind you of this functionality. It also is possible to click on this text to invoke
the help – the mouse cursor will display a question mark when you fly over this text, as shown below:

Dialog box with clickable context sensitivity reminder (notice the mouse cursor)

12 • Help, Tutorials and Examples Biowin 6 Help Manual

Context Sensitive Help on a Window Menu Command
To get context sensitive help on a window menu command, hold your mouse cursor over that command so
that it is highlighted in blue as shown below and press the F1 key on your keyboard.

A highlighted menu command

About the Manual

This manual is available to you in both printed and online format. The content of both formats is identical –
the choice is offered merely for your convenience. For information on printing the manual, please see How
To Print the Manual. For information about the online help system, please see Welcome to the Online Help
System for BioWin.

Layout
Material in this manual divide into several parts:
• Chapter 1 : Welcome To BioWin
• Chapter 2 : Help, Tutorials and Examples
• Chapter 3 : General Operation
• Chapter 4 : Building Configurations
• Chapter 5 : Running Simulations
• Chapter 6 : Data Output
• Chapter 7 : Model Reference
• Chapter 8 : Power in BioWin
• Chapter 9 : Operating Costs in BioWin

Typefaces and conventions used in this manual

The following typefaces and conventions will be used throughout this manual when describing various
procedures and techniques in BioWin:

Typeface Refers To

Example Text Italic text refers to chapter titles.

Example Text Bold text in Arial font is used when

describing objects and controls in

Biowin 6 Help Manual Help, Tutorials and Examples • 13

 dialog boxes, as well as the dialog
box names. When you see text in
this typeface used in the
description of a dialog, that text
will be on the dialog box.

How To Print The Manual

The BioWin manual is shipped in the form of one complete Adobe PDF. The content of this document is
identical to BioWin's online help – the help was built using the manual document as its source

Note: you also may print out individual topics from within the online help system). If you wish, you may
install this document to your computer and print it out as you desire. However, if you wish to save disk
space, you may choose to leave it on the CD, where it is located within the MANUAL directory.

BioWin Tutorials

Learning Objectives
This set of tutorials and case studies is designed as a training exercise in the application of BioWin. The
primary objective is to provide "how to…" training on using the BioWin software itself. The case studies are
not intended as a course in wastewater treatment process engineering. Nevertheless, several of the case
studies focus on process applications and identify interesting design and operating issues.
Start off with Tutorial #1. This explains the basic concepts for applying BioWin and provides an overview of
features. You will be viewing a previously created file from the installation Data directory (a standard path
would be similar to: C:\Program Files\EnviroSim\BioWin x.x\Data where x.x is the version number). The
remaining tutorials all involve setting up new systems. Each tutorial is broken up into a number of
subsections.
The tutorial examples ask you to save files with the name format My Tutorial XX in the Tutorials
subdirectory of the Data directory. Completed tutorial configurations are also stored in that directory for
reference as Tutorial XX.

Suggestion: Keep this Help file open and follow each tutorial step-by-step, switching back and forth to
BioWin. Alternatively, print a copy of the Tutorials (for printing instructions see How to Print the Manual.)

TUTORIAL 1 - BioWin Familiarization

This familiarization tutorial demonstrates a number of the features in BioWin. Aspects covered in this
tutorial include the basic BioWin interface, loading a BioWin configuration file, specifying data for
configuration elements, and running steady state and dynamic simulations.

14 • Help, Tutorials and Examples Biowin 6 Help Manual

The interface and loading a file
Start BioWin and view the main simulator window. All simulation tasks are executed from here. The
interface consists of menus, toolbars, the drawing board, summary panes and a status bar. For a detailed
description, view the Main Simulator Window section of the “General Operation” chapter. In this tutorial
you will only get a brief overview.
1. From the File menu, click on Open and load the An Example.bwc configuration file from the
DATA directory. The screen view will be similar to that shown below.

The example configuration

2. Move the cursor over the toolbar. A fly-by hint appears when you pause over a button.
3. A status bar at the bottom of the window displays various pieces of information.

4. Move the arrow cursor across the drawing board. The cursor changes to a hand ( ) as you cross
over elements on the drawing board. When you pause over an element, information on that
element appears in the two panes below the drawing board – physical data in the left pane and
performance data in the right pane. This function allows you to get a summary overview of system
information.
5. Move the cursor over an element and click the right mouse button. A local menu appears. [Don’t
select any options yet!]. This will allow you to access various options for that element (see below).

Hint: As a general rule when using BioWin, clicking the right mouse button often helps!

Physical and operational data

1. Move the cursor over the Aerobic element (a completely mixed aerated bioreactor) and double
click – or click the right mouse button on the element and select the Properties command. A
tabbed editing dialog box opens (see below). These tabs contain all the physical and operational
data for the element. View the information on the Dimensions and Operation tabs. [Do not

Biowin 6 Help Manual Help, Tutorials and Examples • 15

 change any information yet. We will accept the sizing of this aerated zone with DO controlled at a
setpoint of 2 mg/L].

The Bioreactor Dimensions tab

The Bioreactor Operation tab

16 • Help, Tutorials and Examples Biowin 6 Help Manual

 2. Now try double-clicking on other elements and view the details for this configuration.
3. Click on an element and keep the left mouse button depressed. You can drag and drop the element
in a new position and re-arrange the configuration to your liking.

Hint: Try right-clicking on the arrowhead of a pipe, and view the Properties. There are a number of
options for re-arranging the pipe layout.

Checking influent data

1. Double click on the different Influent elements and click on the Edit data button. At this stage we
won’t change any data.

Hint: When viewing influent data, point the cursor at a column heading and click the right mouse button.
There are many options for entering and manipulating data.

2. Close the dialog.

Hint: The pane at the lower right displays the flow-weighted average influent concentrations.

Viewing information and simulation results

The panes below the drawing board provide a limited overview of system information. Comprehensive
information can be viewed in two ways – via the Explorer or in the Album.
1. Select Explorer from the View menu – or click on the Explorer toolbar button ( )– or press Ctrl
+ E. This opens the Explorer - a tree-like view of system information.
2. Experiment with expanding different levels. Hint: Try double clicking on an element name or the
parameters item in the right panel.
3. Select Album ( ) from the View menu – or click on the Album toolbar button – or press Ctrl + A.
This opens the Album, which contains user-customized information in the form of custom tables,
pre-formatted element information, and charts. The Album can contain many individual pages of
information.
4. Click on the page name tabs along the bottom and view the different examples. Hint: Try clicking
the right mouse button on different parts of the Album pages (including the name tabs at the
bottom).
5. Select Add page from the Album menu (or click the Add page button on the toolbar at the
bottom of the Album – point to the buttons to get fly-by hints on what each does), and choose one
of the layout options. After adding a page, click the right mouse button on a blank panel and
experiment! Expect to encounter difficulties at this stage – subsequent tutorials will provide detailed
instructions.

Running a steady state simulation

Steady state simulations provide a solution for the system based on the flow-weighted average influent
loading to the system (and the time-weighted average for any timed operational changes such as a schedule
of DO setpoints in an aerated reactor).

Biowin 6 Help Manual Help, Tutorials and Examples • 17

 1. Select the Steady state command in the Simulate menu – or click on the Steady State button
on the toolbar. This opens the simulator player dialog. Hint: If you re-position the simulator player
dialog at a convenient spot on the screen that’s where it will appear next time.
2. Click on the play button. A dialog box appears when BioWin has found the solution.

The steady state solver dialog box

Note: Most steady state solutions are found in ten or so iterations. In unusual circumstances the solver may
“stick” – that is, the error value does not change from iteration to iteration. In this situation click on the stop
button. Often this indicates a difficulty with the influent data such as a nutrient deficiency (or an Alkalinity
deficiency in an aerobic digester, perhaps). Alternatively, you may have a “difficult-to-solve” system. One
trick is to try conservative solver settings. To do this, select the menu command Project|Current Project
Options…, click the Numerical parameters tab, and click the Options… button in the Steady State Solver
group. At the bottom of the resulting dialog box there is a large button that you can click to set conservative
solver parameters (see Steady State Solver Options in the “General Operation” chapter).

Running a dynamic simulation

Dynamic simulations show the time-varying system response based on the time-varying influent loading to
the system (and subject to any time-varying operational changes such as a schedule of DO setpoints in an
aerated reactor).
1. Select the Dynamic simulation command in the Simulate menu – or click on the Dynamic Simulation
button ( ) on the toolbar. This opens the simulator player dialog.
2. Click on the play button. This brings up a dialog box where you can set various options such as the
duration of the simulation. Clicking on the Start button starts the dynamic simulation.

The dynamic simulator control dialog box

18 • Help, Tutorials and Examples Biowin 6 Help Manual

 The dynamic simulation options dialog box

Note: Even if you are only interested in dynamic system response, it is useful to first calculate the steady
state solution, and then start the dynamic simulation from these “Current values” or the “Last steady state”.

Note: In the Album a time-series chart set up for 24 hours may appear blank or may not reflect a change you
expected to see. Perhaps you need to change the scale on the bottom axis depending on what you specified
as the starting date for the simulation.

Keeping track of things and generating reports

The project note editor, shown in the picture below, is a tool that may be used to record information
relevant to the current project. You can access the editor via the menu command Project|Notes or by
clicking on the Notes button ( ) on the Main toolbar. The notes that you make can have formatting applied
to them according to the Rich Text Format (*.RTF). These notes are saved internally with the BioWin file, so
they go wherever the BioWin file goes. [In pre-BioWin 4.1 versions, the notes are saved in a separate “*.nts”
file.] This feature is very useful for capturing information about the simulation, and since it is saved
internally in the BioWin “bwc” file, any BioWin user who accesses the BioWin file will be able to see them.
Another enhancement (BioWin 4.1.1 and later) is that the notes can contain pictures in the form of image
files (e.g. PNG, JPEG, EMF). You can right-click on charts and tables in the BioWin album, copy them to the
clipboard, and then paste them to the new enriched notes editor to discuss them. When another BioWin
user opens your BioWin file containing the notes, the notes editor automatically opens so that they are sure
to see the discussion.

Biowin 6 Help Manual Help, Tutorials and Examples • 19

The project notes editor

It also is very easy to get results from BioWin into your word processor, spreadsheet or other applications.
Charts, tables, the drawing board view of the system layout, etc. can be copied from BioWin and pasted to
your report. Tables can be exported as tabbed text and then quickly converted to tables. The File|Report to
Excel™ command generates an Excel spreadsheet containing data, tables and charts from your BioWin
simulation customized using preconfigured Excel templates. The File|Report to Word™ command generates
a customizable Word document that contains a screenshot of the BioWin flowsheet, tables summarizing all
model element dimensions and operating parameters, and the content of the Album (charts are pasted in as
enhanced metafiles for easy transfer between Office applications; tables are pasted as Word tables).

How to Customize BioWin

There are a number of parts and features of BioWin that can be customized to look how you want. When
you customize BioWin, you essentially are changing the default settings of the BioWin work environment

20 • Help, Tutorials and Examples Biowin 6 Help Manual

and all new projects that are created therein. This functionality is accessed via the Project|New Project
Options… or the Tools|Customize… menu commands. A detailed description of the features is provided in
the Customizing BioWin section of the “General Operation” chapter.

Many facets of BioWin may be customized to suit your needs

The Tools|Customize… command defines your “default” setup for when you start a new project; for
example, you may always want to start with US units. You can override these preferences for the current
project through the Project|Current Project Options… command.
Since project options are file specific, they “travel” with that file. For example, if you define a set of project
options for “Project A” on your copy of BioWin and then open the “Project A” file in someone else’s copy of
BioWin, you still will see your defined project options. As before, these project options will override any
similar settings that the owner of the other copy of BioWin has set as defaults using the Tools|Customize…
command. For more information on the various project options that may be set, please see the Managing
BioWin Projects section of the “General Operation” chapter.

TUTORIAL 2A - Building a Configuration

This tutorial demonstrates how to build a new configuration and add tables to the Album. Aspects covered
in this tutorial include building a BioWin configuration, moving and connecting elements on the drawing
board, specifying data for elements, changing model parameter values, and setting up tables to record your
simulation data.

Biowin 6 Help Manual Help, Tutorials and Examples • 21

The tutorial 2A system
A city in the U.S.A. has a nitrification/denitrification system – a Modified Ludzack Ettinger configuration.
Phosphorus removal is achieved in a tertiary chemical precipitation system. The client experiences problems
in the tertiary system. You want to investigate achieving P removal biologically in the existing tankage. The
system has the following characteristics:

Unaerated reactors: Four (each 1 MG) Depth = 12 ft

Aerated reactors: Two (each 7.5 MG) Depth = 12 ft DO = 2 mg/L
Clarifier (Ideal): Area = 123,000 ft2 Depth = 14 ft
Influent: Average Flow = 88 MGD
COD = 246 mg/L TKN = 24 mgN/L
TP = 5.4 mgP/L ISS = 15 mg/L
Alkalinity = 6 mmol/L
Wastewater fBS = 0.12 fUP = 0.10
fractions:
fUS = 0.07 fNA = 0.75
RAS recycle: 44 MGD (50%)
NML recycle: 264 MGD (300%)
Wastage rate: 1 MGD (constant rate)
Temperature: 18°C
Nitrification rate: 0.8 /d

22 • Help, Tutorials and Examples Biowin 6 Help Manual

The Tutorial 2A system configuration

Adding elements to the drawing board

Note: When building the configuration, do not interchange mixers with splitters or influents with effluents.

Note: In this tutorial we are using an ideal secondary settler. Tutorial 1 used a model settler.

1. Run BioWin and change to US units via the Project|Current Project Options… command.
2. Add each of the units shown in the screen view above. [We will connect units with pipes later].
Repeat the following three steps as you build the system in the drawing board:·
• Click the button corresponding to the element you want on the configuration toolbar.

• Move the cursor ( ) onto the drawing board. When you do this, the cursor will change to
the element placement cursor. Click on the drawing board where you want the element to be
placed.
3. Change the names of the elements from the defaults to those shown in the screen view above (i.e.
Influent, Zone #1, Zone #2, Zone #3, Zone #4, Aerobic #1, Aerobic #2, Settler, Effluent, Wastage).
Right-click on each element and select the Name… command from the popup menu.

Biowin 6 Help Manual Help, Tutorials and Examples • 23

Note: No names appear for the mixers, splitters and the settler in the screen view above. This is one of the
customizable features of BioWin. You can make your own selection from the General tab via the
Tools|Customize command.

Note: Your configuration may extend beyond the visible drawing board view. You may wish to change the
drawing board scale from the drop-down list on the Main toolbar.

Note: This configuration includes mixers for the RAS stream and mixed liquor recycle in front of the first
bioreactor. It is not necessary to include these mixers – the streams could be connected directly to the front
of the bioreactor. However, it provides you with a means to look at the combined influent to the first
reactor.

Selecting Multiple Elements on the Drawing Board

To select multiple elements by dragging with the mouse:
1. Click on the element selection tool ( ) from the Configure toolbar.
2. Position the cursor above and to the left of the group of elements on the drawing board you wish to
select.
3. Hold the mouse button and drag the cursor to a position below and to the right of the group of
elements you wish to select. A box will appear around the selected elements.
4. Release the mouse button.
5. Note: the selection box can also be initiated from the top-right, bottom-left or bottom-right corners
around the group of elements to be selected on the drawing board.
To select multiple elements by clicking with the mouse, hold either the Shift or Ctrl key and click on each
element of the group you wish to select.

Rearranging and moving elements on the drawing board

If you want to change an element's position:
1. Click on the element selection tool ( ) from the Configure toolbar (or simply press the ESC button).
2. Move the cursor over the element on the drawing board you wish to move.
3. Click on the element and while holding down the mouse button, drag the element to the desired
new location.
4. Alternatively, for a more precise placement, click on the element to select it, then press the
up/down/left/right arrow buttons to move it a very small distance with each press of the arrow
button.
5. Alternatively, to move the element a set distance, click on the element to select it, then while
holding the fn button, press the up/down/left/right arrow button.

24 • Help, Tutorials and Examples Biowin 6 Help Manual

 6. To align the edges of selected elements, first select the “pivot” element to which the other elements
will be aligned. Then, holding the Ctrl key, select the other elements to be aligned to the “pivot”

element. On the Flowsheet tools toolbar, click the button to align left edges of selected units

or the button to align top edges of selected units.

7. To space units equally between leftmost and rightmost units or topmost and bottommost units,

select the group of elements to be moved and then, on the Flowsheet tools toolbar, click the

button to space units equally between the leftmost and rightmost units or the button to space
units equally between the topmost and bottommost units.

Note: You also can move multiple elements simultaneously. Select the group of elements you wish to move,
and then follow step 3, 4 or 5.

If you want to change the vertical or horizontal orientation of one or multiple elements:
1. Click on the element selection tool ( ) from the Configure toolbar.

2. Select the element(s) to be reoriented and then, on the Flowsheet tools toolbar, click the

button to visually switch the horizontal direction of flow for the selected elements or the
button to visually switch the vertical direction of flow for the selected elements.
3. It is also possible to reorient a single element. Right-click the element, and from the resulting popup
menu, choose Flip horizontal or Flip vertical (the latter option only is available for elements such as
splitters and mixers).

Connecting elements with pipes

1. Click the ( ) on the Configure toolbar.
2. When you move the cursor onto the drawing board, the cursor will change to the "start" cursor (
).
3. Place the cursor over the element area where you wish the pipe to start from.

4. If the location is appropriate, a set of crosshairs will appear on the "pipe start" cursor ( ).

5. If the location is inappropriate, the cursor will change to a circle with a slash through it ( ) to
indicate that a pipe may not begin at that location.
6. Click the left mouse button once and move the cursor to the desired location of the element where
you wish the pipe to end and click the left mouse button again.

Biowin 6 Help Manual Help, Tutorials and Examples • 25

 7. As you move the pipe towards the element where you wish it to end, the cursor will change to the
"pipe end" cursor ( ).
8. If the location of the pipe terminus is appropriate, this cursor will remain.

9. If the location is inappropriate, the cursor will change to a circle with a slash through it ( ) to
indicate that a pipe may not end at that location.
Repeat steps 3-9 until you have connected all your elements with pipes.

Note: To re-arrange a pipe’s position, click once on the arrow head of that pipe. A series of circles appear at
points along the pipe. Try dragging-and-dropping. This is important for arranging the configuration layout.

Note: Try right clicking on the arrow head of a pipe, and view the Properties. There are a number of options
for re-arranging the pipe layout and selecting pipe style.

Note: To copy a pipe’s attributes (style, line and color) to other pipe(s), select the reference pipe with the

attributes you wish to copy. Then on the Flowsheet tools toolbar, click the button to copy the only

the pipe line and color attributes or the button to copy the pipe style, line and color attributes. The
image of the selected button now appears beside the cursor arrow. Click on the pipe(s) that you wish to
have the same attributes as the reference pipe.

Specifying physical and operational data

We now wish to enter all of the physical and operational data for this system specified earlier. Each element
(except influents and effluents) requires physical data, and this is specified in terms of either Volume/Depth
or Area/Depth. Operational data depends on the type of element. For example, units such as bioreactors
require information on aeration and DO levels. Units such as splitters and settlers also require information
on the flow split in the side stream or underflow.

Note: There are many options for specifying operational data for the units in BioWin. We only touch on a
few options in this tutorial. More complete information on the different options for each unit type is
provided in the Element Descriptions section of the “Building Configurations” chapter.

To specify data for each element (leave the influent for now):
1. Double click on the element – or click the right mouse button and select the Properties command.
Specify data from the information listed earlier.
2. For the influent element specify the type as Constant. In this tutorial we only consider steady state
performance.

26 • Help, Tutorials and Examples Biowin 6 Help Manual

 3. When you are finished use the File|Save As… command – or click on the Save button ( ) on the
toolbar - to save the configuration as My Tutorial 2.bwc in BioWin’s Data/Tutorials directory (a
standard path would be:
C:\Program Files\EnviroSim\BioWin x.x\Data\Tutorial where x.x is the version number).

Note: Mixers and splitters can be defined as "dimensionless"; that is, nodes without volume. This is
preferable to using very small volumes compared to other process units in the configuration because small
volumes may result in slow dynamic simulations.

Specifying process temperature(s)

Specify the global temperature for the system (18°C) via the Project|Plant|Liquid temperature… menu.

Note: You can specify a local temperature for many of the units. For example, view the Operation tab in the
bioreactor dialog. This is not necessary in this example, but can be useful for special situations, e.g.
simulating treatment of a high-temperature sidestream.

Changing model parameters

In this example we must specify a maximum Ammonia Oxidizing Biomass (AOB) growth rate (referenced to
20°C) of 0.80 /day. All model parameters for the project are viewed/changed via the Project|Parameters…
command. In this case we want to go to the Kinetic… menu and change the “Max. spec. growth rate” on the
AOB tab from the default of 0.90 to 0.80 /day.

Note: Although not necessary in this example, you can specify local model parameters for many of the units.
For example, view the Model tab in the bioreactor dialog and note the check box labeled Local kinetic
parameters.

Checking that all data have been specified

Before running a simulation BioWin must check to see that data have been specified for each of the
elements.
Select the Check simulate data command from the Simulate menu – or click on the Check data button on
the toolbar. A dialog box appears with a list of elements for which data have not been specified and/or
elements without pipe connections.

Note: Do not worry if you forget the check. BioWin will remind you about missing data. It may seem
unnecessary to check data for elements (such as mixers) where you generally will accept the default values.
However, this makes sure all input data is checked and only is required once.

Adding tables to the Album

You have now completed setting up the configuration. [Remember: You have yet to run a simulation so data
values will be nonsensical]. We now want to add data tables to the Album. Let us set up a table similar to
that shown below on Page 1 of the Album. This table has rows for influent, all bioreactors, effluent and
wastage, and columns for concentrations and mass rates for NH3-N, NO3-N, PO4-P, ISS, flow, VSS, and TSS.

Biowin 6 Help Manual Help, Tutorials and Examples • 27

Table from the tutorial configuration

1. Select Album from the View menu – or click on the Album toolbar button ( ) – or press Ctrl + A.
This opens the Album – it’s blank for now.
2. Select Add Page from the Album menu and click OK.
3. Right-click on the album page.
4. Select Table from the popup menu.

Dialog box used for choosing elements to include in your table

5. The Table editor dialog will open.

28 • Help, Tutorials and Examples Biowin 6 Help Manual

 6. From the Elements tree view, select the element(s) that you wish to include in the table.
• You can expand individual element groups, select specific elements, click on them and push the
right-pointing arrow to move them to the Selected elements list; or move entire element groups
over at once by clicking on the element group (e.g. Bioreactor) and clicking the right-pointing
arrow.
• Note that if the element you have selected has multiple outputs (e.g. a secondary clarifier), all
outputs are added to the Selected elements list by default. If you do not want one of the
outputs (e.g. the underflow of a secondary clarifier), simply click on the entry in the Selected
elements list and press the Delete key on your keyboard.
• If you want to change the order in which the Selected elements will appear in the plot, move
the elements around by clicking on them and clicking the up/down arrows. You can change the
order of a group of elements, by using the Ctrl or Shift key to select the group and then clicking
the up or down arrow. Finally, you can move a selection directly to the top or bottom of the list
by holding the Ctrl key while you click the up or down arrow.
7. Choose a variable to plot from the Element specific, Water Chemistry, State variables, or Combined
lists. If you want to add more than one variable from a given group, you may do so: To select a
contiguous group, click the first variable of the group, and while holding the Shift key, click the last
variable of the group. To select non-contiguous variables, hold the Ctrl key and click the desired
variables in succession. You may also simultaneously select variables from multiple lists.
8. Once you have selected the parameters you want to plot, move them to the Selected variables list
by clicking the right-pointing arrow.
• If you want to change the order in which the Selected variables will appear in the table, move
the variables up or down around by clicking on them and clicking the up/down arrows. You can
change the order of a group of variables, by using the Ctrl or Shift key to select the group and
then clicking the up or down arrow. Finally, you can move a selection directly to the top or
bottom of the list by holding the Ctrl key while you click the up or down arrow.
9. If you wish to re-add certain variables, place a check in the box labeled Duplicates, and re-add the
compounds.
10. Select whether you want to display Concentrations, Mass rates, or Both in your table.
11. If you want to add a blank line between table entries, click the Add blank line button. The blank line
will show as a short dashed line in the Selected elements list. The blank line can be moved up or
down in the list just like other elements. Multiple lines may be added to the list.
12. If you want BioWin to display the total of a table’s columns, click the Add total so far button. The
word “Total” will be added to the Selected elements list. The Total can be moved up or down in the
list just like other elements. Multiple totals may be added to the list; if a total will always totalize the
rows preceding it.
13. Click OK to finish.

Note: You can change the order of rows and columns in the table very easily. Right-click on the table, select
the Edit table command, and use the Up/Down arrows.

Biowin 6 Help Manual Help, Tutorials and Examples • 29

Note: Try clicking the right mouse button on different parts of the Album pages (including the name tabs at
the bottom – you can change the name of your tab to “Table” from “Page 1” if you wish).

Note: Moving the cursor over elements on the drawing board gives you a sneak preview of data in the panes
below the drawing board.

Adding element information to the Album

The previous section showed how to set up a table in the Album. You can also add pre-formatted element-
specific information to the Album. Let us add information on the last aerated bioreactor (Aerobic #2) to Page
2 and for the settler to a new page of the Album.
We will do this by two different methods.
1. Select Album from the View menu – or click on the Album toolbar button ( ) – or press Ctrl + A.
2. Select Add Page from the Album menu and click OK.
3. Right-click on the album page.
4. Select Element info from the popup menu.
5. Select Aerobic #2 from the drop-down element list, and click on the Summary view radio button.
We will add a similar table to the Album for the settler, but using a different method.
6. Close the Album, and move the cursor over the settler in the drawing board.
7. Right-click and select the Add to album|Element info (Summary) command.
8. Select Album from the View menu – or click on the Album toolbar button ( ) – or press Ctrl + A.
The new table should appear on a new Album page.

Note: Summary tables differ depending on the type of element. For example, we see an overflow rate for
the settler summary and an OUR for a bioreactor. For more detailed instructions review the section on
Album Element Information Displays in the "Data Output" chapter.

TUTORIAL 2B - A Nutrient Removal Refresher

This tutorial demonstrates application of BioWin to the system set up in Tutorial 2A. Aspects covered in this
tutorial include phosphorus removal in an anaerobic selector, high-rate P removal systems, and high
nitrification rate/high temperature conditions.

Anaerobic selector modification (including P removal)

1. If you have restarted BioWin open the file Tutorial 2 using the File|Open command – or click on the
Open button ( ) on the toolbar.
2. We will record results in the table below:

30 • Help, Tutorials and Examples Biowin 6 Help Manual

 Temp Nit. Rate NML SRT Effluent Effluent Effluent
Recycle Ammonia Nitrate PO4-P

3. Run the steady state simulation. Tabulate the results, and note the nitrification, denitrification and P
removal performance.
4. You also need to record the SRT. Click on the Project|Plant|Active SRT command – or click on the
Active SRT button on the toolbar. You can give this SRT a name if you like (to distinguish it in case
you want to look at other SRT “scenarios”, e.g. a case where the sludge mass in the settler is
included in the SRT calculation). From the Select elements for total mass button, add all of the
bioreactors. Click the Select wastage elements button, expand the Sludge tree, and select the
Wastage element. If you were successful in finding a steady state solution in the previous steps, the
SRT will now appear on the status bar at the bottom of the screen.
5. Discuss possible retrofit options to achieve biological P removal in the existing tankage.
6. Try incrementally reducing the nitrified mixed liquor recycle rate (continue until this flow has been
reduced to zero).

Note: In specifying the wastage element(s) for the SRT calculation we selected the Wastage sludge output
element. We could also have selected the side stream (S) of the splitter where the waste stream is
withdrawn. However, do not select both elements as this would count the wastage twice!

Note: We are calculating SRT only based on the mass of sludge in the bioreactors. We could include the
sludge in the clarifier.

Note: If we include the secondary effluent in the SRT calculation we would be accounting for solids lost via
that stream.

High Rate P Removal System

1. Now we wish to modify the system to attain P removal without nitrification (with the mixed liquor
recycle set to zero). To do this we increase the wastage rate to reduce SRT and wash out of the
nitrifiers. BioWin provides a convenient way to set the SRT to a specific value, and calculate the
required wastage rate.

Biowin 6 Help Manual Help, Tutorials and Examples • 31

 2. Click on the Project|Plant|Active SRT command – or click on the SRT button ( ) on the toolbar.
Place a check in the Control SRT box – new options appear in the lower part of the dialog.
3. Select WAS splitter from the pull-down list, and specify the last SRT from your table. Re-run the
steady state simulation, and check that the wastage rate is 1 MGD.
4. Re-run for an SRT of 5 days, and tabulate the results. Reduce the SRT further to 4 days. Have we
washed out the nitrifiers?

High Nitrification Rate / High Temperature Conditions

Now we encounter an unusually high temperature summer. What if the nitrification rate is high?
1. Change the maximum AOB growth rate from the value of 0.8 to 1.0/d (Max. spec. growth rate on
the AOB tab).
2. Change the temperature to 24°C.
3. Repeat the simulation for an SRT of 4 days and see if the nitrifiers still wash out.
4. Decrease the SRT further to 3 days, and repeat. Is the P removal performance good?

32 • Help, Tutorials and Examples Biowin 6 Help Manual

TUTORIAL 3 - Nitrification Dynamics and Setting up Charts
This tutorial demonstrates dynamic simulations and a comparison of nitrification performance in a plug flow
versus a completely mixed reactor configuration. We will learn how to set up charts in the Album.

The tutorial 3 system and the influent data

For this demonstration we will split the influent flow (actual field data) equally between two parallel trains
as shown in the BioWin screen view below. The system has the following characteristics:

PFR reactors: Four (each 1.2 ML) Depth = 4.5 m DO = 2 mg/L

CSTR reactor: One (4.8 ML) Depth = 4.5 m DO = 2 mg/L

Clarifier (Ideal): Each Area = 1,000 m2 Depth = 4.8 m
Influent: Accept default wastewater characteristics
RAS recycle: Each 7.5 ML/d (50%)
Wastage rate: Each 0.2 ML/d (constant rate)

Temperature: 20°C
Nitrification rate: 0.9 /d

The Tutorial 3 system configuration layout

Biowin 6 Help Manual Help, Tutorials and Examples • 33

The following diurnal influent loading pattern for flow, COD, TKN, TP and ISS has been established. The
BioWin default values should be used for the remaining input variables.

Time Flow (ML/d) COD (mg/L) TKN (mg/L) TP (mg/L) ISS (mg/L)

0 29.8 437 28.7 5.0 17

2 20.4 401 29.2 5.3 12
4 14.4 333 29.7 5.1 13
6 14.3 341 29.8 4.8 8
8 23.9 260 24.1 3.7 9
10 37.6 279 33.5 4.7 16
12 41.9 402 42.9 7.0 25
14 40.5 383 40.5 6.9 27
16 35.0 419 36.2 6.5 25
18 32.6 411 31.8 5.9 18
20 32.7 364 27.8 4.8 22
22 34.0 406 26.2 4.4 21

Set up the configuration and influent data

1. Select a unit basis of ML and ML/d.
2. Create the configuration shown above and set up all of the physical and operational data.
3. Double click on the influent element, click on the Edit data button, and enter the time-varying
influent data recorded in the table above.

Hint: To save on typing all those numbers, load the influent file “Dynamic Influent.ifd” from the
Data|Tutorials directory containing the table above.

4. Save the file as My Tutorial 3.bwc in the Data/Tutorials directory.

5. Note the AOB Max. spec. growth rate from the Project|Parameters|Kinetic… menu on the AOB tab.

Note: In this system we do not include mixers for the influent and RAS streams. Both streams are connected
directly to the front-end reactors in each train.

Steady State Performance

1. Run the steady state simulation.
2. Open the Album and add a new page with two horizontal panes using the Album|Add page
command.

34 • Help, Tutorials and Examples Biowin 6 Help Manual

 3. In the upper pane, set up a table that shows flow rate, NH3-N, NO3-N, VSS, and TSS for the upper
section (plug flow part) of the plant; that is, in each reactor and in the effluent.
4. Create a similar table in the lower pane, but for the lower section (completely mixed).
5. Re-run the steady state simulation, and discuss the results.
6. The tables on Page 7 (note that your page number may be different if you have started with a blank
album) should be similar to that shown below.

Your results after running a steady state

Setting up charts
There are many options for creating different types of charts in BioWin. This tutorial will only show a few
examples and a limited number of formatting options. These will be the ammonia and oxygen utilization
rate responses in the system. More example charts are included in the An Example.bwc file. For details on
charting options refer to the sections:
1. "Creating Charts & Adding Series"
2. "Chart Formatting Procedures"
3. "Series Formatting Procedures"

Note: The default chart template can be customized under Tools|Chart master.

Create a Time series chart

In this section we set up a time series chart showing the ammonia concentration response in the completely
mixed reactor, Cell CSTR, and in the effluent from this train.
1. Open the Album and use the Album|Add page command to add a page
2. Right click on the blank pane, and select the Chart command.
3. On the Time Series tab, navigate to the Elements list. Expand the Bioreactor group, select Cell CSTR,
and click the right-pointing arrow to move it to the Selected elements list. Expand the Effluent
group, select Effluent CSTR, and click the right-pointing arrow to move it to the Selected elements
list.
4. In the State variables list, locate Ammonia (or NH3-N if you are using short-form naming) and
double-click it (or push the right-pointing arrow) to move it to the Selected variables list.

Biowin 6 Help Manual Help, Tutorials and Examples • 35

 5. Check that the Fast Line option is showing to the left of the Plot selected button; if not, click the
option showing and select Fast Line from the Time series gallery. Click the Plot selected button.
6. Click the Close button in the Add Series dialog box.
7. On Page 2 (once again, your page numbering may be different – this is not a concern) of the Album
set up a time series chart comparing the effluent ammonia concentrations for each of the two
trains.

Note: No lines appear in the chart yet. You must first run a dynamic simulation (see below).

Note: Setting up charts automatically adds the plotted items to the database.

Create a Time series chart with many series

In the last charting example, we added two series simultaneously to a chart. We can add many at a time if
we want! In this section we set up a time series chart showing the ammonia concentration response in each
of the reactors in the plug flow train, Cells #1 to #4.
1. Open the Album and use the Album|Add page command to add a page
2. Right click on the blank pane and select the Chart command.
3. On the Time Series tab, navigate to the Elements list. Expand the Bioreactor group, select Cell #1,
and click the right-pointing arrow to move it to the Selected elements list. Repeat this for the #2, #3,
and #4 cells. Alternatively, you can click on the top level of the Bioreactor group (i.e. on the word
“Bioreactor”), push ALL of the bioreactors to the Selected elements list, and then delete the one
that we do not want (i.e. Cell CSTR) by clicking on it and pressing the Delete key on your keyboard.
4. In the State variables list, locate Ammonia (or NH3-N if you are using short-form naming) and
double-click it (or push the right-pointing arrow) to move it to the Selected variables list.
5. Check that the Fast Line option is showing to the left of the Plot selected button; if not, click the
option showing and select Fast Line from the Time series gallery. Click the Plot selected button.
6. Click the Close button in the Add Series dialog box.

Current value chart

1. In this section we set up a current value chart showing the nitrate concentration in each of the
reactors in the plug flow train, Cells #1 to #4. A current value chart can be presented as an area, bar
or pie plot.
2. Open the Album and use the Album|Add page command to add a page
3. Right click on the blank pane and select the Chart command.
4. Select the Current value tab.
5. Expand the tree in the Elements list and move the four bioreactor cells to the right Selected
elements list.
6. Double-click Nitrate N (or NO3-N if you are using short names) in the State variables list.

36 • Help, Tutorials and Examples Biowin 6 Help Manual

 7. Check that the Bar series option is showing to the left of the Plot selected button; if not, click the
option showing and select Bar from the Time series gallery. Click the Plot selected button...
8. Click the Close button in the Add Series dialog box.

Note: Current value charts also can be used to plot mass rates.

Your own time series charts

Try setting up two time series charts (line plots) on one page in the Album.
1. Open the Album and use the Album|Add page command to add a page. Select the layout with two
horizontal panes.
2. In the upper pane set up a time series chart for the Total oxygen uptake rate (OUR) response in the
four-in-series reactor plug flow train.
3. In the lower pane set up a time series chart for the OUR (total) response in the single reactor
completely mixed train.

Dynamic simulations
1. From the main simulator window, set the dynamic simulation running for 1 day either from the
Simulate|Dynamic simulation menu command or by clicking on the Dynamic simulation toolbar
button ( ). After pressing the start button select the Simulate from project start date and Current
values options, and a simulation time of 1 day.
2. When the dynamic simulation is complete press the stop button in the player dialog.

Note: You can switch to the Album while the simulation runs.

3. View the simulation results in the Album.

4. Continue the simulation for another 4 days. Set the dynamic simulation running from the
Simulate/Dynamic simulation menu command or by clicking on the Dynamic simulation toolbar
button. After pressing the start button select the Continue from and Current values options and set
the simulation time to 4 days.
5. Open the Album while the simulation runs (Ctrl+A).
6. When the dynamic simulation is complete press the stop button in the player dialog.
7. View the results in the Album and think of options for reducing "break-through" of ammonia.
8. Re-run the steady state simulation and then run the dynamic simulation for 2 days using the
Simulate from project start date option. When the simulation is paused at 2 days, double click on
each wastage splitter in the drawing board and reduce each wastage rate from 0.2 to 0.1 ML/d.
Press the start button and continue the dynamic simulation for 8 days.

Hint: Try starting a dynamic simulation by pressing the F7 key when the Album is open or clicking on the
Dynamic simulation button on the Album toolbar located beneath the Album tabs.

Biowin 6 Help Manual Help, Tutorials and Examples • 37

Editing the charts
In setting up the charts you accepted many default charting options. For example, automatic scaling of axes,
the increments on axes, the grid appearance, the color selection, the legend format, the chart titles, etc. The
options are too numerous to list here.
Experiment with the many chart options. Start by right clicking on a chart and selecting the various
commands.

Note: Move the dialog box to one side of the chart. That way you will see the changes happen immediately
without having to close the dialog.

38 • Help, Tutorials and Examples Biowin 6 Help Manual

TUTORIAL 4 – Secondary Clarifier Simulation
This tutorial demonstrates aspects of modeling secondary clarifier performance with the one-dimensional
settler model. Aspects covered in this tutorial include model settler behavior under steady state and
dynamic conditions.

The tutorial 4 system

For the demonstration we set up a simple one-reactor system with a model settler as shown in the BioWin
screen view below. The system has the following characteristics:

Bioreactor: 30 ML Depth = 4.5 m DO = 2 mg/L

Clarifier (Model): Area = 4,000 m2 Depth = 4.0 m
RAS recycle: Initially 100 ML/d (100%)
Wastage rate: 6 ML/d (constant rate)

The Tutorial 4 system configuration

1. Change to SI units (ML and ML/d) and set up the system.

2. Double click on the influent element, click on the From file button, and load the file An Example.ifd
from the DATA directory.
3. Run a steady state simulation to check that you have specified all the necessary data.

Biowin 6 Help Manual Help, Tutorials and Examples • 39

 4. Use the File|Save As command to save the configuration as My Tutorial 4 in the Data/Tutorials
directory.

Note: In this example the wastage stream effectively is withdrawn from the bioreactor, not the underflow.
This is termed hydraulic SRT control. The reason for choosing this mode is that, irrespective of the underflow
rate and the underflow TSS, the reactor TSS concentration will remain relatively constant. By wasting mixed
liquor from the reactor we will maintain a relatively constant SRT even when the underflow rate changes. In
this case wasting 6 ML/d from a bioreactor volume of 30 ML translates into a 5 day SRT (but remember we
are not accounting for sludge in the settler in this SRT calculation).

Recording results and modifying the Album

1. Add a page to the Album with two vertical panes. Display the Element information (summary) for
the bioreactor and the model settler in the two panes.

Note: this step perhaps is not necessary – you will be able to get all the required information from the main
simulator window (TSS values, settler solids loading rate – SLR, settler specific overflow rate – SOR, etc.).

2. We will record simulation results in the table below. All of this information can be found either in
the two-pane page you added to the Album or by moving the cursor over elements in the drawing
board and noting values displayed in the lower right pane.

Underflow Max SLR SOR Effluent Reactor Underflow

Rate Compactability TSS TSS TSS

Setting up a settler profile in the Album

3. We want a view of the TSS concentration profile in the settler. Move the cursor over the settler in
the drawing board, right click, and select the Add to Album command. Select Profile Plot… from the
flyout menu. In the dialog highlight Total suspended solids in the right hand Combined list, select
Current values for the profile type, and the Concentration on X orientation option. Click on the Plot
selected button, select Line in the General series gallery, and close the dialog.
4. The preceding step generated a new plot in the Album. Open the Album – the new page should be
visible. In the plot, concentration is on the x-axis (as selected above), and settler height is on the y-
axis.

Note: In this case we are simulating the settler as 10 layers in the vertical direction – numbered from top to
bottom as 0 to 9.

40 • Help, Tutorials and Examples Biowin 6 Help Manual

 5. While we are editing the chart we should change the bottom axis (concentration) scale to have a
minimum and maximum of 0 mg/L and 15,000 mg/L, respectively. Right click on the chart and select
the Edit Axes command. For the bottom axis, in the Scales tab uncheck the Automatic box, and use
the Change… buttons to specify the Maximum and Minimum axis values. Press the Close button.

Setting up a State Point Chart

1. We want add a State Point Analysis (SPA) diagram in the Album. Move the cursor over the settler in
the drawing board, right click, and select the Add to Album command.
2. Select Chart… from the flyout menu.
3. If you are presented with the choice of adding the series to the current chart or creating a new
chart, click New. This will force the SPA chart to be plotted on its own tab.
4. In the dialog, select the State point tab. Check the box labeled Plot dynamic state point history. Do
not check the box beside Limit state point history, which means that there will be no limit on the
number of points plotted.
5. Press the Plot selected… button
6. The preceding step generated a new plot in the Album. Open the Album – the new page should be
visible. Edit the chart to improve the presentation. What state is the settler in according to flux
theory?

Note: The settling parameters used to generate the gravity flux curve are shown in red at the bottom of the
chart. If you change these parameters, the gravity flux curve will be updated on the fly.

Steady state simulations

1. Run a steady state simulation. Note the effluent and underflow TSS, and the SLR and SOR. View the
settler profile in the Album.
2. Change the underflow rate to 50 ML/d by double-clicking on the settler in the drawing board and
going to the Flow split tab. Repeat the steady state simulation and record the results.
3. Change the underflow rate to 33 ML/d by double-clicking on the settler in the drawing board and
going to the Flow split tab. Repeat the steady state simulation and record the results.

Dynamic Simulations
1. Add a page to the Album with two horizontal panes. In the upper pane set up a time series chart
(Fast Line style) for the settler surface overflow rate, SOR. Set minimum and maximum values on the
left axis of 0 and 20. In the lower pane set up a time series chart (Fast Line style) for the settler
solids loading rate, SLR. Set minimum and maximum values on the left axis of 0 and 200.

Note: Initially the charts will be blank because we have yet to run a dynamic simulation.

2. Add another page to the Album with two horizontal panes. In the upper pane set up a time series
chart (Fast Line style) for the effluent TSS. Set minimum and maximum values on the left axis of 0
and 30. In the lower pane set up a time series chart (Fast Line style) for the settler underflow TSS.
Set minimum and maximum values on the left axis of 0 and 16,000.

Biowin 6 Help Manual Help, Tutorials and Examples • 41

 3. Start a dynamic simulation for 2 days. Observe the predicted performance of the model settler in
the Album.

Hint: If you start the simulation from the BioWin main window the Album disappears. You can keep it open
while the simulation is running if you use the dynamic simulation button in the Album toolbar located below
the Album tabs, or press the F7 key to start the simulation.

4. When the simulation is paused change the RAS rate to 100 ML/d. Continue the simulation for
another 3 days.
5. When the simulation is paused change the RAS rate to flow-paced at 33% (based on the influent
flow). Continue the simulation for another 3 days.
6. From the Project|Parameters|Settling... menu, on the Modified Vesilind tab, change the maximum
sludge compactability to 8,000 mg/L. Continue the dynamic simulation for another 6 days. Watch
the settler profile and effluent TSS in the Album.
7. Try other situations with changes to the settler area/depth, and changes to the sludge settling
properties.

Note: Setting a low sludge compactability may cause problems with steady state simulations not converging.
This is a result of numerical solver problems because there can be multiple solutions to the mass balance
equations. In this situation, what you may wish to do in place of a steady state simulation is run a dynamic
simulation for an extended period of 3 - 4 SRTs. This should move to the steady state solution.

42 • Help, Tutorials and Examples Biowin 6 Help Manual

TUTORIAL 5 - Aeration System Simulation
This tutorial demonstrates diffused aeration system modeling.
Aspects covered in this tutorial include effects of changing oxygen parameters under steady state and
dynamic conditions.

The tutorial 5 system

For the demonstration we will split the influent flow equally between two parallel trains as shown in the
BioWin screen view below. The systems have the following characteristics:

Bioreactors: Each 25 ML Depth = 3.0 m DO = 2 mg/L

Clarifier (Ideal): Each Area = 2,000 m2 Depth = 4.0 m
RAS recycle: Each 50 ML/d (100%)
Wastage rate: Each 1.0 ML/d (constant rate)

The system used for Tutorial 5

1. Change to SI units (ML and ML/d) and set up the system.

2. In the influent element, load the file An Example.ifd from the DATA directory
3. Use the File|Save As command to save the configuration as My Tutorial 5 in the Data/Tutorials
directory.

Biowin 6 Help Manual Help, Tutorials and Examples • 43

Recording results and modifying the Album
1. Add a new page to the Album with two vertical panes. Display the Element information (summary)
for the top reactor and the bottom reactor in the two panes.
2. We will record simulation results in the table below. All of this information can be found in the two-
pane page you added to the Album.

Depth Temp. F DO OUR QAIR OTR SOTE(%)

3.0 20 0.5 2
4.5 20 0.5 2
6.0 20 0.5 2
4.5 12 0.5 2
4.5 20 0.5 4
4.5 20 0.8 2

Steady state simulations

3. Run a steady state simulation and evaluate the predicted performance of the aeration system.

Note: data for the top and bottom reactors should be the same. If not, you must have an error because the
two systems should be set up identically, each receiving half of the influent flow. Tabulate one set of the
results.

4. Change the depth of the lower bioreactor in steps from 3.0 m to 4.5 and then 6.0 m. For each
change, re-run the steady state simulation, and tabulate the results for the new depth.
5. Set the depth of each bioreactor to 4.5 m. The global temperature for the system is 20°C. Double
click on the bottom cell to open the Properties dialog. On the Operation tab, check the local
temperature option, and specify a temperature of 12°C. Re-run the steady state simulation, and
tabulate the results for the new temperature.
6. Re-set the temperature to 20°C. Change the DO setpoint in the lower bioreactor to 4 mg/L, re-run
the steady state simulation, and tabulate the results.
7. Re-set the DO setpoints to 2 mg/L in each reactor. Change  for the lower reactor to 0.8 (double-
click on the Bottom Cell, click the Model tab– you can find aeration parameters such as alpha and
beta on the Model tab). Re-run, and tabulate the results.
8. Switch on oxygen transfer and DO modeling in the Project|Current Project Options… menu on the
Model tab. Re-run the steady state simulation, and discuss differences in model predictions.
9. Re-set the  values to 0. Instead of specifying DO setpoints, switch to air flow rate and adjust the
values.

44 • Help, Tutorials and Examples Biowin 6 Help Manual

Dynamic Simulations
1. Modify the Album to include charts of air flow rate, DO and total oxygen uptake rate for each of the
aerated reactors.
2. Start a dynamic simulation. Observe the response of the aeration parameters.
3. Pause the simulation and change aeration parameters. Attempt to predict the effect of the change
before continuing the simulation.

Biowin 6 Help Manual Help, Tutorials and Examples • 45

TUTORIAL 6 – Setting Up an SBR System
This tutorial provides an introduction to using sequencing batch reactor (SBR) modules in BioWin. The
system considered here is based on the simplest SBR module; namely, a single-tank unit (without pre-zones)
where filling, settling and decanting all occurs in one zone without baffles.
Important Notes:
1. This configuration is not proposed as a potential design. Rather, the objective merely is to illustrate
how to set up an SBR system in BioWin.
2. Detailed Help on the different SBR modules is provided in the Drawing Board Unit Processes section
of the “Building Configurations” chapter.
3. There are certain basic issues to consider when simulating SBR systems. See the introductory notes
of the BioWin Examples section later in this document.

The System
We wish to set up an SBR system with four identical units in parallel. The layout of the system is shown in
the figure below. Each unit will operate on the same cycle, with equal periods for fill, react, settle and
decant (1 hour each, with a total cycle time of 4 hours, and 6 cycles per day). Influent to the system is
directed sequentially to each of the four units for a fill period of one hour. That is, SBR #1 receives influent
for 1 hour (while SBR #2 is decanting, SBR #3 is settling, and SBR #4 is reacting). At the end of the hour
influent is directed to SBR #2 and each of the SBRs moves to the next stage in its cycle (SBR #1 starts the
react period, SBR #3 starts decanting, and SBR #4 starts settling). In summary, each SBR is operated on the
same cycle, but the cycles are offset from the adjacent unit by one hour.

The four-unit SBR system configuration

46 • Help, Tutorials and Examples Biowin 6 Help Manual

Suggested Approach
The response and interactions in a four-unit system like this can be very complex. Even viewing the results
can be confusing! As an example, the chart below shows how the level in each SBR might change over 24
hours. It is strongly suggested that the practical approach is to first set up a system that includes the flow
division, but with only one of the trains; that is, only one SBR unit. The system then can be debugged more
readily.

Volume plot for system incorporating all 4 SBRs

Setting up the One-Unit Configuration

Set up the single-tank SBR system shown in the BioWin screen view below. The characteristics that we will
specify for the system are as follows:

SBR (full) volume 20 ML

Depth 4.5 m
Width 66 m
Minimum decant level 50%
Cycle: Fill 1 hour
React 1 hour
Settle 1 hour
Decant 1 hour
DO (fill and react phases) 2 mg/L
Initial liquid hold-up 50%
SBR underflow (for wastage): 20 ML/d from 1:45 to 2:00 hours in each cycle.

Biowin 6 Help Manual Help, Tutorials and Examples • 47

The Tutorial 6 system configuration

1. Change to SI units (ML and ML/d) and set up the system.

2. Right click on elements to change names.
3. Double click on the influent element, click on the From file button, and load the file An Example.ifd
from the DATA directory.
4. Use the File|Save As command to save the configuration as My Tutorial 6 in the Data/Tutorials
directory.

Specifying the flow distribution information

1. Double click on the first flow splitter element after the influent – or click the right mouse button and
select the Properties command.
2. Select the Flow split tab and specify the splitter as a flow router by placing a check in the box at the
lower left. Click on the Routing pattern button and specify that the flow is Switched at intervals of 2
hours. This directs all the influent to SBRs #1 and #2 for 2 hours, then to SBRs #3 and #4 for 2 hours,
and so on.
3. For each of the flow splitters in front of a pair of SBRs, double click on the element – or click the
right mouse button and select the Properties command. Select the Flow split tab, and specify the
splitter as a Flow router by placing a check in the box at the lower left. Click on the Routing pattern
button and specify that the flow is Switched at intervals of 1 hour. Any flow reaching the router
from the upstream router is alternated between the two SBRs at one-hour intervals.
4. When you are finished use the File|Save As… command – or click on the Save button ( ) on the
toolbar - to save the configuration as My Tutorial 6 in the Data/Tutorials directory.

48 • Help, Tutorials and Examples Biowin 6 Help Manual

Specifying the SBR physical information
1. Double click on the SBR element – or click the right mouse button and select the Properties
command.
2. On the SBR dimensions tab enter the SBR volume (full), depth and width (20 ML, 4.5 m, 66 m).
3. On the Initial values tab enter the initial SBR liquid hold-up as 50% (of the maximum i.e. 10 ML).

Specifying the SBR operational information

For the SBR operation we wish to specify equal 1 hour periods for fill, react, settle and decant; that is, a 4
hour cycle. The fill and react phases define the "mixed" period of operation, where it is assumed that the
reactor contents are well-mixed through either aeration or mechanical mixing.

Hint: It is simplest if you adjust the cycle times in the order Mix start time, Decant start time, Cycle length.
BioWin is continually checking your input data and will not allow things like decanting after the end of the
cycle.

Hint: When reducing times from 1:00:00 (i.e. 1 day, zero hours, zero minutes) to say 4 hours, first increase
the number of hours to 4 (i.e. 1:04:00) and then reduce the day unit (i.e. 0:04:00).

1. On the SBR operation tab start by setting the Mix until / Start settling at time to 2 hours (i.e. fill +
react).
2. Set the Decant / Draw starting at time to 3 hours.
3. Set the Cycle length or duration to 4 hours.
4. Select the To minimum decant level option so that the SBR is decanted to 50% each cycle.
5. Click on the SBR aeration button and specify a constant DO setpoint of 2 mg/L.

Specifying the sludge wastage information

We wish to waste sludge from the SBR at a rate of 20 ML/d for a period from 1:45 to 2:00 during each cycle
(i.e. 1.75 to 2.00 hours in decimal format). This corresponds to a waste volume of 208 m3 per cycle.
• On the SBR underflow tab select the Flow pattern option and click on the Pattern button.
• Select hours in the Time in grid group.
• Set the Cycle time to 4 hours.
• In the grid enter the time and flow data as shown below.

Biowin 6 Help Manual Help, Tutorials and Examples • 49

The SBR underflow tab showing the wastage information

Note: All the required information has been specified. When you are finished use the File|Save As…
command – or click on the Save button ( ) on the toolbar - to save the configuration as My Tutorial 6 in
the Data/Tutorials directory.

Checking the system set-up

We want to check that all the data has been specified correctly. Generally this is achieved most easily by (1)
following the SBR liquid hold-up over a 24 hour period (six cycles), and (2) checking that the flow routers are
distributing the influent flow in the correct sequence. [In this example the influent flow rate varies over the
24 hour cycle, but is specified as constant for two-hour periods. This simplifies checking the SBR volume
response].

Note: No lines appear in the charts until you run a dynamic simulation (see below).

1. Open the Album on Page 1.

2. Right click on the blank pane, and select the Chart command. This opens the variable selection
menu on the Time series tab – the one we want for now.
3. Select SBR #1 in the Element name pull-down list (delete the SBR underflow), highlight Liquid
Volume from the State variables list, and click the Plot selected button. Select the Fast line option
from the Time series gallery, and press OK.
4. Click the Close button to close the dialog box.

50 • Help, Tutorials and Examples Biowin 6 Help Manual

 5. Repeat this procedure to plot the flow to each of the four parallel branches in Page 2. Do this by
sequentially selecting the Output and the Sidestream of each flow router as the series to plot.
6. Repeat this procedure to plot the TSS concentration in SBR #1 in Page 3.
7. Repeat this procedure to plot the influent flow rate in Page 4.
8. Rename the Album pages by right clicking on the tabs at the bottom of the Album.
9. From the main simulator window, select the Project|Database|Data interval option, and change
the Display / data interval to 15 minutes. This is the interval at which monitored data are added to
the database and charts.
10. From the main simulator window, set the dynamic simulation running for 1 day either from the
Simulate|Dynamic simulation menu command or by clicking on the Dynamic simulation toolbar
button ( ) or press the F7 key. After pressing the start button select the Simulate from project
start date and Seed values options, and a simulation time of 1 day.
11. View the response in the Album. While the simulation is running open the Album by pressing Ctrl +
A.
12. Check that each SBR receives influent flow for the appropriate one-hour intervals. The album chart
should appear as shown below.

Influent flow distribution

13. Check that the SBR volume response is correct, as shown in the view below. There should be 6
cycles over the 24 hours. At the start of each cycle the volume should be 10 ML (50% hold-up). For
the first hour, the level increases. From 1:00 to 1:45 the level is constant, and then decreases by a
small amount (208 m3) when wasting occurs over the last 15 minutes of the mixing period.
Decanting starts three hours into the cycle, and continues until the level reaches the 50% minimum
at 4 hours (end of the cycle). During different cycles the extent of filling differs because the influent

Biowin 6 Help Manual Help, Tutorials and Examples • 51

 flow rate changes. It is worth checking that the volume increase during a fill period corresponds to
the amount of influent over that one-hour period.

The SBR liquid volume response

Running the SBR simulation to reach a steady state

1. From the main simulator window, set the dynamic simulation running for 50 days either from the
Simulate|Dynamic simulation menu command or by clicking on the Dynamic simulation toolbar
button( ) or press the F7 key. After pressing the start button select the Simulate from project start
date and Seed values options, and a simulation time of 50 days.
2. In the Album monitor the TSS response as the system approaches a steady state. While the
simulation is running open the Album by pressing Ctrl + A. Right click on the chart and use the Edit
axes option to select the Automatic option for the Bottom axis. This will automatically scale the
chart.
3. When the dynamic simulation is complete press the stop button in the player dialog. For this
system, the response should have stabilized after approximately 40 days as shown in the view
below.

52 • Help, Tutorials and Examples Biowin 6 Help Manual

 TSS response over 50 days starting from Seed values

Viewing the stable SBR response

Now that the system has reached a steady state typically we will want to view the response over 24 hours
(or individual cycles). Usually it is most convenient to "set the clock back to time zero" (the Simulate from
project start date option will do that for you or select the Start from date as June 10 in this case), but start
the simulation based on the Current values; that is the conditions after 50 days of simulation. This will save
us from having to change the time axis repeatedly.
1. From the main simulator window, set the dynamic simulation running for 1 day either from the
Simulate|Dynamic simulation menu command or by clicking on the Dynamic simulation toolbar
button ( ) (or press the F7 key). After pressing the start button select the Simulate from project
start date and Current values options, and a simulation time of 1 day.
2. When the dynamic simulation is complete press the stop button in the player dialog.
3. In the Album view the simulated SBR response. The view below shows the TSS response in SBR #1
over 24 hours (6 cycles). For the first hour in each cycle (during fill) the concentration decreases as
the volume increases. From 2 to 3 hours (during react phase) the TSS remains near constant. When
settling commences the plotted TSS decreases rapidly. This is the TSS concentration in the top layer
of the SBR. The maximum TSS changes from cycle to cycle because the amount of fill (and dilution)
changes.
4. Add additional charts to the Album.
5. At this point use the File|Save As… command – or click on the Save button ( ) on the toolbar - to
save the configuration as My Tutorial 6 in the Data/Tutorials directory.

Note: The file is being saved "as is". This means that at a later date the file can be loaded, and re-run using
the Simulate from project start date and Current values options (i.e. the status of the system at the time of
saving the file). This obviates the need to run for an extended period to reach steady state.

Biowin 6 Help Manual Help, Tutorials and Examples • 53

TSS response over 24 hours

The BioWin file for this system can be found in the Data/Tutorials directory under the name: Tutorial
6.BWC.
The Album includes charts for a large number of parameters.

Important note: Making changes to SBR physical or operational data often requires running the simulation
for an extended period to attain a new steady state.

54 • Help, Tutorials and Examples Biowin 6 Help Manual

BioWin Examples
A number of example configurations are provided with the BioWin installation. The examples can be
accessed via the Pre-Configured File Cabinet (found on the BioWin main window toolbar). Pre-
Configured File Cabinet : Click the arrow next to this button (at the top of the main window) to select and
load pre-configured BioWin process files. These highlight some of the advanced features available in BioWin.
A level of familiarity with BioWin is assumed – detailed instructions for setting up the configurations such as
those given in the Tutorials section of this chapter are not given here. Therefore, it is recommended that
you complete the tutorial exercises earlier in this chapter before investigating these files.

Pre-Configured File Cabinet

Clicking the arrow next to the file cabinet icon ( ) on the main toolbar shows a list of process
configurations that have been created.

Pre-configured File Cabinet

When you click on one of these configurations, BioWin will prompt you to save any work that you currently
have open. Next, the selected file will open in the background and BioWin prompts you to save it under a
different name and in a different location from where it was opened. If you plan to work with the file
extensively, it is recommended that you follow these steps. However, you can select Cancel and do this
later.

Biowin 6 Help Manual Help, Tutorials and Examples • 55

General Operation

Main Simulator Window

The BioWin main window consists of five parts:
1. Menus
2. Toolbars
3. Drawing board
4. Summary panes
5. Status bar

Biowin 6 Help Manual General Operation • 57

The main simulator window

The following sections give an outline of each part.

Main Window Menus

The various menus available in the main window are located at the top of the window. The menus available
are:
• File
• Edit
• Tools
• Project
• View
• Simulate
• Help

58 • General Operation Biowin 6 Help Manual

Each menu may be accessed with either of two methods:
1. Click on the text of the menu, or;
2. Hold down the Alt key on your keyboard and press the letter on the keyboard corresponding to the
underlined letter in the menu title. For example, Alt+F will access the File menu.

Toolbars
This section illustrates the various buttons found on the BioWin main window toolbars, and gives a
description of each button’s function. The BioWin toolbars can be toggled on/off with the menu command
Tools|Toolbars. The Configure toolbar is wrappable and will fit multiple rows of buttons when the BioWin
window narrowed. Note that the Calculator toolbar can also “float” over the drawing board in palette mode,
or be docked along the bottom or side of the drawing board). More information on the Calculator toolbar
may be found in Solids Retention Time Calculation in Managing BioWin Projects.

BioWin drawing board with Configure toolbar buttons on multiple rows

Biowin 6 Help Manual General Operation • 59

BioWin drawing board with docked Calculator toolbar

Note: If a toolbar is closed, use the menu command Tools|Toolbars to get it back.

Flowsheet Tools
The Flowsheet Tools toolbar is aligned to the left of the drawing board and is made visible/hidden by
clicking the Flowsheet Tools button on the Configure toolbar.

60 • General Operation Biowin 6 Help Manual

Flowsheet Tools Toolbar (to left of drawing board) and Flowsheet Tools button (in red box) on Configure Toolbar

The Flowsheet Tools toolbar allows the user to quickly and easily:
• Undo changes made to the drawing board
• Copy pipe attributes
• Align edges of selected units
• Space units equally between left/right- and top/bottom-most units
• Visually switch horizontal/vertical direction of flow for multiple selected elements
• Copy elements (excluding pipes)
For descriptions of the functions of the Flowsheet Tools, please see the Using the Drawing Board section in
the “Building Configurations” chapter.

Main Window Summary Panes

The purpose behind the main window summary panes is to provide quick overview information about
various elements that have been placed on the drawing board. Two summary panes are found at the bottom
of the main simulator window. The left pane contains a small table that lists an element’s name, type, and
its physical dimensions. The right pane contains a picture of the element and detailed, element-specific
information about various compounds and parameters.

View Element Information in the Summary Panes

1. Click on the element selection tool ( ) from the Configure toolbar or press the ESC button.

Biowin 6 Help Manual General Operation • 61

 2. Hold the cursor over the element that you wish to view summary information about.

Note: Information also will be displayed in the summary panes if you hold any one of the “pipe” cursors over
an element. Also note that the air flow rate per diffuser figure shown in the right summary pane for SBR
elements is for the main zone only.

It also is possible to "freeze" the summary panes so that they display information about a specific element
regardless of where you move your cursor. To do this, follow these steps:
1. Hold your mouse cursor over either the left or right pane, and right-click.
2. From the small popup menu that appears, choose Select…
3. A dialog box will open – from the Elements drop list box, select the element in your configuration
that you want to "freeze" the summary panes on.
4. Click the Close button to finish. You should now be able to move the mouse cursor around your
configuration without the summary panes changing.
If at any time you want to return the summary panes to the mode where they display information on the
element your mouse cursor is held over, simply right-click on either of the panes and choose Fly by from the
small popup menu that appears.

Resize the Summary Panes

To change the horizontal dimensions of the summary panes:
1. Position the cursor over the vertical line that divides the two panes such that the horizontal resize
cursor ( ) appears.
2. When the horizontal resize cursor appears, click and drag the cursor until the panes have the
desired widths.
To change the vertical dimensions of the summary panes:
3. Position the cursor at the top of the summary panes, just below the drawing board horizontal scroll
bar such that the vertical resize cursor ( ) appears.
4. When the vertical resize cursor appears, click and drag the cursor until the panes have the desired
heights.

Main Window Status Bar

The status bar at the bottom of the BioWin main window displays two main classes of information –
simulation status information and model details information.

Simulation Status Information

The status bar at the bottom of the main window operates in two modes; different information is displayed
in each mode.
In the first mode, the status bar provides a brief hint or description of toolbar buttons and menu items if the
mouse cursor is held over them.

62 • General Operation Biowin 6 Help Manual

In the second mode (i.e. when the cursor is not held over a toolbar button or menu item), the status bar
displays information about the status of the configuration, and whether a steady state solution has been
found for the configuration:
• When you are adding elements to a configuration, the status bar will display the message Building
configuration.
• When you have connected all the elements with pipes, the status bar will display the message
Configuration complete.
• Once you have specified physical and operating data for all of the elements in the configuration, the
status bar will display the message Ready to simulate.
• During each of these phases, the status bar also will display the message No steady state solution.
• Once you have found a steady state solution, the status bar will display the message Steady state
solution.
• If you have set up SRT calculation for your project (see the Solids Retention Time Calculation
section), the SRT (days) section of the status bar will display the steady state SRT in days.
• If you are performing a dynamic simulation and you have set up SRT calculation, the SRT (days)
section of the status bar will display an "instantaneous" SRT (denoted by an asterisk) in days. This is
calculated based on the current mass and wastage rate in your system. To increase the update
frequency of the status bar, see the Data Interval section.
• The fourth portion (moving from left to right) of the status bar displays the global temperature and
the current database interval separated by a colon. For example: the following display indicates that
the global temperature is 25 degrees Celsius, and the database interval is 2 hours.
25.0 °C: 2.00 Hours
• The fifth portion (moving from left to right) of the status bar will display the number of alarms that
have been triggered for the current configuration. For more information on alarms, please see the
alarm topics in the Customizing BioWin and Managing BioWin Projects sections.
• The sixth portion (moving from left to right) of the status bar will display the hourly power cost.
BioWin calculates this cost by multiplying the specified electricity cost by the instantaneous power
use and energy consumption. For more information on costs, please refer to the Operating Costs in
BioWin section.

Model Details Information

This section of the status bar contains information about the models being used in the current project (note
that if an option is active, the status bar text is bold, not grayed out). There are two rows of information:
• At the top left end of the status bar is a button labeled Model options…Clicking this button offers
rapid access to the model options being used in the current project (see Model Options).
Moving from left to right (on the first row) several model details are given:
• The next two sections notify you whether the BioWin ASDM (integrated activated sludge / anaerobic
digestion model) and/or a user-defined Builder model is being used. Note that at least one of these
options should be active; otherwise BioWin will simply be doing mass and flow balances assuming all
inputs are inert.

Biowin 6 Help Manual General Operation • 63

 • Moving further to the right, the next section notifies you if Oxygen modeling (i.e. O2 modeling) is
toggled on or off. (See reference to Oxygen Modeling in Model Options).
• The next section indicates whether the options to model various stripping processes are active or
not. BioWin allows two levels of control over ammonia stripping (i.e. NH3 stripping). If the option to
model ammonia stripping is active, then the sub-option to model ammonia stripping in anaerobic
digesters also may be turned on (i.e. NH3 stripping in anaer. dig.). BioWin allows control over
hydrogen sulphide stripping (i.e. H2S stripping) across the entire configuration. BioWin also allows
the stripping and degradation of some of the default industrial components included in BioWin.
• The next section indicates whether pH calculations are incorporated in the simulation (i.e. pH
calculation), and if so, whether the activated sludge model biokinetic equations are incorporating pH
inhibition effects (i.e. pH limitation in AS).
• The next section tells you which one-dimensional settler model is being used in model settlers (i.e.
Modified Vesilind/Double exponential).
Moving from left to right (on the second row) the displayed model options are:
• The first section indicates whether chemical phosphorous removal is being modeled and if iron
aluminum or both are used as precipitants. This section can have various messages depending on
the combination of chemical phosphorous options the user selects.
• The second section indicates whether spontaneous precipitation of viviante and iron sulphide are
being modeled (i.e. Vivianite Fe3(PO4)2 & FeS precipitation).
• The third section indicates whether reductions and oxidation reactions are enabled (i.e. Fe
reduction/oxidation reactions).
• The following section indicates whether spontaneous precipitation of struvite (i.e. MAP –
magnesium ammonia phosphate) and calcium phosphates are being modeled (i.e. Struvite & Ca-PO4
precipitation).
• The following section indicates whether or not the option to include nitrous oxide modeling has
been turned on (i.e. N2O modeling).
• The final section indicates whether reactions modelling the interactions between metal salts and
colloidal material are enabled (i.e. Metal salt - colloidal material coagulation reactions).

Managing Other Windows

When investigating simulation results, users may find it useful to open up Mass Balance windows or Rates
windows. Rather than closing these windows, it may be more useful to minimize them, so they can be
looked at later using the View|Other windows… command. This command opens up a list of available
windows; the windows can be re-invoked by double-clicking on the desired window in the list. To close the
list, click the “X” in the upper right corner (note this does not clear the list; the list can be re-opened at any
time with the View|Other windows… command). To remove a window from the list, that window must be
closed by clicking the red “X” in its upper right corner.

64 • General Operation Biowin 6 Help Manual

Using the Windows list to keep track of minimized mass balance windows.

Managing BioWin Projects

Specifying Project Model Parameter Values

BioWin allows you to override the default model parameter values for a project via the Project|Parameters
command. Parameter editors are available for Aeration/Mass transfer, Kinetic, Stoichiometric, Settling,
Biofilm, Physical/Chemical and Other parameters. For information on these dialog boxes, see the Model
Parameter Editors section. The changes made to model parameters using these editors will affect all
elements in the project configuration except those that have local parameters specified. The menu option
Project|Parameters|Set defaults… allows you to set default parameter values for any of the global
parameter lists. Invoking this command presents you with the Set parameters to default values dialog box
shown below. You may move lists from the Selected global parameter lists box to the Available global
parameter lists box using the buttons between the boxes. If you press the button labelled Set selected
parameter lists to default values all parameters in the Selected global parameter lists will be set to their
default values.

Biowin 6 Help Manual General Operation • 65

Dialog used to select and set defaults values for any global parameter lists

Setting Project Options

Project options are specific to the current project. When you set Current Project Options, they will override
any similar settings that you have applied to your BioWin defaults with the Project|New Project Options…
command. For example, if you have set your default flowsheet color to be blue with the Project|New
Project Options… command, but for “Project A” you want the drawing board color to be white, then you
would set the drawing board color to white in “Project A” using the Project|Current Project Options…
command. Now the drawing board color for “Project A” will be white, regardless of the default values you
have set.
Since project options are file specific, they “travel” with that file. For example, if you define a set of project
options for “Project A” on your copy of BioWin and then open the “Project A” file in a colleague's copy of
BioWin, you still will see your defined project options. As before, these project options will override any
similar settings that the owner of the other copy of BioWin has set as defaults using the Project|New
Project Options… command.

Model Options
This section outlines the various project model options that can be modified in order to remedy any solution
problems and improve simulation speed. These parameters may be accessed in the main simulator window
by choosing Project|Current Project Options… from the menu and selecting the Model tab, shown in the
picture below. Also these are available via the Model options… button at the left end of the status bar at the
bottom of the main BioWin simulation window.

66 • General Operation Biowin 6 Help Manual

Current project model options

There are a number of options for the model used in biological processes:
• Use BioWin integrated ASDM: This applies BioWin’s activated sludge process / anaerobic digestion
model (ASDM) in all flowsheet units. Likely the only time that you would un-check this box is if you
want to run another model in the biological processes (e.g. one of the IWA models). For details on
the BioWin ASDM model, please refer to the Activated Sludge Processes and Anaerobic Digestion
Model topics in the Model Reference chapter.
• Use project Model Builder model: If the BioWin model is unselected and the Model Builder model is
selected, then only processes specified in the Model Builder model will be used. If both the BioWin
and Model Builder models are selected, then the Model Builder model will act as an “overlay” to the
BioWin model. For information on using the Model Builder, please see the Model Builder section.

Note: At least one of the above options must be checked to obtain meaningful simulation results. If neither
option is checked, BioWin will display a warning (Warning: no model selected) when you click OK. If you
click OK to the warning and proceed without at least one of the above options turned on, then BioWin
simulations will essentially consider all inputs inert, and the simulation flow and mass balances will reflect
this.

• Include industrial component degradation reactions: This option will be turned on automatically if
an industrial influent element is placed on the drawing board. If a state variable input is instead used
to input any industrial component(s) to the BioWin flowsheet, then this model option should be
turned on manually. Selecting this option will activate kinetics and stoichiometry related to

Biowin 6 Help Manual General Operation • 67

 heterotrophic organisms growing on BioWin’s industrial COD components as well as gas-liquid mass
transfer reactions for these components (if applicable). (See the Modeling of Industrial Components
section of the “Model Reference” chapter).
• Use Oxygen modeling: This option has the following implications:
• If this option is selected, BioWin will model the impact of DO transfer in streams (from unit to unit
and in the recycles, which likely is an important consideration for biological nutrient removal
systems). If this option is not checked, then DO is not tracked between units and in recycles.
• Selecting this option makes it possible to specify an air flow rate in a reactor and have BioWin
calculate the DO concentration. Note that if you specify an air supply rate for a bioreactor-type
element, BioWin will automatically turn on the oxygen modeling option.
• If this option is not selected, BioWin still computes oxygen uptake rates and other aeration features
such as SOTR, OTR, SOTE, OTE, and air flow rate.
• If this option is not selected, BioWin will apply changes to DO or airflow instantaneously. For
example, if a DO setpoint pattern is input, BioWin will assume there is no “lag” between different
DO setpoints in the pattern.
• Model ammonia stripping: Selecting enables ammonia stripping modelling, and ammonia stripping
may occur in flowsheet elements if conditions favor it (e.g. high liquid ammonia concentration and
high pH). A sub-option is offered to model ammonia stripping in anaerobic digester elements. This
has been offered as an option because modeling of ammonia stripping in anaerobic digesters
requires tighter numerical integration controls, and therefore may affect simulation speed.
• Model stripping of H2S: Selecting enables modelling of stripping of dissolved hydrogen sulfide gas
that may be produced as part of BioWin’s sulfur reactions (see the Sulfur Modeling section of the
“Model Reference” chapter).
Model nitrous oxide modeling: Selecting this option activates components of the ASDM that may predict
generation of nitrous oxide by autotrophs and/or heterotrophs under certain process operating conditions.
More information can be found in the nitrous oxide section of the “Model Reference” chapter (see Growth
and Decay of Ordinary Heterotrophic Organisms (OHOs) and Growth and Decay of Methylotrophs).
• Include pH calculations (otherwise pH of 7.0 assumed): Selecting this option enables BioWin’s
comprehensive pH modeling. The pH governs species distributions which impacts the kinetic rates,
the alkalinity, gas-liquid mass transfer and precipitation reactions. If you do not want to calculate
the pH you may uncheck this option, and BioWin will assume a pH of 7.
• Apply pH limitation in activated sludge kinetic equations: Selecting this option enables modeling of
biological inhibition by pH (many of the biological process rates in the BioWin ASDM model are
impacted by pH). If you do not want to account for the impact of pH on biological growth rates, un-
check this option.
• Include chemical reactions for Struvite (MAP), brushite (DCPD) and apatite (HAP): Selecting this
option activates components of the ASDM that may predict these precipitates if the conditions are
favorable (see the Spontaneous Chemical Precipitation section of the “Model Reference” chapter).
• Include ferric-phosphate adsorption/precipitation reactions: Selecting this option activates
components of the ASDM involved in predicting ferric-based phosphorus adsorption/precipitation
reactions. Sub-options are available to model iron reduction/oxidation reactions (e.g. oxidation of
ferrous metal ions to ferric metal ions in oxidizing environments, reduction of ferric metal ions to

68 • General Operation Biowin 6 Help Manual

 ferrous metal ions in reducing environments) and to model vivianite and FeS
precipitation/dissolution reactions. BioWin will prompt / suggest turning these options on if a ferric
or ferrous metal input is placed on the drawing board (see the Chem P section of the “Model
Reference” chapter).
• Include aluminum-phosphate adsorption/precipitation reactions: Selecting this option activates
components of the ASDM involved in predicting aluminum-based phosphorus
adsorption/precipitation reactions. BioWin will prompt / suggest turning this option on if an
aluminum metal input is placed on the drawing board (see the Chem P section of the “Model
Reference” chapter).
• Include metal salt – colloidal material coagulation reactions: Selecting this option activates portions
of the ASDM that (a) transform non-settleable colloidal COD to settleable particulate degradable
COD in the presence of metal salts (either aluminum or ferric based) and (b) results in fewer sites for
phosphorus adsorption on those metal salts (see the Chem P section of the “Model Reference”
chapter).
• Include attached biofilm solids in reactor mass and SRT calculations: Selecting this option means
that BioWin will include the attached biofilm mass in the “total solids mass” calculation for an
attached growth reactor (e.g. in a table or chart, or for SRT calculation). If this option is not selected,
the attached mass will not be included in these calculations.
• Show calculated stoichiometry: Clicking this button opens a window that shows the stoichiometry of
the BioWin biological model that will be used at your current parameter values:

Stoichiometry of BioWin’s ASDM at current parameter values

Biowin 6 Help Manual General Operation • 69

 • Settling model (Model settlers, SBRs and GSSTs): The choice made here determines which of
BioWin’s two available flux theory-based settling models – a Modified Vesilind model or the
Double Exponential model will be applied in model settler and SBR flowsheet elements. This
choice does not impact the operation of point and ideal secondary settlers. For more information on
the Modified Vesilind and Double Exponential secondary settler models, please see the Flux Based
Models section of the “Model Reference” chapter.

Unit System
This section outlines the various options that can be set for the unit system used in a project. The project
unit system may be accessed in the main simulator window by choosing Project|Current Project Options…
from the menu and selecting the Unit system tab, shown in the picture below.

Project unit system options

In the Flow units radio button group, you may choose from the following:
• cubic meters per day (m3/d)
• cubic meters per hour (m3/hr)
• litres per day (L/d)
• megalitres per day (ML/d)
• megagallons per day (mgd)

70 • General Operation Biowin 6 Help Manual

 • gallons per day (gal/d)
It should be noted that the same basis is used for flow and volume. For example, if you choose L/d as your
flow unit, then volumes (e.g. for bioreactors, settling tanks) will be in liters also. Note that air flow rates are
in units of m3/hr.
If you choose US units as your flow basis, then the following US units will be used for other calculations in
BioWin:

Measure US Unit

Length feet (ft)

Area square feet (ft2)

Mass pounds (lbs)

Pressure pounds per square inch (psi)
Air Flow Standard Cubic Feet per Minute (SCFM)
Specific Velocity gal/ft2/d

Mass Loading Rate lbs/ft2/d

Concentration milligrams per litre (mg/L)

In the BOD basis radio button group, you may choose the length of time that BioWin uses to calculate BOD
values. You may choose between 5, 7, and 20 day BOD.

Numerical Parameters
This section outlines the various project model options that can be modified in order to remedy any solution
problems and improve simulation speed. These parameters may be accessed in the main simulator window
by choosing Project|Current Project Options… from the menu and selecting the Numerical Parameters tab,
shown in the picture below.

Biowin 6 Help Manual General Operation • 71

Current project numerical parameters

The Seed sludge age parameter is used to calculate seed values for the biological system. The seed values
help the BioWin solver engine to determine an appropriate solution for the system, or are used at the
beginning of dynamic simulations (if you select to start a dynamic simulation from seed values).
BioWin uses the seed sludge age that you specify, along with the strength of the influent wastewater and
reactor volumes, to perform an approximate steady state calculation in order to guess at what the
concentrations will be in the elements. The analysis is based on continuous flow steady state equations, so
it only is approximate. Note that the seed sludge age in no way affects the actual SRT of a plant
configuration - this is set strictly by the mass of solids that are removed from the system each day (i.e. via
wastage and decant).
If you suspect an inappropriate solution, or if BioWin has trouble finding a steady state solution, the seed
sludge age may be changed in order to provide different seed values. These different seed values may
improve the solution behavior.
The Seeding iterations parameter is used to determine how many iterations will be used in the seeding
process. In some files the seeding procedure is slow and reducing the number of seeding iterations will
increase the seeding speed. However, it is important to note that decreasing the seeding iteration decreases
the quality of the seed and may impact simulation performance.
The Steady state solver is a powerful search algorithm provided in BioWin to solve the model under steady-
state (constant flow, concentration and operating) conditions. The BioWin Hybrid method utilizes a
combination of the Newton-Raphson (NR) second order search, and a Decoupled Linear Search (DLS). Both
algorithms have advantages in certain situations, and BioWin will select the best method and switch

72 • General Operation Biowin 6 Help Manual

between them if necessary. Newton-Raphson prefers smooth, continuous functions, and can reduce the
error by two orders of magnitude in an optimal case. The DLS method uses much smaller steps and is not
sensitive to sharp discontinuities and non-linearities.
The numerical parameters tab also allows the user to select the base options and method (i.e. BWHeun or
BDF) to be used for dynamic simulations. The basic integration method, accuracy and step size control
parameters are available on this tab. Increasing the Relative error for either dynamic method may improve
dynamic simulation speed, but the increased error criterion may also result in poorer mass balances.
The Min. size for relative error calculations (for BWHeun) or the Absolute error tolerance (for BDF) is the
value below which error calculation will switch to absolute error criterion as opposed to a relative error
criterion above this value.
The Step-size scaling factor (Theta) (for BWHeun, Default: 70%) determines how the dynamic solver adjusts
the step size.

Steady State Solver Options

The user can select from the three available methods for steady state convergence. There also are a number
of options (available by pressing the Options… button in the steady state solver section of the numerical
parameters tab) for each of the different methods. Key options are explained here.

Steady state solver options

Hybrid:
• Initial DLS EC (Decoupled Linear Search Error Criteria) (Default: 10) - BioWin will use the DLS
method until it achieves an error of less than the initial DLS error criteria or it performs more than
the initial DLS iterations [DLS Iter's (Default: 2500)] at which time it will switch to the NR method.
• Non conv. (Default: 500) - This value is used to determine if the NR solver is stuck. Increasing it
will make the solver consider itself stuck over a wider range of values.

Biowin 6 Help Manual General Operation • 73

 • Bad NR inver. (Default: 5) - If the NR solver takes this many steps in a direction which results in
an increase in the error then DLS will be activated.
Modified Newton-Raphson:
• Step size (Default: 100%) - Use the original NR estimated steps for each state variable. Can be
reduced to make the method more cautious.
• Derivative Method - This setting can be used to choose between central finite difference and
forward finite difference numerical derivative approximations.
Decoupled Linear Search:
• Grow by (Default: 3) - Step size increasing by 0.03% for successful iterations.
• Shrink by (Default: 18) - Step size decreasing by 1.8% for failed iterations.
• Max negative (Default: 50%) - Maximum allowed negative step.
• Max positive (Default: 50%) - Maximum allowed positive step.
• Initial size (Default: 5%) - Size of initial perturbation.
• Error [0.01 (units of mg/L/d {g/m3/d} if using the default dC/dt and g/d if using dM/dt)] -
Error criteria to stop iterations if mass balance is closer than this to the solution.

Note: You can set the steady state solver to use conservative parameter values if you have trouble finding a
steady state solution for a configuration (see the Tips for Systems that are Difficult to Solve section in the
“Running Simulations” chapter).

Alarm Options
This section shows how certain of BioWin’s alarms can be turned off, thereby becoming inactive for a
project. This functionality may be accessed in the main simulator window by choosing Project|Current
Project Options… from the menu and selecting the Alarm options tab, shown in the picture below.

74 • General Operation Biowin 6 Help Manual

Current project alarm options

All possible alarms are turned on by default for a new project. However, an alarm can be turned off by
unchecking the box next to it. This is useful for the case where the conditions that are triggering an alarm
are expected; e.g. the alarm “Low pH in digester – may be acidic” may be expected in the case where an
anaerobic digester element is being used to simulate primary sludge fermentation where the desired
production of volatile fatty acids will result in a low pH. In cases such as this, the user may want to stop
BioWin from displaying an alarm condition after every simulation.

Drawing Board Options

This section outlines the various project options that can be set for the drawing board. The drawing board
options may be accessed in the main simulator window by choosing Project|Current Project Options… from
the menu and selecting the Drawing board tab, shown in the picture below.

Note: The drawing board is the largest part of the BioWin main window. This is where you set up the
process layout that you will be simulating by placing various elements, specifying their properties, and
connecting them with pipes. A number of procedures can be carried out from the drawing board – some of
the common ones are outlined in the Using the Drawing Board section of the “Building Configurations”
chapter.

Biowin 6 Help Manual General Operation • 75

Current project drawing board options tab

Aspects of the Drawing board appearance that may be changed include the Font and the Color. Clicking
the Font… button will open the font properties dialog box and will allow you to change the font that is used
to label element pictures on the drawing board. Selecting a new color from the drop list box will change the
background color of the drawing board. Notice that a preview of the drawing board background color and
the selected font is given in the dialog box.
The Drawing board size also may be changed. Changing the values in the Width and Height spin edit boxes
will change the overall dimensions of the drawing board. The size of the main window occupied by the
drawing board is not changed. However, the overall size is changed as evidenced by a change in the size of
the scroll box in the scroll bar. The default values of 6,000 by 2,000 translate roughly to 60 by 20 inches. The
zoom limits of the drawing board can be set so that zooming can only take place between minimum and
maximum levels.
The Drawing board snap resolution can be changed in either or both the X and Y directions. The snap
feature helps you align elements precisely on the drawing board. When you place or move an element on
the drawing board, it aligns itself (i.e. “snaps”) to the nearest grid point (grid points are invisible). Increasing
the snap values results in a coarser grid to which the elements can “snap” and consequently means that you
have less control over their placement. Decreasing the snap values results in a finer grid for the elements to
snap to. This means that you have increased control over their placement.
A number of settings related to Element display also may be changed. You can choose whether new
projects show names for elements using the Show element names checkbox, and where they will be shown

76 • General Operation Biowin 6 Help Manual

using the Location of element name (if displayed) relative to element image radio buttons (note that you
specify which elements will show their names on the General tab of the Tools|Cusomtize menu).
You can also choose the default new project display of tags using the Tag display location (relative to
element image) setting. Unless you want tags to show for every element (which often can be somewhat
overwhelming, especially for complex flowsheets), likely it is best to leave this setting on None and use the
tag settings within individual elements to override this setting. Other default new project tag settings such
as whether tags include variable names (in addition to values), whether tags include units, tag font size and
background colour, etc. can be set in this dialogue box. Note that the Tag name format can either be
Abbreviated names (the default) or it can mirror the BioWin global format set via the
Tools|Cusomtize…Display options tab.

Pipe Options
You can control the initial appearance of pipes in your project using the Project|Current Project Options
menu command and selecting the Pipe tab (shown in the figure below). In the Line section, the Width,
Color, and Style of the lines used to represent pipes on the drawing board can be changed. For information
on the various pipe line options, see the Pipes topic in the “Building Configurations” chapter.

Note: To get more than the listed colors, please right click on the Color list box to display the full color
dialog box.

You may increase the arrow size on the lines used to represent pipes. The arrow angle also can be changed.

Note: The “arrow angle” refers to the acute angle between the arrow side and the line. For example, if you
want arrows with “flat” bases, set the arrow side angle to the maximum of 60 degrees.

Biowin 6 Help Manual General Operation • 77

Current project pipe options tab

Clicking the Default/global pipe/configuration specifications button allows you to default properties for
pipes used for calculation of dynamic head for pump elements. Note that these can always be changed for
individual pipes corresponding to a specific pumped flow. For more information on pump power
calculations, please refer to the Pumping Power section of the Power in BioWin chapter.
Note that it also is possible to change pipe line and arrow settings for individual pipes. Access the properties
of the pipe you wish to change by double-clicking its arrowhead or right-clicking its arrowhead and selecting
Properties… from the resulting pop-up menu. Doing this for any pipe will present you with the dialog box
shown below. Each pipe in a flowsheet layout may have its own color, width, line style, etc.

78 • General Operation Biowin 6 Help Manual

Pipe line options dialog box

Note: For more line colors right-click on the color selection drop-list box.

Biowin 6 Help Manual General Operation • 79

Pipe options tab with full color dialog box

Specifying Project Details

This section outlines the various details that can be specified for the project. The project details may be
accessed in the main simulator window via the Project|Info menu command, which will present you with
the dialog box shown below.

Dialog box used for entering project details and information

The Project information group contains details on the current project:

80 • General Operation Biowin 6 Help Manual

 • Creation date: this field indicates the date and time that the current BioWin project was created.
The user may modify the creation date. When you click the down arrow you will be shown a
calendar from which you can choose the date. The current day is circled in red, and the day that
currently is selected is indicated by a solid blue oval. You may use the left and right arrow buttons at
the top of the calendar to move to different months.
• Last saved: this field indicates the date and time that the current BioWin project was saved.
• Simulation start date: use this field to set the date that will be used as the default starting date
for dynamic simulations. Note that if you want to specify another date different from the one you
specify here when doing a dynamic simulation, you may do so. When you click the down arrow you
will be shown a calendar from which you can choose the date. The current day is circled in red, and
the day that currently is selected is indicated by a solid blue oval. You may use the left and right
arrow buttons at the top of the calendar to move to different months.
• User name: use this field to indicate the name of the person responsible for the project.
• Project name: use this field to indicate the name of the project.
• Project reference: use this field to indicate the project reference code.
• Plant name: use this field to indicate the name of the plant that the simulation project is for.

Recording Project Notes

The project note editor, shown in the picture below, is a tool that may be used to record information
relevant to the current project. You can access the editor via the menu command Project|Notes or by
clicking on the Notes button ( ) on the Main toolbar. The notes that you make can have formatting applied
to them according to the Rich Text Format (*.RTF). These notes are saved internally with the BioWin file, so
they go wherever the BioWin file goes. [In pre-BioWin 4.1 versions, the notes are saved in a separate “*.nts”
file.] This feature is very useful for capturing information about the simulation, and since it is saved
internally in the BioWin “bwc” file, any BioWin user who accesses the BioWin file will be able to see them.
Another enhancement (BioWin 4.1.1 and later) is that the notes can contain pictures in the form of image
files (e.g. PNG, JPEG, EMF). You can right-click on charts and tables in the BioWin album, copy them to the
clipboard, and then paste them to the new enriched notes editor to discuss them. When another BioWin
user opens your BioWin file containing the notes, the notes editor automatically opens so that they are sure
to see the discussion.

Biowin 6 Help Manual General Operation • 81

The project notes editor

Solids Retention Time Calculation

BioWin offers the functionality of Solids Retention Time (SRT) calculation for a project process configuration.
Selecting the Project|Plant|Active SRT menu command or the active SRT button on the Main toolbar ( )
provides access to the definition of the currently “active” SRT (i.e. the SRT that is displayed in the status bar
at the bottom of the Main Window).
BioWin has the ability to store multiple SRT calculation scenarios. For example, suppose that you want to
look at the impact of effluent suspended solids on the SRT of a system. To do this you could set up one SRT
calculator that includes the effluent as a wastage element, and one SRT calculator that does not. Another
possible scenario would be to calculate the SRT for each sludge in a two sludge system. This functionality is
accessed on the Calculators toolbar.

82 • General Operation Biowin 6 Help Manual

The first step in setting up an SRT calculator is to click the New SRT… button on the Calculators toolbar.
When you do this, you will be presented with the following dialog box.

Project SRT calculation dialog box

Enter a name for this SRT calculation scenario in the text box provided. You can make this SRT the Active
SRT by clicking the check box with this label. Next, you must specify the elements in the configuration that
will be used to calculate the total mass in the system. To do this, click the Select elements for total mass…
button. When you do this, you will be presented with a two-paned dialog box, shown below.

Note: If you have attached growth elements (e.g. IFAS) in your SRT calculation, you can choose to either
include or exclude the attached biomass in your SRT calculation, via the Model Options setting.

Note: If you have set up more than one SRT calculator, the active SRT will be displayed in the main simulator
window status bar. To change the SRT calculator that currently is active, go to the Calculators toolbar, select
the SRT calculator you want to make active from the drop list, and click the Configure… button.

Biowin 6 Help Manual General Operation • 83

Dialog box used to select elements for total mass in SRT calculation

In the left-hand Elements pane, there is an expandable/collapsible tree view of the various elements in the
configuration. You can expand/collapse the branches of this tree by clicking on the +/- signs next to the
branches, or by double-clicking on the branch labels. Using this navigation technique, locate the elements
that you wish to include in the total mass calculation. When you find an element that you wish to include,
move it to the right-hand Selected elements pane by clicking on the element name and then clicking the
right-pointing arrow located between the two panes. When you have added all the elements that you wish
to include in the total mass calculation, click the OK button.
The next step in SRT calculation is to select the elements in the configuration from which wasting of solids is
taking place. To do this, click the Select wastage elements… button. When you do this, you will be
presented with another two-paned dialog box, shown below.

84 • General Operation Biowin 6 Help Manual

Dialog box used to select wastage elements for SRT calculation

In the left-hand Elements pane, there is an expandable/collapsible tree view of the various elements in the
configuration. You can expand/collapse the branches of this tree by clicking on the +/- signs next to the
branches, or by double-clicking on the branch labels. Using this navigation technique, locate the elements
that solids are being wasted from. When you find an element that you wish to include, you move it to the
right-hand Selected elements pane by clicking on the element name and then clicking the right-pointing
arrow located between the two panes. When you have added all the elements that you wish to include in
the total mass calculation, click the OK button. Note that if any multi-output elements (e.g. clarifiers which
have underflow and overflow outputs) are specified as wastage elements, BioWin assumes that solids
wasting is occurring in their Side or Overflow streams.
Now that you have completed the two required steps for SRT calculation, you may close this dialog by
clicking OK. The next time that you perform a steady state or dynamic simulation, the main window status
bar will be updated and the SRT in time units of days will be displayed. Note that the frequency of this
update is governed by the Summary pane update interval (Project|Database|Data interval…)

Note: To remove an element (or elements) from the Selected elements column of either of the dialog boxes
used to select elements for SRT calculation, click once on the element name so that it is highlighted blue,
and press the Delete key on your keyboard.

Once you have given BioWin the necessary information it needs to calculate the SRT for a configuration, you
can extend BioWin's SRT calculation functionality by telling BioWin to control the wastage of solids from a
particular splitter element in order to achieve a desired SRT. To do this, check the box labeled Control SRT.
The dialog box will now change in appearance to the one shown below.

Biowin 6 Help Manual General Operation • 85

Project SRT calculation and control dialog box

A Control SRT group now occupies the lower portion of the dialog box. Two spin edit boxes (one marked d
for days and one marked h for hours) are used for setting the desired SRT. Using the Select SRT control
splitter drop list box, you then may select the splitter element in the configuration that BioWin will use to
control the wastage rate in order to achieve the desired SRT. BioWin assumes that the side stream of the
splitter will be the wastage stream, and it changes the setting in the splitter element to control the side
stream flow. When you click OK to close this dialog box, you will notice that the splitter that you specified as
the control will have a new drawing board icon that shows a valve on the wastage stream. Note that you will
be unable to close this dialog box with the OK button if you have not specified all the required information.
If you now perform a steady state simulation, BioWin will adjust the wastage rate out of the control splitter
so that the SRT of the configuration is that which you have specified. This SRT will be displayed in the main
window status bar once the steady state solution has been found.

Note: The SRT controller only sets the wastage rate for steady state conditions. To use the wastage flow in
control strategies, the BW Controller module is required.

If you begin a dynamic simulation after you complete a steady state simulation, the wastage flow rate will
remain constant at the value calculated. That is, there is no control of wastage rates during a dynamic
simulation.

Note: It is possible to plot SRT against time. If you have multiple SRT calculators set up, you can plot as many
of them as you wish. For information on setting up an SRT plot, see the Special Series (from Album) section
of the “Data Output” chapter.

Hydraulic Retention Time Calculation

When you point at an element on the flowsheet, BioWin displays the hydraulic retention time for that
element as in the summary pane, as shown below.

86 • General Operation Biowin 6 Help Manual

BioWin also has the ability to define and store multiple HRT calculation scenarios. For example, suppose that
you want to calculate the overall plant nominal retention time based on all volume of all the tanks and the
average influent flow rate. This functionality is accessed on the Calculators toolbar.
The first step in setting up an HRT calculator is to click the New HRT… button on the Calculators toolbar.
When you do this, you will be presented with the following dialog box.

HRT calculation dialog box

Enter a name for this HRT calculation scenario in the text box provided. Next, you must specify the elements
in the configuration that will be used to calculate the total volume used in the HRT calculation. This may
consist of one or several elements, depending on how you want to define the HRT. To do this, click the
Select elements for total volume… button. When you do this, you will be presented with a two-paned
dialog box, shown below.

Biowin 6 Help Manual General Operation • 87

Dialog box used to select elements for total volume in HRT calculation

In the left-hand Elements pane, there is an expandable/collapsible tree view of the various elements in the
configuration. You can expand/collapse the branches of this tree by clicking on the +/- signs next to the
branches, or by double-clicking on the branch labels. Using this navigation technique, locate the elements
that you wish to include in the total volume calculation. When you find an element that you wish to include,
move it to the right-hand Selected elements pane by clicking on the element name and then clicking the
right-pointing arrow located between the two panes. When you have added all the elements that you wish
to include in the total volume calculation, click the OK button.
The next step in HRT calculation is to select the elements in the configuration that will be used to calculate
the flow term in the HRT calculation. To do this, click the Select flow element(s)… button. When you do this,
you will be presented with another two-paned dialog box, shown below.

88 • General Operation Biowin 6 Help Manual

Dialog box used to select wastage elements for HRT calculation

In the left-hand Elements pane, there is an expandable/collapsible tree view of the various elements in the
configuration. You can expand/collapse the branches of this tree by clicking on the +/- signs next to the
branches, or by double-clicking on the branch labels. Using this navigation technique, locate the elements
you want to use to determine the flow term. When you find an element that you wish to include, you move
it to the right-hand Selected elements pane by clicking on the element name and then clicking the right-
pointing arrow located between the two panes. When you have added all the elements that you wish to
include in the flow term, click the OK button. Note that if any multi-output elements (e.g. clarifiers which
have underflow and overflow outputs) are specified as flow term elements, BioWin will use the flow in the
overflow (i.e. the main output stream of the element) or side stream.
Now that you have completed the two required steps for HRT calculation, you may close this dialog by
clicking OK. The next time that you perform a steady state or dynamic simulation, you can select the HRT
calculator from the drop list on the Calculators toolbar and the HRT will be displayed on the toolbar in time
units of hours.

Note: It is possible to plot HRT against time. Even if you have multiple HRT calculators set up, you can plot as
many of them as you wish. For information on setting up an HRT plot, see the Special Series (from Album)
section of the “Data Output” chapter.

Note: To remove an element (or elements) from the Selected elements column of either of the dialog boxes
used to select elements for HRT calculation, click once on the element name so that it is highlighted blue,
and press the Delete key on your keyboard.

Biowin 6 Help Manual General Operation • 89

Specifying Project Liquid Temperature
BioWin allows you to specify a global liquid stream temperature for a project via the Project|Plant|Liquid
temperature… command. Invoking this command presents you with the Edit global temperature dialog box,
shown below.

Dialog used to set the global project temperature

In the Specify temperature by radio button group, you may choose from two options for global
temperature. If you want a constant temperature in your project elements, then enter the desired
temperature value in the Constant value of text edit area. Note that if you wish, you can override this global
temperature in individual elements.
If you want a time-varying temperature pattern, then select the Scheduled radio button. This will activate
the Pattern… button. Clicking this button presents you with the Edit temperature itinerary dialog box.

Specifying Project Inlet Air Conditions

BioWin allows you to specify Inlet air (gas) conditions (i.e. temperature and humidity) for a project via the
Project|Plant|Inlet air conditions… command. Invoking this command presents you with the Inlet air (gas)
conditions dialog box, shown below.

Dialog used to set the inlet air conditions

In the Inlet air temperature radio button group, you may choose from two options for inlet air temperature.
If you want a constant inlet air temperature, then enter the desired temperature value in the Constant
value of text edit area.
If you want a time-varying temperature pattern, then select the Scheduled radio button. This will activate
the Pattern… button. Clicking this button presents you with the Edit Inlet air temperature itinerary dialog
box.

90 • General Operation Biowin 6 Help Manual

In the Inlet air humidity radio button group, you may choose from two options for specifying inlet air
humidity. If you want to specify constant inlet air % humidity, then enter the desired humidity value in the
Constant value of text edit area.
If you want a time-varying humidity pattern, then select the Scheduled radio button. This will activate the
Pattern… button. Clicking this button presents you with the Edit Inlet air humidity itinerary dialog box.

Specifying Project Blower Calculation Method

BioWin allows you to specify a global blower power calculation method for a project via the
Project|Plant|Global blower calculation method… command. Invoking this command presents you with the
Blower calculation dialog box, shown below.

Dialog used to set the global power calculation method

In the Calculate blower power using radio button group, you may choose from three methods for
calculating blower power: Adiabatic/polytrophic power equation, Linear power equation, or User defined
equation. Note that if you wish, you can override this global blower calculation method in individual blower
reactor groups (i.e. air supply groups).

Note: This section details the use of the global power calculation method. Detailed technical information
about blower power equations is provided in the Blower Power section of the Power in BioWin chapter.

Entering User defined equations

Selecting the User defined equation method for calculating blower power activates a text edit box for
specifying the user defined equation, a check box which allows the user to define constants, and a Check
button, shown below.

Biowin 6 Help Manual General Operation • 91

There are two methods for entering blower power equations. If the equation is small and straightforward,
you may be able to enter it directly into the text edit box. For more complex equations, you will probably
find it easier to use the built in equation editor.

Invoking the Equation Editor

To invoke the equation editor, double-click in the text edit box. This will invoke the Equation editor, shown
in the picture below.

Equation editor showing a user defined equation for blower power

Before proceeding further with explanation of the equation editor, the following points on exiting should be
noted:
1. To exit the equation editor without accepting the changes you have made, click the small x in the
upper right hand corner of the equation editor window.
2. To exit the equation editor and accept the changes you have made, click the Close and update
button.
You can use the Set position to button to quickly move the cursor around within the equation editor. The
position refers to the number of spaces from the left (or beginning) of a line of text. In the example picture
above, the cursor has been moved to the eighth position.

Equation Editor Syntax

The equation editor provides you with a window into which you may enter your equation text. You must
take care to use proper mathematical syntax when you enter equations. The required syntax is similar to
that used when entering mathematical equations in computer code or spreadsheet formulas. For example,

92 • General Operation Biowin 6 Help Manual

say you wanted to change the equation shown above to have the first term multiplied by the constant a. The
following syntax would not be correct, because the multiplication operator is missing:

Incorrect multiplication syntax

The equation shown below, with the correct multiplication syntax would be acceptable:

Correct multiplication syntax

Equation Editor Text Editing Features

The equation editor has features commonly found in text editors. You can highlight a section of equation
text by dragging your mouse cursor over it. You can then move the highlighted selection by clicking and
dragging the mouse cursor. The following keyboard shortcuts for using the Windows clipboard also are
available:
• To cut text, use the Ctrl+x keyboard combination;
• To copy text, use the Ctrl+c keyboard combination;
• To paste text, use the Ctrl+v keyboard combination.

Equation Editor Popup Menu

The equation editor also offers the functionality of a right-click popup menu that makes writing your
equations much easier. If you right-click your mouse button anywhere within the equation editor window,
you will be presented with the popup menu shown below.

Equation editor right-click popup menu

Biowin 6 Help Manual General Operation • 93

Selecting one of the popup menu choices will open a small window containing a list of variables, constants,
or function/operator templates that you can place into your equation. For example, selecting the Variable
option opens a window that lists the BioWin model blower variables, shown below:

Model blower variables

To place a variable from this list into your current equation, simply locate the variable in the list and double-
click it. The popup window will close, and you will return to your equation, where you will see that the
variable has been placed where you had located your cursor. Two important points should be mentioned
regarding the use of these popup windows:
1. To close a popup window without adding an item to your equation, click the small x located in the
upper right corner of the popup window.
2. When you double-click an item and add it to your equation, BioWin also adds the item to the
Windows clipboard. Pressing Ctrl+v will add the item to the equation, until another item is added to
the clipboard.
Selecting the Constant option opens a window that lists the constants that you have defined for the
equation that you currently are working on. Note, that we have not yet defined any constants so this
window is currently empty. Constants can be defined on the Blower calculation dialogue box, shown below,
by selecting the Define constants check box. Under the Enter constant name and value text edit box group,
the Name of the constant and Value can be entered directly into the respective text edit boxes. The
constant does not get defined until you click the arrow (>) to send the constant into the Defined constants
lists.

Now if you select the Constant option from the right-click menu options in the Equation editor dialog box,
you will see the defined constant, shown below. To place a constant from this list into your current

94 • General Operation Biowin 6 Help Manual

equation, simply locate the constant in the list and double-click it. The popup window will close, and you will
return to your equation, where you will see that the constant has been placed where you had located your
cursor.

Constant selection window

Selecting the Function / operator option opens a window that lists a number of function / operator
templates that you may place in your equation. To place a function or operator from this list into your
current equation, simply locate the function or operator in the list and double-click it. The popup window
will close, and you will return to your equation, where you will see that the function or operator template
has been placed where you had located your cursor.

Function / operator selection window

For example, suppose you selected the x^y template from the list. Using our previous blower power
equation example, you would see the following:

Inserting a function template into an equation

You could then quickly replace the x and y placeholders by highlighting them, right-clicking, selecting
Variable or one of the constants options, and inserting an item from a popup window. Functions and
operators are described with examples in the next section.

Biowin 6 Help Manual General Operation • 95

Available Functions and Operators
A more comprehensive list of functions and operators is tabulated below:

Operator Description Example

^ Power operator 2 ^ 3 returns 8

* Multiply operator 3 * 4 returns 12
/ Divide operator 8 / 4 returns 2
\ Module operator. Returns the 5 \ 2 returns 1
module of a division.
+ Sum operator 3 + 7 returns 10
- Subtract operator 10 - 4 returns 6
> Greater than operator 4 > 3 returns 1 (true), and 1 > 6 returns 0 (false)
< Less than operator 6 < 3 returns 0 (false), and 2 < 9 returns 1 (true)
>= Greater than or equal to operator 6 >= 3 returns 1 (true)
<= Less than or equal to operator 7 <= 3 returns 0 (false)
<> Not equal to operator 5 <> 3 returns 1 (true)
= Equal to operator 3 = 8 returns 0 (false)
if Logical if operator. Follows if(5<1; 1; 5) returns 5 since the condition tests
format if(condition; result if true; false
result if false)
and Logical and operator 3 and 2 returns 1 (true, because both are true)
or Logical or operator 3 or 0 returns 1 (true)
xor Logical xor operator 1 xor 1 returns 0 (false)

Constant Value

pi 3.1415926535897932385
e 2.71828182846 - Same as Exp(1)

Function Description Example

96 • General Operation Biowin 6 Help Manual

 PolytropicPower(IntakeAir Places the supplied 𝑃𝑜𝑤𝑒𝑟 = 𝐼𝑛𝑡𝑎𝑘𝑒𝐴𝑖𝑟𝐹𝑙𝑜𝑤 × 𝑃𝐼𝑛𝑡𝑎𝑘𝑒
Flow; PIntake; PDischarge; arguments into a 𝑃𝑇𝑃𝐸𝑥𝑝
×
PTPExp) Polytropic power 𝑃𝑇𝑃𝐸𝑥𝑝 − 1
𝑃𝑇𝑃𝐸𝑥𝑝−1
function where 𝑃𝐷𝑖𝑠𝑐ℎ𝑎𝑟𝑔𝑒 𝑃𝑇𝑃𝐸𝑥𝑝
× [( )
PTPExp is the 𝑃𝐼𝑛𝑡𝑎𝑘𝑒
polytropic
compression
− 1]
exponent

AdiabaticPower(IntakeAirF Places the supplied 𝑃𝑜𝑤𝑒𝑟 = 𝐼𝑛𝑡𝑎𝑘𝑒𝐴𝑖𝑟𝐹𝑙𝑜𝑤 × 𝑃𝐼𝑛𝑡𝑎𝑘𝑒

𝛾
low; PIntake; PDischarge) arguments into an ×
𝛾−1
Adiabatic power 𝛾−1
function (assumes 𝑃𝐷𝑖𝑠𝑐ℎ𝑎𝑟𝑔𝑒 𝛾
× [( ) − 1]
1.4 heat capacity 𝑃𝐼𝑛𝑡𝑎𝑘𝑒
ratio for the gas)
LinearPower(IntakeAirFlow Places the supplied 𝑃𝑜𝑤𝑒𝑟 = 𝐼𝑛𝑡𝑎𝑘𝑒𝐴𝑖𝑟𝐹𝑙𝑜𝑤 × (𝑃𝐷𝑖𝑠𝑐ℎ𝑎𝑟𝑔𝑒
; PIntake; PDischarge) arguments into a − 𝑃𝐼𝑛𝑙𝑒𝑡)
Linear power
function where
power is a function
of air flow and
change in pressure.
Neg Returns the negative Neg(5) returns –5
of argument
Not Returns 1 (true) if Not(1) returns 0
argument is 0 (false).
Returns 0 (false) if
argument is not
equal to 0
Re Returns the real part Re(5 + 4j) returns 5
of a complex number
Im Returns the Im(5 + 4j) returns 4
imaginary part of a
complex number
Exp Returns the Exp(1) returns 2.71828182846
exponential of
argument
Ln Returns the natural Ln(2.71828182846) returns 1
log of argument
Sqrt Returns the square Sqrt(9) returns 3
root of argument
Abs Absolute value of Abs(-12) returns 12
argument

Biowin 6 Help Manual General Operation • 97

 Sin Returns the sine of Sin(pi/2) returns 1
argument in radians
Cos Returns the cosine of Cos(pi/2) returns 0
argument in radians
Tan Returns the tangent Tan(pi/4) returns 1
of argument in
radians
Asin Returns in radians Asin(1) returns 1.57079632679 (pi/2)
the inverse sin of
argument

Verifying Equations
As you enter equations, you may want to use the Check… button to ensure that you have no mistakes in
your equations. When you click this button, BioWin checks your equations for undeclared variables and
constants. BioWin also checks your equations for the proper syntax. Finally, BioWin attempts to calculate
the model equations. This may be useful in discovering equation formula errors such as division by zero.
You may find it useful to use the Check… button each time you finish entering an equation.

Note: When a user defined equation is specified globally the check is performed using typical numbers. If a
user defined equation is specified locally for an air supply group, then the check is performed using the
appropriate numbers for that air supply group.

Simplistic User defined equation - Example

In this example, we will use a linear relationship between blower power and airflow similar to the one that
was presented in a paper by Brischke et al. (2005), shown below; to illustrate how a simplistic user defined
equation is specified.

98 • General Operation Biowin 6 Help Manual

Linear relationship between blower power and airflow (Brischke et al., 2005).

We will consider a nitrifying plug flow reactor configuration, shown below.

BioWin configuration used to calculate blower power

Open the Blower calculation dialog box by selecting Project|Plant|Global blower calculation method…. In
the Calculate blower power using radio button group, select the User defined equation radio button.
Double click on the text edit box and enter the following equation into the Equation editor dialog box:

Note: the equation has been modified from above to take care of units; in BioWin power demand is
calculated in terms of kW and air flow units are m3/day in the Equation editor; see the Entering user defined
equations section for more information on entering a user defined equation)

0.00075*IntakeAirFlow+100

Note: AirFlow is not a defined variable in the Blower calculation methods. The variables that are available
for use in a user defined equation for blower power are BlowerEff (Blower Efficiency), PIntake (Intake
pressure), PDischarge (Discharge Pressure), and IntakeAirFlow (Air flow rate at intake conditions; m3/day).
These can be found by right clicking in the Equation editor dialog box and selecting Variables from the
available menu. If you want to use the Discharge airflow rather than the Intake airflow than you must edit
the above equation to calculate the Discharge airflow from the Intake airflow (e.g. assuming ideal gas law,
Discharge airflow = IntakeAirFlow*(PIntake/PDischarge)).

Select the Close and update button to accept the entered equation. Select the Check button to check the
equation for errors or undefined variables

Note: if you entered the word Airflow into the equation you would have gotten the following error message:
Error – Undefined term in user Equation Blower at position 20).

Select the Close button to exit the Blower calculation dialog box. The chart below illustrates the Blower
power calculated with the above linear equation after running a dynamic solution.

Biowin 6 Help Manual General Operation • 99

Instantaneous Power demand calculated with linear relationship between blower power and intake airflow

Applied User defined equation - Example

In this example, we will specify a user defined blower equation for a specific case in which the air is typically
supplied by a high efficiency blower (Blower 1), but under peak conditions, the airflow required exceeds the
high efficiency blower capacity and a lower efficiency blower (Blower 2) is used to provide the additional air
required. The User defined equation will look something like this:

If(IntakeAirFlow>Blower1Capacity;
(AdiabaticPower(Blower1Capacity; PIntake;PDischarge) / BlowerEff) + (AdiabaticPower(IntakeAirFlow-
Blower1Capacity; PIntake;PDischarge) / Blower2Eff);
AdiabaticPower(IntakeAirFlow; PIntake;PDischarge) / BlowerEff)

We will consider a nitrifying plug flow reactor configuration, shown below.

BioWin configuration used to calculate blower power

Open the Blower calculation dialog box by selecting Project|Plant|Global blower calculation method…. In
the Calculate blower power using radio button group, select the User defined equation radio button.

100 • General Operation Biowin 6 Help Manual

Note: as mentioned in the previous example, variables that are available for use in a user defined equation
for blower power are BlowerEff (Blower Efficiency), PIntake (Intake pressure), PDischarge (Discharge
Pressure), and IntakeAirFlow (Air flow rate at intake conditions). Therefore, the parameters
Blower1Capacity and Blower2Eff in the equation above will need to be defined as constants.

Select the Define constants check box and enter the following information in the table, shown below, into
the Enter constant name and value text edit boxes select the right arrow (>) to add the constants to the list
of Defined constants.

Name Value

Blower1Capacity 150000
Blower2Eff 0.45

Blower calculation dialog box

Basically, when the intake airflow rate exceeds the high efficiency blower’s (Blower1) capacity then a second
blower (Blower 2) with a local user defined efficiency of 0.45 is used to supply the remaining air
requirements. Blower 1’s efficiency is defined in the Project blower parameters, which is found by going to
Project|Parameters|Aeration/Mass transfer…. Invoking this command opens the Parameter editor dialog
box. Click on the Blower tab to display the blower parameters, shown below. In this case Blower 1’s
efficiency is a constant value of 0.75.

Biowin 6 Help Manual General Operation • 101

Project Blower parameter editor

On the Blower calculation dialog box double click on the text edit box to open the Equation editor dialog
box. The above equation can either be manually entered or it can be built by right clicking on the dialog box
and using the menu options to: enter functions and operators by selecting the Function/Operator menu
option, enter variables by selecting the Variable menu option, or enter constants by selecting the Constant
menu option. (See Entering User Defined Equations section).
Select the Close and update button to accept the entered equation. Select the Check button to check the
equation for errors or undefined variables. Select the Close button to exit the Blower calculation dialog box.
The following chart illustrates the Blower power obtained using an Adiabatic/polytropic power equation for
the first four days then switching to the user defined equation above and continuing the dynamic simulation
for another four days.

102 • General Operation Biowin 6 Help Manual

Instantaneous Power demand calculated with applied blower equation

References
Brischke, K., Morgan, S., Dold, P.L., Bye, C.M., Newberry, C. Evaluation of Power Savings Through Aeration
Control at Auckland’s Mangere Wastewater Treatment Plant. Water Environment Federation 78th Annual
Conference and Exposition, Washington, D.C., USA, October 29 – November 2, 2005.

Project Air Supply Groups/Blower Specifications

BioWin allows users to define blower air supply groups for a project via the Project|Plant|Air supply
groups/blower specs… command. In this command, you can specify whether an aerated element is part of a
group of bioreactors / aerated zones that is supplied by a common blower. Note that any element that can
be aerated may be added to a group of reactors supplied by a blower, thereby contributing to that blower’s
power requirement. Invoking this command presents you with the Edit air supply groups dialog box, shown
below.

Biowin 6 Help Manual General Operation • 103

Dialog used to edit blower reactor groups

Note: The Edit air supply groups dialog box remains empty until an element that is or could be aerated is
placed on the drawing board. Once a configuration is built, all the elements that can be aerated (i.e. even
elements that are specified as unaerated) will be automatically added to an air supply group (i.e. #1 Air
supply group) and will appear in the Selected list. All reactors – even those that you intend to remain
unaerated – must be included in a blower group. This has been implemented to ensure that if an unaerated
reactor is made aerated at a later time, its air supply requirement will properly be considered and captured
in blower power calculations. Obviously, if a reactor remains unaerated, it will not contribute to the power
calculation of a blower group.

Clicking the Add button will add a new air supply group (i.e. #2 Air supply group). Clicking the Delete…
button will delete the current air supply group specified in the drop list box.

Note: By default all of the elements are placed in a default air supply group (i.e. #1 Air supply group). To
place an element into a new air supply group (i.e. #2 Air supply group) the element will first need to be
removed from the default air supply group.

To removal an element from the air supply group specified in the drop list box, select the element and click
on the left pointing arrow < to move it from the Selected list box into the Available list box (you can also
double-click on an element in the list to move it). Using the double arrows (i.e. <<) will move every item in
the Selected list box over to the Available list box. To move elements form the Available list box select the
element and click the right pointing arrow > to move it to the Selected list (or use the >> arrows to move the
entire group of elements).
If you want a blower group to have parameters that are different from the global blower parameters (e.g.
blower efficiency, discharge pressure, etc.) or to have a different calculation basis than the Global
calculation method (e.g. Adibiatic/Polytropic, Linear, User defined), then you can click the Edit Blower
specification… button to open the Air supply group blower options dialogue box for the specified air supply
group in the drop list box (i.e. #1 Air supply group), shown below.

104 • General Operation Biowin 6 Help Manual

Dialog used to edit Air supply group blower options

In the Calculate power for group using radio button group, you may choose from four methods for
calculating blower power: Global power calculation method, Adiabatic/polytrophic power equation, Linear
power equation, or User defined equation.
If Global power calculation method is selected, the method specified under Project|Plant|Global blower
calculation method…will be used to calculate blower power.

Note: the method specified in the Global blower calculation method is visible in brackets for the Global
power calculation method radio button (i.e. in the dialog box above the Global blower calculation method is
specified as User defined).

If Adiabatic/Polytropic power equation is selected, the adiabatic/polytropic power equation will be used to
calculate blower power.
If Linear power equation is selected, the linear power equation will be used to calculate blower power.
Selecting the User defined equation radio button, activates a text edit box for specifying the user defined
equation, a check box which allows the user to define constants, and a Check button, shown below. Detailed
information/help on specifying a user defined equation is provided in the Entering User Defined Equations
subsection of the Specifying Project Blower Calculation Method section .

Biowin 6 Help Manual General Operation • 105

Dialog used to specify a user defined equation for blower power

Note: This section details the use of the Air supply group blower options dialog. Detailed technical
information on blower power equations is provided in the Blower Power Calculations section of the Power
in BioWin chapter.

You also can specify Local blower parameters for the specified air supply group. If you click on the check box
for local blower parameters, then clicking the Edit local blower parameters… button opens the Blower
performance dialog box, shown below, allowing you to modify blower parameters. (Note that this changes
the blower parameters on a local level only).

106 • General Operation Biowin 6 Help Manual

Local blower parameters editor dialog

Specifying Project Electricity Costs

BioWin allows you to specify electricity costs for a project via the Project|Costs/Energy|Electricity…
command. Invoking this command presents you with the Electricity costs dialog box, shown below.

Dialog used to set the electricity costs

Biowin 6 Help Manual General Operation • 107

In the Energy Consumption tab, you may choose from three options for specifying electricity costs. If you
want to use a constant electricity cost, then enter the desired cost value in the Constant value of text edit
area.
If you want a time-varying cost pattern, then select the Scheduled radio button. This will activate the
Pattern… button. Clicking this button presents you with the Edit Electricity cost itinerary dialog box. You can
use this option to create any electricity cost pattern you wish.
If you want a seasonal and time varying cost pattern, then select the Seasonal radio button. This will
activate the Details… button. Clicking this button presents you with the Seasonal electricity cost dialog box,
shown below.

Dialog used to set the seasonal electricity costs

The Seasonal electricity cost dialog box allows you to define the day and month for the start of a season (i.e.
summer or winter); on-peak, mid-peak, off-peak electricity rates and time periods; as well as a rate
classification for weekends.
In the Summer/Winter options groups you can specify the start date for the Summer or Winter season by
expanding the Start date drop box and using the calendar to select the month and day.
In the Rates group you can edit the electricity cost for On-peak, Mid-peak, and Off-Peak electricity use by
entering a value directly into the respective text edit boxes.
In the Period definitions group you can use the spin edit boxes to change the start times for Period 1-4. Use
the drop list boxes to define Period 1-4 as either On-peak, Mid-peak or Off-Peak. The default Summer and
Water start dates and the four Period definitions follow the schedule set out in the following figure

108 • General Operation Biowin 6 Help Manual

(HydroOne, 2015). The seasons and daily periods can be adjusted to match those used by your local energy
provider.

Default Season start dates and Period definitions (HydroOne, 2015)

In the Year round group you can specify whether or not to define the weekends as Off-peak by either
checking or unchecking the Weekends Off-peak check box. Unchecking the Weekends Off-peak check box
activates the check boxes for Saturdays Off-peak and Sundays Off-Peak. If you uncheck these boxes the
period definitions defined for each season will be used to determine the rates for the weekends instead of
the seasonal off-peak rate.
On the Other charges tab shown below, you can input information for supply costs. A Service charge cost
can be entered into the text edit box. Under the Demand charge group, both a peak demand charge and
base demand can be entered into the text edit boxes.

Note: the Service charge and demand charge are specified on a monthly basis. The peak demand charge for
month “n” is calculated by multiplying the user-input Peak demand charge value ($/kW) by the plant peak
power demand (kW) observed over a 15 minute period in month “n-1”.

Obviously, when you start a simulation, there is no “previous month” for BioWin to sample for a peak power
demand, so it uses the user-input Base demand as the “previous month” peak power demand for calculating
the first month’s peak demand charge.

Dialog used to set other electricity charges

Biowin 6 Help Manual General Operation • 109

Specifying Project Fuel/Chemical Costs
BioWin allows you to specify chemical (i.e. methanol, ferric, aluminum), fuel (i.e. natural gas, heating oil,
diesel, custom fuel) and Biogas sale price costs for a project via the Project|Costs/Energy|Fuel/Chemical…
command. Invoking this command presents you with the Heating fuel/Chemical Costs dialog box, shown
below.

Dialog used to set the fuel/chemical costs

Note: Specified chemical costs will only be used if the user chooses to include the methanol addition
element and/or the metal addition element in chemical cost calculations by checking the corresponding
check box in the Costs tab of the methanol addition element (see Costs (Methanol)) and/or metal addition
element (See Costs (Metal Addition)) property dialog box.

Note: Specified fuel costs will only be used if the Boiler (Fuel) Heating Method is specified in an Anaerobic
Digester element or Thermal hydrolysis unit element. See Heating Power and Power Recovery.

Note: The Biogas sale price specified will only be used if the option to Sell excess gas (all gas if “Flare/Sell all”
selected) is specified for gas use in an Anaerobic Digester element. See Fuel (Heating and/or Sale).

On the Calorific values of heating fuels tab shown below, users can find the calorific values of various
heating fuels. These specified calorific values will only be used if the Boiler (Fuel) Heating Method specified
in an Anaerobic Digester element or Thermal hydrolysis unit element. See Heating Power and Power
Recovery.

110 • General Operation Biowin 6 Help Manual

Dialog used to specify calorific values for heating fuels

On the Density of liquid heating fuels tab shown below, users can find the density values of liquid heating
fuels. These specified density values will only be used if the Boiler (Fuel) Heating Method is specified in an
Anaerobic Digester element or Thermal hydrolysis unit element and a liquid fuel source is selected. The
specified density values are used for calculation of liquid fuel costs [See Fuel (Heating and/or Sale)].

Biowin 6 Help Manual General Operation • 111

Dialog used to specify density values for heating fuels

Specifying Project Combined Heat and Power Parameters

BioWin allows you to specify heat and power recovery parameters for Combined Heat and Power (CHP) in
the anaerobic digester via the Project|Costs/Energy|Combined Heat and Power (CHP)… command.
Invoking this command presents you with the Parameter editor dialog box, shown below.

Parameters editor dialog used to set CHP parameters

Both the Methane heat of combustion and Hydrogen heat of combustion are used to determine how much
energy is produced from biogas generated in anaerobic digesters and potentially available for CHP
conversion. The division of this potential energy is specified locally in anaerobic digester elements if their
CHP options are turned on.
The CHP engine heat price is the price at which heat generated from the CHP unit is sold only if the user
does not specify to use the CHP heat for the boilers in the anaerobic digester unit (see Anaerobic Digesters).
The CHP engine power price is the price at which CHP power is sold back to the utility grid.
In the CHP power use radio button group you may choose from two options for specifying CHP power use. If
you want to use CHP power onsite and sell any excess power back to the utility grid, then select On-site use
(sell any excess). If you want to sell all of the CHP power generated back to the utility grid, then select Sell
all CHP Engine power generated.

112 • General Operation Biowin 6 Help Manual

Specifying Project HVAC Power
BioWin allows you to specify Heating Ventilation And Cooling (i.e. HVAC) power requirements for a project
via the Project|Costs/Energy|HVAC… command. Invoking this command presents you with the HVAC
Power Requirements dialog box, shown below.

HVAC dialog used to set HVAC power

In the HVAC power consumption tab, you may choose from two options for specifying HVAC power. If you
want to use a constant HVAC power, then enter the desired power value in the Constant value of text edit
area.
If you want a time-varying power pattern, then select the Scheduled radio button. This will activate the
Pattern… button. Clicking this button presents you with the Edit HVAC power itinerary dialog box.

Managing Data
Data management is an important component of BioWin projects. This section covers topics related to the
database BioWin uses to store simulation-generated and imported data for a project. Data options and
manipulation are accessed via the Project|Database menu in the main simulator window, and the Database
menu in the album.

Data Interval
BioWin allows you to set data monitoring intervals on a project-to-project basis, via the
Project|Database|Data Interval… command. This will present you with the Data interval editor, shown
below.

Project data interval settings

There are two data intervals that you may set if you wish, using the appropriate spin edit boxes. The first is
the Display / data interval. This is the data interval that will be used by BioWin to log data into the
database, and this value also will be used as the point drawing interval on charts and the data refresh

Biowin 6 Help Manual General Operation • 113

interval for tables and element information displays. For very dynamic systems (e.g. SBRs), it might be
necessary to decrease the interval to be able to see sudden changes in concentrations.
The second is the Summary pane update interval. This is the time interval that BioWin will use to refresh
the main window summary panes and status bar. It should be noted that if this value is set to a very low
number (i.e. high refresh frequency), it might result in decreased simulator speed because of the necessity
to redraw the contents of the main window summary pane. If you don't wish the summary panes to have
any automatic refresh, enter a value of zero in each spin edit box. One final point should also be mentioned.
Regardless of the value that you enter, the contents of the main window summary pane may be refreshed
by holding the mouse cursor over an element, as long as the summary panes are in Fly by mode.

Monitoring Data
You have complete control over the project simulation data that are logged to the database. This allows you
to optimize the size of the project database so that you only record what you are interested in. Selecting
Project|Database|Monitor item… will present you with the dialog box shown below used for specifying the
variables/parameters you want logged to the database.

Dialog used to set up monitoring for elements in a project configuration

Select the element you wish to monitor an item for from the Element name drop list box. The Location radio
button group is used to choose the location in the element (i.e. Input, Output {overflow}, Underflow) where
you wish to obtain the data to be logged. Note that this group changes depending on the type of element
you have selected. For example, the underflow location only is shown for elements that have an underflow
such as settlers. For a selected element, you may choose the parameters/variables you wish to monitor
using the Element specific, State variables, Water chemistry or Combined check list boxes. Like the
Location group, the Element specific list is dependent on the type of element selected.
Another method to set up monitoring for an element is to use the Monitor items tab. You can access this
tab by right-clicking on the element in the drawing board and selecting Properties… from the resulting
popup menu, or by double-clicking on the element. Use of this tab is identical to that of the

114 • General Operation Biowin 6 Help Manual

Project|Database|Monitor item… dialog, except for the fact that you do not select an element (you have
done this by clicking on the element in the drawing board).
If you find that you are always monitoring the same items in the same types of elements from project to
project, you may want to use BioWin's Auto-logging feature. You can use this feature to tell BioWin to
always monitor certain parameters/variables on an element-type basis. For more information, please see
Automatic Logging Options.

Un-monitoring Data
BioWin offers the functionality of un-monitoring state variables and parameters. You can un-monitor an
item by following the procedure outlined for monitoring items (except that you un-check boxes for variables
that had been previously monitored). This gives users increased control over what is logged to the BioWin
database. The following points regarding un-monitoring should be noted:
• When you plot a time series chart, BioWin automatically monitors the variables / parameters that
you plot. If the chart is deleted later, the items will be un-monitored.
• If you set up monitoring for items following the procedure outlined above, create a chart of these
items, and then delete the chart, the items will still be monitored.
• If you set up monitoring for items following the procedure outlined above, create a chart of these
items, and then attempt to un-monitor the items, BioWin will not allow the items to be un-
monitored. That is, the items will still be monitored because this is required for the chart(s) using
them.

Note: if you delete the chart, the items will be un-monitored, i.e. BioWin “remembers” your disallowed
attempt at un-monitoring and carries out the request when the chart(s) using the items are no longer
present.

Database Inventory
BioWin offers a means to display what is being monitored to the project database, as well as manage data
that have been imported. Selecting Project|Database|Inventory list… will present you with the inventory
dialog box, shown below.

Biowin 6 Help Manual General Operation • 115

The database inventory list of monitored items

This dialog lists the Database column titles. Since these are named with the convention "ElementName
MonitoredParameter", by looking at the list you can see what is being logged to the database. If you select
the box labeled Include imported columns, the list also will show the column titles of any imported data
that are contained in the database.
This dialog box also gives you the facility to manage data that you have imported into a BioWin project.
Clicking the Manage imported tab reveals the following dialog box.

Dialog box used for managing imported data

You can use the Imported name(s) drop list box to view the contents of the various data files that have been
imported to the BioWin project database. When you select a file, the column names are displayed in the X
Value column and Y Value column(s) lists. This is useful to verify that the file you have imported contains

116 • General Operation Biowin 6 Help Manual

the data you are interested in. If you decide that you no longer want the file to be included in the database,
clicking the Delete… button will remove it.
If you wish to import a data file into the database, clicking the Import… button will launch the procedure for
doing so. You will be presented with the Open File dialog box. Once you have selected the file you want to
import, the Import Wizard will take you through the remaining steps.

Importing Data
BioWin offers two methods for importing data to the project database. You may import data from:
1. A file, or;
2. The clipboard if you have copied a selection.
If you choose to import data from a file via the Project|Database|Import from file… command, you will be
presented with the Open File dialog box. Once you have selected the file you want to import, the Import
Wizard will take you through the remaining steps.
If you choose to import data from the clipboard via the Project|Database|Paste clipboard to database…
command, you will be presented with a dialog box that allows you to enter a brief description of the data,
shown below.

Dialog box for entering description of data imported from clipboard

This dialog gives you a chance to assign a descriptive name to the data that you are importing from the
clipboard. This name will be associated with the block of data so that you recognize it when you attempt to
use the imported data in other BioWin operations, such as plotting. This option is not required for file
imports as the file name is used to identify the data. Once you have provided the clipboard data block with a
name (or accepted the default name – do this with caution as you may end up with multiple identically-
named imported data), the Import Wizard will take you through the remaining steps.

Import Wizard
In this section, the BioWin import wizard is discussed in detail. The import wizard is invoked when you paste
data into BioWin from the Windows Clipboard or from a file. The import wizard takes you through the
following steps:
1. In the first step, you specify the type of delimiters that separate individual data values in the group
that you are pasting. From the Specify delimiter radio button group, select from Comma, Space,
Tab, or Other (where you enter the delimiter that is used). The viewing area at the bottom of the
dialog box that shows the contents of the file that you are pasting is meant to assist you in choosing
the correct delimiter by displaying the delimiters in the file. The viewing area has a file size limit of
64 KB, so you will not be able to properly preview your file if it exceeds this limit. This does not
compromise BioWin's ability to import your data if the file size is greater than 64 KB.

Biowin 6 Help Manual General Operation • 117

 The first step of the import wizard

Note: If you have instances in your data file where you have data values separated by multiple delimiters,
then you should check the box labeled Treat consecutive delimiters as one. This will avoid pasting gaps into
the itinerary. This option will be enabled only when you have spaces or other delimiters in your data, to
decrease the chances of this option causing BioWin to treat a missing data value as an extra delimiter, which
would result in the deletion of the column containing the missing data value.

2. In the second step, you are shown a preview of what the data will look like when it is pasted into the
itinerary. This is helpful to ensure that you have selected the proper options in the first step. If you
are not satisfied with the way the data looks, you can return to the previous step by clicking the
Back button. You can transpose the data you are pasting by switching between the Rows and
Columns button in the Data in: radio button group. The preview will change to reflect these
changes. Also, if you wish to exclude the first row or several rows, you can increase the value in the
Data starts in row spin edit box. Once again, the preview will change to reflect these changes.

118 • General Operation Biowin 6 Help Manual

The second step of the import wizard

When you are happy with the preview of the data that will be pasted into the itinerary, click the OK button
to finish the operation.

Importing Data for Plotting - Example

The following section outlines the steps for importing data from a spreadsheet program into BioWin using
the copy/paste method. A typical reason for doing this would be for plotting observed plant data in BioWin
as part of a model calibration exercise.
For the purpose of this example, suppose that we want to plot the following data that we have in Excel in a
BioWin chart:

Biowin 6 Help Manual General Operation • 119

Note: The date/time format has one of Excel’s pre-defined formats applied to it (i.e. year-month-day
hh:mm). BioWin does not recognize these formats, so the first step is to prepare a duplicate date/time
column with this Excel formatting removed. One way to do this is to simply make a copy of the date/time
column and format the duplicate column as General (this has been done in the column labeled Numerical
Date in the screenshot below). A second method could be to once again format the duplicate column as
General and use the first date/time as “time zero” (this has been done in the column labeled Relative Date
in the screenshot below). Note that both methods have been shown in the example screenshot below.
However, it is only necessary to do one. The remaining steps of this example assume that only the
Numerical Date method has been implemented in the spreadsheet. Note also that there are descriptive
headings for each column in the spreadsheet. It’s easiest if these are on a single line.

120 • General Operation Biowin 6 Help Manual

Once you have identified and organized the data you want to import to BioWin, select the data block in
Excel and choose Edit|Copy from the menu, or use the keyboard short-cut Ctrl+C.
In BioWin, use either the Project|Database menu command from the main simulator window or the
Database menu command from the Album to click on the Paste clipboard to database… command. You will
then see a dialog box that allows you to enter a brief description of the data, as shown below. The name you
provide will be associated with the block of data so that you can recognize it when you attempt to use the
imported data in other BioWin operations, such as plotting.

Next, the import wizard will take you through the following steps:
1. In the first step, you specify the type of delimiters that separate individual data values in the group
that you are pasting. Typically when importing from a spreadsheet, the Tab option can be selected.

Biowin 6 Help Manual General Operation • 121

 2. In the second step, you are shown a preview of what the data will look like when it is pasted into
BioWin’s database. This is helpful to ensure that you have selected the proper options in the first
step. Note for the example here, we have told BioWin that the numerical data starts in row 1 and
that the column titles are in row 0 (BioWin counts lists starting from zero).

Once OK has been clicked, the data will have been imported into BioWin’s internal database.
Note that if there had been data missing from some cells in the spreadsheet, and/or there were non-
numeric entries (which is very common, for example, if a lab test has yielded a “non-detect” result) then
BioWin would provide a warning about that for each occurrence. Typically, you would click the Ignore all
option in this case so that BioWin will not plot the invalid non-numeric data.

122 • General Operation Biowin 6 Help Manual

Now that the data have been imported, they are ready to plot as a time-series in a chart. The steps to do
this are as follows:
3. Right-click on an album chart and click Add Series in the resulting popup menu.
4. Click on the Imported tab of the Add Series dialog box.
5. Using the Imported Name(s) drop list box, select the name of a file or block of data (from the
clipboard) you have already imported to the database. In our example the name Effluent Ammonia
would be selected.
6. Choose the Time series option.
7. From the X Value column list, select the column that you want to use as the independent variable in
the plot. In our example, this would be the column labeled Numerical Date. Because this example
has a date column that does not start at zero, the box labeled Add simulation start date/time to X
values should not be checked. This box only should be checked if the first time of the date column is
zero (i.e. the Relative Date discussed above).
8. From the Y Value column(s) list, select the columns that you want to plot. In our example, this
would be the name Obs Eff NH3 (mgN/L) column.
9. Click the Plot selected button.
10. From the General series gallery, choose the desired series style that you wish to apply. Often it is
useful to plot observed data as a Point Series and plot BioWin simulated results as Line or Fast Line
series.
11. Click the Close button to finish.

Exporting Data
BioWin offers two methods for exporting data from the project database. You may export data to:
1. A file, or;
2. The clipboard.
If you choose to export data to a file via the Project|Database|Export to File… command, you will be
presented with the Save File dialog box. You may choose to export to one of the following file formats:
1. Text file (*.txt) – in this format, columns of data will be delimited by tabs, which is a suitable format
for import to a spreadsheet application.
2. Comma-separated values (*.csv) – in this format, columns of data will be delimited by commas. This
file format also may be imported to a spreadsheet application.
3. All file (*.*) – in this format, columns of data will be separated with a delimiter of your choice.
Once you have used the Save File dialog box to specify a name, file type, and location for you exported data
file you will be presented with the following dialog box:

Biowin 6 Help Manual General Operation • 123

Dialog box showing data to be exported to file

A list shows the database column titles that will be exported. By checking the box labeled Include imported
columns, you can also export to this file any data that you have previously imported to the database. Note
that the Specify delimiter for export radio button group only will be available if you have selected the All
file (*.*) file format from the above list.
If you choose to export data to the clipboard via the Project|Database|Export to Clipboard… command,
you will be presented with a dialog box identical to the one shown above with the exception that no choice
of delimiters is offered. Tabs will separate the data columns you paste to the clipboard since this is the best
format for copying the data into a spreadsheet application.

Custom Export Utility

BioWin offers you an increased level of control over what is exported from the database, via the
Database|Custom Export to File… and Database|Custom Export to Clipboard… commands.
These commands are different from the “non-custom” export database commands in that they allow you to
select which elements you want to export data for, the variables that you want to export, and the order of
the variables.
If you choose to export data to a file via the Database|Custom Export to File… command, you will be
presented with the Save File dialog box. You may choose to export to one of the following file formats:
1. Text file (*.txt) – in this format, columns of data will be delimited by tabs, which is a suitable format
for import to a spreadsheet application.
2. Comma-separated values (*.csv) – in this format, columns of data will be delimited by commas. This
file format also may be imported to a spreadsheet application.
3. All file (*.*) – in this format, columns of data will be separated with a delimiter of your choice.
If you choose to export data to the clipboard via the Database|Custom Export to Clipboard… command, no
choice of delimiters is offered. Tabs will separate the data columns you paste to the clipboard since this is
the best format for copying the data into a spreadsheet application.

124 • General Operation Biowin 6 Help Manual

Each of these commands allows you to select the elements that you want to export data for, using the
following dialog box.

Dialog used to select elements for the custom export commands

From the Elements tree view, select the element(s) that you wish to export data for.
• If you wish to include all the elements from a group (for example, all the Bioreactors), click on the
group heading and then click the right-pointing arrow to move them all to the Selected elements
list.
• If you wish to include only certain elements from a group (or groups), then click on the plus sign (+)
next to the group heading to expand it, click on the specific element you want to include, and then
click the right-pointing arrow to move it to the Selected elements list.
• If you want to change the order of the Selected elements columns in the export, move the elements
around by clicking on them and then clicking the Up/Down arrows. In the above example, the
leftmost columns of your exported data would be occupied by monitored variables you have
exported for the element named Anoxic, followed by those for the Aerobic element.
Once you have selected the elements to export data for, click on the Choose compounds tab to select the
variables that you want to export for the selected elements. This tab is shown below:

Biowin 6 Help Manual General Operation • 125

Dialog used to select parameters for the custom export commands

In the Compounds list, select the compounds that you wish to appear in your table, and add them to the
Selected compounds list by clicking the right-pointing arrow. To select multiple compounds:
• Select contiguous multiple compounds by clicking on the first desired compound, holding down the
Shift key, and clicking the last desired compound.
• Select non-contiguous multiple series by holding the Ctrl key and clicking on the different desired
compounds.
If you want to change the order of the Selected compounds in the export, move the compounds around by
clicking on them and then clicking the Up/Down arrows.
By checking the box labeled Imported columns, you can also export any data that you have previously
imported to the database.

Note: using these two dialogs to export data requires that you have previously set up monitoring for the
parameters in the appropriate elements, and run a dynamic simulation. Use of these dialogs to export data
does not set up monitoring.

Exporting To GFX Files

From the Album|Database|Export to GFX Files… menu, you can export the database in GFX format. When
you execute this command, you will be presented with the following dialog box.

126 • General Operation Biowin 6 Help Manual

Dialog used for setting up database export to GFX file

GFX *.Pn files may contain up to 16 variables (e.g. VSS, TSS, CODT, etc.). GFX *.Sn files contain the data
corresponding to the *.Pn files. The data are in hexadecimal integer format, and missing parameters (i.e. if
the Pn file contains less than 16 parameters) are padded with FFFF. These files will be stored in the
subdirectory name that you specify in the Basename text entry area. This subdirectory will be located
beneath the BioWin Data directory.
You must specify the Data log type as Boundary value or Linear average. GFX assumes 15-minute intervals;
data logged to this file are expected to be the average for the 15 minutes (for the best approximation of this
you can set the BioWin data interval to 15 minutes).
• A Boundary value export uses data taken from the BioWin database at 15-minute intervals.
• A Linear average export uses data taken from the BioWin database at 15-minute intervals, but the
data are linearly interpolated at the midpoints (i.e. 7.5, 22.5, 37.5 minutes) using surrounding data.
Clicking the Start export button allows you to select the elements that you want to export data for, using
the following dialog box:

Biowin 6 Help Manual General Operation • 127

Dialog used to select elements for the GFX export

From the Elements tree view, select the element(s) that you wish to export data for.
• If you wish to include all the elements from a group (for example, all the bioreactors), click on the
group heading and then click the right-pointing arrow to move them all to the Selected elements
list.
• If you wish to include only certain elements from a group (or groups), then click on the plus sign (+)
next to the group heading to expand it, click on the specific element you want to include, and then
click the right-pointing arrow to move it to the Selected elements list.
• If you want to change the order of the Selected elements columns, move the elements around by
clicking on them and then clicking the Up/Down arrows. In the above example, the leftmost
columns of your exported data would be occupied by monitored parameters you have exported for
the element named Anoxic, followed by those for the Aerobic element.
Once you have selected the elements to export data for, click on the Choose compounds tab to select the
parameters that you want to export for the selected elements. This tab is shown below:

128 • General Operation Biowin 6 Help Manual

Dialog used to select parameters for the GFX export

In the Compounds list, select the compounds that you wish to appear in your table, and add them to the
Selected compounds list by clicking the right-pointing arrow. To select multiple compounds:
• Select contiguous multiple compounds by clicking on the first desired compound, holding down the
Shift key, and clicking the last desired compound.
• Select non-contiguous multiple series by holding the Ctrl key and clicking on the different desired
compounds.
If you want to change the order of the Selected compounds in the export, move the compounds around by
clicking on them and then clicking the Up/Down arrows.

Note: using these two dialogs to export data requires that you have previously set up monitoring for the
parameters in the appropriate elements, and run a dynamic simulation. Use of these dialogs to export data
does not set up monitoring.

Once you have selected the elements and compounds for exporting to the GFX file, click OK to begin the
export process. The status bar on the main exporting dialog will show the progress of the export process.
When this is finished, you can find the files in the folder with your specified Basename under the BioWin
Data directory (The exact folder location is depending on your BioWin installation. However, a typical path
is: C:\Program Files\EnviroSim\BioWin x.x\Data; where x.x is the version number).

Biowin 6 Help Manual General Operation • 129

Alarms
BioWin will notify you when certain conditions occur while you are performing a simulation. At the end of a
steady state simulation, BioWin will always display the following alert if any alarm conditions have been
detected:

Notification displayed at the end of a steady state simulation if alarm conditions have been detected

If you have set the Alarm list (on the General tab accessed via the Tools|Customize… menu command) to
any value greater than zero, clicking OK on the above notification will display a list showing the element in
which the alarm condition occurred and the alarm condition. The list also can be viewed at any time via the
View|Alarms command. An example of such a list is shown below.

An example of an alarm list

The alarm list also shows you the number of Current alarms (this information also is shown in the main
window status bar), and the Maximum number of alarms logged (set in the Alarm list on the General tab
accessed via the Tools|Customize… menu command).
If you have un-checked the box labeled Suppress alarms in dynamic simulations (on the General tab
accessed via the Tools|Customize… menu command), BioWin will log alarm conditions encountered during
dynamic simulations. For these alarms, the time when they occurred is displayed in the alarm list (see third
column in the screen shot above). The list will be displayed when you choose to end a dynamic simulation.
You may clear an alarm list by right-clicking in the list and selecting Clear from the resulting popup menu.
Note that users can turn off one or more alarms for a project by selecting Project|Current Project Options,
clicking the Alarm options tab, and unchecking the box next to the alarm that they wish to turn off.

Alarm conditions
This section describes the various alarms that you may encounter in a project.

130 • General Operation Biowin 6 Help Manual

Recursive Configuration
You will be presented with this warning if your configuration is laid out in such a manner that you are
attempting to connect a node splitter directly to a node mixer without first passing through an element that
has a volume. The simplest case illustrating this is shown below.

A simple example of a recursive configuration

This situation is not allowed because there is no physical meaning to two node elements joined in sequence
and the flow solver does not allow this physical impossibility.

Flow Specifications Could Not Be Achieved

This alarm occurs when the flow rate specified by the user could not be achieved because other constrains
within the system override the user setting. For example; the flow rate specified will result in negative flows
elsewhere in the system, a variable volume tank with a specified outflow rate has run dry (or is overflowing),
a constant rate split specification exceeds the influent flow to the splitter.

Biofilm, media and liquid volume exceeds tank volume. Increase the assumed
biofilm thickness to address this problem.
This alarm occurs when the volume occupied by the media, biofilm and bulk liquid becomes too large
(exceeds the tank physical volume). To reduce the volume allocated for bulk liquid (and increase the volume
allocated for biofilm) increase the “Assumed Film thickness for tank volume correction” parameter under
Project > Parameters > Biofilm > Biofilm general tab to match (or exceed) the simulated biofilm thickness.

Biowin 6 Help Manual General Operation • 131

Nitrogen Limited Conditions Occurred
This alarm occurs when the nitrogen (ammonia and nitrate nitrogen) in a biological zone is sufficiently low to
cause a 50% or more reduction in the reaction rates.

Phosphorus Limited Conditions Occurred

This alarm occurs when the phosphate (soluble PO4) concentration in a biological zone is sufficiently low to
cause a 50% or more reduction in the growth reaction rates.

Consider Turning On Ammonia Stripping Model and Gas Phase Modelling

Even when ammonia stripping is not being modelled (i.e. the default setting), BioWin performs a check on
ammonia stripping potential as follows: BioWin calculates 0.75% of the effluent ammonia and adds it to the
gas phase. This concentration is used to determine the saturation concentration for transfer, and if the
direction is from the liquid to the gas the alarm is triggered. Essentially the alarm is triggered if BioWin
considers that there is potential for about 1% (or more) of the effluent ammonia to be stripped.

Calcium or Magnesium limited conditions occured

This alarm occurs when the calcium or magnesium concentrations in a biological zone are sufficiently low to
cause a 50% or more reduction in the in the growth of organisms.

More than 10% of effluent N is stripped as ammonia

This alarm occurs when it appears that 10% or more of the effluent N from a biological zone is being
stripped by the gas phase.

The Air Flow Required To Achieve The DO Setpoint Exceeds The Maximum Air Flow
Rate
This alarm occurs when the air flow rate required to achieve the DO setpoint entered by the user is higher
than the maximum air flow rate specified by the user.

The air flow rate required to achieve the DO setpoint is below the specified
minimum air flow rate
This alarm occurs when the air flow rate required to achieve the DO setpoint entered by the user is lower
than the minimum air flow rate specified by the user.

Specified D.O setpoint above 90% saturation value - using 90% of saturation value
This alarm occurs when the dissolved oxygen setpoint specified by the user exceeds 90% of the D.O.
saturated concentration for the specified gas phase concentration (supply or off-gas as appropriate).

132 • General Operation Biowin 6 Help Manual

The desired air flow rate was adjusted to within the range specified
This alarm occurs when a specified air flow rate was not withing the air flow rate range specified and BioWin
has adjusted the flow accordingly.

Specified DO setpoint cannot be achieved - specify a lower value

This alarm occurs in a trickling filter when the D.O. setpoint cannot be achieved due to mass transfer
limitations.

The Power Supply Required To Achieve The DO Setpoint Exceeds The Maximum
Power Supply Rate
This alarm occurs when the power supply rate required to achieve the DO setpoint entered by the user is
higher than the maximum power supply rate specified by the user.

The Power Supply Requested Exceeds The Maximum Power Supply Rate
This alarm occurs when the power supply requested is higher than the maximum power supply rate (as
specified by the user).

High Air Flow / Diffuser

This alarm occurs when the simulated air flow rate per diffuser exceeds the maximum air flow rate per
diffuser specified by the user.

DO In Tank Is Higher Than Specified Setpoint Due To DO In Input (Even Without

Aeration)
This alarm occurs when the DO setpoint specified by the user could not be achieved because the influent DO
is higher than the DO setpoint and there is insufficient oxygen demand to lower the DO to the setpoint
specified.

Low / High pH Inhibition

This alarm can apply to:
• Autotrophs
• Heterotrophs
These alarms occur when the pH in a biological zone is at a level where it is inhibiting the growth rate by
50% or more.

Low pH in digester - may be acidic

This alarm occurs when the pH in a digester falls below 6.

Biowin 6 Help Manual General Operation • 133

Calculated pH and specified pH are quite different from each other
This alarm occurs when the specified pH in a digester is more than half of a pH unit from the calculated
value.

pH (or IS) Could Not Be Calculated

This alarm occurs when there is an error calculating the pH or ionic strength. This may be caused when the
pH or ionic strength hits one of the bounds (high and low bounds apply) or when a solution to the pH could
not be found.

Warning: High Ionic Strength (Activity Coefficients)

These alarms occur when the ionic strength is too high to calculate the approximate activity coefficients. The
activity coefficients approximations calculated at an ionic strength of 3 are used instead.

Anion or Cation limitation for growth

This alarm occurs when concentration levels of “Other anions” or “Other cations” are low enough to reduce
the growth rate of organisms by 50% or more.

Error: Unable to schedule electricity use costs

This alarm occurs when there is a problem scheduling the required changes to the seasonal electricity costs
(i.e. the electricity cost pattern could not be properly implemented).

Error: Unable to calculate diffuser density

This alarm occurs when there are no diffuser parameters. If this occurs then BioWin uses a diffuser density
of 10%.

Error calculating pacer element flow

This alarm occurs when BioWin is unable to calculate/set a flow paced element.

Unable to match pH / alkalinity specification

This alarm occurs during a dynamic simulation when BioWin is unable to match the specified influent pH and
alkalinity.

Error: Possible flow race condition. Volume bound may be violated - check results
This alarm occurs when BioWin encouters unacheiveable/conflicting flow specifications during a dynamic
simulation.

134 • General Operation Biowin 6 Help Manual

Opening Files from Previous Versions
When you open a file created in an earlier version of BioWin, you will be presented with a dialog box that
contains "conversion notes". These warnings reflect changes that have been made to the underlying model
structure of BioWin.
The content of the conversion notes window depends on which version of BioWin the file being loaded was
created in. The most important aspects to recognize when loading a file from a previous BioWin version are:
• Review inputs: The state vector of the most recent BioWin version might be different from the
previous version. You should review your input elements to check that you have appropriate values
for the new state variables and/or wastewater characteristic fractions.
• Check model parameters: This version of BioWin uses the most recent version of the BioWin ASDM
model. It is imperative that all model parameters (kinetic, stoichiometric, switching function
parameters, etc.) should be checked carefully when loading a file created in an earlier version of
BioWin.
• Re-run the simulation: When loading a file created in a previous BioWin version, you must re-run
any simulations to get meaningful results.

Conversion Notes
Conversion notes are displayed when you open a file created in an earlier version of BioWin. These are
intended to prompt you to make changes in the BioWin file that will make it compatible with the latest
version. It is imperative that all model parameters (kinetic, stoichiometric, switching function parameters,
etc.) should be checked carefully. The following sections provide brief explanations for the different
messages that appear, depending on the file version being loaded.

Some Default Parameters Have Changed – Check All Project Parameter Tabs:
Kinetic, Stoich., Biofilm, Other – Typically Update to New Defaults
When a file created in a previous version of BioWin is opened, EnviroSim strongly recommends opening all
the model parameter tabs and updating to new defaults. In many cases, several parameters will require
changing. Certain parameters that have been calibrated by users (e.g. nitrifier maximum specific growth
rates) may be left at their changed values, whereas others (e.g. OHO hydrolysis rate) may require
recalibration.

All Alkalinities Will Be Converted

Alkalinity is not a state variable in BioWin, in some older versions of BioWin alkalinity was a state variable
and this message will be displayed if you open a file from one of those versions of BioWin. In influent
streams you can enter alkalinity (and pH) and BioWin will calculate the required dissolved CO2, anions and
cations. BioWin calculates the alkalinity, but now it is determined from the equilibrium chemistry of the
stream, rather than by a pseudo state variable.

Additional State Variables Included - Review Inputs

BioWin has several additional state variables. You should review your input elements to check that you have
appropriate values for the new state variables and/or wastewater characteristic fractions, and that an
appropriate pH is specified.

Biowin 6 Help Manual General Operation • 135

Additional State Variables Included AND/OR Parameters Should Be Changed And
New Parameters Added
BioWin incorporates additions and some modifications to the activated sludge and anaerobic digestion
model that was used in the version of BioWin that created the file. In the case of model additions, BioWin
will assign default values to all model parameters for the new model components. In the case of model
modifications parameter values from the earlier version will be mapped to the appropriate parameter in
BioWin and default values will be assigned to new model parameters. It is imperative that all model
parameters (kinetic, stoichiometric, switching function parameters, etc.) should be checked carefully
particularly when loading a file created in an earlier version of BioWin.

Unable to convert Alkalinity

When loading an old file BioWin attempts to match the old alkalinity, by adding acid or base. If it is unable to
achieve a match this note occurs. If you see this note you should check your influent streams and pH’s.

Alkalinity Is No Longer A State Variable - Equation Discarded

Alkalinity is not a BioWin state variable (it is still reported, but now it is determined from the equilibrium
chemistry of the stream, rather than by a pseudo state variable). This message occurs because you have
used Alkalinity in a Model Builder model, but since it is not available as a state variable you will need to
adjust your model to account for this.

“PolyP bound cations” Is No Longer A State Variable - Equation Discarded

“PolyP bound cations” is no longer a BioWin state variable. This message occurs because you have used this
state in a Model Builder model, but since it is not available as a state variable you will need to adjust your
model to account for this.

Process name not found - removed

When loading an old file BioWin is unable to match a process rate that was plotted in the old file. The
process has been removed or modified in the new version.

Enter Head Space Volume For Digesters

The gas phase of the anaerobic digester element is now modeled and you must specify the volume that
BioWin should use for these calculations. Some older versions of BioWin did not model the gas phase.

Methane Production Now Reported As A Fraction

Methane is now reported as a fraction. In older versions of BioWin it was reported as a Methane production
rate. You will need to adjust your chart scales to see the new value (which should always be below 1).

136 • General Operation Biowin 6 Help Manual

Hydrogen Production Now Reported As A Fraction
Hydrogen is now reported as a fraction. In older versions of BioWin it was reported as a Hydrogen
production rate. You will need to adjust your chart scales to see the new value (which should always be less
than 1).

OUR And Denitrification Rate No Longer Reported For Anaerobic Digesters

OUR and denitrification rate are not available for anaerobic digesters in BioWin (OUR should generally be
low in these vessels anyway).

Aerobic Denit half sat. no longer used check your parameters

The aerobic denitrification half saturation concentration is no longer available as a parameter. BioWin has
determined that you were previously using a non-default value for this parameter so you should review your
parameter settings. BioWin now uses a single dissolved oxygen half saturation concentration.

Variable XXX No Longer Available - Check Your Graphs

The variable “XXX” is no longer available but BioWin has detected that you were monitoring it. You will need
to check your graphs as any series based on this will now be “static” showing only the values from the last
simulation in the BioWin version that created the file.

Digester gas now reported in m3/hr for SI units system

Digester gas flow rate now reported in units of m3/hr at field conditions.

Aeration Parameters Can Now Also Be Global

Aeration parameters can be globally specified now. Older files are loaded with local aeration parameters so
that any settings like alpha, beta etc. are preserved. In certain cases you may wish to have “local” aeration
parameters (for example in a pure oxygen system where you need to change the oxygen content of the gas).
You can do this by selecting the Local parameters check box on the Operation tab.

New program version - Check pacer element settings

The file loaded was created in an earlier version of BioWin with a pacer element - you should review your
pacer element settings prior to performing any simulations.

New program version – re-simulate to get meaningful results.

The file loaded was created in an earlier version of BioWin. You must re-run any simulations to get
meaningful results.

Very old file - check carefully.

The file loaded was created in BioWin 2.x or earlier. Significant changes in the model and files structure have
occurred - you should check all of your parameter settings, charts and other input data carefully.

Biowin 6 Help Manual General Operation • 137

Old file - review model builder models carefully
The file loaded was created in BioWin 2.x or earlier. Review model builder models carefully.

N and P associated with endogenous residue are now modeled as a fraction of Ze

The file loaded was created in an earlier version of BioWin in which the nitrogen and phosphorus content of
the endogenous material was stored in the state variables “Part. inert N” (XIN) and “Part. inert P” (XIP)
together with N and P associated with influent inert particulate COD (XI). In BioWin the nitrogen and
phosphorus associated with the endogenous material are stored as fractions of the endogenous material.
This means that the states “Part. inert N” and “Part. inert P” now represent only influent unbiodegradable
material associated with the influent “Part. inert COD” (XI). Consequently you must re-run any simulations
to get meaningful results.

Water chemistry concentrations are now reported in mmoles/L

The file loaded was created in an earlier version of BioWin in which the water chemistry was reported in
mass rather than molar terms.

Anaerobic model introduced. Additional state variables included

The file loaded was created in a very old version of BioWin before the introduction of an anaerobic model.

CH4 production rate no longer reported for activated primaries

A file created in a pre-3.x version of BioWin will no report methane production rate for an activated primary.

Customizing BioWin

Customizing the Project Appearance

There are a number of parts and features of BioWin that can be customized to look how you want. When
you customize BioWin, you essentially are changing the default settings of the BioWin work environment
and all new projects that are created therein. The following sections discuss the dialog boxes that are
accessed via the Project|New Project Options… menu command that may be used to customize BioWin.
The difference between customizing BioWin and setting individual project options should be emphasized.
For more information on the various project options which may be set for individual projects, refer to the
Managing BioWin Projects section.

Drawing Board
This section outlines the various project options that can be set for the default drawing board. The drawing
board options may be accessed in the main simulator window by choosing Project|New Project Options…
from the menu and selecting the Drawing board tab, shown in the picture below.

138 • General Operation Biowin 6 Help Manual

New project drawing board options tab

Aspects of the Drawing board appearance that may be changed include the Font and the Color. Clicking the
Font… button will open the font properties dialog box and will allow you to change the font that is used to
label element pictures on the drawing board. Selecting a new color from the drop list box will change the
background color of the drawing board. Notice that a preview of the drawing board background color and
the selected font is given in the dialog box.
The Drawing board size also may be changed. Changing the values in the Width and Height spin edit boxes
will change the overall dimensions of the drawing board. The size of the main window occupied by the
drawing board is not changed, however, the overall size is changed as evidenced by a change in the size of
the scroll box in the scroll bar. The default values of 6,000 by 2,000 translate roughly to 60 by 20 inches. The
zoom limits of the drawing board can be set so that zooming can only take place between minimum and
maximum levels.
The Drawing board snap resolution can be changed in either or both the X and Y directions. The snap
feature helps you align elements precisely on the drawing board. When you place or move an element on
the drawing board, it aligns itself (i.e. “snaps”) to the nearest grid point (grid points are invisible). Therefore,
increasing the snap values results in a coarser grid for the elements to snap to. This means that you have
less control over their placement. Decreasing the snap values results in a finer grid for the elements to snap
to, which means that you have increased control over their placement.
A number of settings related to Element display also may be changed. You can choose whether new
projects show names for elements using the Show element names checkbox, and where they will be shown

Biowin 6 Help Manual General Operation • 139

using the Location of element name (if displayed) relative to element image radio buttons (note that you
specify which elements will show their names on the General tab of the Tools|Cusomtize menu).
You can also choose the default new project display of tags using the Tag display location (relative to
element image) setting. Unless you want tags to show for every element (which often can be somewhat
overwhelming, especially for complex flowsheets), likely it is best to leave this setting on None and use the
tag settings within individual elements to override this setting. Other default new project tag settings such
as whether tags include variable names (in addition to values), whether tags include units, tag font size and
background colour, etc. can be set in this dialogue box. Note that the Tag name format can either be
Abbreviated names (the default) or it can mirror the BioWin global format set via the
Tools|Cusomtize…Display options tab.

Pipe Options
You also can control the default appearance of pipes in your project, using the Project|New Project
Options… menu command and selecting the Pipe tab, shown in the figure below. In the Line section, the
Width, Color, and Style of the lines used to represent pipes on the drawing board can be changed.

Note: To get more than the listed colors, please right click on the Color list box to display the full color
dialog box.

You may increase the arrow size on the lines used to represent pipes in the Arrow section. The arrow angle
also can be changed.

Note: The “arrow angle” refers to the acute angle between the arrow side and the line. For example, if you
want arrows with “flat” bases, set the arrow side angle to the maximum of 60 degrees.

140 • General Operation Biowin 6 Help Manual

New project pipe options tab

Note: It also is possible to change pipe line and arrow settings for individual pipes. Access the properties of
the pipe you wish to change by double-clicking it or right-clicking it and selecting Properties… from the
resulting pop-up menu. You will be presented with the same set of options that have just been outlined;
however, these changes will affect this particular pipe only.

Setting the Unit System

This section outlines the various options that can be set for the unit system used in a project. The project
unit system may be accessed in the main simulator window by choosing Project|New Project Options…
from the menu and selecting the Unit system tab, shown in the picture below.

Biowin 6 Help Manual General Operation • 141

New project unit system options

In the Flow units radio button group, you may choose from the following:
• cubic meters per day (m3/d)
• cubim meters per hour (m3/hr)
• litres per day (L/d)
• megalitres per day (ML/d)
• megagallons per day (mgd)
• gallons per day (gal/d)
It should be noted that the same basis is used for flow and volume. For example, if you choose L/d as your
flow unit, then volumes (e.g. for bioreactors, settling tanks) will be in liters also.

Note: Air flow rates are in units of m3/hr (normalized to 20 degrees Celsius and 1 atmosphere of pressure).

If you choose US units as your flow basis, then the following US units will be used for other calculations in
BioWin:

Measure US Unit

142 • General Operation Biowin 6 Help Manual

 Length feet (ft)
Area square feet (ft2)

Mass pounds (lbs)

Pressure pounds per square inch (psi)
Air Flow Standard Cubic Feet per Minute (SCFM)
Specific Velocity gal/ft2/d

Mass Loading Rate lbs/ft2/d

Concentration milligrams per liter (mg/L)

In the BOD basis radio button group, you may choose the length of time that BioWin uses to calculate BOD
values. You may choose between 5, 7, and 20 day BOD.

Using Project Templates

This section outlines the various options that can be set for the album and notes templates you can use in a
project. Templates for albums and notes may be accessed in the main simulator window by choosing
Project|New Project Options… from the menu and selecting the Templates tab, shown in the picture
below.

New project templates dialog box

When you first open the BioWin album, it will contain a default number of pages. You can customize the
number of pages using the New Album starts with spin edit box.

Biowin 6 Help Manual General Operation • 143

Note: These default pages contain one pane; if you want pages with multiple panes, you must add these
manually.

If you have a number of album pages set up with pane and display configurations set to your liking, you can
set this group of pages as your default album template file so that the album will open containing these
pages. If you click the New Album from template radio button, the Select template file… button will be
activated. Clicking this button will open a Select template dialog box allowing you to specify an album
template pages (*.atp) file you have previously created in BioWin.
The Use notes template file check box allows you to specify a file to use as a template when you execute
the Project|Notes command. Checking this box will activate the Select template file… button which will
open a Select template dialog box when it is clicked, allowing you to specify a Rich Text Format (*.RTF) or
Text (*.TXT) file that you have created with another application such as Microsoft Word. For example, a
modeling project QA/QC form could be drawn up in Word and then loaded as a BioWin Notes template file.

Customizing the Work Environment

There are a number of parts and features of BioWin that can be customized to behave how you want. When
you customize BioWin, you essentially are changing the default settings of the BioWin work environment
and all new projects that are created therein. The following sections discuss the dialog boxes that are
accessed via the Tools|Customize… menu command that may be used to customize BioWin.
The difference between customizing BioWin and setting individual project options should be emphasized.
For more information on the various project options which may be set for individual projects, refer to the
Managing BioWin Projects section.

General Options
The General tab, shown below, may be used to customize General settings for BioWin.

144 • General Operation Biowin 6 Help Manual

Tab used to customize general options

The number of files that are listed in the most recently used file list at the bottom of the main simulator
window File menu can be changed using the Recent file list spin edit box.
The number of alarms that are displayed at one time in the alarm list can be controlled by using the Alarm
list spin edit box. If you want BioWin to ignore alarms during dynamic simulations, place a check in the box
labeled Suppress alarms in dynamic simulations. Checking this box stops BioWin from checking any alarm
conditions, so no alarms will be logged during dynamic simulations regardless of the number you have
entered in the Alarm list spin edit box.
You can specify whether you want BioWin to save dynamic runs automatically, and the frequency (in terms
of dynamic simulation days) at which to save. If this option is selected, BioWin will create backup files
named filename.X, where filename is the name you have selected for the currently open BioWin file. X will
be integers indicating the number of automatic saves that have been performed. For example, say you set
up BioWin to save dynamic runs automatically every 10 days, and then commence a 30 day dynamic
simulation on a file you have saved as myBioWinfile.bwc. At the 10th day of the dynamic simulation, BioWin
will save a file called myBioWinfile.1. At the 20th day of the dynamic simulation, BioWin will save a file called
myBioWinfile.2. At the 30th day of the dynamic simulation, BioWin will save a file called myBioWinfile.3.

Biowin 6 Help Manual General Operation • 145

You can specify whether you want BioWin to save backup files of the project file. Selecting this option will
create a temporary file with an “.abw” extension. The saving frequency is every eight minutes. The
temporary file is deleted automatically when you exit BioWin normally (i.e. a “non-crash” exit).
Most users will want to allow BioWin to pre-allocate database memory for dynamic simulations. When this
option is selected, BioWin obtains the required amount of memory it will need before starting a dynamic
simulation (the amount of memory required depends on the number of parameters being monitored in the
database, the database monitoring frequency, and the length of the dynamic simulation). Selecting this
option may result in a slight delay at the beginning of long dynamic simulations, but will avoid problems with
BioWin slowing down during long dynamic runs
You can specify whether you want BioWin to automatically show notes after loading file. Selecting this
option will open any saved note file automatically when the program is first opened.
When steady state simulation table updates or dynamic simulation table updates is selected then BioWin
will update all tables in the Album as the relative simulation progresses, based on the data interval specified
in Project|Database|Data Interval…. When these options are unchecked, tables in the Album will only be
updated at the end of the respective simulation. Updating tables only at the end of a simulation (i.e. by
unchecking these two options) will improve the simulation speed of files with large tables, so it is
recommended that these options are left unchecked except for special cases.
The default model parameters for BioWin can be controlled using the Edit parameter defaults… button in
the Parameter defaults section. This button opens the Parameter editor dialog box (see the Model
Parameter Editors section). Parameters can be modified and printed from this location. Use the Reset
BioWin Defaults button to restore the original settings for these parameters.

Display Options
Through using the Tools|Customize… menu command, on the Display options tab shown below, it is
possible to customize a number of settings related to what information is shown and how it is shown in
BioWin.

146 • General Operation Biowin 6 Help Manual

Tab used to customize display options

You can control how many decimal places are displayed throughout BioWin using the Decimal places spin
edit boxes. You are able to have separate decimal place settings for Concentrations (e.g. ammonia
concentration, pH values), Mass rates, and Others (e.g. flow values, OURs, OTRs). Selecting the Use
thousands separator option will display the localized Windows separator (e.g. a “,” in many European
countries or a “.” in North America).
You also may control the Column starting width of the columns used to display results in the Explorer and
other table views in BioWin, and the alignment of the data using the Align drop list box. If you select Title
width, then table columns will automatically size to display the full title for that column (if you change the
width, BioWin will remember your change for that table). If you select Fixed width, then table columns will
be the size that you specify (if you change the width, BioWin will remember your change for that table).
In many places throughout the BioWin interface, when you point at something with the mouse cursor you
get a small tool tip or Hint that will provide further information. The elapsed time in milliseconds before
showing the Hint can be customized using the Delay setting; the time in milliseconds that the Hint actually is
displayed can be customized using the Hide Delay setting.
The Element section may be used to choose the types of elements for which you want to Show element
names for on the drawing board – by placing a check beside the desired elements. Note that whether or not

Biowin 6 Help Manual General Operation • 147

the settings in this section take effect are controlled by the Element display setting on the Drawing board
tab of the Project|New project dialoague box.
If you check the box labelled Display option to store previous time series plots in the album, BioWin will
present you with the option to keep time series from previous dynamic simulations in the Album each time
you run a dynamic simulation. This option is useful for comparing the results of one simulation run with
others. When you restart a dynamic simulation, any series plotted from previous runs will remain on their
respective charts. The saved series keep their names but will have a number appended to them indicating
with which run they are associated. The naming convention is as follows:
• Saved series are numbered 0 to n-1
• Active series are numbered n
where n is the current simulation run number.
It is important to remember that saved series are simply lines on the charts for comparison purposes. They
are no longer contained in the database. Perhaps this is best illustrated with an example. Say you conduct a
dynamic simulation for five days and plot effluent ammonia. To assess the impact of the estimated
maximum nitrifier growth rate, you change this model parameter. You start another five-day dynamic
simulation from the same start date as the first run, and save the effluent ammonia time series.

Note: you are able to format saved series as you would any other. This includes assigning them new names
if you wish.

On your chart, there would be two series, "YourSeriesName#0" and "YourSeriesName#1". The series with 0
appended to its name is the saved series containing results from the first five day run. The series with 1
appended to its name contains results from the second five day run. Now suppose at the end of the second
five day run you decide to continue for another 5 days. On your chart you would see "YourSeriesName#1"
continuing to ten days, while "YourSeriesName#0" would be stopped at five days. If you exported the
database at the end of the second run, you would export ten days of effluent ammonia data generated with
the second maximum nitrifier growth rate.
In the Explorer summary items checklist, you may specify the variables that will be displayed for an element
when you click on its node or its parent node in the BioWin Explorer tree view. You can also toggle the
display of Mass rates in the Explorer on and off.
Alphabetical sorting of variables throughout BioWin can be toggled on or off.
To control the display of state variable naming, use the radio buttons in the State variable naming section to
choose between Full names, Abbreviated (cryptic), or Abbreviated (IWA). For example, the full name for
ordinary heterotrophs is “Biomass-Ordinary heterotrophic”, the abbreviated (cryptic) name is “B-Zh” and
the abbreviated name according to the IWA notation is “X_OHO”.

Print Options
The Printing options tab, shown below, may be used to customize print settings for BioWin.

148 • General Operation Biowin 6 Help Manual

Customize printing options dialog box

You can set up default printing Margins. With the Page % spin edit boxes in the section labeled Margins, you
can set the top, bottom, left, and right margins to a desired set of values. Use the Panel % spin edit box to
increase or decrease the white space between panes when you are printing out an album page.
There are some defaults that apply only to Drawing board prints. If you do not wish to print the border of
the drawing board, then de-select the box labeled Print bounding rectangle. By checking or un-checking the
boxes in the Include group, you can control whether or not the details entered via the Project|Info…
command will display on the printout. If you choose to have some or all of this information displayed on
drawing board printouts, then you can control the Font size using the spin edit box.
You can specify a default level of Chart Detail to adjust the text size on your print jobs. Sliding the scroll
towards More decreases the size of text on your chart and gives greater prevalence to the chart on the
printout. Sliding the scroll towards Normal increases the size of the text on your chart and gives less
prevalence to the chart on the printout.

Note: When you are printing the drawing board or an album display, you will have the opportunity to
override these defaults before finally sending the job to the printer.

There also are a number of options that apply only to printing of Tables. The Title size % sets the size of the
title font relative to the font size of the table text. Adjusting the Cell padding % changes the amount of

Biowin 6 Help Manual General Operation • 149

space between the text in a table cell and the table cell boundaries. The Grid pen width controls the
thickness of grid lines drawn in the table. If you want the printed table scaled to fit into the print area that
you have specified, select the Fit to print area option. You can control the drawing of grid lines by selecting
or de-selecting the Horizontal grid lines and Vertical grid lines options. You also may choose to print your
table as a BioWin Standard table, which is an elegant table with three horizontal lines: at the top of the
table, underlining the title, and at the bottom of the table. To have equally sized columns in the table, select
the Even column widths option. Since the entries in the first column quite often are longer than other
columns (since they contain names), there is an option to Autofit column 1 to avoid the truncation of the
first column entries.
If you want to include the project file name on the drawing board printout or on table printouts, check the
box labeled Include file name.

Report Options
You may customize the information that is included in reports generated by BioWin using the Report
options tab, shown below.

Tab used to control BioWin report information

This tab may be used to specify what will be included in BioWin Word and Excel reports. Options for the
two report types are discussed in the following sections.

150 • General Operation Biowin 6 Help Manual

Word Report options
The top Include section of the tab can be used to specify whether or not general information items will be
included in the report. These are explained in the table below:

Item Description

Project info. Selecting this item will include information such as the Project Name, Plant
Name, Username, file creation date, etc., as specified in Project|Info…
Flowsheet Selecting this item will include a picture of the BioWin flowsheet in the report.
Global parameters Selecting this item will include a tabular printout of all the model parameters.
Global temperature Selecting this item will include the global temperature in the report.
Album pages Selecting this item will include each album page (both tabular and chart).
SRT (if available) Selecting this item will include the SRT in the report, if one is available.
Notes Selecting this item will include the contents of the Notes editor in the report.
The contents of reports may be further customized on an element-by-element basis, using the Select
element type report options section. The Element types list contains all the possible element types that
could be included in a BioWin configuration. To include information for various element types in reports:
1. Click on the element type you want to include in the Element types list, so that it is highlighted blue.
2. Click the box labeled Include this element type in the report.
3. Click the boxes next to the different types of information (Physical data, Operating data, Local
settling parameters, Local biological parameters, Aeration parameters, Local blower parameters,
Pumping/Piping parameters).
4. Repeat this process for all the element types you wish to include in the report.

Note: Possibly not all the types of information may apply to a given element – if so, it will simply not be
included in the report.

Excel Report options

The bottom Excel reports section of the Report options tab can be used to select excel template(s) and
specify whether or not general information items will be included in the report. Excel reports are generated
using customizable report templates. For more information on customizing report templates, please see the
following section, Chart Template Options. The Select templates… button allows you to choose the
template (or templates) that will be used to generate the final report. Clicking this button will open the
dialogue box shown below, which will list all Excel files (*.xls format) located in the BioWin \Templates
installation directory:

Biowin 6 Help Manual General Operation • 151

Template files are selected by clicking on the file name in the Available templates list and clicking the right-
pointing arrow (or by double-clicking a file in the Available templates list). If you select more than one
report template, the final report can merge all the tabs in each template file, in the order in which files are
listed. Note that you can change the order of the selected report template files with the up/down arrows,
and remove selected templates using the Delete key on the keyboard. Note that a template file does not
strictly need to follow BioWin’s report template syntax (discussed in the Creating an Excel™ Report section
of the Data Output chapter); for example, if you have a spreadsheet that is used for other purposes that you
would like appended to the final report file, then it can be added to the selected templates list.
If you want BioWin to automatically generate an Excel file containing charts that you have added to the
Album, check the Album charts box. [Note that Album charts in an Excel report will be a “live” Excel chart
and the data for each chart will be exported to the same tab as the chart.] Similarly, if you want BioWin to
automatically generate an Excel file containing steady state and dynamic data for all monitored items, check
the Database box. The Excel report can also include / exclude various table types that you may have added
to the BioWin Album, depending on whether the box for that type of table is selected. You can also control
how many tables are written to each Excel report tab using the spin edit control (a value of zero will cause
BioWin to put all the tables of this type on the same Excel tab).
To merge all of the Excel report files into one final Excel report (i.e. the report generated by the template
file(s), the file containing the Album charts and tables, and the database file), check the Merge output files
box. This likely will be the option that most users will prefer. Note that when this option is selected, a
separate Excel file containing only the Album charts and a .png file containing the BioWin flow sheet will also
be generated.
The following points are also worth noting:
• The Excel report templates are completely customizable. Customization can be as simple as
changing the order of/removing sheets that will appear in the final report; it can be as advanced as
creating completely new sheets with user-designed output tables.

152 • General Operation Biowin 6 Help Manual

 • It is possible to use more than one template and have BioWin merge the results into one final Excel
report file.
• It is also possible to include a spreadsheet that contains no “BioWin report syntax” as a report
template. BioWin can merge this spreadsheet into its generated Excel report file. For example, if you
have a spreadsheet that contains various design calculations, loading information, etc. that you
would like included in the final BioWin Excel report, simply choose this spreadsheet as one of your
templates.

Default tags
You can customize the default information shown in element tags if they are displayed using the Default
tags tab, shown below.

Tab used to customize the default information shown in element tags

From the Element types list, select the element that you wish to set up the default tag information for.
Using the Location radio button group, specify where you want to obtain element data from, i.e. Output, or
Underflow.

Note: The second location only will be shown for element types that have an underflow such as settling
tanks.

Biowin 6 Help Manual General Operation • 153

Finally, in the State variables, Combined, Water chemistry and Element specific check list boxes, select the
items that you wish to be shown for tags of that element type by default. For example, the screenshot
above shows that by default, a tag displayed for an ideal primary settling tank will include the Element HRT,
Percent TSS removal, Percent BOD removal, Surface overflow rate, and TSS.

Note: The default choices for any element type can be overridden on an element by element basis via the
Tags tab within each element on a flowsheet.

Automatic Logging Options

You can customize BioWin to automatically monitor element data using the Automatic logging tab, shown
below. For more information on managing data in BioWin, please see the Managing Data section.

Tab used to customize automatic logging settings

From the Element types list, select the element that you wish to set up auto-logging for. Using the Location
radio button group, specify where you want to obtain element data from, i.e. Output, or Underflow.

Note: The second location only will be shown for element types that have an underflow such as settling
tanks.

154 • General Operation Biowin 6 Help Manual

Finally, in the State variables, Combined, Water chemistry and Element specific check list boxes, select the
items that you wish to be logged automatically to the database.
When you set up auto-logging for an element type, the data that you specified to be monitored will
automatically be written to the database for any elements added from that time forward, i.e. in the current
project and all future projects (you can always modify the auto-logging options if you wish). Elements
already in the configuration (or other configurations) are not affected by this setting.

File Location Options

You may customize the locations where BioWin saves various file types using the File locations tab, shown
below.

Tab used to customize BioWin file locations

To change the location of a file type, double-click on the file type’s row of the file type/location list or click
the row once and then click the Modify location… button. You will then be presented with a dialog box that
you can use to specify a new location, such as the one shown below.

Biowin 6 Help Manual General Operation • 155

Dialog box used to specify new file locations (appearance may differ depending on Windows version)

Select the drive you want to store the files on using the Drive: drop list box. Navigate through the existing
folder structure by double-clicking on the folder icons. If you wish to create a folder, click the New Folder
button. When you are satisfied with the new location, click OK to return to the File locations tab.
Clicking the Advanced… button will allow you to access the Advanced file locations tab. From this tab you
may choose to specify folders where you have placed custom drawing board image files or BioWin binary
files.

Note: Do not change these unless you are aware of the implications – this option is for advanced users only.

System Settings Options

The System settings tab, shown below, may be used to customize how BioWin accesses your computer’s
hardware.

156 • General Operation Biowin 6 Help Manual

Tab used to customize BioWin access to computer hardware

Adjusting these settings is recommended for individuals with advanced knowledge of computer hardware
only.

Chart Template Options

BioWin offers a wide range of formatting options so that you may customize charts. While this range gives
users a great deal of power and flexibility in specifying the appearance of their charts, it also could result in a
good deal of repetition if you plan to generate a number of charts which will have the same appearance.
However, this repetition is eliminated by another useful feature of BioWin’s charting package – Chart
Templates.
The idea behind chart templates is to provide users with a means to pre-format their charts. You can format
the chart template to have the appearance that you want the charts to have. Your current chart template
(the chart shown in the Chart Master) is used as the basis for each new chart that you add to the album. To
change existing charts you can "Apply" the current chart template to those charts. (See Applying a Chart
Template).

Creating a Chart Template

To create a new chart template, select the Tools|Chart Master… menu command to open the dialog box
shown below.

Biowin 6 Help Manual General Operation • 157

Chart Master used to customize the appearance of new charts

The default color and line thickness for each series can be edited using the Series (1-16) buttons and Line
thickness spin edit box in the Series defaults section.
All other formatting options can be adjusted by double-clicking on the elements of the sample chart, or by
selecting the appropriate option from the context menu (right click). The sample chart includes two sample
series which are used to define the initial format of current value and time series plots. The tabs visible in
the chart editor depend on how it was accessed. For example, double clicking on the current value series
opens the chart editor dialog box as shown below but double clicking on the chart title, or legend opens the
chart editor with those tabs visible.

158 • General Operation Biowin 6 Help Manual

Chart editor dialog box

This dialog box allows you to adjust all other content and formatting aspects of the chart that you can
incorporate into your template. Please refer to the Chart Formatting Procedures in the “Data Output”
chapter for further information about using this dialog.
Once you have adjusted the settings as required, click the Close button to finish.

Saving a Chart Template

To save your chart formatting options into a template file for later use, click the Save as template file…
button to open the Save dialog box. Chart template files are saved with a .BCM file extension. This file may
be utilized later by clicking the Load template file… button and selecting the file from the Open dialog box.

Note: You may still customize the chart formatting using the normal series editing procedures in the album.

Applying a Chart Template

Once the desired template is loaded using the Load template file… button, you have the option of applying
it to all charts in the project or just selected charts. BioWin also allows you to control which specific
formatting options will be applied from the template you are using.
1. To control the specific formatting options you want to apply from the template you have loaded,
click the Change "Apply" settings… button to open the Chart Master options dialog box.

Biowin 6 Help Manual General Operation • 159

 Chart Master options dialog box

2. To apply a template to all charts in the project, click the Apply to All charts button.
3. To apply a template to selected charts only, click the Apply to selected charts… button to open the
Selected charts dialog box, shown below.

Chart selection dialog box

160 • General Operation Biowin 6 Help Manual

 4. Click on the desired chart in the area labeled Available on the left and press the button to add it
to the Selected list on the right.
5. Click the Apply button, and then click the Close button to finish. The loaded template will then be
applied to the selected charts only.

Changing Chart Master Options

The Chart Master allows you to control exactly which aspects of your template you wish to apply. For
example, you may have already adjusted the Font used for your chart title, and do not wish to apply the
Font used in your template. Chart Master will allow you to exclude this when you apply the template to your
chart if you click the Change "Apply" settings… button.

Change apply settings dialog box

Each category will offer a variety of relevant settings with check boxes. By removing the check from a
setting, you are removing that feature from the template.
Entire categories can be removed using the check box labeled Apply this category. If you uncheck this box,
all options for the category will be ignored when the template is applied.
This dialog box also allows you to remove the Colors and Width settings in the section labeled Apply default
series.

Useful BioWin Interface Tools and Techniques

Model Parameter Editors

BioWin model parameter editors, such as the example shown below, are used to change the parameters
used in all of the various models employed by BioWin to perform simulations. Parameter editors are
accessed via the Project|Parameters menu command.

Biowin 6 Help Manual General Operation • 161

Note: This section details the use of the model parameter editors. For technical information about model
parameters, please see the “Model Reference” chapter.

An example model parameter editor

In model parameter editors, a spreadsheet-like interface is provided for entering parameter values.
Parameter names are listed in the first column, default values in the second column, and current values in
the third column. In the case of kinetic parameters, temperature dependency coefficients for each
parameter also are listed. Only the non-grey columns may be modified. If you change a model parameter
from the default value and accept your change, the value will be highlighted in bold red text the next time
you view the editor. Clicking the Set current tab to default values button will reset all parameter values on
the current tab to their default values.
Note that you can also set all model parameters on all or multiple tabs back to their default values using the
Project|Parameters|Set defaults… command, shown in the screen capture below:

162 • General Operation Biowin 6 Help Manual

This command opens the following dialogue box, which is used to select the parameter tabs that will be set
to default values:

Any model parameter tab in the Selected global parameter lists group will have its parameters set to
default values if the Set selected parameter list values to default values button is clicked before clicking the
Close button. The parameter lists are named / sorted according to their groups (e.g. Aeration/mass transfer,
Biofilm, Kinetic, etc.) so that they can be found easily. In the example screenshot above, all parameters will
be set to default if the Set selected parameter list values to default values button is clicked before clicking
the Close button because all parameter lists have been moved from the Available global parameter lists
group to the Selected global parameter lists group. Note that any model parameters that have been set
locally within an element will not be affected by this command.

Note: Changing temperature dependency coefficients will increase or decrease the impact that a change in
temperature will have on the model parameters.

Biowin 6 Help Manual General Operation • 163

To change a value, click on the cell you would like to modify and enter a new value, or click on the number in
the cell to edit that value. You can use the arrow keys to move from one cell to the next. A number of
options for copying and pasting data, printing the editor tab, and multiplying column values are available by
right clicking on the editor tab - these are outlined below.
When you are working in a model parameter editor, several options for manipulating the parameter values
are available by right clicking anywhere on a model parameter editor tab. If you right-click and select Add to
notes, BioWin will place a tab-delimited text version of the currently selected model parameter tab into the
Simulation Notes editor. This is useful for keeping records of model parameter values used in different
simulation runs.
If you right-click and select Copy from the resulting popup menu, the contents of the tab (including column
headings, the values in non-editable cells, and the values in editable cells) will be copied to the Windows
clipboard. The clipboard contents then may be pasted into another application such as a word processor (all
values will be separated by tabs) or a spreadsheet (each value will be placed in a separate cell).
You also may paste data from the clipboard into a model parameter editor by right-clicking and selecting
Paste from the resulting popup menu.

Note: The cell that currently is selected in the model parameter editor corresponds to the first value in the
first column of the data that you are pasting from the clipboard.

If BioWin does not recognize the format of the data that you are attempting to paste in, or if you select
Paste special or Paste from file, the import wizard will be opened.
If you want to print the model parameter editor values in tabular form, then you can right-click and select
Print from the resulting popup menu. When you do so, you will be presented with the following dialog box.

Dialog box used for printing model parameters

Use the Printer drop list box to select the printer you want to use for printing. The Printer Setup… button
will open the printer setup dialog box which will allow you to access the printer’s properties, set paper size,
page orientation, and a number of other printer options (the options presented to you will be dependent on

164 • General Operation Biowin 6 Help Manual

the printer you have). The Print button will send the print job to the printer and the printout will match the
preview, which is shown. The Close button closes this dialog box and returns you to the Model Parameter
Editor.
Using the Paper Orientation group, specify whether you want the printing to be done on a Portrait or
Landscape page. The print preview gives you an idea of what the printout will look like under each format.
If you do not wish to see the size of the margins for your print job, you may de-select the box labeled View
Margins. You can control the margins using three different methods:
1. Using the Margins (%) spin edits, you can adjust each margin as you like. The four spin edit boxes
each control the margin that shares its position, that is, the top spin edit controls the top margin,
the bottom spin edit controls the bottom margin, and so on. When you change a value, you will see
changes in the print preview accordingly.
2. You may drag each margin using the mouse. Position the mouse cursor over the margin you wish to
adjust until the horizontal ( ) or vertical ( ) resize cursor appears. Click the mouse button, hold it,
and drag the margin to the position you wish it to occupy. Notice that when you finish dragging it,
the values in the Margins (%) spin edits will have been updated.
3. By moving the object to be printed around on the page. When the mouse cursor takes the form of a
hand ( ), you may click and drag the entire object around on the page until it is in the desired
position. Notice that when you finish dragging it, the values in the Margins (%) spin edits will have
been updated
If after applying any one of these methods of adjusting margins you wish to reset the margins to the default
values, you may do so by clicking the Reset Margins button.

Note: If you are having trouble with a print preview not fitting into the margins, ensure that you have a
True Type font (font styles with a TT after their name) selected in your Project|Current Project Options… -
Drawing board tab.

If you want to print all of the tabs in the model parameter editor, click the Print all button at the bottom of
the model parameter editor dialog box as opposed to right-clicking and selecting Print from the resulting
popup menu on each individual model parameter editor tab.

Itinerary Editors
Several elements have properties that may be entered as scheduled patterns rather than constant values. In
this section, the use of the interfaces (called itinerary editors in BioWin) for entering these schedules is
discussed.
Several options for manipulating the itinerary data are available by right clicking anywhere on the itinerary
tab. If you right-click and select Add to notes, BioWin will place a tab-delimited text version of the currently
selected model parameter tab into the Simulation Notes editor. This is useful for keeping track of changes
you make when doing multiple simulation runs on a configuration.
If you right-click and select Copy from the resulting popup menu, the contents of the tab (not including
column headings) will be copied to the clipboard. This option is best for copying the pattern from one
itinerary editor to another within a BioWin flowsheet. If you right-click and select Copy All from the resulting
popup menu, the contents of the tab (including column headings, the values in non-editable cells, and the

Biowin 6 Help Manual General Operation • 165

values in editable cells) will be copied to the clipboard. This option may be best for copying the itinerary
information to another application such as a word processor (all values will be separated by tabs) or a
spreadsheet (each value will be placed in a separate cell).
You also may paste data from the clipboard into an itinerary by right-clicking and selecting Paste from the
resulting popup menu.

Note: The cell that currently is selected in the itinerary editor corresponds to the first value in the first
column of the data that you are pasting from the clipboard.

If BioWin does not recognize the format of the data that you are attempting to paste in, or if you select
Paste special or Paste from file, the import wizard will be opened.
If you want to print the itinerary in tabular form, then you can right-click on the itinerary tab and select Print
from the resulting popup menu. When you do so, you will be presented with the following dialog box.

The print itinerary dialog

Use the Printer drop list box to select the printer you want to use for printing. The Printer Setup… button
will open the printer setup dialog box which will allow you to access the printer’s properties, set paper size,
page orientation, and a number of other printer options (the options presented to you will be dependent on
the printer you have). The Print button will send the print job to the printer and the printout will match the
preview, which is shown. The Close button closes this dialog box and returns you to the Itinerary Editor.
Using the Paper Orientation group, specify whether you want the printing to be done on a Portrait or
Landscape page. The print preview gives you an idea of what the printout will look like under each format.
If you do not wish to see the size of the margins for your print job, you may de-select the box labeled View
Margins. You can control the margins using three different methods:
1. Using the Margins (%) spin edits, you can adjust each margin as you like. The four spin edit boxes
each control the margin that shares its position, that is, the top spin edit controls the top margin,
the bottom spin edit controls the bottom margin, and so on. When you change a value, you will see
changes in the print preview accordingly.

166 • General Operation Biowin 6 Help Manual

 2. You may drag each margin using the mouse. Position the mouse cursor over the margin you wish to
adjust until the horizontal ( ) or vertical ( ) resize cursor appears. Click the mouse button, hold
it, and drag the margin to the position you wish it to occupy. Notice that when you finish dragging it,
the values in the Margins (%) spin edits will have been updated.
3. By moving the object to be printed around on the page. When the mouse cursor takes the form of a
hand ( ), you may click and drag the entire object around on the page until it is in the desired
position. Notice that when you finish dragging it, the values in the Margins (%) spin edits will have
been updated
If after applying any one of these methods of adjusting margins you wish to reset the margins to the default
values, you may do so by clicking the Reset Margins button.

Note: If you are having trouble with a table print preview not fitting into the margins, ensure that you have a
True Type font (font styles with a TT after their name) selected in your Project|Current Project Options… -
Drawing board options tab.

If you wish to apply a multiplication factor to one of the columns in the itinerary, right-click on the itinerary
and select Multiply a column from the resulting popup menu. When you do this, you will be presented with
the following dialog box.

Utility for multiplying a column of an itinerary

Using the Multiply column number spin edit box, select the column that you wish to apply the
multiplication factor to.

Note: As you change the value in this spin edit box, the label beside it changes to the heading of the selected
column so you know exactly which values you will be changing. Once you have selected the column, enter
the multiplication factor in the by text edit box. To complete the multiplication operation, click OK.

If you wish to clear a column in an itinerary, right-click on the itinerary and select Clear a column from the
resulting popup menu. When you do this, you will be presented with the following dialog box.

Utility for clearing a column of an itinerary

Biowin 6 Help Manual General Operation • 167

Using the Clear column number spin edit box, select the column that you wish to clear.

Note: As you change the value in this spin edit box, the label beside it changes to the heading of the selected
column so you know exactly which values you will be deleting. Once you have selected a column, click OK to
clear it.

The procedures outlined above are common to all itinerary editors in BioWin. For the purpose of this
manual, itinerary editors are divided into two broad classes:
1. Standard Itineraries
2. Special Itineraries
Details and examples of these two classes are given in the following sections.

Standard BioWin Itineraries

The following points highlight the use of standard itineraries. In the following sections, examples of standard
itineraries are given.
• The timed pattern may span minutes, days, or even months, depending on the length of the
simulation period.
• You can enter an influent pattern using the spreadsheet provided on this tab; start times may be
entered in the first column, flow rates in the second column.
• To enter or change a value, click on the cell you would like to modify and enter a new value, or click
on the number in the cell to edit that value. When you are satisfied with the value in a cell you may
press the Enter (or Return) key on your keyboard, or click in another cell. You can use the arrow keys
to move from one cell to the next; click the right mouse button to view a list of editing options.
• The Cycle time is specified using an edit box; this is the duration of the pattern, and must be
specified so that the simulator knows when to start repeating the cycle.

Note: If you have an event outside of the range of your cycle time, a warning will be displayed in red text at
the bottom of the itinerary and you will not be able to close the itinerary until you rectify this. You also may
specify a Cycle offset; this will have the effect of offsetting your timed pattern from the start time of the
simulation - that is, you "step into" your timed pattern by an amount equal to the cycle offset.

• Time units may be selected using the radio buttons; you can specify days, hours, or minutes. This
window may also contain a group of radio buttons for specifying Flow units; there are six different
unit options: L/d, ML/d, m3/d, m3/hr, mgd (US), and gal/d (US).
• You can increase or decrease the number of Rows (i.e. intervals) in a timed pattern using the spin
edit box.
• If there are blanks in your time column, you can click on the check box to Interpolate blank time cells
(all influent specifications require associated time values). There are a number of options for
replacing blanks in the other columns. You may choose from one of the following Blank fill styles:
the last value or zero, a time-weighted average value, an interpolated value, or an average value.
Blank values are interpolated by default.

168 • General Operation Biowin 6 Help Manual

 • If you select Last value or zero, then a blank cell will be filled with the value that is contained in the
previous non-blank cell. If BioWin finds no values in a column, then the column will be filled with
zeros. This way, if you want a column filled with zeros, you don't have to enter a zero in the first cell.
• If you select Time weighted average value, BioWin will use the column's non-blank, non-zero cells
to compute a time-weighted average. This calculated time-weighted average will then be placed in
all blank cells.
• If you select Interpolated value, BioWin will fill the blank cell (or groups of contiguous blank cells)
with a linearly interpolated value. The linear interpolation is based only on the points immediately
adjacent to the blank cell(s).

Note: If there are no values in the column and this option is selected, the column will be filled with zeros.

• If you select Average value, BioWin will use the column's non-blank, non-zero cells to compute a
straight arithmetic average. This calculated average will then be placed in all blank cells.
As outlined earlier, a number of options for copying and pasting data, printing the itinerary, and multiplying
column values are available by right clicking on the itinerary tab.

Split Itinerary
This itinerary editor, shown below, allows the user to enter a scheduled pattern for an element's split
method. This dialog box applies to elements that split flows such as splitters, settlers (primary and
secondary), grit tanks, and dewatering elements.

The split itinerary editor

Biowin 6 Help Manual General Operation • 169

DO Setpoint Itinerary
This itinerary editor, shown below, allows the user to enter a scheduled pattern for an element's DO
setpoint. This dialog box applies to aerated elements such as bioreactors and aerobic digesters.

A DO setpoint itinerary editor

Air Flow Rate Itinerary

This itinerary editor, shown below, allows the user to enter a scheduled pattern for an element's air flow
rate. This dialog box applies to aerated elements such as bioreactors and aerobic digesters.

An air flow rate itinerary editor

170 • General Operation Biowin 6 Help Manual

Power Itineraries
The itinerary editors for specifying power (described below) include Power Itinerary, Power Supply
Rate Itinerary, Power (per unit flow) Itinerary and Power (per unit volume) Itinerary.

Power Itinerary

This itinerary editor, shown below, allows the user to enter a scheduled pattern for an element's power
supply. This dialog box applies to all elements where mixing, mechanical and pumping power can be
specified (i.e. pump, bioreactor, equalization tank, anaerobic digester, primary clarifier, model clarifier, etc.).
The dialogue text will show which type of power is being entered (i.e. pumping, mixing or mechanical).

A power supply pattern itinerary editor

Power Supply Rate Itinerary

This itinerary editor, shown below, allows the user to enter a scheduled pattern for an element's power
supply rate. This dialog box applies to surface aerated elements such as surface aerator bioreactors and
brush aerator bioreactors, and elements where solid/liquid separation or disinfection power can be
specified such as effluent, dewatering unit, point clarifier, microscreen, cyclone and ISS cyclone elements.

Biowin 6 Help Manual General Operation • 171

A power supply rate itinerary editor

Power (per unit flow) Itinerary

This itinerary editor, shown below, allows the user to enter a scheduled pattern for an element's power per
unit flow to the element. This dialog box applies to all elements where mechanical power and solid/liquid
separation or disinfection power can be specified (i.e. trickling filter, grit tank, thermal hydrolysis unit, ideal
clarifier, model clarifier, ideal primary settling tank, effluent, dewatering unit, point clarifier, microscreen,
cyclone, ISS cyclone).

A power per unit flow itinerary editor

Power (per unit volume) Itinerary

172 • General Operation Biowin 6 Help Manual

This itinerary editor, shown below, allows the user to enter a scheduled pattern for an element's power per
unit volume. This dialog box applies to all elements where mixing power can be specified (i.e. bioreactor,
membrane bioreactor, media bioreactor, variable volume bioreactor, aerobic digester, side stream reactor,
submerged aerated filter, equalization tank, Anaerobic Digester, single-tank SBR, etc.).

A power per unit volume itinerary editor

Temperature Itinerary
This itinerary editor, shown below, allows the user to enter a scheduled pattern for an element's liquid
temperature. This dialog box applies to elements incorporating temperature such as bioreactors, SBRs and
aerobic digesters.

Biowin 6 Help Manual General Operation • 173

A temperature itinerary editor

Underflow Rate Itinerary

This itinerary editor, shown below, allows the user to enter a scheduled pattern for an element's (e.g. an
SBR or clarifier) liquid underflow.

Dialog box for entering a liquid underflow pattern

Internal Recycle Flow Rate Itinerary

This itinerary editor, shown below, allows the user to enter a scheduled pattern for an element's (e.g. SBR +
2 always-mixed prezones) internal recycle flow rate.

174 • General Operation Biowin 6 Help Manual

Dialog box for entering an internal liquid recycle flow rate pattern

Liquid Outflow Itinerary

This itinerary editor, shown below, allows the user to enter a scheduled pattern for an element's (e.g. a
variable volume/batch bioreactor) liquid outflow.

Dialog box for entering a liquid outflow pattern

Biowin 6 Help Manual General Operation • 175

Wasting Rate Itinerary
This itinerary editor, shown below, allows the user to enter a scheduled pattern for an element’s (e.g. a
Granular Sludge Sequencing Tanks (GSST)) wasting rate.

Dialog box for entering a wasting rate pattern

Percent Removal Itinerary

This itinerary editor, shown below, allows the user to enter a scheduled pattern for percent removal of
solids in a solid/liquid separation element (e.g. ideal primary settling tanks, ideal secondary settling tanks,
dewatering unit, cyclone) liquid outflow.

176 • General Operation Biowin 6 Help Manual

Dialog box for entering a percent removal pattern

Alpha Itinerary
This itinerary editor, shown below, allows the user to enter a scheduled pattern for the aeration parameter
alpha in any element that can be aerated (e.g. bioreactor, membrane bioreactor, media bioreactor, brush
aerator bioreactor, surface aerator bioreactor, variable volume reactor, etc.).

Dialog box for entering an alpha pattern

Beta Itinerary
This itinerary editor, shown below, allows the user to enter a scheduled pattern for the aeration parameter
beta in any element that can be aerated (e.g. bioreactor, membrane bioreactor, media bioreactor, brush
aerator bioreactor, surface aerator bioreactor, variable volume reactor, etc.).

Biowin 6 Help Manual General Operation • 177

Dialog box for entering a beta pattern

Inlet Air Temperature Itinerary

This itinerary editor, shown below, allows the user to enter a scheduled pattern for inlet air temperature.
The inlet air temperature is used for the calculation of blower power.

Dialog box for entering an Inlet air temperature pattern

178 • General Operation Biowin 6 Help Manual

Inlet Air Humidity Itinerary
This itinerary editor, shown below, allows the user to enter a scheduled pattern for inlet air humidity. The
inlet air humidity is used for the calculation of blower power.

Dialog box for entering an Inlet air humidity pattern

Electricity Cost Itinerary

This itinerary editor, shown below, allows the user to enter a scheduled pattern for electricity cost.

Dialog box for entering an Electricity cost pattern

Biowin 6 Help Manual General Operation • 179

HVAC Power Itinerary
This itinerary editor, shown below, allows the user to enter a scheduled pattern for HVAC power.

Dialog box for entering a HVAC power pattern

Heat loss Itinerary

This itinerary editor, shown below, allows the user to enter a scheduled pattern for heat loss in the
Anaerobic Digester element.

Dialog box for entering a heat loss pattern

180 • General Operation Biowin 6 Help Manual

Special BioWin Itineraries
In the following sections, examples of special itineraries are given, along with the distinguishing feature that
makes them different from standard itineraries.
• The timed pattern may span minutes, days, or even months, depending on the length of the
simulation period.
• You can enter an influent pattern using the spreadsheet provided on this tab; start times may be
entered in the first column, flow rates in the second column.
• To enter or change a value, click on the cell you would like to modify and enter a new value, or click
on the number in the cell to edit that value. When you are satisfied with the value in a cell you may
press the Enter (or Return) key on your keyboard, or click in another cell. You can use the arrow keys
to move from one cell to the next; click the right mouse button to view a list of editing options.
• The Cycle time is specified using an edit box; this is the duration of the pattern, and must be
specified in so that the simulator knows when to start repeating the cycle.

Note: If you have an event outside of the range of your cycle time, a warning will be displayed in red text at
the bottom of the itinerary and you will not be able to close the itinerary until you rectify this. You also may
specify a Cycle offset; this will have the effect of offsetting your timed pattern from the start time of the
simulation - that is, you "step into" your timed pattern by an amount equal to the cycle offset.

• Time units may be selected using the radio buttons; you can specify days, hours, or minutes. This tab
may also contain a group of radio buttons for specifying Flow units; there are six different unit
options: L/d, ML/d, m3/d, m3/hr, mgd (US), and gal/d (US).
• You can increase or decrease the number of Rows (i.e. intervals) in a timed pattern using the spin
edit box.
• If there are blanks in your time column, you can click on the check box to Interpolate blank time cells
(all influent specifications require associated time values). There are a number of options for
replacing blanks in the other columns. You may choose from one of the following Blank fill styles:
the last value or zero, a time-weighted average value, an interpolated value, or an average value.
Blank values are interpolated by default.
• If you select Last value or zero, then a blank cell will be filled with the value that is contained in the
previous non-blank cell. If BioWin finds no values in a column, then the column will be filled with
zeros. This way, if you want a column filled with zeros, you don't have to enter a zero in the first cell.
• If you select Time weighted average value, BioWin will use the column's non-blank, non-zero cells
to compute a time-weighted average. This calculated time-weighted average will then be placed in
all blank cells.
• If you select Interpolated value, BioWin will fill the blank cell (or groups of contiguous blank cells)
with a linearly interpolated value. The linear interpolation is based only on the points immediately
adjacent to the blank cell(s).

Note: If there are no values in the column and this option is selected, the column will be filled with zeros.

• If you select Average value, BioWin will use the column's non-blank, non-zero cells to compute a
straight arithmetic average. This calculated average will then be placed in all blank cells.

Biowin 6 Help Manual General Operation • 181

As outlined earlier, several options for copying and pasting data, printing the itinerary, and multiplying
column values are available by right clicking on the itinerary tab.

Note: Use care when switching back and forth between constant and scheduled influents. BioWin assigns
the constant values to the first row of your schedule, and vice versa. So, in the case where you are switching
between a constant influent that is different from the first row of your scheduled influent, ensure that the
values are what you want them to be before running simulations.

Influent Itinerary
The appearance of the influent itinerary editor depends on whether the influent type is constant or variable,
and whether the influent element specifies wastewater composition in terms of totals and fractions (i.e. a
standard influent), state variable concentrations (i.e. a state variable influent), a BOD influent, a methanol
input, or a metal addition influent. If the influent is constant, then the influent data are entered in the
simple dialogs shown below.

A constant COD influent itinerary

182 • General Operation Biowin 6 Help Manual

A constant state variable influent itinerary

A constant BOD influent itinerary

Biowin 6 Help Manual General Operation • 183

A constant methanol influent itinerary

A constant metal addition influent itinerary

If the influent type is variable, then the influent itinerary will appear as shown below. This will allow the user
to enter a scheduled pattern.

184 • General Operation Biowin 6 Help Manual

A variable COD influent itinerary

A variable state variable influent itinerary

Biowin 6 Help Manual General Operation • 185

A variable BOD influent itinerary

A variable methanol influent itinerary

186 • General Operation Biowin 6 Help Manual

A variable metal addition influent itinerary

SBR DO Setpoint Itinerary

This itinerary editor, shown below, allows the user to enter a scheduled pattern for an SBR element's DO
setpoint.

An SBR DO setpoint itinerary editor

Biowin 6 Help Manual General Operation • 187

Note: For the SBR DO setpoint itinerary, the Cycle time cannot be specified since it is linked to the SBR
Operation cycle time. The itinerary editor provides you with feedback by telling you the Maximum time
span in which you can aerate (this is set by the SBR Mixing/Aeration cycle length – you cannot have aeration
occurring during the Settling/Decant phase).

Note: If you have an aeration event outside of the range of your maximum allowable time, a warning will be
displayed in red text at the bottom of the itinerary and you will not be able to close the itinerary until you
rectify this. Notice also that you may not have a different Cycle offset than that of your SBR operation cycle
offset.

SBR Air Flow Rate Itinerary

This itinerary editor, shown below, allows the user to enter a scheduled pattern for an SBR element's air
flow rate.

An SBR air flow rate itinerary editor

Note: For the SBR air flow rate itinerary, the Cycle time cannot be specified since it is linked to the SBR
Operation cycle time. The itinerary editor provides you with feedback by telling you the Maximum time
span in which you can aerate (this is set by the SBR Mixing/Aeration cycle length – you cannot have aeration
occurring during the Settling/Decant phase).

Note: If you have an aeration event outside of the range of your maximum allowable time, a warning will be
displayed in red text at the bottom of the itinerary and you will not be able to close the itinerary until you

188 • General Operation Biowin 6 Help Manual

rectify this. Notice also that you may not have a different Cycle offset than that of your SBR operation cycle
offset.

GSST DO Setpoint Itinerary

This itinerary editor, shown below, allows the user to enter a scheduled pattern for a Granular Sludge
Sequencing Tank (GSST) element's DO setpoint.

A GSST DO setpoint itinerary editor

Note: For the GSST DO setpoint itinerary, the Cycle time cannot be specified since it is linked to the GSST
Operation cycle time. The itinerary editor provides you with feedback by telling you the Maximum time
span in which you can aerate (this is set by the GSST Mixing/Aeration cycle length – you cannot have
aeration occurring during the Settling/Decant phase).

Note: If you have an aeration event outside of the range of your maximum allowable time, a warning will be
displayed in red text at the bottom of the itinerary and you will not be able to close the itinerary until you
rectify this. Notice also that you may not have a different Cycle offset than that of your GSST operation cycle
offset.

GSST Air Flow Rate Itinerary

This itinerary editor, shown below, allows the user to enter a scheduled pattern for a GSSTs element's air
flow rate.

Biowin 6 Help Manual General Operation • 189

A GSST air flow rate itinerary editor

Note: For the GSST air flow rate itinerary, the Cycle time cannot be specified since it is linked to the GSST
Operation cycle time. The itinerary editor provides you with feedback by telling you the Maximum time
span in which you can aerate (this is set by the GSST Mixing/Aeration cycle length – you cannot have
aeration occurring during the Settling/Decant phase).

Note: If you have an aeration event outside of the range of your maximum allowable time, a warning will be
displayed in red text at the bottom of the itinerary and you will not be able to close the itinerary until you
rectify this. Notice also that you may not have a different Cycle offset than that of your GSST operation cycle
offset.

Router Itinerary
This itinerary editor, shown below, allows the user to specify a flow routing pattern for a splitter element.

190 • General Operation Biowin 6 Help Manual

A router itinerary for alternating flow routing

You may specify either to Switch at intervals, or you may use a Scheduled pattern. Click on the radio button
to select the option you want. If you select to switch the flow at regular intervals, you may enter the interval
length in the edit boxes (hours and minutes). If you choose a scheduled pattern, click on the Pattern button
to open the router itinerary editor, shown below. The operation of this itinerary editor is the same as other
standard itinerary editors.

Dialog box for entering a router pattern

Model Builder
The model builder, shown in the picture below, is used to enter stoichiometry and kinetic rate equations for
user-defined models. The model builder may be invoked by clicking the Specify local model… button (if the
Local Builder model option is selected) on the Model tab of the Model builder element. Alternatively, the
model builder may be invoked by selecting the Model builder… command from the Project menu.

Biowin 6 Help Manual General Operation • 191

The model builder with activated sludge model number one (ASM 1) loaded

The model builder allows you to perform a number of tasks related to creating your own models:
• Enter stoichiometry and rate constants;
• Enter processes which act on the BioWin state variables;
• Enter stoichiometry and rate equations using a powerful equation editor;
• Manage your model(s) by allowing you to import and export to various file formats.
These tasks are explained in more detail in the following sections.

Managing Models
• Models that you create can be either project-specific (i.e. they are available only within the project
where they were created), or you may save them in “.mod” files to use in other BioWin projects.
• If you create a model using the Project | Model Builder… command, then that model:
• Will be used by all model builder elements that you place in your configuration, provided those
models do not override this by using a Local Builder model. You can also have individual models
that are local to a particular model builder element (select the Local Builder model option on
the Model tab).
• Will be used by all elements that include reactions if you select Use project Model Builder model
from the Project | Current Project Options | Model tab.
• If you create a model using the Specify local model… button on the Model tab of a model
builder element, then that model will only be used by that model builder element.
• Once you have created a model, either in the Project | Model Builder… or through Specify
local model… you can save it to disk using the Save or Save as buttons as appropriate. Saving a
model allows you to Open a model in any project, or model builder element.

192 • General Operation Biowin 6 Help Manual

 • Several model builder models are shipped with BioWin. You can access these by opening the Model
Builder (by selecting Project | Model builder... from the main BioWin window). Within the
model builder interface there is a Cabinet models drop down list; to load a model click the arrow to
reveal the list and then click the model you want to use. A model loaded from the Cabinet models
list can be edited and saved in the normal fashion; this does not impact the underlying template
model file (unless you specifically overwrite the template model).

Using Add-on Modules (Builder Models)

The BioWin Model Builder provides the user with the ability to build a new model using existing state
variables (including the four user defined variables), or enhance/modify/add to the BioWin ASDM model.
1. Build the configuration as usual.
2. In Model Options (accessible by clicking the button at the bottom left-hand side of the BioWin main
simulator window, or from Project | Current Project Options | Model), select the Use project
Model Builder model option. Leave the BioWin ASDM model option and any other options selected
that are desired.
3. In the Project | Model Builder dialog box, click the Open … button to select a model file from disk or
use one of the Cabinet models.

General considerations for using ASMs

The following points should be noted when using these Builder Models. The ASM series models have fewer
state variables than the ASDM model in BioWin. The following steps must be taken in order to build a
configuration using these additional models:
1. Build the configuration as usual. Take into account that the ASM series is meant to simulate only
BOD removal, nitrification, denitrification, and in the case of ASM2d, biological phosphorus removal
and precipitation. Do not use elements and processes that cannot be simulated with these models
(digester, chemical addition, etc.)
2. In Model Options (accessible by clicking the button at the bottom left-hand side of the BioWin main
simulator window, or from Project | Current Project Options | Model), disable the BioWin
integrated model, pH calculation and pH limitation. Select the Use project Model Builder model
option (see below). DO modeling is optional.

Biowin 6 Help Manual General Operation • 193

 3. In the Project|Model Builder dialog box, select the model that you require from the Cabinet models
drop down list.
4. In all influent elements, make sure that there are no influent concentrations (fractions) that cannot
be handled by the specific model. The following table aids with identifying the various state
variables that have different names in the ASM models and their ASDM equivalent.

Description Units BioWin ASM1 ASM2d ASM3

Ordinary heterotrophic mgCOD/L ZBH XBH XH XBH
organisms (OHOs)
Readily biodegradable mgCOD/L SBSC SS SF SS
complex COD (non-VFA)
Acetate mgCOD/L SBSA SA
Soluble inert COD mgCOD/L SUS SI SI SI
Slowly biodegradable mgCOD/L XSP XS XS XS
particulate COD

194 • General Operation Biowin 6 Help Manual

 Particulate inert COD mgCOD/L XI XI XI XI
Endogenous products mgCOD/L ZE XP
Dissolved oxygen mgO2/L DO SO SO2 SO
Autotrophs: mgCOD/L ZAOB XBA XAUT XBA
Ammonia oxidizing biomass ZNOB
Nitrite oxidizing biomass
Particulate biodegradable mgN/L XON XND fraction fraction
organic nitrogen
Soluble biodegradable mgN/L NOS SND fraction fraction
organic nitrogen
Ammonia N mgN/L NH3-N SNH SNH4 SNH
Nitrate N mgN/L NO3-N SNO SNO3 SNO
Polyphosphate accumulating mgCOD/L ZBP XPAO
organisms (PAOs)
Stored PHA mgCOD/L SPHB XPHA XSTO
PO4 (including Metal mgP/L PO4-P SPO4
complexed)
Releasable stored polyP mgP/L PP-LO XPP
Ferric hydroxide mgFe(OH)3/L UD3 XMEOH
Ferric phosphate mgFePO4/L UD4 XMEP

5. Uncheck pH calculations since the ASM series does not provide information about pH.
6. Recall that BioWin’s model calculates alkalinity, but it is not a BioWin state variable. In most of the
cabinet ASM models, BioWin’s user-defined variable UD1 has been used to represent alkalinity. You
should also ensure that there is some alkalinity in the influent (e.g. influent UD1 concentration
should be set to 6 mmol/L).
7. In the IAWPRC STR #1 (the original ASM1 document) there isn’t a “default" value for the autotroph
decay coefficient listed. In the IWA STR #9 “Activated sludge models ASM1, ASM2, ASM2d, and
ASM3”, the typical Mumax_autotroph and b_aut values recommended for ASM2, ASM2d, and ASM3
are 1.0 and 0.15, respectively. However, for ASM1, the “default” Mumax_autotroph is 0.8, lower
than that for other ASM models but once again no “default” decay rate is recommended. Note that
in the cabinet implementation of the ASM1 the value of b_ANO was adjusted to achieve a similar
washout SRT for ASM1 and ASM2d / 3 their “defaults” were used.
8. Model parameter values for Builder Models are changed in the Project|Model Builder window.
9. This procedure replaces the BioWin model for all the elements in the configuration. It is possible to
use any of the models in specific tanks, if the Model Builder unit is placed in a configuration. This
way it is possible to compare different models within the same configuration.

Biowin 6 Help Manual General Operation • 195

 10. Editing the model: On double-clicking on an entry field in the Model Builder window, an equation
editor window appears. The window will contain the equation or value if a stoichiometry matrix
element was clicked. The equation or element value can be changed in this window. The Set
position to button at the bottom of the equation editor window puts the cursor to the desired
position but any part of an equation can be changed by moving to the desired position using the
arrows or mouse, and editing. When finished editing, click on the Close and update button at the
bottom right hand side of the equation editor window. Or simply close the window if no changes are
desired. The Stoichiometry window displays the Petersen matrix for the model. Also the matrix can
be edited by double-clicking on a value.
11. To change a rate constant value: Click on the rate constant. The rate constant name will appear in
the Name box in the middle of the pane and its value will appear in the value box below the Name
box. Type the new value for the parameter. Then click on the Add to rate constants button to
register the change.
12. If a stoichiometric constant is to be changed, click on it and follow the procedure in the previous
point except click on the Add to stoich. constants button to register the change.
13. The Verify equations… button should be pressed after all changes to ensure that the model is
verified by BioWin.
14. Be aware that combined variables (TSS, BOD, etc.) are always calculated according to the BioWin
method. It is recommended that only the model state variables are used to evaluate the model’s
performance. The Explorer (CTRL-E) is a useful tool to verify that only those state variables have
values that are included in the model selected. Any influent state variable that is not handled by the
model will be treated as inert and will flow through the plant model unchanged.
• OURc – the displayed value for this parameter is the carbonaceous OUR for the BioWin
model only. Therefore when a Model Builder model is active, oxygen demand from any
user-defined processes are not included (OURn is similar but only applies to the oxygen
utilized for AOB and NOB growth). In summary, OURc and OURn only reflect the BioWin
model terms; if BioWin’s ASDM model is switched off then they will be zero.
• OURt is calculated from the sum of all process rates that use or produce oxygen.
Consequently if the BioWin reactions are ON then:
• OURt - OURn - OURc = the OUR from the Model Builder reactions
and if BioWin reactions are Off then:
• OURt = the OUR from the Model Builder reactions.

Opening and Saving Model Files

You can save the model you are currently editing to disk by clicking the Save as … button. This opens the
Save model file dialog box, which operates exactly like the standard File Save dialog box. You may save your
model in one of three possible file formats:
1. Model files (*.mod)
2. Text files (tab delimited) [*.txt]
3. CSV files (no spaces) [*.CSV]
Model files (*.mod) are an excellent method for saving your files as they move between projects seamlessly,
and they also can be imported into Microsoft Excel as comma delimited files.

196 • General Operation Biowin 6 Help Manual

Note: If you have specified a filename you can save the file using the Save button, which does not open the
Save model file dialog box.

You may open a model from a file using the Open … button. This will open the Open model file dialog box,
which operates exactly like a standard File Open dialog. You may open a file saved in any of the three
formats discussed above. Recently saved Model files are listed in a dropdown menu on the Open button.

Cabinet Models
BioWin ships with several Model Builder models that can be accessed directly from the Model Builder
interface. The Cabinet models are listed in the dropdown list below the Open… button (as shown below).
Clicking on one of the items in the drop down list will load the appropriate model (replacing the current
model). For example, in the screenshot below the item “ASM #1” was selected from the dropdown list.

The Model Builder editor

Entering Model Constants

You must assign your model constants a name and a value. To enter a model constant, type the name of the
constant in the Name text edit area. Next, type the value you wish to assign to the constant in the Value
text edit area.
When you are satisfied with the name and value you have assigned to your constant, you may enter it into
your model as a rate constant by clicking the Add to rate constants button. To enter the constant into your
model as a stoichiometry constant, click the Add to stoich. constants button.

Note: When you add a constant to one of the two lists, the constant name and value remain in their
respective text edit areas. This makes it easy for you to enter the constant into both lists with the same
name and value if you wish.

Biowin 6 Help Manual General Operation • 197

If you wish to change a model constant, click on it in the Rate constants list or in the Stoichiometric
constants list so that it is highlighted blue. You can now delete the constant if you wish by pressing the
Delete key on your keyboard. You can also edit the name and/or value of the constant by editing the entry
in the Name and/or Value text edit area, and pressing the appropriate Add to… button.

Entering Model Processes

To add processes to your model, increase the value of the Number of processes spin edit box. When you do
this, additional unnamed processes will be added to your model. In the example shown below, the unnamed
processes Process 4 and Process 5 have been added to the model in the Stoichiometry and Rate equations
sections.

Note: Values of 0 are entered for stoichiometry and rate equations.

Adding additional processes to your model

To assign the processes names, simply click on the process name in the Stoichiometry section of the editor
so that it is highlighted blue, and type in the new name. Your changes will automatically be reflected in the
Rate equations section. In the example below, the new process named Process 4 has been renamed to a
process called New Process.

198 • General Operation Biowin 6 Help Manual

Changing the name of a process

Entering Model Equations

There are two methods for entering model equations. If the equation is small and straightforward, you may
be able to enter it directly into the appropriate model cell. To do this, click in the stoichiometry or rate
equation cell where you wish to enter the equation. When you do this, the text currently in the cell will be
highlighted blue. Clicking in the blue highlighted area will present you with a cursor that will allow you to
enter your equation. For more complex lengthy equations, you will probably find it easier to use the built in
equation editor.

Invoking the Equation Editor

To invoke the equation editor, double-click in the stoichiometry or rate cell where you wish to enter an
equation. This will invoke the Equation editor, shown in the picture below.

Equation editor showing the stoichiometric equation for the Dissolved Oxygen state variable for aerobic growth process of
autotrophic organisms.

Before proceeding further with explanation of the equation editor, the following points on exiting should be
noted:
1. To exit the equation editor without accepting the changes you have made, click the small x in the
upper right hand corner of the equation editor window.
2. To exit the equation editor and accept the changes you have made, click the Close and update
button.

Biowin 6 Help Manual General Operation • 199

You can use the Set position to button to quickly move the cursor around within the equation editor. The
position refers to the number of spaces from the left (or beginning) of a line of text. In the example picture
above, the cursor has been jumped to the sixth position.

Equation Editor Syntax

The equation editor provides you with a window into which you may enter your equation text. You must
take care to use proper mathematical syntax when you enter equations. The required syntax is similar to
that used when entering mathematical equations in computer code or spreadsheet formulas. For example,
say you wanted to change the equation shown above to have the term in brackets multiplied by the
constant Ya. The following syntax would not be correct, because the multiplication operator is missing:

Incorrect multiplication syntax

The equation shown below, with the correct multiplication syntax would be acceptable:

Correct multiplication syntax

Equation Editor Text Editing Features

The equation editor has features commonly found in text editors. You can highlight a section of equation
text by dragging your mouse cursor over it. You can then move the highlighted selection by clicking and
dragging the mouse cursor. The following keyboard shortcuts for using the Windows clipboard also are
available:
• To cut text, use the Ctrl+x keyboard combination;
• To copy text, use the Ctrl+c keyboard combination;
• To paste text, use the Ctrl+v keyboard combination.

Equation Editor Popup Menu

The equation editor also offers the functionality of a right-click popup menu that makes writing your
equations much easier. If you right-click your mouse button anywhere within the equation editor window,
you will be presented with a popup menu similar to the one shown below (depending whether the editor
was opened from a stoichiometry or a rate equation cell):

200 • General Operation Biowin 6 Help Manual

Equation editor right-click popup menu (opened from a rate equation cell)

Equation editor right-click popup menu (opened from a stoichiometry cell)

Selecting one of the popup menu choices will open a small window containing a list of variables, constants,
or function/operator templates that you can place into your equation. For example, selecting the Variable
option opens a window that lists the BioWin state variables, shown below:

State variable selection window

To place a variable from this list into your current equation, simply locate the variable in the list and double-
click it. The popup window will close, and you will return to your equation, where you will see that the
variable has been placed where you had located your cursor. Two important points should be mentioned
regarding the use of these popup windows:
1. To close a popup window without adding an item to your equation, click the small x located in the
upper right corner of the popup window.
2. When you double-click an item and add it to your equation, BioWin also adds the item to the
Windows clipboard. Pressing Ctrl+v will add the item to the equation, until another item is added to
the clipboard.
Selecting the Stoichiometry constant option (when opening the equation editor from a stoichiometry cell)
opens a window that lists the stoichiometry constants that you have defined for the model that you
currently are working on. For example, in the picture shown below, note that the constants listed coincide
with those shown in the Stoichiometric constants list in the main model builder window shown previously.

Biowin 6 Help Manual General Operation • 201

To place a constant from this list into your current equation, simply locate the constant in the list and
double-click it. The popup window will close, and you will return to your equation, where you will see that
the constant has been placed where you had located your cursor.

Stoichiometry constant selection window

Selecting the Rate constant option (when opening the equation editor from a stoichiometry cell) opens a
window that lists the rate constants that you have defined for the model that you currently are working on.
For example, in the picture shown below, note that the constants listed coincide with those shown in the
Rate constants list in the main model builder window shown previously. To place a constant from this list
into your current equation, simply locate the constant in the list and double-click it. The popup window will
close, and you will return to your equation, where you will see that the constant has been placed where you
had located your cursor.

Rate constant selection window

Selecting the Function / operator option opens a window that lists a number of function / operator
templates that you may place in your equation. To place a function or operator from this list into your
current equation, simply locate the function or operator in the list and double-click it. The popup window
will close, and you will return to your equation, where you will see that the function or operator template
has been placed where you had located your cursor.

202 • General Operation Biowin 6 Help Manual

Function / operator selection window

For example, suppose you selected the x^y template from the list. Using our previous DO stoichiometry
equation example, you would see the following:

Inserting a function template into an equation

You could then quickly replace the x and y placeholders by highlighting them, right-clicking, selecting
Variable or one of the constants options, and inserting an item from a popup window. Functions and
operators are described with examples in the next section.

Available Functions and Operators

A more comprehensive list of functions and operators is tabulated below:

Operator Description Example

^ Power operator 2 ^ 3 returns 8

* Multiply operator 3 * 4 returns 12
/ Divide operator 8 / 4 returns 2
\ Module operator. Returns the module of 5 \ 2 returns 1
a division.
+ Sum operator 3 + 7 returns 10

Biowin 6 Help Manual General Operation • 203

 - Subtract operator 10 - 4 returns 6
> Greater than operator 4 > 3 returns 1 (true), and 1 > 6 returns 0
(false)
< Less than operator 6 < 3 returns 0 (false), and 2 < 9 returns 1
(true)
>= Greater than or equal to operator 6 >= 3 returns 1 (true)
<= Less than or equal to operator 7 <= 3 returns 0 (false)
<> Not equal to operator 5 <> 3 returns 1 (true)
= Equal to operator 3 = 8 returns 0 (false)
if Logical if operator. Follows format if(5<1; 1; 5) returns 5 since the condition
if(condition; result if true; result if false) tests false
and Logical and operator 3 and 2 returns 1 (true, because both are
true)
or Logical or operator 3 or 0 returns 1 (true)
xor Logical xor operator 1 xor 1 returns 0 (false)

Constant Value

pi 3.1415926535897932385
e 2.71828182846 - Same as Exp(1)

Function Description Example

Conc Switch Ks Applies the Ks switch to the variable Alk Switch KsAlk applies the
Conc switching function KsAlk to the
variable Alk
TD(Const;Theta;Temp) Applies an Arrhenius temperature Const⋅𝛩(Temp−20)
dependency relationship using the
supplied arguments
TDRT(Const;Theta;Temp;R Applies an Arrhenius temperature Const⋅𝛩(Temp−RefTemp)
efTemp) dependency relationship using the
supplied arguments
Monod(RateAtTemp; Places the supplied arguments into a Substrate
RateAtTemp ⋅ [ ]
Substrate; Ks) Monod function 𝐾𝑆 + Substrate

Monod[TD(Const;Theta; Places the supplied arguments into a

Temp); Substrate; Ks] temperature-dependent Monod (Const⋅𝛩(Temp−20) )
function Substrate
⋅[ ]
𝐾𝑆 + Substrate

204 • General Operation Biowin 6 Help Manual

 PhInhib(phLow; pHHigh; Places the supplied arguments into a 1 + 2 ∗ 10(𝑝𝐻𝐿𝑜𝑤−𝑝𝐻𝐻𝑖𝑔ℎ)
pH) two-sided pH inhibition function 1 + 10(𝑝𝐻−𝑝𝐻𝐻𝑖𝑔ℎ) + 10(𝑝𝐻𝐿𝑜𝑤−𝑝𝐻)

Neg Returns the negative of argument Neg(5) returns –5

Not Returns 1 (true) if argument is 0 Not(1) returns 0
(false). Returns 0 (false) if argument is
not equal to 0
Re Returns the real part of a complex Re(5 + 4j) returns 5
number
Im Returns the imaginary part of a Im(5 + 4j) returns 4
complex number
Exp Returns the exponential of argument Exp(1) returns 2.71828182846
Sin Returns the sine of argument in Sin(pi/2) returns 1
radians
Cos Returns the cosine of argument in Cos(pi/2) returns 0
radians
Tan Returns the tangent of argument in Tan(pi/4) returns 1
radians
Asin Returns in radians the inverse sin of Asin(1) returns 1.57079632679
argument (pi/2)

Verifying Equations
As you enter equations in your model, you may want to use the Verify equations… button to ensure that
you have no mistakes in your equations. When you click this button, BioWin checks your equations for
undeclared variables and constants (rate and stoichiometric). BioWin also checks your equations for the
proper syntax. Finally, BioWin attempts to calculate the model equations. This may be useful in discovering
equation formula errors such as division by zero.
You may find it useful to use the Verify equations… button each time you finish entering an equation.

Copying, Pasting, and Printing Equations

A number of options for manipulating your model equation entries are available by right clicking in the
stoichiometry and rate equation matrices.
If you right-click and select Copy from the resulting popup menu, the contents of the stoichiometry or rate
matrix (including column headings, the values in non-editable cells, and the values in editable cells) will be
copied to the clipboard. The clipboard contents then may be pasted into another application such as a word
processor (all values will be separated by tabs) or a spreadsheet (each value will be placed in a separate
cell).
You also may paste data from the clipboard into the stoichiometry or rate equations by right-clicking and
selecting Paste from the resulting popup menu.

Biowin 6 Help Manual General Operation • 205

Note: The cell that currently is selected in the stoichiometry or rate matrix corresponds to the first value in
the first column of the data that you are pasting from the clipboard.

If BioWin does not recognize the format of the data that you are attempting to paste in, or if you select
Paste special or Paste from file, the import wizard will be opened.
If you want to print the stoichiometry or rate equation matrix in tabular form, you can right-click and select
Print from the resulting popup menu. When you do so, you will be presented with the BioWin print dialog
box, which is explained in detail in the Model Parameter Editor section earlier in this chapter.

Cabinet Models provided with BioWin

The BioWin Model Builder cabinet comes with slightly adapted versions of ASM1 (temperature dependency
and Monod term for ammonia), ASM2d, ASM3, and an Add-on Module for Inert Conversion.

Inert conversion Add-on

This model add-on will extend the validity of the BioWin model for very long sludge ages or systems where
alternating environmental conditions cause “inert” components to degrade. Under conditions where
cumulative SRT is longer than 30 days, organic components that are normally considered inert (Xi and Ze)
may start degrading. This add-on will introduce a first order reaction rate to inert organics (Xi) and
endogenous residue (Ze) and convert them to slowly degradable particulates (Xsp).
The rate constant Kdxi (default value of 0.0) can be found and edited (Enter constant name and value) in the
Model Builder Editor (Project|Model Builder).
The overall result from using this add-on is that higher VSS destruction rates can be achieved in agreement
with measurements in aerobic digesters and other high sludge age systems.
Influent Inorganic Suspended Solids may dissolve under long SRT conditions. This is also added as a third
rate, generating cations and anions. At the moment there are no reliable measurements to estimate a rate
constant, so the default value of zero is provided.

206 • General Operation Biowin 6 Help Manual

Building Configurations

Using the Drawing Board

The drawing board is the largest part of the BioWin main window. This is where you set up the process
layout that you will be simulating by placing various elements, specifying their properties, and connecting
them with pipes. A number of procedures can be carried out from the drawing board – some of the common
ones are outlined in this section.

Note: Before using the drawing board, it is a good idea to check the Project|Current Project Options
(Drawing Board, Pipe, Unit System etc.) according to the requirements of your system (see the Setting
Project Options section of the “General Operation” chapter for more information).

Place an Element on the Drawing Board

1. With the mouse cursor, click on one of the element icons on the Configure toolbar.
2. Move the cursor onto the drawing board. When you do this, the cursor will change to the element
placement cursor ( ). Click on the drawing board where you want the element to be placed.
3. If you wish to place more elements of the same type, continue clicking on the desired drawing board
locations. Every click places one more element.
4. Repeat steps 1-3 for all of the different element types in your configuration.

Selecting Multiple Elements on the Drawing Board

To select multiple elements by dragging with the mouse:
1. Click on the element selection tool ( ) from the Configure toolbar.
2. Position the cursor above and to the left of the group of elements on the drawing board you wish to
select.
3. Hold the mouse button and drag the cursor to a position below and to the right of the group of
elements you wish to select. A box will appear around the selected elements.
4. Release the mouse button.

Biowin 6 Help Manual Building Configurations • 207

Note: the selection box can also be initiated from the top-right, bottom-left or bottom-right corners around
the group of elements to be selected on the drawing board.

To select multiple elements by clicking with the mouse, hold either the Shift or Ctrl key and click on each
element of the group you wish to select.

Rearranging and Moving Elements on the Drawing Board

If you want to change an element's position:
1. Click on the element selection tool ( ) from the Configure toolbar (or simply press the ESC button).
2. Move the cursor over the element on the drawing board you wish to move.
3. Click on the element and while holding down the mouse button, drag the element to the desired
new location.
4. Alternatively, for a more precise placement, click on the element to select it, then press the
up/down/left/right arrow buttons to move it a very small distance with each press of the arrow
button.
5. Alternatively, to move the element a set distance, click on the element to select it, then while
holding the fn button, press the up/down/left/right arrow button.
6. To align the edges of selected elements, first select the “pivot” element to which the other elements
will be aligned. Then, holding the Ctrl key, select the other elements to be aligned to the “pivot”

element. On the Flowsheet tools toolbar, click the button to align left edges of selected units

or the button to align top edges of selected units.

7. To space units equally between leftmost and rightmost units or topmost and bottommost units,

select the group of elements to be moved and then, on the Flowsheet tools toolbar, click the

button to space units equally between the leftmost and rightmost units or the button to space
units equally between the topmost and bottommost units.

Note: You also can move multiple elements simultaneously. Select the group of elements you wish to move,
and then follow step 3, 4 or 5.

If you want to change the vertical or horizontal orientation of one or multiple elements:
1. Click on the element selection tool ( ) from the Configure toolbar.

2. Select the element(s) to be reoriented and then, on the Flowsheet tools toolbar, click the

button to visually switch the horizontal direction of flow for the selected elements or the
button to visually switch the vertical direction of flow for the selected elements.

208 • Building Configurations Biowin 6 Help Manual

 3. It is also possible to reorient a single element. Right-click the element, and from the resulting popup
menu, choose Flip horizontal or Flip vertical (the latter option only is available for elements such as
splitters and mixers).

Name an Element on the Drawing Board

1. Click on the element selection tool ( ) from the Configure toolbar.
2. Move the cursor over the element on the drawing board you wish to name. When you do so, the
cursor will change to the element selection cursor ( ).
3. Right-click on the element. In the resulting popup menu, select Name…
4. Enter the desired name for the element in the resulting dialog box and click OK.

Copy Elements on the Drawing Board

1. Click on the element selection tool ( ) from the Configure toolbar.
2. Move the cursor over the element you wish to copy. When you do so, the cursor will change to the
element selection cursor ( ).

3. Click the element to select it. On the Flowsheet tools toolbar, click the button to copy the
element.
4. Another way to copy the element once it is selected is to hold down the Ctrl key, position the cursor
over the element, then press and hold the mouse and drag the cursor to the location on the drawing
board where you want the copy of the element to appear. Release the mouse button and the Ctrl
key.

Note: You also can copy multiple elements simultaneously. Select the group of elements you wish to copy,

then click the button on the Flowsheet tools toolbar to copy the elements. Alternatively, once you
have selected the group of elements to be copied, position the cursor over one of the elements in the group
and then proceed to step 4 above.

Delete an Element from the Drawing Board

1. Click on the element selection tool ( ) from the Configure toolbar.
2. Move the cursor over the element on the drawing board you wish to delete. When you do so, the
cursor will change to the element selection cursor ( ).
3. Click on the element and press the Delete key on your keyboard. Click Yes on the resulting
confirmation dialog.
4. Repeat steps 1-3 for the various elements in your configuration you wish to delete.

Biowin 6 Help Manual Building Configurations • 209

Note: You also can delete multiple elements simultaneously. Select the group of elements that you wish to
delete, press the Delete key on your keyboard, and click Yes on the confirmation dialog.

Connect Elements with Pipes

1. Click the ( ) on the Configure toolbar.
2. When you move the cursor onto the drawing board, the cursor will change to the "start" cursor (
).
3. Place the cursor over the element area where you wish the pipe to start from.

4. If the location is appropriate, a set of crosshairs will appear on the "pipe start" cursor ( ).

5. If the location is inappropriate, the cursor will change to a circle with a slash through it ( ) to
indicate that a pipe may not begin at that location.
6. Click the left mouse button once and move the cursor to the desired location of the element where
you wish the pipe to end and click the left mouse button again.
7. As you move the pipe towards the element where you wish it to end, the cursor will change to the
"pipe end" cursor ( ).
8. If the location of the pipe terminus is appropriate, this cursor will remain.

9. If the location is inappropriate, the cursor will change to a circle with a slash through it ( ) to
indicate that a pipe may not end at that location.
Repeat steps 3-9 until you have connected all your elements with pipes.

Note: To re-arrange a pipe’s position, click once on the arrow head of that pipe. A series of circles appear at
points along the pipe. Try dragging-and-dropping. This is important for arranging the configuration layout.

Note: Try right clicking on the arrow head of a pipe, and view the Properties. There are a number of options
for re-arranging the pipe layout and selecting pipe style.

Note: To copy a pipe’s attributes (style, line and color) to other pipe(s), select the reference pipe with the

attributes you wish to copy. Then on the Flowsheet tools toolbar, click the button to copy the only

the pipe line and color attributes or the button to copy the pipe style, line and color attributes. The
image of the selected button now appears beside the cursor arrow. Click on the pipe(s) that you wish to
have the same attributes as the reference pipe.

210 • Building Configurations Biowin 6 Help Manual

Undo Drawing Board Actions

Drawing board actions may be “undone” by clicking the Undo button on the Flowsheet tools toolbar.
The following actions may be “undone”:
• Pipe attributes applied to a particular pipe in Pipe Properties
• Copy pipe attributes (“line and color” or “style, line and color”)
• Align edges of selected units
• Equally space units between leftmost/rightmost and topmost/bottommost units
• Reorient elements (flip horizontal, flip vertical)
• Copy elements
• Reposition element(s)
• Delete element(s)
• Add new element(s) to drawing board
The following points are worth noting with respect to the “scope” of the Undo function:
• It is not possible to “undo” steady-state or dynamic simulations to revert back to a previous
solution.
if an element is deleted from a completed configuration and new pipes are connected to complete the
configuration, only the new pipes can be undone; the deleted element cannot be undone. That is, drawing
pipes to connect elements marks a new “starting point” for the Undo tracking.

Access Element Properties from the Drawing Board

1. Click on the element selection tool ( ) from the Configure toolbar.
2. Move the cursor over the element on the drawing board you wish to view the properties of. When
you do so the cursor will change to the element selection cursor ( ).
3. Right-click on the element and select Properties… in the resulting pop-up menu, or double-click on
the element.

Note: You may also access an element's properties by double-clicking the element.

Zoom In on a Drawing Board Area

1. Click on the zoom tool ( ) from the Configure toolbar.
2. Move the zoom cursor ( ) to a position above and to the left of the area on the drawing board that
you wish to zoom in on.
3. Click and drag the cursor down and to the right of the area you wish to zoom in on.

Biowin 6 Help Manual Building Configurations • 211

 4. Release the mouse button to finish.
You may also zoom in by selecting or typing in a desired zoom percentage setting ( ) on the Configure
toolbar.

Printing the Drawing Board

You can print out the BioWin drawing board using the File|Print Flowsheet… command. This command will
invoke the print drawing board dialog box, which is shown below:

Dialog box used for printing the drawing board

Use the Printer drop list box to select the printer you want to use for printing. The Printer Setup… button
will open the printer setup dialog box which will allow you to access the printer’s properties, set paper size,
page orientation, and a number of other printer options (the options presented to you will be dependent on
the printer you have selected). The Print button will send the print job to the printer and the printout will
match the preview that is shown. The Close button closes this dialog box and returns you to the drawing
board.
Using the Paper Orientation group, specify whether you want the printing to be done on a Portrait or
Landscape page. The print preview gives you an idea of what the printout will look like under each format.
If you do not wish to see the size of the margins for your print job, you may de-select the box labeled View
Margins. You can control the margins using three different methods:
1. Using the Margins (%) spin edits, you can adjust each margin as you like. The four spin edit boxes
each control the margin that shares its position, that is, the top spin edit controls the top margin,
the bottom spin edit controls the bottom margin, and so on. When you change a value, you will see
changes in the print preview accordingly.

212 • Building Configurations Biowin 6 Help Manual

 2. You may drag each margin using the mouse. Position the mouse cursor over the margin you wish to
adjust until the horizontal ( ) or vertical ( ) resize cursor appears. Click the mouse button, hold it,
and drag the margin to the position you wish it to occupy. Notice that when you finish dragging it,
the values in the Margins (%) spin edits will have been updated.
3. By moving the object to be printed around on the page. When the mouse cursor takes the form of a
hand ( ), you may click and drag the entire object around on the page until it is in the desired
position. Notice that when you finish dragging it, the values in the Margins (%) spin edits will have
been updated.
If after applying any one of these methods of adjusting margins you wish to reset the margins to the default
values, you may do so by clicking the Reset Margins button.
If you want the printed picture of the drawing board to have the same length and width proportions as the
actual drawing board, then select the box labeled Fix aspect.

Element Descriptions

Influents
COD Influent
The COD Influent element is used to control the wastewater flow and composition to your process
configuration. When you add a COD Influent element to your configuration, you can control the type (i.e.
constant or variable) of influent and the wastewater fractions. For information on monitoring
parameters/variables for this element, please see the Monitoring Data section in the “General Operation”
chapter.

Biowin 6 Help Manual Building Configurations • 213

The Monitor items tab of a COD Influent element
For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

214 • Building Configurations Biowin 6 Help Manual

The Tags tab of a COD Influent element

Influent Type
The Influent type tab, shown in the figure below, is used to specify the influent element as one of two
possible types: Constant or Variable. If Constant is selected then you specify the flow and one set of influent
concentrations which are used during simulations. The wastewater flow/composition of a Constant influent
may be changed during a dynamic simulation, but only when the simulator is paused.

Biowin 6 Help Manual Building Configurations • 215

The Influent type tab of a COD Influent element

A variable influent element represents a user-specified time-varying flow / composition stream entering the
system. For steady state calculations the mass average of the time-varying flow / composition pattern is
used. Each set of conditions has an associated starting time; this time is the dynamic simulation time at
which these conditions will start to be used. The scheduled influent places the following restrictions on the
starting time for each set of conditions:
1. The starting time for each set of conditions must be greater than the starting time for the previous
set.
2. The first set of conditions must start at time 0.
3. The starting time of the final set of conditions must be less than the time specified in the Cycle
duration edit box.
During a dynamic simulation each set of influent conditions is used from when the simulation time equals its
starting time until the simulation time reaches the starting time of the following set of conditions. The final
set of influent conditions is used from its starting time until the Cycle duration time is reached. At the end of
the cycle the process is repeated using the Cycle duration time as time zero.
Clicking the Edit data button will present you with a dialog that is dependent on the type of influent. If the
influent is constant, you will be presented with the Edit influent dialog box. If the influent is scheduled, you
will be presented with the Edit influent itinerary dialog box. For more information on the use of these dialog
boxes, please see the Itinerary Editors section of the “General Operation” chapter.

216 • Building Configurations Biowin 6 Help Manual

Clicking the Check pH and alkalinity settings button will check that the pH and alkalinity values that you
have entered are consistent. That is, that BioWin is able to provide an acceptable mix of dissolved carbon
dioxide, anions and cations to match the settings you have specified. This process is recommended although
it can be time consuming for large influent itineraries (e.g. greater than one thousand rows). Should you
decide not to do it then BioWin will generate an alarm if the condition is encountered during a simulation.
You also may input data by loading a previously saved data file. Clicking the Open file button will present
you with the Open influent file dialog box. Using this dialog box, select the influent data file you want
(influent files that may be opened with this type of influent will have an “ifd” extension) and click Open to
finish.
You also may save a data file if you feel that you may want to use it again. Clicking the Save file button will
present you with the Save influent file dialog box. Using this dialog box, save the data file under a name and
location that you will remember.

Wastewater Fractions
The Wastewater fractions tab, shown in the figure below, is used to specify the fractional composition of
the influent wastewater.

The wastewater fractions tab of a COD Influent element

You may specify the following fractional values:

Biowin 6 Help Manual Building Configurations • 217

 Name Description
Fbs Fraction of total influent COD which is readily biodegradable
[(Sbsc + Sbsa) / Total influent COD]
Fac Fraction of readily biodegradable COD which is VFAs
[ Sbsa / (Sbsa+Sbsc) ]
Fxsp Fraction of slowly biodegradable influent COD which is particulate [Xsp
/ (Xsc + Xsp)]
Fus Fraction of total influent COD which is soluble unbiodegradable
Fup Fraction of total influent COD which is particulate unbiodegradable
Fcel Fraction of particulate unbiodegradable COD that is cellulose
Fna Fraction of influent TKN which is ammonia
Fnox Fraction of influent biodegradable organic nitrogen which is particulate
Fnus Fraction of influent TKN which is soluble unbiodegradable
Fpo4 Fraction of influent TP which is phosphate
FupN The N:COD ratio for the influent particulate unbiodegradable COD
FupP The P:COD ratio for the influent particulate unbiodegradable COD
Fsr Fraction of influent sulfur that is in reduced form
FZbh Fraction of total influent COD which is ordinary heterotrophic
organisms (OHOs).
FZbm Fraction of total influent COD which is anoxic methanol utilizing
organisms (Methylotrophs)
FZao Fraction of total influent COD which is ammonia oxidizing organisms
(AOB).
FZno Fraction of total influent COD which is nitrite oxidizing organisms
(NOB).
FZaao Fraction of total influent COD which is anaerobic ammonia oxidizing
organisms (AAO).
FZppa Fraction of total influent COD which is phosphorus accumulating
organisms (PAOs).
FZpa Fraction of total influent COD which is propionic acid acetogen
organisms (Acetogens).
FZam Fraction of total influent COD which is acetoclastic methanogen
organisms (acetoclastic Methanogens).
FZhm Fraction of total influent COD which is H2-utilizing methanogen
organisms (H2-utilizing Methanogens)
FZso Fraction of total influent COD which is sulfur oxidizing

218 • Building Configurations Biowin 6 Help Manual

 FZsrpa Fraction of total influent COD which is sulfur reducing propionic
acetogens
FZsra Fraction of total influent COD which is sulfur reducing acetotrophs
FZsrh Fraction of total influent COD which is sulfur reducing
hydrogenotrophic
FZE Fraction of total influent COD which is endogenous residue.

Note: If you enter values for FZbh, FZbm, FZaob, FZnob, FZaao, FZbp, FZbpa, FZbam, FZbhm, or FZE remember that
organisms contain nitrogen, phosphorus, and cellular inert suspended solids.

If you don’t know values for the organism fractions, it is recommended that you leave them at the default
values. Setting these fractions to zero may result in steady state solution difficulties.

An explanation of the fractionation of influent nitrogen may be helpful at this point. Ammonia is given by:
NH3 = Fna  TKNt

Soluble unbiodegradable organic nitrogen is given by:

NUS = Fnus  TKNt

Nitrogen from organisms present in the influent is calculated by the sum of the products of the various
organism concentrations and their respective nitrogen fractions, i.e.:
OrganismsN=  Zb  f N,ZB

Unbiodegradable particulate nitrogen is given by:

X IN = Fup,N  Fup  CODt

The remaining organic nitrogen is broken into particulate and soluble components. Particulate
biodegradable organic nitrogen is given by:
XON = (TKNt − NH3 − NUS − XIN − OrganismsN
)  Fnox
Soluble biodegradable organic nitrogen is given by:
NOS = (TKNt − NH3 − NUS − XIN − OrganismsN
)  (1 − Fnox )
Similarly, an explanation of the fractionation of influent phosphorus is as follows. Soluble orthophosphate is
given by:
PO4 = Fpo4  TP

Phosphorus from organisms present in the influent is calculated by the sum of the products of the various
organism concentrations and their respective phosphorus fractions, i.e.:
OrganismsP=  Zb  f P,ZB

Unbiodegradable particulate phosphorus is given by:

X IP = Fup,P  Fup  CODt

The remaining particulate biodegradable organic phosphorus is given by:

Biowin 6 Help Manual Building Configurations • 219

X OP = TP − PO4 − X IP − OrganismsP

Stream (State Variable) Influent

The Stream (SV) influent element is used to control the wastewater flow/composition to your process
configuration. The Stream (SV) Influent element differs from the standard influent element in that its
composition is specified in terms of model state variable concentrations, rather than total concentrations
(e.g. COD, TKN) and fractions (e.g. FUP, fNA). For information on monitoring parameters/variables for this
element, please see the Monitoring Data section in the “General Operation” chapter.

The Monitor items tab of a Stream (SV) Influent element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

220 • Building Configurations Biowin 6 Help Manual

The Tags tab of a Stream (SV) Influent element

Stream Input Type

The Stream Input type (state variable) tab, shown in the figure below, is used to specify the state variable
influent element as one of two possible types: Constant or Variable. If Constant is selected then you specify
the flow and one set of influent concentrations which are used during simulations. The wastewater
flow/composition of a Constant state variable influent may be changed during a dynamic simulation but
only when the simulator is paused.

Biowin 6 Help Manual Building Configurations • 221

The Stream Input Type tab of a Stream (state variable) Influent element

A variable Stream (SV) Influent element represents a user-specified time-varying flow / composition stream
entering the system. For steady state calculations the mass average of the time-varying flow / composition
pattern is used. Each set of conditions has an associated starting time; this time is the dynamic simulation
time at which these conditions will start to be used. The variable state variable influent places the following
restrictions on the starting time for each set of conditions:
1. The starting time for each set of conditions must be greater than the starting time for the previous
set.
2. The first set of conditions must start at time 0.
3. The starting time of the final set of conditions must be less than the time specified in the Cycle
duration edit box.
During a dynamic simulation each set of state variable influent conditions is used from when the simulation
time equals its starting time until the simulation time reaches the starting time of the following set of
conditions. The final set of state variable influent conditions is used from its starting time until the Cycle
duration time is reached. At the end of the cycle the process is repeated using the Cycle duration time as
time zero.
Clicking the Edit data button will present you with a dialog that is dependent on the type of state variable
influent. If the state variable influent is constant, you will be presented with the Edit influent dialog box. If
the influent is scheduled, you will be presented with the Edit influent itinerary dialog box. For more

222 • Building Configurations Biowin 6 Help Manual

information on the use of these dialog boxes, please see the Itinerary Editors section of the “General
Operation” chapter.
You also may input data by loading a previously saved data file. Clicking the From file button will present
you with the Open influent file dialog box. Using this dialog box, select the influent data file you want
(influent files that may be opened with this type of influent will have an “sif” extension) and click Open to
finish.
You also may save a data file if you feel that you may want to use it again. Clicking the To file button will
present you with the Save influent file dialog box. Using this dialog box, save the data file under a name and
location that you will remember.

Costs
The Costs tab, shown in the figure below, is used to specify the costs associated with the Stream (SV)
Influent.

The Stream Costs tab of a Stream (state variable) Influent element

Checking the Include this element in chemical costs calculation check box activates the Chemical cost text
edit box. Users can specify a chemical cost on a unit volume basis by entering a value into the text edit box.

BOD Influent
The BOD Influent element is used to control the wastewater flow/composition to your process
configuration. The BOD Influent element differs from the COD Influent element in that its organic strength is
specified in terms of BOD concentration, rather than COD concentration. For information on monitoring

Biowin 6 Help Manual Building Configurations • 223

parameters/variables for this element, please see the Monitoring Data section in the “General Operation”
chapter.

The Monitor items tab of a BOD Influent element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

224 • Building Configurations Biowin 6 Help Manual

The Tags tab of a BOD Influent element

Input Type
The Input Type (BOD Influent) tab, shown in the figure below, is used to specify the BOD influent element as
one of two possible types: Constant or Variable. If Constant is selected then you specify the flow and one
set of influent concentrations which are used during simulations. The wastewater flow/composition of a
Constant BOD influent may be changed during a dynamic simulation but only when simulator is paused.

Biowin 6 Help Manual Building Configurations • 225

The Input type tab of a BOD Influent element

A variable BOD influent element represents a user-specified time-varying flow / composition stream
entering the system. For steady state calculations the mass average of the time-varying flow / composition
pattern is used. Each set of conditions has an associated starting time; this time is the dynamic simulation
time at which these conditions will start to be used. The BOD influent places the following restrictions on the
starting time for each set of conditions:
1. The starting time for each set of conditions must be greater than the starting time for the previous
set.
2. The first set of conditions must start at time 0.
3. The starting time of the final set of conditions must be less than the time specified in the Cycle
duration edit box.
During a dynamic simulation each set of BOD influent conditions is used from when the simulation time
equals its starting time until the simulation time reaches the starting time of the following set of conditions.
The final set of BOD influent conditions is used from its starting time until the Cycle duration time is
reached. At the end of the cycle the process is repeated using the Cycle duration time as time zero.
Clicking the Edit data button will present you with a dialog that is dependent on the type of BOD influent. If
the BOD influent is constant, you will be presented with the Edit influent dialog box. If the influent is
scheduled, you will be presented with the Edit influent itinerary dialog box. For more information on the
use of these dialog boxes, please see the Itinerary Editors section of the “General Operation” chapter.

226 • Building Configurations Biowin 6 Help Manual

You also may input data by loading a previously saved data file. Clicking the From file button will present
you with the Open influent file dialog box. Using this dialog box, select the influent data file you want
(influent files that may be opened with this type of influent will have a “bif” extension) and click Open to
finish.
Clicking the Check pH and alkalinity settings button will check that the pH and alkalinity values that you
have entered are consistent. That is, that BioWin is able to provide an acceptable mix of dissolved carbon
dioxide, anions and cations to match the settings you have specified. This process is recommended although
it can be time consuming for large influent itineraries (e.g. greater than one thousand rows). Should you
decide not to do it then BioWin will generate an alarm if the condition is encountered during a simulation.
You also may save a data file if you feel that you may want to use it again. Clicking the To file button will
present you with the Save influent file dialog box. Using this dialog box, save the data file under a name and
location that you will remember.

Wastewater Fractions (BOD Influent)

The Wastewater fractions tab, shown in the figure below, is used to specify the fractional composition of
the BOD Influent wastewater. Note that these fractions are in terms of COD. Even though the overall
wastewater strength is entered in terms of BOD, the BioWin model calculates the strength in terms of COD,
and uses these fractions to place values in the state vector.
It should also be noted that the value of the fraction Fxsp is calculated by BioWin based on the given VSS of
the BOD Influent. Therefore any value entered by the user for this fraction will be overwritten.

Biowin 6 Help Manual Building Configurations • 227

The Wastewater Fractions tab of a BOD Influent element

You may specify the following fractional values:

Name Description
Fbs Fraction of total influent COD which is readily biodegradable
[(Sbsc + Sbsa) / Total influent COD]
Fac Fraction of readily biodegradable COD which is VFAs
[ Sbsa / (Sbsa+Sbsc) ]
Fxsp Fraction of slowly biodegradable influent COD which is particulate [Xsp / (Xsc + Xsp)]. Note
that this value is back-calculated by BioWin based on the VSS value entered in the BOD
influent.
Fus Fraction of total influent COD which is soluble unbiodegradable
Fup Fraction of total influent COD which is particulate unbiodegradable
Fcel Fraction of particulate unbiodegradable COD that is cellulose
Fna Fraction of influent TKN which is ammonia
Fnox Fraction of influent biodegradable organic nitrogen which is particulate

228 • Building Configurations Biowin 6 Help Manual

 Fnus Fraction of influent TKN which is soluble unbiodegradable
FupN The N:COD ratio for the influent particulate unbiodegradable COD
Fpo4 Fraction of influent TP which is phosphate
FupP The P:COD ratio for the influent particulate unbiodegradable COD
Fsr Fraction of influent total sulfur in reduced form
FZbh Fraction of total influent COD which is ordinary heterotrophic organisms (OHOs).
FZbm Fraction of total influent COD which is anoxic methanol utilizing organisms (Methylotrophs)
FZao Fraction of total influent COD which is ammonia oxidizing organisms (AOB).
FZno Fraction of total influent COD which is nitrite oxidizing organisms (NOB).
FZaao Fraction of total influent COD which is anaerobic ammonia oxidizing organisms (AAO).
FZppa Fraction of total influent COD which is phosphorus accumulating organisms (PAOs).
FZpa Fraction of total influent COD which is propionic acid acetogen organisms (Acetogens).
FZam Fraction of total influent COD which is acetoclastic methanogen organisms (acetoclastic
Methanogens).
FZhm Fraction of total influent COD which is H2-utilizing methanogen organisms (H2-utilizing
Methanogens)
FZso Fraction of total influent COD which is sulfur oxidizing
FZsrpa Fraction of total influent COD which is sulfur reducing propionic acetogens
FZsra Fraction of total influent COD which is sulfur reducing acetotrophs
FZsrh Fraction of total influent COD which is sulfur reducing hydrogenotrophic
FZE Fraction of total influent COD which is endogenous residue.

Note: If you enter values for FZbh, FZbm, FZaob, FZnob, FZaao, FZbp, FZbpa, FZbam, FZbhm, or FZE remember that
organisms contain nitrogen, phosphorus, and cellular inert suspended solids.

If you don’t know values for the organism fractions, it is recommended that you leave them at the default
values. Setting these fractions to zero may result in steady state solution difficulties.

An explanation of the fractionation of influent nitrogen may be helpful at this point. Ammonia is given by:
NH3 = Fna  TKNt

Soluble unbiodegradable organic nitrogen is given by:

NUS = Fnu  TKNt

Nitrogen from organisms present in the influent is calculated by the sum of the products of the various
organism concentrations and their respective nitrogen fractions, i.e.:
OrganismsN=  Zb  fN,ZB

Unbiodegradable particulate nitrogen is given by:

Biowin 6 Help Manual Building Configurations • 229

X IN = Fup,N  Fup  CODt

The remaining organic nitrogen is broken into particulate and soluble components. Particulate
biodegradable organic nitrogen is given by:
XON = (TKNt − NH3 − NUS − XIN − OrganismsN
)  Fnox
Soluble biodegradable organic nitrogen is given by:
NOS = (TKNt − NH3 − NUS − XIN − OrganismsN
)  (1 − Fnox )
Similarly, an explanation of the fractionation of influent phosphorus is as follows. Soluble orthophosphate is
given by:
PO4 = Fpo4  TP

Phosphorus from organisms present in the influent is calculated by the sum of the products of the various
organism concentrations and their respective phosphorus fractions, i.e.:
OrganismsP=  Zb  f P,ZB

Unbiodegradable particulate phosphorus is given by:

X IP = Fup,P  Fup  CODt

The remaining particulate biodegradable organic phosphorus is given by:

X OP = TP − PO4 − X IP − OrganismsP

Industrial COD Influent

The Industrial COD Influent element and the COD Influent are used to control the wastewater flow and
composition to your process configuration. The choice of influent element type, industrial COD influent or
traditional COD influent, depends on the type of wastewater stream that you are considering. You should
look at the wastewater fractionation sections for each of these element types to assist you to determine the
most appropriate influent element to use.
When you add an Industrial COD Influent element to your configuration, you can control the type (i.e.
constant or variable) of influent and the wastewater fractions. For information on monitoring
parameters/variables for this element, please see the Monitoring Data section in the “General Operation”
chapter.

230 • Building Configurations Biowin 6 Help Manual

The Monitor items tab of an Industrial COD Influent element

Influent Type
The Influent type tab, shown in the figure below, is used to specify the influent element as one of two
possible types: constant or variable. A constant influent’s wastewater flow/composition is constant during
a steady state simulation, but may be modified by the user during a dynamic simulation. The wastewater
flow/composition of a constant influent may be changed during a dynamic simulation only if the simulator is
paused.

Biowin 6 Help Manual Building Configurations • 231

The Influent type tab of an Industrial COD Influent element

A variable influent element represents a user-specified time-varying flow / composition stream entering the
system. For steady state calculations the mass average of the time-varying flow / composition pattern is
used. Each set of conditions has an associated starting time; this time is the dynamic simulation time at
which these conditions will start to be used. The scheduled influent places the following restrictions on the
starting time for each set of conditions:
1. The starting time for each set of conditions must be greater than the starting time for the previous
set.
2. The first set of conditions must start at time 0.
3. The starting time of the final set of conditions must be less than the time specified in the Cycle
duration edit box.
During a dynamic simulation each set of influent conditions is used from when the simulation time equals its
starting time until the simulation time reaches the starting time of the following set of conditions. The final
set of influent conditions is used from its starting time until the Cycle duration time is reached. At the end
of the cycle the process is repeated using the Cycle duration time as time zero.
Clicking the Edit data button will present you with a dialog that is dependent on the type of influent. If the
influent is constant, you will be presented with the Edit influent dialog box. If the influent is scheduled, you
will be presented with the Edit influent itinerary dialog box. For more information on the use of these
dialog boxes, please see the Itinerary Editors section of the “General Operation” chapter.

232 • Building Configurations Biowin 6 Help Manual

Clicking the Check pH and alkalinity settings button will check that the pH and alkalinity values that you
have entered are consistent. That is, that BioWin is able to provide an acceptable mix of dissolved carbon
dioxide, anions and cations to match the settings you have specified. This process is recommended
although it can be time consuming for large influent itineraries (e.g. greater than one thousand rows).
Should you decide not to do it then BioWin will generate an alarm if the condition is encountered during a
simulation.
You also may input data by loading a previously saved data file. Clicking the Open file button will present
you with the Open influent file dialog box. Using this dialog box, select the influent data file you want and
click Open to finish.
You also may save a data file if you feel that you may want to use it again. Clicking the Save file button will
present you with the Save influent file dialog box. Using this dialog box, save the data file under a name
and location that you will remember.

Wastewater Fractions
The Wastewater fractions tab, shown in the figure below, is used to specify the fractional composition of
the influent wastewater.

The wastewater fractions tab of an Industrial COD influent element

You may specify the following fractional values:

Biowin 6 Help Manual Building Configurations • 233

 Name Description
Fi1 Fraction of total influent COD which is “Industrial COD component #1”. This component
is soluble and can be modeled as either volatile or non-volatile (default).
[(SInd1) / Total influent COD]
Fi2 Fraction of total influent COD which is “Industrial COD component #2”. This component
is soluble and can be modeled as either volatile (default) or non-volatile.
[(SInd2) / Total influent COD]
Fi3 Fraction of total influent COD which is “Industrial COD component #3”. This component
is soluble and can be modeled as either volatile or non-volatile (default).
[(SInd3) / Total influent COD]
Fhc Fraction of total influent COD which is “Hydrocarbon COD”. This component is soluble
but can only be utilized after it has been adsorbed. It is non-volatile.
[(Shc) / Total influent COD]
Fus Fraction of total influent COD which is soluble unbiodegradable.
Fup Fraction of total influent COD which is particulate unbiodegradable
Fcel Fraction of particulate unbiodegradable COD that is cellulose
Fxs Fraction of total influent COD which is slowly biodegradable COD [Xs / Total influent
COD ]
Fxsp Fraction of slowly biodegradable influent COD which is particulate [Xsp / (Xsc + Xsp)]
Fsr The fraction of the influent sulfur that is in a reduced form (H2S).
Fna Fraction of influent TKN which is ammonia
Fnox Fraction of influent biodegradable organic nitrogen which is particulate
Fnus Fraction of influent TKN which is soluble unbiodegradable
FupN The N:COD ratio for the influent particulate unbiodegradable COD
Fpo4 Fraction of influent TP which is phosphate
FupP The P:COD ratio for the influent particulate unbiodegradable COD
FZbh Fraction of total influent COD which is ordinary heterotrophic organisms (OHOs).
FZm Fraction of total influent COD which is anoxic methanol utilizing organisms
(Methylotrophs)
FZao Fraction of total influent COD which is ammonia oxidizing organisms (AOB).
FZno Fraction of total influent COD which is nitrite oxidizing organisms (NOB).
FZaao Fraction of total influent COD which is anaerobic ammonia oxidizing organisms (AAO).
FZppa Fraction of total influent COD which is phosphorus accumulating organisms (PAOs).
FZpa Fraction of total influent COD which is propionic acid acetogen organisms (Acetogens).
FZam Fraction of total influent COD which is acetoclastic methanogen organisms (acetoclastic
Methanogens).

234 • Building Configurations Biowin 6 Help Manual

 FZhm Fraction of total influent COD which is H2-utilizing methanogen organisms (H2-utilizing
Methanogens)
FZso Fraction of total influent COD which is sulfur oxidizing organisms (SOO)
FZsrpa Fraction of total influent COD which is sulfur reducing propionate to acetate (propionate
degrading SRB)
FZsra Fraction of total influent COD which is acetate utilizing sulfur reducers (acetotrophic SRB)
FZsrh Fraction of total influent COD which is H2-utilizing sulfur reducers (hydrogenotrophic
SRB)
FZE Fraction of total influent COD which is endogenous residue

Note: If you enter values for any of the organism fractions remember that nitrogen, phosphorus, and celluar
inert suspended solids is associated with this COD.

If you don’t know values for the organism fractions, it is recommended that you leave them at the default
values. Setting these fractions to zero may result in steady state solution difficulties.

An explanation of the fractionation of influent nitrogen may be helpful at this point. Ammonia is given by:
NH3 = Fna  TKNt

Soluble unbiodegradable organic nitrogen is given by:

NUS = Fnus  TKNt

Nitrogen from organisms present in the influent is calculated by the sum of the products of the various
organism concentrations and their respective nitrogen fractions, i.e.:
OrganismsN=  Zb  f N,ZB

Unbiodegradable particulate nitrogen is given by:

X IN = Fup,N  Fup  CODt

The remaining organic nitrogen is broken into particulate and soluble components. Particulate
biodegradable organic nitrogen is given by:
XON = (TKNt − NH3 − NUS − XIN − OrganismsN
)  Fnox
Soluble biodegradable organic nitrogen is given by:
NOS = (TKNt − NH3 − NUS − XIN − OrganismsN
)  (1 − Fnox )
Similarly, an explanation of the fractionation of influent phosphorus is as follows. Soluble orthophosphate is
given by:
PO4 = Fpo4  TP

Phosphorus from organisms present in the influent is calculated by the sum of the products of the various
organism concentrations and their respective phosphorus fractions, i.e.:
OrganismsP=  Zb  f P,ZB

Biowin 6 Help Manual Building Configurations • 235

Unbiodegradable particulate phosphorus is given by:
X IP = Fup,P  Fup  CODt

The remaining particulate biodegradable organic phosphorus is given by:

X OP = TP − PO4 − X IP − OrganismsP

Methanol addition
The Methanol addition influent element is used to control the flow/composition of a methanol addition
stream to your process configuration. For information on monitoring parameters/variables for this element,
please see the Monitoring Data section in the “General Operation” chapter.

The Monitor items tab of a Methanol addition influent element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

236 • Building Configurations Biowin 6 Help Manual

The Tags tab of a Methanol addition influent element

Influent Type (Methanol)

The Input type tab (Methanol addition), shown in the figure below, is used to specify the methanol influent
element as one of three possible types: Constant, Variable or Paced. If Constant is selected then you specify
the methanol concentration and flow which are used during simulations. The methanol flow/composition
may be changed during a dynamic simulation but only when the simulator is paused.

Biowin 6 Help Manual Building Configurations • 237

The Input type tab of a Methanol addition influent element

A methanol influent element represents a user-specified time-varying flow / composition stream entering
the system. For steady state calculations the mass average of the time-varying flow / composition pattern is
used. Each set of conditions has an associated starting time; this time is the dynamic simulation time at
which these conditions will start to be used. The Methanol addition influent places the following restrictions
on the starting time for each set of conditions:
1. The starting time for each set of conditions must be greater than the starting time for the previous
set.
2. The first set of conditions must start at time 0.
3. The starting time of the final set of conditions must be less than the time specified in the Cycle
duration edit box.
During a dynamic simulation each set of methanol influent conditions is used from when the simulation time
equals its starting time until the simulation time reaches the starting time of the following set of conditions.
The final set of methanol influent conditions is used from its starting time until the Cycle duration time is
reached. At the end of the cycle the process is repeated using the Cycle duration time as time zero.
Clicking the Edit data button will present you with a dialog that is dependent on the type of methanol
addition. If the methanol addition is constant, you will be presented with the Edit influent dialog box. If the
methanol addition is scheduled, you will be presented with the Edit influent itinerary dialog box. For more
information on the use of these dialog boxes, please see the Itinerary Editors section of the “General

238 • Building Configurations Biowin 6 Help Manual

Operation” chapter. If the methanol addition is flow paced, you will be presented with the Methanol Pacing
Specification dialog box.

The methanol pacing specification dialog box

There are two options for pacing method:

1. Mass flow paced
2. Flow paced
If Mass flow paced is selected, you may enter a number in the Pace at text box area as a % of the mass of,
and then select an influent component as the basis for flow pacing from the drop list of components. You
can also specify the influent element as the basis for mass flow pacing from the drop list of influent
elements in the configuration.
If Flow paced is selected, you may enter a number in the Pace at text box area as a %, and then select the
influent element as the basis for flow pacing from the drop list of influent elements in the configuration.
You also may input variable methanol influent data by loading a previously saved data file. Clicking the From
file button will present you with the Open influent file dialog box. Using this dialog box, select the methanol
influent data file you want and click Open to finish.
You also may save a data file if you feel that you may want to use it again. Clicking the To file button will
present you with the Save influent file dialog box. Using this dialog box, save the data file under a name and
location that you will remember.

Specifying Methanol Influent Concentrations

BioWin places default values for a 100 % methanol solution in the methanol influent element. This section
outlines how these numbers are calculated. Using the following methodology, you can specify concentration
values for different methanol strengths.
COD / Mass Ratio
The COD / mass ratio for methanol (CH3OH) can be calculated as follows from balancing the equation for the
complete oxidation of methanol to carbon dioxide and water:

Biowin 6 Help Manual Building Configurations • 239

 3
CH3OH + O2  CO2 + 2H2O
2
That is, 1.5 moles (48 g) of oxygen is required to oxidize 1 mole (32 g) of methanol. So the COD / mass ratio
for methanol is (48 g / 32 g) 1.5. You can see the methanol concentration number changing by a factor of 1.5
in BioWin when you change between methanol concentration units of mg/L and mg COD/L.
Methanol Composition
From Chemical Engineer's Handbook, the specific gravity of pure methanol is 0.792. That is, it has a density
of 0.792 kg/L. Using the COD / mass ratio calculated above, this corresponds to a COD concentration of
(1.5*0.792) 1.188 kg COD/L, or 1,188,000 mg COD/L.
Note that if your methanol solution is specified in terms of molar concentration; convert to a mass
concentration using the molecular weight for methanol of 32 g / mole.
Reference
Perry, R.H., Chilton, C.H. (1973) Chemical Engineer's Handbook. McGraw-Hill Inc.

Costs (Methanol)
The Costs tab for the Methanol addition element is shown in the figure below.

The Costs tab of a Methanol addition influent element

Users can specify whether the cost of methanol addition should be included in project cost estimates by
checking the Include this element in chemical costs calculation check box. The actual cost of methanol is
specified in Project|Costs/Energy|Fuel/Chemical….

240 • Building Configurations Biowin 6 Help Manual

SSO (Source Separated Organics) Influent
The SSO Influent element is intended to simplify the addition of “external” organics, nitrogen, and
phosphorus to a BioWin configuration. An example application would be the addition of externally-sourced
food waste to an anaerobic digester to increase biogas production. The particulate COD, N, and P
concentrations can be specified; the VSS of the stream is calculated from the input COD and the Solid
organic COD:VSS ratio found on the Common tab of the Project|Parameters|Stoichiometric menu. For
information on monitoring parameters/variables for this element, please see the Monitoring Data section in
the “General Operation” chapter.

The Monitor items tab of an SSO Influent element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

Biowin 6 Help Manual Building Configurations • 241

The Tags tab of an SSO Influent element

Input Type
The Input Type (SSO Influent) tab, shown in the figure below, is used to specify the SSO influent element as
one of two possible types: Constant or Variable. If Constant is selected, then you specify the flow and one
set of influent concentrations which are used during simulations. The wastewater flow/composition of a
Constant SSO influent may be changed during a dynamic simulation but only when simulator is paused.

242 • Building Configurations Biowin 6 Help Manual

The Input type tab of an SSO Influent element

A variable SSO influent element represents a user-specified time-varying flow / composition stream entering
the system. For steady state calculations the mass average of the time-varying flow / composition pattern is
used. Each set of conditions has an associated starting time; this time is the dynamic simulation time at
which these conditions will start to be used. The SSO influent places the following restrictions on the starting
time for each set of conditions:
1. The starting time for each set of conditions must be greater than the starting time for the previous
set.
2. The first set of conditions must start at time 0.
3. The starting time of the final set of conditions must be less than the time specified in the Cycle
duration edit box.
During a dynamic simulation each set of SSO influent conditions is used from when the simulation time
equals its starting time until the simulation time reaches the starting time of the following set of conditions.
The final set of SSO influent conditions is used from its starting time until the Cycle duration time is reached.
At the end of the cycle the process is repeated using the Cycle duration time as time zero.
Clicking the Edit data button will present you with a dialog that is dependent on the type of SSO influent. If
the SSO influent is constant, you will be presented with the Edit influent dialog box. If the influent is
scheduled, you will be presented with the Edit influent itinerary dialog box. For more information on the
use of these dialog boxes, please see the Itinerary Editors section of the “General Operation” chapter.

Biowin 6 Help Manual Building Configurations • 243

You also may input data by loading a previously saved data file. Clicking the Open file button will present
you with the Open influent file dialog box. Using this dialog box, select the influent data file you want
(influent files that may be opened with this type of influent will have a “bif” extension) and click Open to
finish.
Clicking the Check pH and alkalinity settings button will check that the pH and alkalinity values that you
have entered are consistent. That is, that BioWin can provide an acceptable mix of dissolved carbon dioxide,
anions and cations to match the settings you have specified. This process is recommended although it can
be time consuming for large influent itineraries (e.g. greater than one thousand rows). Should you decide
not to do it then BioWin will generate an alarm if the condition is encountered during a simulation.
You also may save a data file if you feel that you may want to use it again. Clicking the Save file button will
present you with the Save influent file dialog box. Using this dialog box, save the data file under a name and
location that you will remember.

Costs (SSO)
The Costs tab of the SSO element is shown in the figure below.

The Costs tab of an SSO element

Users can specify whether the cost of SSO addition should be included in project chemical cost estimates by
checking the Include this element in chemical costs calculation check box. Note that SSO also can count as a
“credit” toward operating costs, if the “Credit” option is selected.

244 • Building Configurations Biowin 6 Help Manual

Metal Addition Influent
The Metal Addition influent elements are used to control the flow/composition of a metal addition stream
to your process configuration. There are three types of metal that can be input to a BioWin configuration:
• Iron-Ferric
• Iron-Ferrous
• Aluminum
For information on monitoring parameters/variables for this element, please see the Monitoring Data
section in the “General Operation” chapter.
Important note about the updated chemical phosphorus removal model in BioWin 6.0: This model
requires that metal streams must be added to elements that have volume. It is no longer applicable to add
a metal input stream to a mixing node element. If you want to simulate adding a metal stream to a channel
at your plant, you should use the new Plug Flow Channel element. The Plug Flow Channel element should be
sized appropriately; e.g. it should have a linear flow velocity of between 0.3 and 0.5 m/s, and likely an HRT
on the order of a few minutes. It also may be necessary to increase the velocity gradient in the first zone of
the plug flow channel to reflect turbulent mixing conditions. You can also add a metal input stream directly
to a bioreactor; BioWin will use the velocity gradient it calculates based on factors such as flow through the
reactor, air flow rates, and specified mixing intensity in the chemical phosphorus model calculations.

The Monitor items tab of an Iron (Ferric) metal addition influent element

Biowin 6 Help Manual Building Configurations • 245

For information on tags for these elements, please see the Customizing the Project Appearance subsection
in the Customizing BioWin section in the “General Operation” chapter.

The Tags tab of a Metal addition influent element

Influent Type (Metal Addition)

The Input type tab (Metal addition), shown in the figure below, is used to specify the Metal Addition
influent element as one of three possible types: constant, variable, or paced. If Constant is selected then
you specify the metal concentration and flow which are used during simulations. The metal
flow/composition may be changed during a dynamic simulation but only when the simulator is paused.

246 • Building Configurations Biowin 6 Help Manual

The Metal Input Type tab of an Iron (Ferric) metal addition element

A Metal Addition influent element represents a user-specified time-varying flow / composition stream
entering the system. For steady state calculations the mass average of the time-varying flow / composition
pattern is used. Each set of conditions has an associated starting time; this time is the dynamic simulation
time at which these conditions will start to be used. The metal addition influent places the following
restrictions on the starting time for each set of conditions:
1. The starting time for each set of conditions must be greater than the starting time for the previous
set.
2. The first set of conditions must start at time 0.
3. The starting time of the final set of conditions must be less than the time specified in the Cycle
duration edit box.
During a dynamic simulation each set of metal addition influent conditions is used from when the simulation
time equals its starting time until the simulation time reaches the starting time of the following set of
conditions. The final set of metal addition influent conditions is used from its starting time until the Cycle
duration time is reached. At the end of the cycle the process is repeated using the Cycle duration time as
time zero.
Clicking the Edit data button will present you with a dialog that is dependent on the type of metal addition
influent. If the metal addition influent is constant, you will be presented with the Edit influent dialog box. If
the metal addition influent is scheduled, you will be presented with the Edit influent itinerary dialog box.
For more information on the use of these dialog boxes, please see the Itinerary Editors section of the

Biowin 6 Help Manual Building Configurations • 247

“General Operation” chapter. If the metal addition influent is flow paced, you will be presented with the
Metal Pacing Specification dialog box.

The Metal Pacing specification dialog box for an Iron (Ferric) metal addition element

248 • Building Configurations Biowin 6 Help Manual

The Metal Pacing specification dialog box for an Iron (Ferrous) metal addition element

The Metal Pacing specification dialog box for an Aluminum metal addition element

There are two options for pacing method:

1. Mass flow paced
2. Flow paced
If Mass flow paced is selected, you may enter a number in the Pace at text box area as a % of the mass of,
and then select an influent component as the basis for flow pacing from the drop list of components. You
can also specify the influent element as the basis for mass flow pacing from the drop list of influent
elements in the configuration.
If Flow paced is selected, you may enter a number in the Pace at text box area as a %, and then select the
influent element as the basis for flow pacing from the drop list of influent elements in the configuration.
You also may input data by loading a previously saved data file. Clicking the From file button will present
you with the Open influent file dialog box. Using this dialog box, select the metal addition influent data file
(*.mef) you want and click Open to finish.
You also may save a data file if you feel that you may want to use it again. Clicking the To file button will
present you with the Save influent file dialog box. Using this dialog box, save the data file under a name and
location that you will remember.

Note: You can change the metal used by the metal addition influent on the Model tab which can be
accessed via the Project|Current Project Options menu command.

Biowin 6 Help Manual Building Configurations • 249

Costs (Metal Addition)
The Costs tab of the Metal Addition element is shown in the figure below.

The Costs tab of an Aluminum metal addition element

Users can specify whether the cost of metal addition should be included in project chemical cost estimates
by checking the Include this element in chemical costs calculation check box. Actual metal costs are
specified in Project|Costs/Energy|Fuel/Chemical….

Effluents
Effluent
The Effluent element has no model. It is used as a receptacle for the conduit from the final element in a
chain. As such the Effluent element is used primarily for the various checks that BioWin performs on the
system integrity. For information on monitoring parameters/variables for this element, please see the
Monitoring Data section in the “General Operation” chapter.

250 • Building Configurations Biowin 6 Help Manual

The Monitor items tab of an Effluent element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

Biowin 6 Help Manual Building Configurations • 251

The Tags tab of an Effluent element

Effluent Power/Costs
The Power/Costs tab, shown below, allows the user to specify power and/or costs associated with the
Effluent element.

252 • Building Configurations Biowin 6 Help Manual

The Power/Costs tab of an Effluent element

Checking the Include this effluent in power/cost calculations check box activates the Effluent options (for
power/cost calculations) group. A cost can be specified for Chlorine disinfection by checking the Chlorine
disinfection check box and specifying a value in the text edit box. Costs associated with this checkbox will be
accounted for under the Chemicals group in cost charts and tables. The user can specify a flow-based power
requirement for Filtration by checking the Filtration check box and specifying a value in the text edit box
(note that this option could be used for some other unit process that consumes power associated with
tertiary effluent treatment). The user can also specify a flow-based power requirement for UV Disinfection
by checking the UV Disinfection check box and entering a value in the text edit box.
Additional options for specifying power in the Effluent element are available by checking the Power check
box. This activates the Power supply rate group. The users can choose to specify a fixed power, or a power
per unit flow by checking the Power per unit flow to this element checkbox. The user can enter a constant
value for power or power per unit flow by selecting the Constant value of radio button and entering a value
in the text edit box provided. Alternatively, the user can enter a power or power per unit flow pattern by
selecting the Scheduled radio button. This activates the Pattern…button. Clicking this button will open the
Power Itinerary editor. Power calculated for the Effluent element will be grouped under the “Solids/Liquids
Separation/Disinfection” category in power charts and tables.

Sludge Effluent
The Sludge Effluent element has no model. It is used as a receptacle for the conduit from the final element
in a chain. As such the effluent element is used primarily for the various checks that BioWin performs on the
system integrity. For information on monitoring parameters/variables for this element, please see the
Monitoring Data section in the “General Operation” chapter.

Biowin 6 Help Manual Building Configurations • 253

The Sludge Effluent element differs from a regular effluent element only in the information that is displayed
in the Main Simulator Window Summary Panes when you hover over it with the cursor. Information
displayed includes VSS and TSS expressed in % solids, nutrient percentages of the sludge, and sludge mass
rates. Therefore, this element is useful as a receptacle for WAS flows and other solids train process flows.

The Monitor items tab of a Sludge Effluent element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

254 • Building Configurations Biowin 6 Help Manual

The Tags tab of a Sludge Effluent element

Sludge Power/Costs
The Power/Costs tab, shown below, allows the user to specify disposal costs and power associated with the
Sludge element.

Biowin 6 Help Manual Building Configurations • 255

The Power/Costs tab of a Sludge element

Checking the Include this sludge in power/cost calculations checkbox activates the Sludge options (for
power/cost calculations) group.
• The user can specify a cost for haulage/disposal based on the dry mass of total suspended solids in
the sludge stream by checking the Sludge disposal (dry) checkbox and specifying a value in the
text edit box.
• The user can specify a cost for haulage/disposal based on the volumetric flow of the sludge stream
by checking the Sludge disposal (volumetric) checkbox and specifying a value in the resulting
text edit box provided.
• The user can specify a cost for haulage/disposal based on the wet mass of total suspended solids in
the sludge stream by checking the Sludge disposal (wet tonne) checkbox and specifying a value
in the text edit box. Options for specifying power in the Sludge element are available by checking
the Power check box. This activates the Mechanical power specification group.
• The user can choose to specify a fixed power, or a power per unit flow by checking the Power per
unit flow to this element checkbox.
• The user can enter a constant value for power or power per unit flow by selecting the Constant
value of radio button and entering a value in the text edit box.
• Alternatively, the user can enter a power or power per unit flow pattern by selecting the
Scheduled radio button. This activates the Pattern…button. Clicking this button will open the

256 • Building Configurations Biowin 6 Help Manual

 Power Itinerary editor. Power calculated for the sludge element will be grouped under the
“Mechanical power” category in power charts and tables.

Note: By default, none of the power/cost options are selected in a Sludge Element.

Model Builder Unit

The Model Builder Unit element allows you to incorporate your own models into BioWin simulations. This
element allows you to input your own stoichiometry and rate equations involving any or all of BioWin's state
variables. You may specify parameters related to the operation and control of the model builder reactor
element, the volume variability, and the model that it uses. For information on monitoring
parameters/variables for this element, please see the Monitoring Data section in the “General Operation”
chapter.

The Monitor items tab of a Model Builder Unit element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

Biowin 6 Help Manual Building Configurations • 257

The Tags tab of a Model Builder Unit element

Model Builder Reactor Dimensions

The Dimensions tab, shown below, allows the user to enter the physical dimensions of a model builder
reactor element.

258 • Building Configurations Biowin 6 Help Manual

The Dimensions tab of a Model Builder Unit element

There are two methods for entering the dimensions: by Area and depth, or by Volume and depth. The
method is specified by clicking on the appropriate radio button.
• If you select by Area and depth, the model builder reactor element area and depth must be
entered in the Area and Depth text edit boxes.
• If you select by Volume and depth, the model builder reactor element volume and depth must be
entered in the Volume and Depth text edit boxes.
Regardless of the method you choose, you also must specify a Width for the element. Units are shown to
the right of the edit boxes. The element name and type, and a picture of the element also are shown.

Model Builder Reactor Operation

The Operation tab, shown below, allows the user to enter operating parameters for a Model builder reactor
element such as aeration and diffuser specifications, as well as a local temperature.

Biowin 6 Help Manual Building Configurations • 259

The Operation tab of a Model Builder Unit element

There are two methods for specifying aeration: either by a DO setpoint or by an Air flow rate. The aeration
method is specified by clicking on the appropriate radio button. When DO setpoint is selected, the setpoint
concentration must be specified. You may specify either a Constant setpoint or a Scheduled DO setpoint
pattern (clicking the Pattern… button will open the Edit DO setpoint itinerary dialog box). You may wish to
place a restriction on the minimum and maximum allowable air flow rate that may be used to achieve the
desired DO setpoint by setting a minimum or maximum allowable airflow in the Air flow rate constraints
group. This is a useful feature for investigating the ability of air equipment to achieve desired DO setpoints.
When Air flow rate is selected, the air flow rate must be specified. You may specify either a Constant air
flow rate or a Scheduled air flow rate pattern (clicking the Pattern… button will open the Edit air flow
itinerary dialog box).

Note: If you specify an air supply rate, BioWin will automatically turn on the oxygen modeling option.

You may also specify that the model builder reactor element is Unaerated.
There are three methods for entering diffuser information: by a Density(%), by an ATAD, or by the Number
of Diffusers. The diffuser information is specified by clicking on the appropriate radio button.
• If you select Density(%), the diffuser density (%) (i.e. the total area of diffusers in aeration tank /
area of aeration tank expressed as a percent) must be specified in the Density(%) text edit box.
• If ATAD is selected, the ATAD (i.e. area of aeration tank/total area of diffusers in aeration tank) must
be specified in the text edit box.

260 • Building Configurations Biowin 6 Help Manual

 • If Number of Diffusers is selected, the number of diffusers must be specified in the text edit box.
A Local temperature also may be specified for a model builder reactor element. When you click on the
check box for local temperature, the temperature radio button group is enabled. You may then specify
either a Constant or Scheduled temperature.
• If constant temperature is selected, you may enter the value in the edit box.
• If scheduled temperature is selected the Pattern… button becomes active. Clicking this button
presents you with the Edit temperature itinerary dialog box.

Model Builder Unit Outflow

The Model Builder Unit element Outflow tab, shown below, is used to specify the overflow behavior. The
overflow behavior can be generalized as follows:
• Whenever the model builder reactor element is full, it overflows at the influent rate, regardless of
the overflow setting.
• Whenever the model builder reactor element is empty and the outflow rate is set higher than the
influent rate, the model builder reactor element will only have an outflow equal to the influent flow,
so as not to have negative volume. If the outflow rate is set lower than the influent rate, then the
model builder reactor element will begin to fill up.
• If the Constant volume (i.e. outflow=inflow) option is checked, then the entire liquid volume entered
on the Dimensions tab is used and the volume will be constant.

Note: Remember for steady state simulations, the initial liquid hold-up volume will be used for calculations.

The following is a description of the behavior of the three outflow settings:

• Overflow only – the model builder reactor element fills up, and then overflows at the influent flow
rate (this setting could be used to simulate start-up of a bioreactor).
• Constant outflow – the outflow always tries to attain the specified constant rate, except when
physically constrained (i.e. when the Model Builder Unit element is full or empty)
• Flow pattern – the outflow always tries to attain the current specified pattern rate, except when
physically constrained (i.e. when the Model Builder Unit element is full or empty). To specify a
pattern, click the Pattern… button when it becomes active. For more information, see the Liquid
outflow itinerary section in the “General Operation” chapter.

Biowin 6 Help Manual Building Configurations • 261

 The Outflow tab of a Model Builder Unit element

Model Builder Reactor Initial Values

The Initial values tab, shown below, is used for specifying the initial settings for model builder reactor
element concentrations and volume.

262 • Building Configurations Biowin 6 Help Manual

The Initial values tab of a Model Builder Unit element with the Default option active

Use the Initial liquid hold-up field to enter a value to specify the % of full setting. This initial liquid hold-up
volume will be used for steady state calculations. It should be noted here that the lower and upper limits on
this value are 0.02 and 99.98 %, respectively. This reflects the fact that this is the liquid volume, and allows
for small differences between liquid volume and reactor volume for inlet and outlet pipes.
There are two methods for setting up Initial concentrations in the model builder reactor element.
The dialog box shown above illustrates the first case where the Default option is selected. When this option
is selected, BioWin applies default seed values for all the state variables (except volume, which you specify)
in the same manner it would for bioreactor elements.
The dialog box shown below illustrates the second case where the User defined option is selected. In this
case, an editable list of state variables is displayed in the dialog box. This allows you to enter your own seed
values or initial concentrations for state variables in the model builder reactor element.

Biowin 6 Help Manual Building Configurations • 263

The Initial values tab of a Model Builder Unit element with the User defined option active

If you choose User defined initial concentrations, there are two conditions when the User defined initial
concentrations can be used.
If the box labeled “Set these values now …” is checked then the concentrations specified are inserted in the
state vector as soon as the OK button is clicked.
If the box labeled “Set these values now …” is NOT checked then the initial concentrations will be inserted
in the model builder reactor state vector when you begin a dynamic or steady state simulation and choose
to start the simulation from seed values

Note: If “Set these values now …” is checked, the specified values are placed in the reactor state variable
vector when you click OK overriding any existing state variable vector values. Consequently, a dynamic
simulation started from this point will use the User defined initial concentrations regardless of whether you
choose to start from Seed values or Current values.

The use of this option is illustrated in the example at the end of the Variable Volume/Batch Bioreactor Initial
Values section later in this chapter.

Model Builder Reactor Power

The Power tab, shown below, allows the user to enter power specifications for mechanical mixing.

264 • Building Configurations Biowin 6 Help Manual

The Power tab of a Model Builder Unit element

Power can be specified on a power per unit volume basis or on a fixed basis by checking or unchecking the
Power per unit vol check box, respectively. The user can enter a constant value for power or power per unit
volume by selecting the Constant value of radio button and entering a value in the text edit box.
Alternatively, the user can enter a power or power per unit volume pattern by selecting the Scheduled radio
button. This activates the Pattern…button. Clicking this button will open the the Power Itinerary editor.
Power calculated for the Model Builder element will be grouped under the “Mixing power” category in
power charts and tables.

Model Builder Reactor Model

The Model tab, shown below, allows the user to enter user-defined model stoichiometry and rate
equations, as well as change local model parameters.

Biowin 6 Help Manual Building Configurations • 265

The Model tab of a Model Builder Unit element

There are several methods for specifying what model the model builder reactor element uses. If you want to
have a local, user-defined model where you set up stoichiometry and rate equations, select the box labeled
Local Builder model. This will activate the button labeled Specify local model…. Clicking this button will
open the Model Builder dialog box, which allows you to enter stoichiometry and rate equations for any or
all BioWin's state variables. The use of this tool is explained in more detail in the Model Builder section.
If you wish, you may also choose to incorporate BioWin reactions into your model builder reactor element.
If you want to do this, select the box labeled Include BioWin reactions.
You also can specify Local BioWin kinetic parameters for the activated sludge model used in the model
builder reactor element, if you have selected the Include BioWin reactions option. If you click on the check
box for local BioWin kinetic parameters, then clicking the Edit local kinetic parameters… button opens the
Parameter editor dialog box allowing you access to the various activated sludge model kinetic parameters.
If you wish to override the project global aeration parameters with local values specific to this element only,
select the box labeled Local aeration parameters. This will activate the button labeled Edit local aeration
parameters…. Clicking this button will open the Aeration dialog box, which allows you to modify aeration
parameters.
If you wish to override the project global diffuser parameters with local values specific to this element only,
select the box labeled Local diffuser parameters. This will activate the button labeled Edit local diffuser
parameters…. Clicking this button will open the Diffuser dialog box, which allows you to modify diffuser
parameters.

266 • Building Configurations Biowin 6 Help Manual

To model the concentrations of the constituents of the aeration gas (e.g. oxygen, carbon dioxide, etc.),
check the box labeled Model gas phase. If this option is selected you may also enter a percentage value for
the Gas hold-up (i.e. the percentage of the total reactor volume occupied by aeration gas).
You can also specify the aeration parameters Alpha F and Beta. You may specify either a Constant value or a
Scheduled pattern for each parameter (clicking the Pattern… button will open the Edit Alpha itinerary or
Edit Beta itinerary dialog box). If you wish to plot Alpha and/or Beta click on the graph button. This will add
a time series plot of alpha and/or beta to the BioWin Album.

Bioreactors
Bioreactor
The Bioreactor element simulates the activated sludge process in a continuous stirred tank reactor (CSTR).
Complex activated sludge systems can be configured by arranging a number of bioreactors in series/parallel.
You may specify parameters related to the operation and control of the bioreactor element. For information
on monitoring parameters/variables for this element, please see the Monitoring Data section in the
“General Operation” chapter.

The Monitor items tab of a Bioreactor element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

Biowin 6 Help Manual Building Configurations • 267

The Tags tab of a Bioreactor element

Bioreactor Dimensions

The Dimensions tab, shown below, allows the user to enter the physical dimensions of a Bioreactor
element.

268 • Building Configurations Biowin 6 Help Manual

The Dimensions tab of a Bioreactor element

There are two methods for entering the dimensions: by Area and depth, or by Volume and depth. The
method is specified by clicking on the appropriate radio button.
• If you select by Area and depth, the bioreactor area and depth must be entered in the Area and
Depth text edit boxes.
• If you select by Volume and depth, the bioreactor volume and depth must be entered in the Volume
and Depth text edit boxes.
Regardless of the method you choose, you also must specify a Width for the element. Units are shown to
the right of the edit boxes. The element name and type, and a picture of the element also are shown.

Bioreactor Operation

The Operation tab, shown below, allows the user to enter operating parameters for a Bioreactor element,
such as aeration and diffuser specifications, as well as specify a local temperature.

Biowin 6 Help Manual Building Configurations • 269

The Operation tab of a Bioreactor element

There are two methods for specifying aeration: either by a DO setpoint or by an Air flow rate. The aeration
method is specified by clicking on the appropriate radio button.
• When DO setpoint is selected, the setpoint concentration must be specified. You may specify either
a Constant setpoint or a Scheduled DO setpoint pattern (clicking the Pattern… button will open the
Edit DO setpoint itinerary dialog box). You may wish to place a restriction on the minimum and
maximum allowable air flow rate that may be used to achieve the desired DO setpoint by setting a
minimum or maximum allowable airflow in the Air flow rate constraints group. This is a useful
feature for investigating the ability of air equipment to achieve desired DO setpoints.
• When Air flow rate is selected, the air flow rate must be specified. You may specify either a Constant
air flow rate or a Scheduled air flow rate pattern (clicking the Pattern… button will open the Edit air
flow itinerary dialog box). Note that if you specify an air supply rate, BioWin will automatically turn
on the oxygen modeling option.
There are three methods for entering diffuser information: by a Density(%), by an ATAD, or by the Number
of Diffusers. The diffuser information is specified by clicking on the appropriate radio button.
• If you select Density(%), the diffuser density (%) (i.e. the total area of diffusers in aeration tank /
area of aeration tank expressed as a percent) must be specified in the Density(%) text edit box.
• If ATAD is selected, the ATAD (i.e. area of aeration tank/total area of diffusers in aeration tank) must
be specified in the edit box.
• If Number of Diffusers is selected, the number of diffusers must be specified in the edit box.

270 • Building Configurations Biowin 6 Help Manual

A Local temperature also may be specified for a bioreactor element. When you click on the check box for
local temperature, the Specify temperature by radio button group is enabled. You may then specify either a
Constant or Scheduled temperature.
• If constant temperature is selected, you may enter the value in the edit box.
• If scheduled temperature is selected the Pattern… button becomes active. Clicking this button
presents you with the Edit temperature itinerary dialog box.

Bioreactor Power
The Power tab, shown below, allows the user to enter power specifications for mechanical mixing.

The Power tab of a Bioreactor element

Power can be specified on a power per unit volume basis or on a fixed basis by checking or unchecking the
Power per unit vol check box, respectively. The user can enter a constant value for power or power per unit
volume by selecting the Constant value of radio button and entering a value in the text edit box.
Alternatively, the user can enter a power or power per unit volume pattern by selecting the Scheduled radio
button. This activates the Pattern…button. Clicking this button will open the Power Itinerary editor. Power
calculated for the Bioreactor element will be grouped under the “Mixing power” category in power charts
and tables.

Bioreactor Model
The Model tab, shown below, allows the user to change local model parameters.

Biowin 6 Help Manual Building Configurations • 271

The Model tab of a Bioreactor element

You can specify Local kinetic parameters for the activated sludge model used in the bioreactor element. If
you click on the check box for local kinetic parameters, then clicking the Edit local kinetic parameters…
button opens the Parameter editor dialog box allowing you access to the various activated sludge model
kinetic parameters.
If you wish to override the project global aeration parameters with local values specific to this element only,
select the box labeled Local aeration parameters. This will activate the button labeled Edit local aeration
parameters…. Clicking this button will open the Aeration dialog box, which allows you to modify aeration
parameters.
If you wish to override the project global diffuser parameters with local values specific to this element only,
select the box labeled Local diffuser parameters. This will activate the button labeled Edit local diffuser
parameters…. Clicking this button will open the Diffuser dialog box, which allows you to modify diffuser
parameters.
To model the concentrations of the constituents of the aeration gas (e.g. oxygen, carbon dioxide, etc.),
check the box labeled Model gas phase. If this option is selected you must also enter a percentage value for
the Gas hold-up (i.e. the percentage of the total reactor volume occupied by aeration gas).
You can also specify the aeration parameters Alpha F and Beta. You may specify either a Constant value or a
Scheduled pattern for each parameter (clicking the Pattern… button will open the Edit Alpha itinerary or
Edit Beta itinerary dialog box). If you wish to plot Alpha and/or Beta click on the graph button. This will add
a time series plot of alpha and/or beta to the BioWin Album.

272 • Building Configurations Biowin 6 Help Manual

Membrane Bioreactor
This element simulates the activated sludge process in a Membrane bioreactor (MBR). You may specify
parameters related to the operation and control of the MBR, membrane characteristics (e.g. displaced
volume), and membrane performance (e.g. capture of colloidal material). For information on monitoring
parameters/variables for this element, please see the Monitoring Data section in the “General Operation”
chapter.

The Monitor items tab of a Membrane bioreactor element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

Biowin 6 Help Manual Building Configurations • 273

The Tags tab of a Membrane bioreactor element

Membrane Bioreactor Dimensions

The Dimensions tab, shown below, allows the user to enter the physical dimensions and membrane packing
information for a Membrane bioreactor element.

274 • Building Configurations Biowin 6 Help Manual

The Dimensions tab of a Membrane bioreactor element

There are two methods for entering the dimensions: by Area and depth, or by Volume and depth. The
method is specified by clicking on the appropriate radio button.
• If you select by Area and depth, the bioreactor area and depth must be entered in the Area and
Depth text edit boxes.
• If you select by Volume and depth, the bioreactor volume and depth must be entered in the Volume
and Depth text edit boxes.
Regardless of the method you choose, you also must specify a Width for the element. Units are shown to
the right of the edit boxes. The element name and type, and a picture of the element also are shown.
The bottom portion of the dialog box is where information on membrane packing and membrane physical
characteristics is entered. You may enter either the number of Cassettes, or the Packing density. You can
also input the Displaced volume/cassette and the Membrane surface area/cassette. The displaced
volume/cassette value is used along with the total MBR element volume to calculate the volume percentage
of the MBR tank occupied by the membrane cassettes (note this number is not updated as soon as you
change the number of cassettes or the packing density – it only is updated when you click the OK button).
The membrane surface area/cassette value is used to convert between packing density and number of
cassettes, and in the membrane flux calculation.

Note: If you specify a packing density, changing the MBR volume will change the number of cassettes and
the calculated membrane flux. Note that the membrane flux is not an operational parameter that is entered;
rather, it is calculated based on the flow and load to the MBR. The flux may be viewed in the main window
summary pane by pointing to an MBR on a flowsheet, and it can also be plotted.

Biowin 6 Help Manual Building Configurations • 275

Membrane Bioreactor Operation

The Operation tab, shown below, allows the user to enter operating parameters for a Membrane bioreactor
element, such as aeration and diffuser specifications as well as local temperature.

The Operation tab of a Membrane bioreactor element

There are two methods for specifying aeration: either by a DO setpoint or by an Air flow rate. The aeration
method is specified by clicking on the appropriate radio button.
• When DO setpoint is selected, the setpoint concentration must be specified. You may specify either
a Constant setpoint or a Scheduled DO setpoint pattern (clicking the Pattern… button will open the
Edit DO setpoint itinerary dialog box). You may wish to place a restriction on the minimum and
maximum allowable air flow rate that may be used to achieve the desired DO setpoint by setting a
minimum or maximum allowable airflow in the Air flow rate constraints group. This is a useful
feature for investigating the ability of air equipment to achieve desired DO setpoints.
• When Air flow rate is selected, the air flow rate must be specified. You may specify either a Constant
air flow rate or a Scheduled air flow rate pattern (clicking the Pattern… button will open the Edit air
flow itinerary dialog box). Note that if you specify an air supply rate, BioWin will automatically turn
on the oxygen modeling option.
There are three methods for entering diffuser information: by a Density(%), by an ATAD, or by the Number
of Diffusers. The diffuser information is specified by clicking on the appropriate radio button.

276 • Building Configurations Biowin 6 Help Manual

 • If you select Density(%), the diffuser density (%) (i.e. the total area of diffusers in aeration tank /
area of aeration tank expressed as a percent) must be specified in the Density(%) text edit box.
• If ATAD is selected, the ATAD (i.e. area of aeration tank/total area of diffusers in aeration tank) must
be specified in the edit box.
• If Number of Diffusers is selected, the number of diffusers must be specified in the edit box.
A Local temperature also may be specified for a bioreactor element. When you click on the check box for
local temperature, the Specify temperature by radio button group is enabled. You may then specify either a
Constant or Scheduled temperature.
• If constant temperature is selected, you may enter the value in the edit box.
• If scheduled temperature is selected the Pattern… button becomes active. Clicking this button
presents you with the Edit temperature itinerary dialog box.

Membrane Bioreactor Split Method

The Flow split tab, shown below, allows the user to specify the flow split method for a Membrane
bioreactor element.

The Flow split tab of a Membrane bioreactor element

The method of specifying the flow split (i.e. mixed liquor return flow) for a membrane bioreactor may be
selected from a number of options. You can specify the flow using a Ratio, Fraction, or Mixed liquor (i.e. the
actual mixed liquor return flow) by clicking on the corresponding radio button. If you specify the Mixed
liquor rate (denoted by the symbol ML), it will result in a constant flow or user-defined flow pattern out the

Biowin 6 Help Manual Building Configurations • 277

bottom of the membrane bioreactor. Note that when the membrane bioreactor is operating in this mode, if
the influent flow is less than the set Mixed liquor rate, then there will be no permeate flow out of the MBR.
If you specify either the Ratio or Fraction split method, then the underflow will be calculated using the
corresponding formula based on the permeate flow (denoted by the symbol P) and the mixed liquor flow
rate ML.
Next to the split method radio group is an edit box; if the split method is selected from the radio group, the
value may be entered in the edit box. Units are shown adjacent to the edit box (where applicable) and the
label of the edit box changes to indicate the chosen split method.
The split method group also contains a Constant check box; if the flow split does not vary with time this box
should be checked. It should be noted that this check box applies only to the split methods listed in the radio
group and is checked by default. If the Constant check box is unchecked, the Pattern… button becomes
active so you can enter a time-varying pattern for the flow split. Clicking this button presents you with the
Edit split itinerary dialog box.
The mixed liquor return flow also can be Paced with an influent stream. To select the flow paced option,
click on the Mixed liquor paced at check box. The percentage of the influent flow rate may then be
specified, and the influent stream for flow pacing may be selected from the drop list box which shows all
influent streams available for your system.

Membrane Bioreactor Power

The Power tab, shown below, allows the user to enter power specifications for mechanical mixing.

The Power tab of a Membrane bioreactor element

278 • Building Configurations Biowin 6 Help Manual

Power can be specified on a power per unit volume basis or on a fixed basis by checking or unchecking the
Power per unit vol check box, respectively. The user can enter a constant value for power or power per unit
volume by selecting the Constant value of radio button and entering a value in the text edit box.
Alternatively, the user can enter a power or power per unit volume pattern by selecting the Scheduled radio
button. This activates the Pattern…button. Clicking this button will open the Power Itinerary editor. Power
calculated for the Membrane bioreactor element will be grouped under the “Mixing power” category in
power charts and tables.

Membrane Bioreactor Model

The Model tab, shown below, allows the user to enter membrane performance parameters, such as overall
solids retention and colloidal material capture rate, as well as change local model parameters.

The Model tab of a Membrane bioreactor element

You also can specify Local kinetic parameters for the activated sludge model used in the MBR element. If
you click on the check box for local kinetic parameters, then clicking the Edit local kinetic parameters…
button opens the Parameter editor dialog box allowing you access to the various activated sludge model
kinetic parameters.
By default, the boxes labeled Local aeration parameters and Local diffuser parameters are checked for MBR
elements. This is done so that MBR elements use local aeration and diffuser parameters that are reflective
of coarse bubble aeration. Certain pertinent changes are noted below:

Biowin 6 Help Manual Building Configurations • 279

 • the off-gas composition has been changed slightly (higher oxygen lower CO2) to reflect the
decreased transfer observed in coarse bubble systems.
• the diffuser parameters K1, K2, Y, etc. have been changed. One thing to note is that K1 is very low
(nearly zero). What this does is essentially remove diffuser density from the oxygen transfer
equations. As such, the model is insensitive to the value input for diffuser area and density.
The objective of these changes is to match the expected performance in terms of SOTE for a coarse bubble
system. Typically the SOTE responses for coarse bubble systems have two main features:
1. the SOTE values are lower in comparison to those for fine bubble systems at a given air flow; and
2. the shape is flatter and tends to increase linearly with increasing air flow (as opposed to fine bubble
SOTE responses that show semi-exponential decreasing efficiency with increasing air flow).
You can also specify the aeration parameters Alpha F and Beta. You may specify either a Constant value or a
Scheduled pattern for each factor (clicking the Pattern… button will open the Edit Alpha itinerary or Edit
Beta itinerary dialog box). If you wish to plot alpha and/or beta click the graph button. This will add a time
series plot of alpha and/or beta to the BioWin Album. By default, the alpha value is 0.4 for MBR elements.
This value was chosen to reflect the decreased transfer of a coarse bubble system.
The default aeration parameters in the MBR element serve as a good starting point to achieve the objective
of matching coarse bubble performance. However, it should be noted that these are not intended to be
definitive, and if you have manufacturer SOTE data then the aeration parameters should be adjusted
accordingly. Note that if you are happy with the general “pattern” of the SOTE curve for the coarse bubble
system (i.e. slight increase with increasing air flow), you can shift the curves up and down by increasing or
decreasing the K2 parameter. The K2 parameter essentially translates SOTE curves up and down vertically.

Suggested coarse bubble aeration system settings for MBR element aeration parameters

280 • Building Configurations Biowin 6 Help Manual

Suggested coarse bubble aeration system settings for MBR element diffuser parameters

To model the concentrations of the constituents of the aeration gas (e.g. oxygen, carbon dioxide, etc.),
check the box labeled Model gas phase. If this option is selected you may also enter a percentage value for
the Gas hold-up (i.e. the percentage of the total reactor volume occupied by aeration gas).
The Solids percent retention defines the percentage of the incoming solids mass stream that is retained by
the MBR and is reported to the mixed liquor (ML) return stream. For example, if you specify a 99% solids
retention, the MBR reports 99% of the incoming total suspended solids mass to the ML stream, and the
remaining 1% reports to the permeate stream.
At steady state conditions, the mass coming out of the MBR will be the same as the mass entering it, and
specifying the flow split (e.g. the ML flow rate) and the percent solids retention will completely define the
solids mass balance around the MBR.
The Colloidal percent retention defines the percentage of the incoming unadsorbed colloidal COD that is
retained by the MBR and is reported to the mixed liquor (ML) return stream. This setting can be used to de-
couple solids retention and permeate COD to a degree if there is unadsorbed colloidal material in the
influent to the MBR.

Media Bioreactor
The Media bioreactor can be used to simulate activated sludge processes which involve a mixture of fixed
and suspended phases. Complex activated sludge systems can be configured by arranging a number of
media bioreactors in series/parallel. You may specify parameters related to the operation and control of the
media bioreactor element. For information on monitoring parameters/variables for this element, please see
the Monitoring Data section in the “General Operation” chapter.

Biowin 6 Help Manual Building Configurations • 281

The Monitor items tab of a Media bioreactor element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

282 • Building Configurations Biowin 6 Help Manual

The Tags tab of a Media bioreactor element

Media Bioreactor Dimensions

The Dimensions tab, shown below, allows the user to enter the physical dimensions of a media bioreactor
element as well as the characteristics of the media to be used in the vessel.

Biowin 6 Help Manual Building Configurations • 283

The Dimensions tab of a Media bioreactor element

There are two methods for entering the dimensions: by Area and depth, or by Volume and depth. The
method is specified by clicking on the appropriate radio button.
• If you select by Area and depth, the media bioreactor area and depth must be entered in the Area
and Depth text edit boxes.
• If you select by Volume and depth, the media bioreactor volume and depth must be entered in the
Volume and Depth text edit boxes.
Regardless of the method you choose, you also must specify a Width for the element. Units are shown to
the right of the edit boxes. The element name and type, and a picture of the element also are shown.
The specific area and volume of the media, and the percentage of reactor filled with media must be entered
in the Specific area, Specific volume and % of reactor filled with media text edit boxes.
The “% of the reactor filled with media” determines the amount of media and consequently the area of
media for biofilm growth. The media volume is calculated by multiplying the reactor volume with the media
fill fraction (the percentage/100) and the “Specific volume”. The area for biofilm growth is calculated by
multiplying the reactor volume with the media fill fraction (the percentage/100) and the “Specific area”.
BioWin also attempts to correct the liquid volume for the media and biofilm growth. The liquid volume in
the media bioreactor element is determined as follows:
Liquid volume = Vessel volume
– Media Volume
– (Media area * Assumed Film thickness for tank volume correction)

284 • Building Configurations Biowin 6 Help Manual

Media Bioreactor Operation

The Operation tab, shown below, allows the user to enter operating parameters for a Media bioreactor
element, such as aeration and diffuser specifications, as well as local temperature.

The Operation tab of a Media bioreactor element

There are two methods for specifying aeration: either by a DO setpoint or by an Air flow rate. The aeration
method is specified by clicking on the appropriate radio button.
• When DO setpoint is selected, the setpoint concentration must be specified. You may specify either
a Constant setpoint or a Scheduled DO setpoint pattern (clicking the Pattern… button will open the
Edit DO setpoint itinerary dialog box). You may wish to place a restriction on the minimum and
maximum allowable air flow rate that may be used to achieve the desired DO setpoint by setting a
minimum or maximum allowable airflow in the Air flow rate constraints group. This is a useful
feature for investigating the ability of air equipment to achieve desired DO setpoints.
• When Air flow rate is selected, the air flow rate must be specified. You may specify either a Constant
air flow rate or a Scheduled air flow rate pattern (clicking the Pattern… button will open the Edit air
flow itinerary dialog box). Note that if you specify an air supply rate, BioWin will automatically turn
on the oxygen modeling option.
There are three methods for entering diffuser information: by a Density(%), by an ATAD, or by the Number
of Diffusers. The diffuser information is specified by clicking on the appropriate radio button.

Biowin 6 Help Manual Building Configurations • 285

 • If you select Density(%), the diffuser density (%) (i.e. the total area of diffusers in aeration tank /
area of aeration tank expressed as a percent) must be specified in the Density(%) text edit box.
• If ATAD is selected, the ATAD (i.e. area of aeration tank/total area of diffusers in aeration tank) must
be specified in the edit box.
• If Number of Diffusers is selected, the number of diffusers must be specified in the edit box.
A Local temperature also may be specified for a Media bioreactor element. When you click on the check box
for local temperature, the Specify temperature by radio button group is enabled. You may then specify
either a Constant or Scheduled temperature.
• If constant temperature is selected, you may enter the value in the edit box.
• If scheduled temperature is selected the Pattern… button becomes active. Clicking this button
presents you with the Edit temperature itinerary dialog box.

Media Bioreactor Power

The Power tab, shown below, allows the user to enter power specifications for mechanical mixing.

The Power tab of a Media bioreactor element

Power can be specified on a power per unit volume basis or on a fixed basis by checking or unchecking the
Power per unit vol check box, respectively. The user can enter a constant value for power or power per unit
volume by selecting the Constant value of radio button and entering a value in the text edit box.
Alternatively, the user can enter a power or power per unit volume pattern by selecting the Scheduled radio

286 • Building Configurations Biowin 6 Help Manual

button. This activates the Pattern…button. Clicking this button will open the Power Itinerary editor. Power
calculated for the Media bioreactor element will be grouped under the “Mixing power” category in power
charts and tables.

Media Bioreactor Model

The Model tab, shown below, allows the user to change local model parameters, as well as to specify
whether the media should be considered for this simulation, the number of layers to use when modeling the
biofilm attached to the media and the liquid boundary layer thickness.

The Model tab of a Media bioreactor element

If you wish to change any of the biofilm model parameters, select the box labeled Local biofilm parameters.
This will activate the button labeled Edit local biofilm parameters…. Clicking this button will open the
Parameter editor dialog box, which allows you to modify biofilm parameters. (Note that this changes the
biofilm parameters on a local level only).
If you wish to override the project global aeration parameters with local values specific to this element only,
select the box labeled Local aeration parameters. This will activate the button labeled Edit local aeration
parameters…. Clicking this button will open the Aeration dialog box, which allows you to modify aeration
parameters.
If you wish to override the project global diffuser parameters with local values specific to this element only,
select the box labeled Local diffuser parameters. This will activate the button labeled Edit local diffuser
parameters…. Clicking this button will open the Diffuser dialog box, which allows you to modify diffuser
parameters.

Biowin 6 Help Manual Building Configurations • 287

To model the concentrations of the constituents of the aeration gas (e.g. oxygen, carbon dioxide, etc.),
check the box labeled Model gas phase. If this option is selected you may also enter a percentage value for
the Gas hold-up (i.e. the percentage of the total reactor volume occupied by aeration gas).
You can also specify the aeration parameters Alpha F and Beta. You may specify either a Constant value or a
Scheduled pattern for each parameter (clicking the Pattern… button will open the Edit Alpha itinerary or
Edit Beta itinerary dialog box). If you wish to plot Alpha and/or Beta click on the graph button. This will add
a time series plot of alpha and/or beta to the BioWin Album.

Side Stream Media Bioreactor

The Side Stream Media bioreactor can be used to simulate activated sludge processes which involve a
mixture of fixed and suspended phases and is numerically seeded differently from the “standard” media
bioreactor to facilitate treatment of high-strength sidestreams. As such, this element is suitable for
simulating processes such as ANITA Mox ™. For information on monitoring parameters/variables for this
element, please see the Monitoring Data section in the “General Operation” chapter.

The Monitor items tab of a Side Stream Media bioreactor element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

288 • Building Configurations Biowin 6 Help Manual

The Tags tab of a Side Stream Media bioreactor element

Side Stream Media Bioreactor Dimensions

The Dimensions tab, shown below, allows the user to enter the physical dimensions of a side stream media
bioreactor element as well as the characteristics of the media to be used in the vessel.

Biowin 6 Help Manual Building Configurations • 289

The Dimensions tab of a Side Stream Media bioreactor element

There are two methods for entering the dimensions: by Area and depth, or by Volume and depth. The
method is specified by clicking on the appropriate radio button.
• If you select by Area and depth, the side stream media bioreactor area and depth must be entered
in the Area and Depth text edit boxes.
• If you select by Volume and depth, the side stream media bioreactor volume and depth must be
entered in the Volume and Depth text edit boxes.
• Regardless of the method you choose, you also must specify a Width for the element. Units are
shown to the right of the edit boxes. The element name and type, and a picture of the element also
are shown.
The specific area and volume of the media, and the percentage of reactor filled with media must be entered
in the Specific area, Specific volume and % of reactor filled with media text edit boxes.
The “% of the reactor filled with media” determines the amount of media and consequently the area of
media for biofilm growth. The media volume is calculated by multiplying the reactor volume with the media
fill fraction (the percentage/100) and the “Specific volume”. The area for biofilm growth is calculated by
multiplying the reactor volume with the media fill fraction (the percentage/100) and the “Specific area”.
BioWin also attempts to correct the liquid volume for the media and biofilm growth. The liquid volume in
the side stream media bioreactor element is determined as follows:
Liquid volume = Vessel volume
– Media Volume

290 • Building Configurations Biowin 6 Help Manual

 – (Media area * Assumed Film thickness for tank volume correction)

Side Stream Media Bioreactor Operation

The Operation tab, shown below, allows the user to enter operating parameters for a Side Stream Media
bioreactor element, such as aeration and diffuser specifications, as well as local temperature.

The Operation tab of a Side Stream Media bioreactor element

There are two methods for specifying aeration: either by a DO setpoint or by an Air flow rate. The aeration
method is specified by clicking on the appropriate radio button.
• When DO setpoint is selected, the setpoint concentration must be specified. You may specify either
a Constant setpoint or a Scheduled DO setpoint pattern (clicking the Pattern… button will open the
Edit DO setpoint itinerary dialog box). You may wish to place a restriction on the minimum and
maximum allowable air flow rate that may be used to achieve the desired DO setpoint by setting a
minimum or maximum allowable airflow in the Air flow rate constraints group. This is a useful
feature for investigating the ability of air equipment to achieve desired DO setpoints. Note that
these constraints only are applied by BioWin during dynamic simulations.
• When Air flow rate is selected, the air flow rate must be specified. You may specify either a Constant
air flow rate or a Scheduled air flow rate pattern (clicking the Pattern… button will open the Edit air
flow itinerary dialog box). Note that if you specify an air supply rate, BioWin will automatically turn
on the oxygen modeling option.

Biowin 6 Help Manual Building Configurations • 291

There are three methods for entering diffuser information: by a Density(%), by an ATAD, or by the Number
of Diffusers. The diffuser information is specified by clicking on the appropriate radio button.
• If you select Density(%), the diffuser density (%) (i.e. the total area of diffusers in aeration tank /
area of aeration tank expressed as a percent) must be specified in the Density(%) text edit box.
• If ATAD is selected, the ATAD (i.e. area of aeration tank/total area of diffusers in aeration tank) must
be specified in the edit box.
• If Number of Diffusers is selected, the number of diffusers must be specified in the edit box.
A Local temperature is specified by default for a Side Stream Media bioreactor element, in anticipation of
this element being used to treat side streams that are at a higher temperature than the main liquid process.
Because this box is checked, the Specify temperature by radio button group is enabled. You may then
specify either a Constant or Scheduled temperature.
• If constant temperature is selected, you may enter the value in the edit box.
• If scheduled temperature is selected the Pattern… button becomes active. Clicking this button
presents you with the Edit temperature itinerary dialog box.

Side Stream Media Bioreactor Power

The Power tab, shown below, allows the user to enter power specifications for mechanical mixing.

The Power tab of a Side Stream Media bioreactor element

292 • Building Configurations Biowin 6 Help Manual

Power can be specified on a power per unit volume basis or on a fixed basis by either checking or
unchecking the Power per unit vol check box, respectively. The user can enter a constant value for power or
power per unit volume by selecting the Constant value of radio button and entering a value in the text edit
box. Alternatively, the user can enter a power or power per unit volume pattern by selecting the Scheduled
radio button. This activates the Pattern…button. Clicking this button will open the Power Itinerary editor.
Power calculated for the Side Stream Media element will be grouped under the “Mixing power” category in
power charts and tables.

Side Stream Media Bioreactor Model

The Model tab, shown below, allows the user to change local model parameters. The Film model options
area allows the user to specify whether the media should be considered for this simulation, the number of
layers to use when modeling the biofilm attached to the media and the liquid boundary layer thickness.

The Model tab of a Side Stream Media bioreactor element

You can specify Local kinetic parameters and/or Local biofilm parameters for the activated sludge model
used in the Side Stream Media bioreactor element. If you click on the check box for local kinetic parameters
and/or local biofilm parameters, then clicking the Edit local kinetic parameters…or Edit local biofilm
parameters button opens the Parameter editor dialog box allowing you access to the various activated
sludge model kinetic/biofilm parameters.
If you wish to override the project global aeration parameters with local values specific to this element only,
select the box labeled Local aeration parameters. This will activate the button labeled Edit local aeration
parameters…. Clicking this button will open the Aeration dialog box, which allows you to modify aeration
parameters.

Biowin 6 Help Manual Building Configurations • 293

If you wish to override the project global diffuser parameters with local values specific to this element only,
select the box labeled Local diffuser parameters. This will activate the button labeled Edit local diffuser
parameters…. Clicking this button will open the Diffuser dialog box, which allows you to modify diffuser
parameters.
To model the concentrations of the constituents of the aeration gas (e.g. oxygen, carbon dioxide, etc.),
check the box labeled Model gas phase. If this option is selected you may also enter a percentage value for
the Gas hold-up (i.e. the percentage of the total reactor volume occupied by aeration gas).
You can also specify the aeration parameters Alpha F and Beta. You may specify either a Constant value or a
Scheduled pattern for each parameter (clicking the Pattern… button will open the Edit Alpha itinerary or
Edit Beta itinerary dialog box). If you wish to plot Alpha and/or Beta click on the graph button. This will add
a time series plot of alpha and/or beta to the BioWin Album.

Trickling Filter
The Trickling Filter element is used to simulate trickling filter attached growth processes for a variety of
media types (mixed media trickling filters are not available). You may specify parameters related to the
operation and control of the trickling filter element. For information on monitoring parameters/variables for
this element, please see the Monitoring Data section in the “General Operation” chapter.

The Monitor items tab of a trickling filter element

294 • Building Configurations Biowin 6 Help Manual

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

The Tags tab of a Trickling filter element

Trickling Filter Dimensions

The Dimensions tab, shown below, allows the user to enter the physical dimensions of a trickling filter
element as well as specify the type of media used.

Biowin 6 Help Manual Building Configurations • 295

The Dimensions tab of a trickling filter element

There are two methods for entering the dimensions: by Area and depth, or by Volume and depth. The
method is specified by selecting the appropriate radio button.
• If you select by Area and depth, the trickling filter area and depth must be entered in the Area and
Depth text edit boxes.
• If you select by Volume and depth, the trickling filter volume and depth must be entered in the
Volume and Depth text edit boxes. The depth of the trickling filter is divided into three “sections” of
equal height; the sections are used for modeling aspects such as oxygen transfer from the top of the
trickling filter to the bottom (if the gas phase modeling feature of BioWin is used) and also to
simulate removal gradients down the depth of the trickling filter. Units are shown to the right of the
edit boxes. The element name and type, and a picture of the element also are shown (note that the
flowsheet image for the trickling filter changes depending on the type of media selected; hence the
image shown on the Dimensions tab indicates a mix of media types).

Note: Trickling filter elements in BioWin are assumed to be 100% filled with media.

The following choices are available: Rock, Horizontal, Structured plastic (crossflow), Loose media (random),
and Custom. Toggling between the first four of these changes the Specific area and Specific volume (i.e. 1-
porosity) fields to typical values for the media type selected. Clicking on Custom makes the Specific area and
Specific volume fields editable. For convenience, when you click on the Custom option the fields are filled
with the values from the previously selected media type. For example, if you are using a trickling filter filled

296 • Building Configurations Biowin 6 Help Manual

with Rock media that has slightly different Specific area and Specific volume characteristics than BioWin’s
defaults, you can click on the Rock option to start and then click on the Custom option to modify the values.
The Liquid thickness parameter is editable for any type of media. This is the thickness of the liquid layer next
to the biofilm, and it is used to calculate the hydraulic residence time of the trickling filter. Making this
parameter larger will increase the hydraulic residence time of a trickling filter, and making it smaller will
decrease the hydraulic residence time of a trickling filter (all other things being equal).
The area available for Gas transfer to the liquid phase perhaps is the most important parameter in modeling
trickling filter performance because it has a direct impact on the amount of oxygen available to the biofilm.
Two factors impact the area available for gas transfer for any type of media. Before discussing the factors,
we define the terms used:
• Media Surface Area = Media specific area * Empty filter volume
• Hydraulic Loading Rate = Filter input flow rate / Filter cross-sectional area

Note: The terms Hydraulic Loading Rate and Wetting Rate are used interchangeably. Also, input flow rate
includes all flow to the filter (including recycles).

In BioWin the area for gas transfer is calculated as:

• Gas Transfer Area = Effective Area Fraction * Media Surface Area * Hydraulic Loading Factor
For any media type, not all of the media surface area is available for gas transfer. For example, pieces of
media rest against each other, blocking off part of the surface and reducing the area available for gas
transfer, and the area for gas transfer is less than the media surface area. The Effective Area Fraction
specifies the fraction of the media area available for gas transfer area (liquid/gas interface) under optimal
hydraulic loading conditions. We can think of this as the fraction of media surface over which the liquid film
flows when liquid is optimally distributed over the filter cross-sectional area. The Effective Area Fraction
may be quite different for different media types, and probably also is somewhat different for freshly
installed media compared with media that has been operational for some extended time. Adjusting the
value of the Effective Area Fraction provides a means for coarse calibration of filter performance.
Hydraulic loading also may impact the area available for gas transfer. If the wetting rate is too low then not
all of the media will be “wet” so the gas transfer area will be reduced. On the other hand, if the hydraulic
loading rate gets too high then it is possible that the air spaces between the media become filled with liquid,
which also will reduce the available gas transfer area. The Hydraulic Loading Factor attempts to account for
these less-than-optimal conditions. The Hydraulic Loading Factor is determined by a two-sided continuous
switching function; examples using rock media and non-rock media/other media types are shown below:

Biowin 6 Help Manual Building Configurations • 297

Hydraulic loading factor as a function of hydraulic loading for Rock Media

Hydraulic loading factor as a function of hydraulic loading for Non-rock/Other Media types

Over an optimal range of hydraulic loading the Hydraulic Loading Factor is equal to or close to unity (1). The
value decreases towards zero for extreme low or high loading rates. The form of the continuous switching
function is defined by the Low hydraulic loading rate switch value and the High hydraulic loading rate
switch value. These are the low and high hydraulic loading rates where the Hydraulic Loading Factor has a
value of 0.5 (i.e. the area for gas transfer is reduced to half of the effective area). Different media types have

298 • Building Configurations Biowin 6 Help Manual

characteristic high and low loading rates. These are shown in the Low hydraulic loading rate switch and
High hydraulic loading rate switch fields, and they change accordingly when any of the first four media
types are selected. If Custom is selected, the user may edit the switch values.

Trickling Filter Operation

The Operation tab, shown below, allows the user to enter operating parameters for a trickling filter element
(e.g. aeration method), as well as enter a local temperature.

The trickling filter Operation tab

There are two methods for specifying aeration: either by a Dissolved oxygen concentration or by an Air
flow rate. The aeration method is specified by clicking on the appropriate radio button.
• When Dissolved oxygen concentration is selected, the dissolved oxygen concentration must be
specified. You may specify either a Constant value or a Scheduled value pattern (clicking the
Pattern… button will open the Edit DO itinerary dialog box).
• When Air flow rate is selected, the air flow rate must be specified. You may specify either a Constant
air flow rate or a Scheduled air flow rate pattern (clicking the Pattern… button will open the Edit air
flow itinerary dialog box).
To model the concentrations of the constituents of the aeration gas (e.g. oxygen, carbon dioxide, etc.),
check the box labeled Model gas phase.

Biowin 6 Help Manual Building Configurations • 299

Note: For a trickling filter element, both the oxygen modeling feature and gas phase modeling must be
turned on if an air supply rate is specified. If a DO setpoint is specified, then neither of these model features
is strictly required. The following table summarizes the consequences of selecting different combinations of
aeration modeling features [Reference is made in the table to “sections” of the trickling filter; recall in the
previous Dimensions section it was outlined that the Depth specified for the trickling filter is divided into
three equal sections – top, middle, and bottom]:

Specification Oxygen modeling Gas phase Description of resulting gas transfer

modeling features
Dissolved oxygen on/off off Specified dissolved oxygen
concentration concentration is applied to each section
(top, middle, bottom) of the trickling
filter. The required air flow rate is
estimated by BioWin based on the
required OTR and a minimum driving
force.
Dissolved oxygen on/off on The specified dissolved oxygen
concentration concentration value is applied to the top
section of the trickling filter. BioWin
models the gas-liquid mass transfer in all
three sections and the dissolved oxygen
concentration is calculated for the
middle and bottom sections.
Air supply rate on on The specified air supply rate is input to
the top section. BioWin models the gas-
liquid mass transfer in all three sections
and the dissolved oxygen concentration
is calculated for all three sections.

A Local temperature also may be specified. When you click on the check box for local temperature, the
Specify temperature by radio button group is enabled. You may then specify either a Constant or Scheduled
temperature.
If constant temperature is selected, you may enter the value in the edit box.
If scheduled temperature is selected the Pattern… button becomes active. Clicking this button presents you
with the Edit temperature itinerary dialog box.

Trickling Filter Power

The Power tab, shown below, allows the user to specify mechanical power for the Trickling Filter element.

300 • Building Configurations Biowin 6 Help Manual

The trickling filter Power tab

You can specify whether to include the trickling filter element in power calculations by checking the Include
this unit in power calculation check box. Checking this option activates the Power specification group.
Power can be specified on a power per unit flow basis or on a fixed basis by checking or unchecking the
Power per unit flow to this element check box, respectively. The user can enter a constant value for power
or power per unit flow by selecting the Constant value of radio button and entering a value in the text edit
box. Alternatively, the user can enter a power or power per unit flow pattern by selecting the Scheduled
radio button. This activates the Pattern…button. Clicking this button will open the Power Itinerary editor.
Power calculated for the Trickling Filter element will be grouped under the “Mechanical power” category in
power charts and tables.

Trickling Filter Model

The Model tab, shown below, allows the user to change local modeling parameters.

Biowin 6 Help Manual Building Configurations • 301

The trickling filter Model tab

You can specify Local kinetic parameters and/or Local biofilm parameters for the activated sludge model
used in the trickling filter element. If you click on the check box for local kinetic parameters and/or local
biofilm parameters, then clicking the Edit local kinetic parameters… or Edit local biofilm parameters…
button opens the Parameter editor dialog box allowing you access to the various activated sludge model
kinetic parameters.
If you wish to override the project global aeration parameters with local values specific to this element only,
select the box labeled Local aeration parameters. This will activate the button labeled Edit local aeration
parameters…. Clicking this button will open the Aeration dialog box, which allows you to modify aeration
parameters.
You can also specify the aeration parameters Alpha F and Beta. You may specify either a Constant value or a
Scheduled pattern for each parameter (clicking the Pattern… button will open the Edit Alpha itinerary or
Edit Beta itinerary dialog box). If you wish to plot Alpha and/or Beta click on the graph button. This will add
a time series plot of alpha and/or beta to the BioWin Album.
The Film model options area allows the user to specify the number of layers to use for modeling the biofilm
attached to the media and the liquid boundary layer thickness.

Submerged Aerated Filter (SAF)

The submerged aerated filter (SAF) can be used to simulate bioreactors with fully submerged fixed media in
an upflow configuration. You may specify parameters related to the operation and control of the SAF

302 • Building Configurations Biowin 6 Help Manual

element. For information on monitoring parameters/variables for this element, please see the Monitoring
Data section in the “General Operation” chapter.

The Monitor items tab of a SAF element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

Biowin 6 Help Manual Building Configurations • 303

The Tags tab of a Submerged aerated filter element

Submerged Aerated Filter Dimensions

The Dimensions tab, shown below, allows the user to enter the physical dimensions of a SAF element and to
specify the type and quantity of media to be used in the vessel.

304 • Building Configurations Biowin 6 Help Manual

The Dimensions tab of a SAF element

There are two methods for entering the dimensions: by Area and depth, or by Volume and depth. The
method is specified by clicking on the appropriate radio button.
• If you select by Area and depth, the media bioreactor area and depth must be entered in the Area
and Depth text edit boxes.
• If you select by Volume and depth, the media bioreactor volume and depth must be entered in the
Volume and Depth text edit boxes. Units are shown to the right of the edit boxes. The element
name and type, and a picture of the element also are shown.
The specific area and volume of the media, and the percentage of reactor filled with media must be entered
in the Specific area, Specific volume and % of reactor filled with media text edit boxes.
The “% of the reactor filled with media” determines the amount of media and consequently the area of
media for biofilm growth. The media volume is calculated by multiplying the reactor volume with the media
fill fraction (the percentage/100) and the “Specific volume”. The area for biofilm growth is calculated by
multiplying the reactor volume with the media fill fraction (the percentage/100) and the “Specific area”.
BioWin also attempts to correct the liquid volume for the media and biofilm growth. The liquid volume in
the media bioreactor element is determined as follows:
Liquid volume = Vessel volume
– Media Volume
– (Media area * Assumed Film thickness for tank volume correction)

Biowin 6 Help Manual Building Configurations • 305

Submerged Aerated Filter Operation

The Operation tab, shown below, allows the user to enter operating parameters for a SAF element, such as
aeration and diffuser specifications, as well as change the local temperature.

The Operation tab of a SAF element

There are two methods for specifying aeration: either by a DO setpoint or by an Air flow rate. In modeling
the SAF, the depth is split into three “slices”; the DO setpoint that you specify is for the bottom “slice” which
is where flow enters the SAF unit. The aeration method is specified by clicking on the appropriate radio
button.
• When DO setpoint is selected, the setpoint concentration must be specified. You may specify either
a Constant setpoint or a Scheduled DO setpoint pattern (clicking the Pattern… button will open the
Edit DO setpoint itinerary dialog box). You may wish to place a restriction on the minimum and
maximum allowable air flow rate that may be used to achieve the desired DO setpoint by setting a
minimum or maximum allowable airflow in the Air flow rate constraints group. This is a useful
feature for investigating the ability of air equipment to achieve desired DO setpoints. Note that
these constraints only are applied by BioWin during dynamic simulations.
• When Air flow rate is selected, the air flow rate must be specified. You may specify either a Constant
air flow rate or a Scheduled air flow rate pattern (clicking the Pattern… button will open the Edit air
flow itinerary dialog box). Note that if you specify an air supply rate, BioWin will automatically turn
on the oxygen modeling option.

306 • Building Configurations Biowin 6 Help Manual

There are three methods for entering diffuser information: by a Density(%), by an ATAD, or by the Number
of Diffusers. The diffuser information is specified by clicking on the appropriate radio button.
• If you select Density(%), the diffuser density (%) (i.e. the total area of diffusers in aeration tank /
area of aeration tank expressed as a percent) must be specified in the Density(%) text edit box.
• If ATAD is selected, the ATAD (i.e. area of aeration tank/total area of diffusers in aeration tank) must
be specified in the edit box.
• If Number of Diffusers is selected, the number of diffusers must be specified in the edit box.
A Local temperature also may be specified for a SAF element. When you click on the check box for local
temperature, the Specify temperature by radio button group is enabled. You may then specify either a
Constant or Scheduled temperature.
• If constant temperature is selected, you may enter the value in the edit box.
• If scheduled temperature is selected the Pattern… button becomes active. Clicking this button
presents you with the Edit temperature itinerary dialog box.
To model the concentrations of the constituents of the aeration gas (e.g. oxygen, carbon dioxide, etc.),
check the box labeled Model gas phase. If this option is selected you may also enter a percentage value for
the Gas hold-up (i.e. the percentage of the total reactor volume occupied by aeration gas).

Submerged Aerated Filter Power

The Power tab, shown below, allows the user to enter power specifications for mechanical mixing.

The Power tab of a SAF element

Biowin 6 Help Manual Building Configurations • 307

Power can be specified on a power per unit volume basis or on a fixed basis by checking or unchecking the
Power per unit vol check box, respectively. The user can enter a constant value for power or power per unit
volume by selecting the Constant value of radio button and entering a value in the text edit box.
Alternatively, the user can enter a power or power per unit volume pattern by selecting the Scheduled radio
button. This activates the Pattern…button. Clicking this button will open the Power Itinerary editor. Power
calculated for the SAF element will be grouped under the “Mixing power” category in power charts and
tables.

Submerged Aerated Filter Model

The Model tab, shown below, allows the user to change local model parameters.

The Model tab of a SAF element

You can specify Local kinetic parameters and/or Local biofilm parameters for the activated sludge model
used in the SAF element. If you click on the check box for local kinetic parameters and/or local biofilm
parameters, then clicking the Edit local kinetic parameters… or Edit local biofilm parameters… button
opens the Parameter editor dialog box allowing you access to the various activated sludge model kinetic
parameters.
If you wish to override the project global aeration parameters with local values specific to this element only,
select the box labeled Local aeration parameters. This will activate the button labeled Edit local aeration
parameters…. Clicking this button will open the Aeration dialog box, which allows you to modify aeration
parameters.

308 • Building Configurations Biowin 6 Help Manual

You can also specify the aeration parameters Alpha F and Beta. You may specify either a Constant value or a
Scheduled pattern for each parameter (clicking the Pattern… button will open the Edit Alpha itinerary or
Edit Beta itinerary dialog box). If you wish to plot Alpha and/or Beta click on the graph button. This will add
a time series plot of alpha and/or beta to the BioWin Album.
The Film model options area allows the user to specify whether the media should be considered for this
simulation, the number of layers to use when modeling the biofilm attached to the media and the liquid
boundary layer thickness.

Shallow Submerged Aerated Filter (SSAF)

The shallow submerged aerated filter (SSAF) can be used to simulate bioreactors with fully submerged fixed
media in an upflow configuration. You may specify parameters related to the operation and control of the
SAF element. For information on monitoring parameters/variables for this element, please see the
Monitoring Data section in the “General Operation” chapter.

The Monitor items tab of a SSAF element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

Biowin 6 Help Manual Building Configurations • 309

The Tags tab of a SSAF element

Note: the primary difference between the shallow SAF and the “normal” SAF is that the shallow SAF has one
completely mixed liquid volume and one biofilm mass/volume. The “normal” SAF has its depth split into
three “slices” and there is a liquid volume and biofilm mass/volume associated with each “slice”. As a result,
the SSAF is less plug-flow in nature when compared to the SAF.

Shallow Submerged Aerated Filter Dimensions

The Dimensions tab, shown below, allows the user to enter the physical dimensions of a SSAF element as
well as specify the type and quantity of media to be used in the vessel.

310 • Building Configurations Biowin 6 Help Manual

The Dimensions tab of a SSAF element

There are two methods for entering the dimensions: by Area and depth, or by Volume and depth. The
method is specified by clicking on the appropriate radio button.
• If you select by Area and depth, the media bioreactor area and depth must be entered in the Area
and Depth text edit boxes.
• If you select by Volume and depth, the media bioreactor volume and depth must be entered in the
Volume and Depth text edit boxes. Units are shown to the right of the edit boxes. The element
name and type, and a picture of the element also are shown.
The specific area and volume of the media, and the percentage of reactor filled with media must be entered
in the Specific area, Specific volume and % of reactor filled with media text edit boxes.
The “% of the reactor filled with media” determines the amount of media and consequently the area of
media for biofilm growth. The media volume is calculated by multiplying the reactor volume with the media
fill fraction (the percentage/100) and the “Specific volume”. The area for biofilm growth is calculated by
multiplying the reactor volume with the media fill fraction (the percentage/100) and the “Specific area”.
BioWin also attempts to correct the liquid volume for the media and biofilm growth. The liquid volume in
the media bioreactor element is determined as follows:
Liquid volume = Vessel volume
– Media Volume
– (Media area * Assumed Film thickness for tank volume correction)

Biowin 6 Help Manual Building Configurations • 311

Shallow Submerged Aerated Filter Operation

The Operation tab, shown below, allows the user to enter operating parameters for a SSAF element, such as
aeration and diffuser specifications, as well as change local temperature.

The Operation tab of a SSAF element

There are two methods for specifying aeration: either by a DO setpoint or by an Air flow rate. The aeration
method is specified by clicking on the appropriate radio button.
• When DO setpoint is selected, the setpoint concentration must be specified. You may specify either
a Constant setpoint or a Scheduled DO setpoint pattern (clicking the Pattern… button will open the
Edit DO setpoint itinerary dialog box). You may wish to place a restriction on the minimum and
maximum allowable air flow rate that may be used to achieve the desired DO setpoint by setting a
minimum or maximum allowable airflow in the Air flow rate constraints group. This is a useful
feature for investigating the ability of air equipment to achieve desired DO setpoints. Note that
these constraints only are applied by BioWin during dynamic simulations.
• When Air flow rate is selected, the air flow rate must be specified. You may specify either a Constant
air flow rate or a Scheduled air flow rate pattern (clicking the Pattern… button will open the Edit air
flow itinerary dialog box). Note that if you specify an air supply rate, BioWin will automatically turn
on the oxygen modeling option.
There are three methods for entering diffuser information: by a Density(%), by an ATAD, or by the Number
of Diffusers. The diffuser information is specified by clicking on the appropriate radio button.

312 • Building Configurations Biowin 6 Help Manual

 • If you select Density(%), the diffuser density (%) (i.e. the total area of diffusers in aeration tank /
area of aeration tank expressed as a percent) must be specified in the Density(%) text edit box.
• If ATAD is selected, the ATAD (i.e. area of aeration tank/total area of diffusers in aeration tank) must
be specified in the edit box.
• If Number of Diffusers is selected, the number of diffusers must be specified in the edit box.
A Local temperature also may be specified for a SSAF element. When you click on the check box for local
temperature, the Specify temperature by radio button group is enabled. You may then specify either a
Constant or Scheduled temperature.
• If constant temperature is selected, you may enter the value in the edit box.
• If scheduled temperature is selected the Pattern… button becomes active. Clicking this button
presents you with the Edit temperature itinerary dialog box.

Shallow Submerged Aerated Filter Power

The Power tab, shown below, allows the user to enter power specifications for mechanical mixing.

The Power tab of a SSAF element

Power can be specified on a power per unit volume basis or on a fixed basis by checking or unchecking the
Power per unit vol check box, respectively. The user can enter a constant value for power or power per unit
volume by selecting the Constant value of radio button and entering a value in the text edit box.
Alternatively, the user can enter a power or power per unit volume pattern by selecting the Scheduled radio
button. This activates the Pattern…button. Clicking this button will open the Power Itinerary editor. Power

Biowin 6 Help Manual Building Configurations • 313

calculated for the SSAF element will be grouped under the “Mixing power” category in power charts and
tables.

Shallow Submerged Aerated Filter Model

The Model tab, shown below, allows the user to change local model parameters.

The Model tab of a SSAF element

You can specify Local kinetic parameters and/or Local biofilm parameters for the activated sludge model
used in the SSAF element. If you click on the check box for local kinetic parameters and/or local biofilm
parameters, then clicking the Edit local kinetic parameters… or Edit local biofilm parameters… button
opens the Parameter editor dialog box allowing you access to the various activated sludge model kinetic
parameters.
If you wish to override the project global aeration parameters with local values specific to this element only,
select the box labeled Local aeration parameters. This will activate the button labeled Edit local aeration
parameters…. Clicking this button will open the Aeration dialog box, which allows you to modify aeration
parameters.
If you wish to override the project global diffuser parameters with local values specific to this element only,
select the box labeled Local diffuser parameters. This will activate the button labeled Edit local diffuser
parameters…. Clicking this button will open the Diffuser dialog box, which allows you to modify diffuser
parameters.

314 • Building Configurations Biowin 6 Help Manual

To model the concentrations of the constituents of the aeration gas (e.g. oxygen, carbon dioxide, etc.),
check the box labeled Model gas phase. If this option is selected you may also enter a percentage value for
the Gas hold-up (i.e. the percentage of the total reactor volume occupied by aeration gas).
You can also specify the aeration parameters Alpha F and Beta. You may specify either a Constant value or a
Scheduled pattern for each parameter (clicking the Pattern… button will open the Edit Alpha itinerary or
Edit Beta itinerary dialog box). If you wish to plot Alpha and/or Beta click on the graph button. This will add
a time series plot of alpha and/or beta to the BioWin Album.
The Model options area allows the user to specify whether the media should be considered for this
simulation, the number of layers to use when modeling the biofilm attached to the media and the liquid
boundary layer thickness.

Surface Aerator Bioreactor

The Surface aerator bioreactor element simulates the activated sludge process in a continuous stirred tank
reactor (CSTR) similarly to a regular bioreactor. However, aeration may be entered in terms of power supply
rather than air supply. You may specify parameters related to the operation and control of the Surface
aerator bioreactor element. For information on monitoring parameters/variables for this element, please
see the Monitoring Data section in the “General Operation” chapter.

The Monitor items tab of a Surface aerator bioreactor element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

Biowin 6 Help Manual Building Configurations • 315

The Tags tab of a Surface aerator bioreactor element

Surface Aerator Bioreactor Dimensions

The Dimensions tab, shown below, allows the user to enter the physical dimensions of a Surface aerator
bioreactor element.

316 • Building Configurations Biowin 6 Help Manual

The Dimensions tab of a Surface aerator bioreactor element

There are two methods for entering the dimensions: by Area and depth, or by Volume and depth. The
method is specified by clicking on the appropriate radio button.
• If you select by Area and depth, the surface aerator bioreactor area and depth must be entered in
the Area and Depth text edit boxes.
• If you select by Volume and depth, the surface aerator bioreactor volume and depth must be
entered in the Volume and Depth text edit boxes.
• Regardless of the method you choose, you also must specify a Width for the element. Units are
shown to the right of the edit boxes. The element name and type, and a picture of the element also
are shown.

Surface Aerator Bioreactor Operation

The Operation tab, shown below, allows the user to enter operating parameters for a Surface aerator
bioreactor element, such as aeration specifications, as well as enter a local temperature.

Biowin 6 Help Manual Building Configurations • 317

The Operation tab of a Surface aerator bioreactor element

There are two methods for specifying aeration: either by a DO setpoint or by a Power supply rate. The
aeration method is specified by clicking on the appropriate radio button.
1. When DO setpoint is selected, the setpoint concentration must be specified. You may specify either
a Constant setpoint or a Scheduled DO setpoint pattern (clicking the Pattern… button will open the
Edit DO setpoint itinerary dialog box). You may wish to place a restriction on the maximum
allowable power supply rate that may be used to achieve the desired DO setpoint. This is a useful
feature for investigating the ability of air equipment to achieve desired DO setpoints.
2. When Power supply rate is selected, the power supply rate must be specified. You may specify
either a Constant power supply rate or a Scheduled power supply rate pattern (clicking the
Pattern… button will open the Edit power supply rate itinerary dialog box).
A Local temperature also may be specified for a surface aerator bioreactor element. When you click on the
check box for local temperature, the Specify temperature by radio button group is enabled. You may then
specify either a Constant or Scheduled temperature.
If constant temperature is selected, you may enter the value in the edit box.
If scheduled temperature is selected the Pattern… button becomes active. Clicking this button presents you
with the Edit temperature itinerary dialog box.

Surface Aerator Bioreactor Model

The Model tab, shown below, allows the user to change local model parameters.

318 • Building Configurations Biowin 6 Help Manual

The Model tab of a Surface aerator bioreactor element

You can specify Local kinetic parameters for the activated sludge model used in the surface aerator
bioreactor element. If you click on the check box for local kinetic parameters, then clicking the Edit local
kinetic parameters… button opens the Parameter editor dialog box allowing you access to the various
activated sludge model kinetic parameters.
If you wish to override the project global aeration parameters with local values specific to this element only,
select the box labeled Local aeration parameters. This will activate the button labeled Edit local aeration
parameters…. Clicking this button will open the Aeration dialog box, which allows you to modify aeration
parameters.
If you wish to change any of the aerator model parameters, select the box labeled Local aerator
parameters. This will activate the button labeled Edit local aerator parameters…. Clicking this button with
open the Surface aerators dialog box, which allows you to modify surface aerator parameters. (Note that
this changes the surface aerator model parameters on a local level only).
You can also specify the aeration parameters Alpha F and Beta. You may specify either a Constant value or a
Scheduled pattern for each parameter (clicking the Pattern… button will open the Edit Alpha itinerary or
Edit Beta itinerary dialog box). If you wish to plot Alpha and/or Beta click on the graph button. This will add
a time series plot of alpha and/or beta to the BioWin Album.

Brush Aerator Bioreactor

The Brush aerator bioreactor element simulates the activated sludge process in a continuous stirred tank
reactor (CSTR) similarly to a regular bioreactor. However, aeration may be entered in terms of power supply
rather than air supply. You may specify parameters related to the operation and control of the Brush aerator

Biowin 6 Help Manual Building Configurations • 319

bioreactor element. For information on monitoring parameters/variables for this element, please see the
Monitoring Data section in the “General Operation” chapter.

The Monitor items tab of a Brush aerator bioreactor element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

320 • Building Configurations Biowin 6 Help Manual

The Tags tab of a Brush aerator bioreactor element

Brush Aerator Bioreactor Dimensions

The Dimensions tab, shown below, allows the user to enter the physical dimensions of a Brush aerator
bioreactor element.

Biowin 6 Help Manual Building Configurations • 321

The Dimensions tab of a Brush aerator bioreactor element

There are two methods for entering the dimensions: by Area and depth, or by Volume and depth. The
method is specified by clicking on the appropriate radio button.
• If you select by Area and depth, the brush aerator bioreactor area and depth must be entered in the
Area and Depth text edit boxes.
• If you select by Volume and depth, the brush aerator bioreactor volume and depth must be entered
in the Volume and Depth text edit boxes.
Regardless of the method you choose, you also must specify a Width for the element. Units are shown to
the right of the edit boxes. The element name and type, and a picture of the element also are shown.

Brush Aerator Bioreactor Operation

The Operation tab, shown below, allows the user to enter operating parameters for a Brush aerator
bioreactor element, such as aeration specifications and local temperature.

322 • Building Configurations Biowin 6 Help Manual

The Operation tab of a Brush aerator bioreactor element

There are two methods for specifying aeration: either by a DO setpoint or by a Power supply rate. The
aeration method is specified by clicking on the appropriate radio button.
• When DO setpoint is selected, the setpoint concentration must be specified. You may specify either
a Constant setpoint or a Scheduled DO setpoint pattern (clicking the Pattern… button will open the
Edit DO setpoint itinerary dialog box). You may wish to place a restriction on the maximum
allowable power supply rate that may be used to achieve the desired DO setpoint. This is a useful
feature for investigating the ability of air equipment to achieve desired DO setpoints.
• When Power supply rate is selected, the power supply rate must be specified. You may specify
either a Constant power supply rate or a Scheduled power supply rate pattern (clicking the Pattern…
button will open the Edit power supply rate itinerary dialog box).
A Local temperature also may be specified for a brush aerator bioreactor element. When you click on the
check box for local temperature, the Specify temperature by radio button group is enabled. You may then
specify either a Constant or Scheduled temperature.
• If constant temperature is selected, you may enter the value in the edit box.
• If scheduled temperature is selected the Pattern… button becomes active. Clicking this button
presents you with the Edit temperature itinerary dialog box.

Brush Aerator Bioreactor Model

Biowin 6 Help Manual Building Configurations • 323

The Model tab, shown below, allows the user to change local model parameters.

The Model tab of a Brush aerator bioreactor element

You can specify Local kinetic parameters for the activated sludge model used in the brush aerator
bioreactor element. If you click on the check box for local kinetic parameters, then clicking the Edit local
kinetic parameters… button opens the Parameter editor dialog box allowing you access to the various
activated sludge model kinetic parameters.
If you wish to override the project global aeration parameters with local values specific to this element only,
select the box labeled Local aeration parameters. This will activate the button labeled Edit local aeration
parameters…. Clicking this button will open the Aeration dialog box, which allows you to modify aeration
parameters.
If you wish to change any of the aerator model parameters, select the box labeled Local aerator
parameters. This will activate the button labeled Edit local aerator parameters…. Clicking this button with
open the Surface aerators dialog box, which allows you to modify surface aerator parameters. (Note that
this changes the surface aerator model parameters on a local level only).
You can also specify the aeration parameters Alpha F and Beta. You may specify either a Constant value or a
Scheduled pattern for each parameter (clicking the Pattern… button will open the Edit Alpha itinerary or
Edit Beta itinerary dialog box). If you wish to plot Alpha and/or Beta click on the graph button. This will add
a time series plot of alpha and/or beta to the BioWin Album.

324 • Building Configurations Biowin 6 Help Manual

Variable Volume/Batch Bioreactor
The Variable volume/batch bioreactor simulates the activated sludge process in a variable volume
continuous stirred tank reactor (CSTR). You can specify parameters related to the operation and control of
the variable volume/batch bioreactor element, as well as parameters related to the initial conditions. For
information on monitoring parameters/variables for this element, please see the Monitoring Data section in
the “General Operation” chapter.

The Monitor items tab of a Variable volume/batch bioreactor element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

Biowin 6 Help Manual Building Configurations • 325

The Tags tab of a Variable volume bioreactor element

Variable Volume/Batch Bioreactor Dimensions

The Dimensions tab, shown below, allows the user to enter the physical dimensions of a Variable
volume/batch bioreactor element.

326 • Building Configurations Biowin 6 Help Manual

The Dimensions tab of a Variable volume/batch bioreactor element

There are two methods for entering the dimensions: by Area and depth, or by Volume and depth. The
method is specified by clicking on the appropriate radio button.
• If you select by Area and depth, the variable volume/batch bioreactor area and depth must be
entered in the Area and Depth text edit boxes.
• If you select by Volume and depth, the variable volume/batch bioreactor volume and depth must be
entered in the Volume and Depth text edit boxes.
• Regardless of the method you choose, you also must specify a Width for the element. Units are
shown to the right of the edit boxes. The element name and type, and a picture of the element also
are shown.

Variable Volume/Batch Bioreactor Operation

The Operation tab, shown below, allows the user to enter operating parameters for a Variable
volume/batch bioreactor element, such as aeration and diffuser specifications as well as local temperature.

Biowin 6 Help Manual Building Configurations • 327

The Operation tab of a Variable volume/batch bioreactor element

There are two methods for specifying aeration: either by a DO setpoint or by an Air flow rate. The aeration
method is specified by clicking on the appropriate radio button.
• When DO setpoint is selected, the setpoint concentration must be specified. You may specify either
a Constant setpoint or a Scheduled DO setpoint pattern (clicking the Pattern… button will open the
Edit DO setpoint itinerary dialog box). You may wish to place a restriction on the minimum and
maximum allowable air flow rate that may be used to achieve the desired DO setpoint by setting a
minimum or maximum allowable airflow in the Air flow rate constraints group. This is a useful
feature for investigating the ability of air equipment to achieve desired DO setpoints. Note that
these constraints only are applied by BioWin during dynamic simulations.
• When Air flow rate is selected, the air flow rate must be specified. You may specify either a Constant
air flow rate or a Scheduled air flow rate pattern (clicking the Pattern… button will open the Edit air
flow itinerary dialog box). Note that if you specify an air supply rate, BioWin will automatically turn
on the oxygen modeling option.
There are three methods for entering diffuser information: by a Density(%), by an ATAD, or by the Number
of Diffusers. The diffuser information is specified by clicking on the appropriate radio button.
• If you select Density(%), the diffuser density (%) (i.e. the total area of diffusers in aeration tank /
area of aeration tank expressed as a percent) must be specified in the Density(%) text edit box.
• If ATAD is selected, the ATAD (i.e. area of aeration tank/total area of diffusers in aeration tank) must
be specified in the edit box.
• If Number of Diffusers is selected, the number of diffusers must be specified in the edit box.

328 • Building Configurations Biowin 6 Help Manual

A Local temperature also may be specified for a Variable volume/batch bioreactor element. When you click
on the check box for local temperature, the Specify temperature by radio button group is enabled. You may
then specify either a Constant or Scheduled temperature.
• If constant temperature is selected, you may enter the value in the edit box.
• If scheduled temperature is selected the Pattern… button becomes active. Clicking this button
presents you with the Edit temperature itinerary dialog box.

Variable Volume/Batch Bioreactor Outflow

The Variable volume/batch bioreactor element Outflow tab, shown below, is used to specify the overflow
behavior. The overflow behavior can be generalized as follows:
• Whenever the Variable volume/batch bioreactor is full, it overflows at the influent rate, regardless
of the overflow setting.
• Whenever the Variable volume/batch bioreactor is empty and the outflow rate is set higher than the
influent rate, the Variable volume/batch bioreactor will only have an outflow equal to the influent
flow, so as not to have negative volume. If the outflow rate is set lower than the influent rate, then
the Variable volume/batch bioreactor will begin to fill up.
• If the Constant volume (i.e. outflow=inflow) option is checked, then the entire liquid volume entered
on the Dimensions tab is used and the volume will be constant.

Note: Remember for steady state simulations, the initial liquid hold-up volume will be used for calculations.

The following is a description of the behavior of the three outflow settings:

• Overflow only – the Variable volume/batch bioreactor fills up, and then overflows at the influent
flow rate (this setting would be used to simulate start-up of a bioreactor).
• Constant outflow – the outflow always tries to attain the specified constant rate, except when
physically constrained (i.e. when the Variable volume/batch bioreactor is full or empty)
• Flow pattern – the outflow always tries to attain the current specified pattern rate, except when
physically constrained (i.e. when the Variable volume/batch bioreactor is full or empty). To specify a
pattern, click the Pattern… button when it becomes active. For more information, see the Liquid
outflow itinerary section in the “General Operation” chapter.

Biowin 6 Help Manual Building Configurations • 329

The Outflow settings tab of a Variable volume/batch bioreactor element

Variable Volume/Batch Bioreactor Initial Values

The Initial values tab, shown below, is used for setting up the initial settings for variable volume/batch
bioreactor concentrations and volume.

330 • Building Configurations Biowin 6 Help Manual

The Initial values tab with the Default option active (Variable volume/batch bioreactor element)

Use the Initial liquid hold-up field to enter a value to specify the % of full setting. This initial liquid hold-up
volume will be used for steady state calculations. It should be noted here that the lower and upper limits on
this value are 0.02 and 99.98%, respectively. This reflects the fact that this is the liquid volume, and allows
for small differences between liquid volume and reactor volume for inlet and outlet pipes.
There are two methods for setting up Initial concentrations in the Variable volume/batch bioreactor. The
dialog box shown above illustrates the first case where the Default option is selected. When this option is
selected, BioWin applies default seed values for all the state variables (except volume, which you specify) in
the same manner it would for other bioreactor elements.
The dialog box shown below illustrates the second case where the User defined option is selected. In this
case, an editable list of state variables is displayed in the dialog box. This allows you to enter your own seed
values for state variables in the variable volume/batch bioreactor element.

Biowin 6 Help Manual Building Configurations • 331

The Initial values tab with the User defined option active (Variable volume/batch bioreactor element)

• If you choose User defined initial concentrations, then there are two conditions when the User
defined initial concentrations can be used.
• If the box labeled “Set these values now …” is checked then the concentrations specified are
inserted in the state vector as soon as the OK button is clicked.
• If the box labeled “Set these values now …” is NOT checked then the initial concentrations will be
inserted in the reactor state vector when you begin a dynamic or steady state simulation and choose
to start the simulation from seed values.

Note: If “Set these values now …” is checked, the specified values are placed in the reactor state variable
vector when you click OK overriding any existing state variable vector values. Consequently, a dynamic
simulation started from this point will use the User defined initial concentrations regardless of whether you
choose to start from Seed values or Current values.

The use of this option is best explained by the example illustrated below. In this example, we want to feed a
Variable volume/batch bioreactor (the bottom train with blue pipes) with a portion of the waste from a
normal bioreactor that is running at steady state conditions (i.e. the top train with red pipes). However, we
do not want the Variable volume/batch bioreactor to start up at steady state – we want to specify start-up
conditions and then investigate the dynamic behavior.

332 • Building Configurations Biowin 6 Help Manual

Example system illustrating the use of Variable volume / batch bioreactor seeding options

To obtain steady state conditions, set up the configuration and run a steady state simulation. Next, on the
Variable volume/batch bioreactor Initial values tab, select User defined initial concentrations and enter the
desired state variable start-up conditions for the batch test. Place a check mark in the box labeled “Set these
values now …” so that the start-up values are immediately placed in the Variable volume/batch bioreactor.
Now when the dynamic simulation is started, choose to use the Current values in elements to begin. In this
example, the box labeled “Set these values now …” option is what allows us to have unique start-up
conditions in the batch test.

Variable Volume/Batch Bioreactor Power

The Power tab, shown below, allows the user to enter power specifications for mechanical mixing in a
Variable volume/batch bioreactor element.

Biowin 6 Help Manual Building Configurations • 333

The Power tab of a Variable volume/batch bioreactor element

Power can be specified on a power per unit volume basis or on a fixed basis by checking or unchecking the
Power per unit vol check box, respectively. The user can enter a constant value for power or power per unit
volume by selecting the Constant value of radio button and entering a value in the text edit box.
Alternatively, the user can enter a power or power per unit volume pattern by selecting the Scheduled radio
button. This activates the Pattern…button. Clicking this button will open the Power Itinerary editor. Power
calculated for the Variable volume/batch bioreactor element will be grouped under the “Mixing power”
category in power charts and tables.

Variable Volume/Batch Bioreactor Model

The Model tab, shown below, allows the user to change local model parameters.

The Model tab of a Variable volume/batch bioreactor element

You can specify Local kinetic parameters for the activated sludge model used in the Variable volume/batch
bioreactor element. If you click on the check box for local kinetic parameters, then clicking the Edit local
kinetic parameters… button opens the Parameter editor dialog box allowing you access to the various
activated sludge model kinetic parameters.
If you wish to override the project global aeration parameters with local values specific to this element only,
select the box labeled Local aeration parameters. This will activate the button labeled Edit local aeration
parameters…. Clicking this button will open the Aeration dialog box, which allows you to modify aeration
parameters.

334 • Building Configurations Biowin 6 Help Manual

If you wish to override the project global diffuser parameters with local values specific to this element only,
select the box labeled Local diffuser parameters. This will activate the button labeled Edit local diffuser
parameters…. Clicking this button will open the Diffuser dialog box, which allows you to modify diffuser
parameters.
To model the concentrations of the constituents of the aeration gas (e.g. oxygen, carbon dioxide, etc.),
check the box labeled Model gas phase. If this option is selected you may also enter a percentage value for
the Gas hold-up (i.e. the percentage of the total reactor volume occupied by aeration gas).
You can also specify the aeration parameters Alpha F and Beta. You may specify either a Constant value or a
Scheduled pattern for each parameter (clicking the Pattern… button will open the Edit Alpha itinerary or
Edit Beta itinerary dialog box). If you wish to plot Alpha and/or Beta click on the graph button. This will add
a time series plot of alpha and/or beta to the BioWin Album.

Sidestream reactor
The Sidestream reactor simulates the activated sludge process in a continuous stirred tank reactor (CSTR).
Complex activated sludge systems can be configured by arranging a number of Sidestream reactors in
series/parallel. You may specify parameters related to the operation and control of the Sidestream reactor
element. For information on monitoring parameters/variables for this element, please see the Monitoring
Data section in the “General Operation” chapter.

The Monitor items tab of a Sidestream reactor element

Biowin 6 Help Manual Building Configurations • 335

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

The Tags tab of a Sidestream reactor element

Sidestream Reactor Dimensions

The Dimensions tab, shown below, allows the user to enter the physical dimensions of a Sidestream reactor
element.

336 • Building Configurations Biowin 6 Help Manual

The Dimensions tab of a Sidestream reactor element

There are two methods for entering the dimensions: by Area and depth, or by Volume and depth. The
method is specified by clicking on the appropriate radio button.
• If you select by Area and depth, the sidestream reactor area and depth must be entered in the Area
and Depth text edit boxes.
• If you select by Volume and depth, the sidestream reactor volume and depth must be entered in the
Volume and Depth text edit boxes.
Regardless of the method you choose, you also must specify a Width for the element. Units are shown to
the right of the edit boxes. The element name and type, and a picture of the element also are shown.

Sidestream Reactor Operation

The Operation tab, shown below, allows the user to enter operating parameters for a Sidestream reactor
element, such as aeration and diffuser specifications, as well as a local temperature.

Biowin 6 Help Manual Building Configurations • 337

The Operation tab of a Sidestream reactor element

There are two methods for specifying aeration: either by a DO setpoint or by an Air flow rate. The aeration
method is specified by clicking on the appropriate radio button.
When DO setpoint is selected, the setpoint concentration must be specified. You may specify either a
Constant setpoint or a Scheduled DO setpoint pattern (clicking the Pattern… button will open the Edit DO
setpoint itinerary dialog box). You may wish to place a restriction on the minimum and maximum allowable
air flow rate that may be used to achieve the desired DO setpoint by setting a minimum or maximum
allowable airflow in the Air flow rate constraints group. This is a useful feature for investigating the ability of
air equipment to achieve desired DO setpoints. Note that these constraints only are applied by BioWin
during dynamic simulations.
When Air flow rate is selected, the air flow rate must be specified. You may specify either a Constant air
flow rate or a Scheduled air flow rate pattern (clicking the Pattern… button will open the Edit air flow
itinerary dialog box). Note that if you specify an air supply rate, BioWin will automatically turn on the
oxygen modeling option.
There are three methods for entering diffuser information: by a Density(%), by an ATAD, or by the Number
of Diffusers. The diffuser information is specified by clicking on the appropriate radio button.
1. If you select Density(%), the diffuser density (%) (i.e. the total area of diffusers in aeration tank /
area of aeration tank expressed as a percent) must be specified in the Density(%) text edit box.
2. If ATAD is selected, the ATAD (i.e. area of aeration tank/total area of diffusers in aeration tank) must
be specified in the edit box.
3. If Number of Diffusers is selected, the number of diffusers must be specified in the edit box.

338 • Building Configurations Biowin 6 Help Manual

A Sidestream reactor element has the Local temperature option selected by default as it is frequently used
to model digester effluents that may be elevated in temperature. Although the default setting is a constant
temperature of 35 degrees Celsius the Specify temperature by radio button allows you to specify either a
Constant or Scheduled temperature. If constant temperature is selected, you may enter the value in the
edit box. If scheduled temperature is selected the Pattern… button becomes active. Clicking this button
presents you with the Edit temperature itinerary dialog box.

Sidestream Reactor Power

The Power tab, shown below, allows the user to enter power specifications for mechanical mixing in a
Sidestream reactor element.

The Power tab of a Sidestream reactor element

Power can be specified on a power per unit volume basis or on a fixed basis by checking or unchecking the
Power per unit vol check box, respectively. The user can enter a constant value for power or power per unit
volume by selecting the Constant value of radio button and entering a value in the text edit box.
Alternatively, the user can enter a power or power per unit volume pattern by selecting the Scheduled radio
button. This activates the Pattern…button. Clicking this button will open the Power Itinerary editor. Power
calculated for the Sidestream reactor element will be grouped under the “Mixing power” category in power
charts and tables.

Sidestream Reactor Model

The Model tab, shown below, allows the user to change local model parameters.

Biowin 6 Help Manual Building Configurations • 339

The Model tab of a Sidestream reactor element

You can specify Local kinetic parameters for the activated sludge model used in the Variable volume/batch
bioreactor element. If you click on the check box for local kinetic parameters, then clicking the Edit local
kinetic parameters… button opens the Parameter editor dialog box allowing you access to the various
activated sludge model kinetic parameters.
If you wish to override the project global aeration parameters with local values specific to this element only,
select the box labeled Local aeration parameters. This will activate the button labeled Edit local aeration
parameters…. Clicking this button will open the Aeration dialog box, which allows you to modify aeration
parameters.
If you wish to override the project global diffuser parameters with local values specific to this element only,
select the box labeled Local diffuser parameters. This will activate the button labeled Edit local diffuser
parameters…. Clicking this button will open the Diffuser dialog box, which allows you to modify diffuser
parameters.
To model the concentrations of the constituents of the aeration gas (e.g. oxygen, carbon dioxide, etc.),
check the box labeled Model gas phase. If this option is selected you may also enter a percentage value for
the Gas hold-up (i.e. the percentage of the total reactor volume occupied by aeration gas).
You can also specify the aeration parameters Alpha F and Beta. You may specify either a Constant value or a
Scheduled pattern for each parameter (clicking the Pattern… button will open the Edit Alpha itinerary or
Edit Beta itinerary dialog box). If you wish to plot Alpha and/or Beta click on the graph button. This will add
a time series plot of alpha and/or beta to the BioWin Album.

340 • Building Configurations Biowin 6 Help Manual

SBRs
Single-Tank Sequencing Batch Reactor
The Single-tank sequencing batch reactor (STSBR) in BioWin can be used to simulate single reaction zone
SBRs. See later sections for other possible SBR arrangements. You may specify parameters related to the
STSBR dimensions, cycle operation, starting values, and underflow rates. For information on monitoring
parameters/variables for this element, please see the Monitoring Data section in the “General Operation”
chapter.

The Monitor items tab of a Single-tank SBR

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

Biowin 6 Help Manual Building Configurations • 341

The Tags tab of a Single-tank SBR element

STSBR Dimensions
The Dimensions tab, shown below, allows the user to enter the physical dimensions of a STSBR element.

342 • Building Configurations Biowin 6 Help Manual

The Dimensions tab of a Single-tank SBR

There are two methods for entering the dimensions: by Area and depth, or by Volume and depth. The
method is specified by clicking on the appropriate radio button.
• If you select by Area and depth, the STSBR area and depth must be entered in the Area and Depth
text edit boxes.
• If you select by Volume and depth, the STSBR volume and depth must be entered in the Volume and
Depth text edit boxes.
Regardless of the method you choose, you also must specify a Width for the STSBR. Units are shown to the
right of the edit boxes.

Biowin 6 Help Manual Building Configurations • 343

 DECANT AND/OR
OVERFLOW

FLOW IN
1 2 3

UNDERFLOW

LENGTH

Flow distribution in a Single-tank SBR

BioWin uses the Width parameter to calculate the length of the STSBR. The length is then divided into three
equally sized zones. Flow enters the first zone at the level specified by the Feed layer. Underflow leaves the
STSBR at the bottom of the third zone, and decant and/or overflow leaves the STSBR at the top of the third
zone.
Some further explanation of how BioWin uses the SBR dimensions is warranted. When you set the
dimensions, you specify a Volume, Depth and Width (and Length is calculated). Now think of a 2-d side-on
view of the SBR with flow from left to right, as shown above.
For example, imagine the full depth is 5 m and the length is 15 m. When settling starts, this is what happens:
• The horizontal length of the SBR is divided into three equal-length subsections (each 5 m in this
case).
• The vertical direction is divided into 10 equal-depth layers. [Note: as the level goes down during
decanting - with no feed - the number of layers stays at 10, and the depth of each layer decreases].
That is, think of each length section as being 10 layers stacked on top of each other (and there are 3
sections).
• Each of the three sections is treated as a vertical settler. That is, the SBR (during settling) is 3 side-
by-side settlers, with a total of 30 cells (each completely mixed i.e. of uniform composition).
Consider the dimensions of each of the 30 cells:
• The horizontal area of each cell is Width * (Length/3) = W * 5 m here.
• The end area of each cell is Width * (Liquid Depth/10) = W * 0.5 m (0.5 m when it is full). [Note: in
this case the ratio of cell horizontal to side area is 5 : 0.5 = 10 : 1 (if tank is full - but ratio increases
when tank level drops)].
For the moment, assume that there is no inflow during decanting. Decant is removed from the top-right cell.
During decanting several things happen (apart from settling in each of the 3 sections):

344 • Building Configurations Biowin 6 Help Manual

 • Say 1 (incremental) unit of volume is removed from the top-right cell (at the composition of the top
right cell).
• Overall, the volume of each of the 30 cells must be decreased by 1 unit / 30 (the length of each cell
is fixed, so the depth must decrease).
• 29/30ths of the unit volume must get into the top right cell. That is, overall 1/30th of the volume
must be removed from each of the other 29 cells.
• The 29/30ths gets into the top right cell from the cell to the left and from the cell below it.
• The cell at the bottom left of the SBR is a special case - there is no flow into it - only outflow of
1/30th. This flow leaves via the top surface and via the right-hand end surface. The flow leaving each
of the 2 surfaces is proportional to the areas of each surface.
• Flow balances around each of the other 28 cells are handled in a similar manner, doing a
simultaneous flow balance on each cell. For the typical cell, there can be:
• Flow out of the top surface;
• Flow out the right side;
• Flow in through the bottom surface; and
• Flow in through the left surface.
If there is influent flow during decanting, the flow balance is just slightly more complex, but happens in a
similar fashion. Note that this explanation makes the process sound like a step-by-step calculation. In reality,
what happens is a whole series of simultaneous integrations with error checking.
A Minimum decant level must also be specified as a percentage of the total STSBR volume. This level is the
lowest liquid level that can be achieved by decanting liquid out of the top of the STSBR. Note that it is
possible to obtain lower liquid levels in a cycle than this value, but to get lower than this level, the liquid
would have to go out via the underflow.
The Feed layer also is specified on this tab. This is the layer where liquid flow is introduced to the element.
Note that the layers are numbered such that layer 1 is near the top, and number 9 is near the bottom. The
feed flow is distributed throughout the STSBR according to the vessel geometry.

STSBR Operation
The Operation tab, shown below, allows the user to enter operating parameters for a STSBR element, such
as cycle patterns, decant flow rates, aeration specifications and local temperature.

Biowin 6 Help Manual Building Configurations • 345

The Operation tab of a Single-tank SBR

The major operational settings of the STSBR are those related to Cycle settings. The Cycle length or duration
is the total time that will elapse before the cycle begins to repeat itself. The first event to take place in the
cycle is the end of the mixing phase/beginning of the settling phase. You specify this event time with the Mix
until/Start settling at: spin edit control. Note that the dialog provides you with feedback as to the length of
your settling period. The second event to take place is the beginning of the decant phase. You specify this
event time with the Decant/Draw starting at: spin edit control. Note that the dialog provides you with
feedback as to the length of your decant period. Experimenting with these settings will reveal that settling
and decanting take place simultaneously – but the settling phase length always must be greater than the
decant phase length. Finally, you may set up a cycle offset if you wish using the Offset cycle by: control.
The Offset cycle by function is used to set up systems with multiple SBR units. The cycle offset is the "time
into the cycle" for that unit at the start of the simulation (when the reference unit - SBR 1 in the figure
below - first receives influent). In other words, at the start of the simulation, each SBR unit has to be at a
point in its cycle such that the feeding phase starts when the flow is directed to it. All other settings can be
kept at the original values of the reference SBR.
Example: The figure below shows a three SBR system in which each SBR has a cycle length of 6 hours and a
feeding phase of 2 hours.
To set up your multiple SBR system:
• The SBR getting the first influent feed is identified as the reference (SBR 1 in the figure below) and
has no “cycle offset” assigned.

346 • Building Configurations Biowin 6 Help Manual

 • Then for each of the other SBRs the question is: At time zero, how far into the cycle are we for this
SBR?
From the diagram below, we see that:
SBR 2: Four hours into the cycle (that is, at the end of the Reaction phase and the beginning of the Settling
phase)
SBR 3: Two hours into the cycle (that is, in transition from the Fill phase to the Reaction phase).
Those are the cycle offset values!

Simulation time [h]

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
SBR 1 (reference) Fill React Sett Dec Fill React Sett Dec Fill React Sett Dec Fill React Sett Dec
SBR 2 Fill React Sett Dec Fill React Sett Dec Fill React Sett Dec Fill React Sett Dec Fill React
SBR 3 Fill React Sett Dec Fill React Sett Dec Fill React Sett Dec Fill React Sett Dec Fill

Offset SBR 2

Offset
SBR 3

The next operational setting is the Decant flow rate setting. You may specify this with one of two possible
methods. If you know the flow rate you wish to decant at, then choose the At a constant rate of: option and
enter the desired value. If you wish BioWin to calculate the decant flow rate for you, select the To minimum
decant level option. The decant flow rate is calculated as follows. At the beginning of the decant period, the
simulator looks at the difference between the current liquid volume and the specified minimum decant
volume. It then calculates the necessary flow rate to decant the available liquid during the decant period.

Note: BioWin calculates the required decant flow rate based on the assumption that there is no influent or
underflow activity during the decant period (even if there is).

You can specify the STSBR aeration settings by clicking the SBR aeration… button which will show the
following dialog box.

The Aeration setting dialog box of a Single-tank SBR

Biowin 6 Help Manual Building Configurations • 347

There are two methods for specifying aeration: either by a DO setpoint or by an Air flow rate. The aeration
method is specified by clicking on the appropriate radio button.
• When DO setpoint is selected, the setpoint concentration must be specified. You may specify either
a Constant setpoint or a Scheduled DO setpoint pattern (clicking the Pattern… button will open the
SBR DO setpoint itinerary dialog box). You may wish to place a restriction on the minimum and
maximum allowable air flow rate that may be used to achieve the desired DO setpoint by setting a
minimum or maximum allowable airflow in the Air flow rate constraints group. This is a useful
feature for investigating the ability of air equipment to achieve desired DO setpoints.
• When Air flow rate is selected, the air flow rate must be specified. You may specify either a
Constant air flow rate or a Scheduled air flow rate pattern (clicking the Pattern… button will open
the SBR air flow rate itinerary dialog box). Note that if you specify an air supply rate, BioWin will
automatically turn on the oxygen modeling option.
There are three methods for entering diffuser information: by a Density(%), by an ATAD, or by the Number
of Diffusers. The diffuser information is specified by clicking on the appropriate radio button.
1. If you select Density(%), the diffuser density (%) (i.e. the total area of diffusers in aeration tank /
area of aeration tank expressed as a percent) must be specified in the Density(%) text edit box.
2. If ATAD is selected, the ATAD (i.e. area of aeration tank/total area of diffusers in aeration tank) must
be specified in the edit box.
3. If Number of Diffusers is selected, the number of diffusers must be specified in the edit box.
A Local temperature also may be specified for a STSBR element. When you click on the check box for local
temperature, the Specify temperature by radio button group is enabled. You may then specify either a
Constant or Scheduled temperature.
• If constant temperature is selected, you may enter the value in the edit box.
• If scheduled temperature is selected the Pattern… button becomes active. Clicking this button
presents you with the Edit temperature itinerary dialog box.

STSBR Underflow
The STSBR Underflow tab shown below allows you to set up underflow rates and patterns for the STSBR
element.

348 • Building Configurations Biowin 6 Help Manual

The SBR underflow settings tab of a Single-tank SBR

The Underflow type may be specified as a Constant underflow or a Flow pattern by selecting the
appropriate option. If you select Constant underflow, you may enter the desired underflow rate in the edit
field. If you select Flow pattern, clicking the Pattern… button will open the Underflow rate itinerary dialog
box.
The STSBR underflow may be used for several functions:
1. As a wastage stream;
2. A mixed liquor recycle to a mixer element in front of the STSBR;
3. As both a wastage and a recycle by placing a splitter element between the underflow and the mixer
element in front of the STSBR.

STSBR Initial Values

The Initial values tab, shown below, is used for setting up the initial settings for STSBR element
concentrations and volume.

Biowin 6 Help Manual Building Configurations • 349

The Initial values tab with the Default option active (Single-tank SBR)

Use the Initial liquid hold-up field to enter a value to specify the % of full setting. It should be noted here
that the lower and upper limits on this value are 0.02 and 99.98%, respectively.
There are two methods for setting up Initial concentrations in the STSBR. The dialog box shown above
illustrates the first case where the Default option is selected. When this option is selected, BioWin applies
default seed values for all the state variables (except volume, which you specify) in the same manner it
would for other bioreactor elements.
The dialog box shown below illustrates the second case where the User defined option is selected. In this
case, an editable list of state variables is displayed in the dialog box. This allows you to enter your own seed
values for state variables in the STSBR.

350 • Building Configurations Biowin 6 Help Manual

The Initial values tab with the User defined option active (Single-tank SBR)

• If you choose User defined initial concentrations then there are two conditions when the User
defined initial concentrations can be used.
• If the box labeled “Set these values now …” is checked then the concentrations specified are
inserted in the state vector as soon as the OK button is clicked.
• If the box labeled “Set these values now …” is NOT checked then the initial concentrations will be
inserted in the reactor state vector when you begin a dynamic or steady state simulation and
choose to start the simulation from seed values.

Note: If “Set these values now …” is checked, the specified values are placed in the reactor state variable
vector when you click OK overriding any existing state variable vector values. Consequently a dynamic
simulation started from this point will use the User defined initial concentrations regardless of whether you
choose to start from Seed values or Current values.

The use of this option is illustrated in the example at the end of the Variable Volume/Batch Bioreactor Initial
Values section later in this chapter.

STSBR Power Options

The Power tab, shown below, allows the user to enter power specifications for mechanical mixing in the
Single-tank SBR.

Biowin 6 Help Manual Building Configurations • 351

The Power tab (Single-tank SBR)

Power can be specified on a power per unit volume basis or on a fixed basis by checking or unchecking the
Power per unit vol check box, respectively. The user can enter a constant value for power or power per unit
volume by selecting the Constant value of radio button and entering a value in the text edit box.
Alternatively, the user can enter a power or power per unit volume pattern by selecting the Scheduled radio
button. This activates the Pattern…button. Clicking this button will open the Power Itinerary editor. Power
calculated for the Single-tank SBR element will be grouped under the “Mixing power” category in power
charts and tables.

STSBR Model Options

The Model tab, shown below, allows the user to enter model-related information for a STSBR element, such
as settling phase behavior; kinetic, aeration and diffuser model settings, etc.

352 • Building Configurations Biowin 6 Help Manual

The Model options and parameters tab of a Single-tank SBR

There are three Settling model options that you can specify for the settling phase of an SBR. In order from
most numerically complex (slowest simulation speed) to less numerical complexity (fastest simulation
speed), there are:
1. Reactive
2. Non-reactive
3. Fast approximate simulation
The Reactive option is the “traditional” BioWin method for modeling the settling phase in an SBR. That is,
the entire state variable list is maintained in each SBR cell, so that the complete biological model can be
active during settling. This method enables BioWin to simulate phenomena such as denitrification during the
settling phase. However, because of the complexity of simultaneously solving settling and biological
equations, there is a noticeable simulation speed decrease during the settle phase.
The Non-reactive option offers a degree of simplification compared to the Reactive option. If this option is
selected, the entire state variable list is maintained in each SBR cell, but the biological model is not active
during settling. An advantage of this option is that because the complete state variable list is maintained in
each SBR cell, the effect of any changes in SBR influent composition (i.e. either particulate or soluble state
variables) that may take place during the settling phase (e.g. for a continuous flow SBR) will be
approximated in the individual SBR cells. To take a simple example, if there is a change in the SBR feed ISS
composition during the settling phase, this will be properly accounted for in the appropriate SBR cells
because each SBR cell still has “knowledge” about the ISS state variable. With this method, there is less of a

Biowin 6 Help Manual Building Configurations • 353

simulation speed decrease during the settle phase because BioWin no longer is simultaneously solving
settling and biological equations.
The Fast approximate simulation option offers the greatest degree of simplification. If this option is
selected, state variables are “grouped” (e.g. individual particulate state variables are combined into
common particulate variables) during the settling phase so that the settling equations are required to track
fewer variables. Also, because individual state variables are no longer maintained in each SBR cell,
calculation of biological reactions is not possible. Finally, it should be noted that if the SBR feed composition
happens to change during the settling phase (i.e. either particulate or soluble state variables), this change
will only be approximated with this option active – because the individual state variables are no longer being
tracked in the SBR cells. Using this settling model method, there is even less of a simulation speed decrease
during the settle phase because BioWin is not simultaneously solving settling and biological equations, and
the settling equations involve significantly fewer variables. This option is best suited for SBRs that do not
receive feed during the settle phase. It is also useful for trouble-shooting the initial setup of SBR models (e.g.
checking of flow distribution, liquid volume levels, etc.).
You also can specify Local kinetic parameters for the activated sludge model used in the STSBR
decant/settling phase. For the mixing phase, the global model parameter values are used. If you click on the
check box for local kinetic parameters, then clicking the Edit local kinetic parameters… button opens the
Parameter editor dialog box allowing you access to the various activated sludge model kinetic parameters.
If you wish to override the project global aeration parameters with local values specific to this element only,
select the box labeled Local aeration parameters. This will activate the button labeled Edit local aeration
parameters…. Clicking this button will open the Aeration dialog box, which allows you to modify aeration
parameters.
If you wish to override the project global diffuser parameters with local values specific to this element only,
select the box labeled Local diffuser parameters. This will activate the button labeled Edit local diffuser
parameters…. Clicking this button will open the Diffuser dialog box, which allows you to modify diffuser
parameters.
To model the concentrations of the constituents of the aeration gas (e.g. oxygen, carbon dioxide, etc.),
check the box labeled Model gas phase. If this option is selected you may also enter a percentage value for
the Gas hold-up (i.e. the percentage of the total reactor volume occupied by aeration gas).
You can also specify the aeration parameters Alpha F and Beta. You may specify either a Constant value or a
Scheduled pattern for each parameter (clicking the Pattern… button will open the Edit Alpha itinerary or
Edit Beta itinerary dialog box). If you wish to plot Alpha and/or Beta click on the graph button. This will add
a time series plot of alpha and/or beta to the BioWin Album.

SBR with Always-Mixed Prezone(s)

This type of SBR allows you to have hydraulically-linked prezones that are continuously mixed, even when
the decant zone is in settle mode. The following SBR/always-mixed prezone combinations are available:
• SBR+1 Prezone
• SBR+2 Prezones
BioWin allows you to have internal recycles between the prezones and the SBR, as shown in the following
diagram.

354 • Building Configurations Biowin 6 Help Manual

 MIXED SBR
PREZONE ZONE

1st MIXED 2nd MIXED SBR

PREZONE PREZONE ZONE

Flow recycles and patterns that can be set up between an SBR and its prezone(s)

The following sections describe the dialog boxes for the SBR with one and two always-mixed prezone(s),
respectively.

SBR + 1 Always-Mixed Prezone

This type of SBR provides one hydraulically linked, always-mixed zone separated from the fill/draw SBR zone
by a baffle. You may specify parameters related to the SBR dimensions, cycle operation, starting values, and
underflow rates. You also may specify operating conditions for the always-mixed prezone. For information
on monitoring parameters/variables for this element, please see the Monitoring Data section in the
“General Operation” chapter.

Biowin 6 Help Manual Building Configurations • 355

The Monitor items tab of an SBR + 1 always-mixed prezone

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

356 • Building Configurations Biowin 6 Help Manual

The Tags tab of an SBR + 1 always-mixed prezone element

SBR + 1 Always-Mixed Prezone Dimensions

The SBR Dimensions tab, shown below, allows the user to enter the physical dimensions of the SBR zone of
an SBR + 1 always-mixed prezone element.

Biowin 6 Help Manual Building Configurations • 357

The SBR dimensions tab of an SBR + 1 always-mixed prezone

358 • Building Configurations Biowin 6 Help Manual

There are two methods for entering the dimensions: by Area and depth, or by Volume and depth. The
method is specified by clicking on the appropriate radio button.
• If you select by Area and depth, the SBR zone area and depth must be entered in the Area and
Depth text edit boxes.
• If you select by Volume and depth, the SBR zone volume and depth must be entered in the Volume
and Depth text edit boxes.
Regardless of the method you choose, you also must specify a Width for the SBR zone. Units are shown to
the right of the edit boxes.

DECANT AND/OR
OVERFLOW

FLOW IN
1 2 3

UNDERFLOW

LENGTH

Flow distribution in the SBR zone

BioWin uses the Width parameter to calculate the length of the SBR zone. The length is then divided into
three equally sized zones. Flow enters the first zone at the level specified by the Feed layer. Underflow
leaves the SBR zone at the bottom of the third zone, and decant and/or overflow leaves the SBR zone at the
top of the third zone.
Some further explanation of how BioWin uses the SBR dimensions is warranted. When you set the
dimensions, you specify a Volume, Depth and Width (and Length is calculated). Now think of a 2-d side-on
view of the SBR with flow from left to right, as shown above.
For example, imagine the full depth is 5 m and the length is 15 m. When settling starts, this is what happens:
• The horizontal length of the SBR is divided into three equal-length subsections (each 5 m in this
case).
• The vertical direction is divided into 10 equal-depth layers. [Note: as the level goes down during
decanting - with no feed - the number of layers stays at 10, and the depth of each layer decreases].
That is, think of each length section as being 10 layers stacked on top of each other (and there are 3
sections).
• Each of the three sections is treated as a vertical settler. That is, the SBR (during settling) is 3 side-
by-side settlers, with a total of 30 cells (each completely mixed i.e. of uniform composition).

Biowin 6 Help Manual Building Configurations • 359

Consider the dimensions of each of the 30 cells:
• The horizontal area of each cell is Width * (Length/3) = W * 5 m here.
• The end area of each cell is Width * (Liquid Depth/10) = W * 0.5 m (0.5 m when it is full). [Note: in
this case the ratio of cell horizontal to side area is 5 : 0.5 = 10 : 1 (if tank is full - but ratio increases
when tank level drops)].
For the moment, assume that there is no inflow during decanting. Decant is removed from the top-right cell.
During decanting several things happen (apart from settling in each of the 3 sections):
• Say 1 (incremental) unit of volume is removed from the top-right cell (at the composition of the top
right cell).
• Overall, the volume of each of the 30 cells must be decreased by 1 unit / 30 (the length of each cell
is fixed, so the depth must decrease).
• 29/30ths of the unit volume must get into the top right cell. That is, overall 1/30th of the volume
must be removed from each of the other 29 cells.
• The 29/30ths gets into the top right cell from the cell to the left and from the cell below it.
• The cell at the bottom left of the SBR is a special case - there is no flow into it - only outflow of
1/30th. This flow leaves via the top surface and via the right hand end surface. The flow leaving each
of the 2 surfaces is proportional to the areas of each surface.
• Flow balances around each of the other 28 cells are handled in a similar manner, doing a
simultaneous flow balance on each cell. For the typical cell, there can be:
• Flow out of the top surface;
• Flow out the right side;
• Flow in through the bottom surface; and
• Flow in through the left surface.
If there is influent flow during decanting, the flow balance is just slightly more complex, but happens in a
similar fashion. Note that this explanation makes the process sound like a step-by-step calculation. In reality,
what happens is a whole series of simultaneous integrations with error checking.
A Minimum decant level must also be specified as a percentage of the height. This level is the lowest liquid
level that can be achieved by decanting liquid out of the top of the SBR zone. Note that it is possible to
obtain lower liquid levels in a cycle than this value, but to get lower than this level, the liquid would have to
go out via the underflow.
The Feed layer also is specified on this tab. This is the layer where liquid flow from the always mixed
prezone is introduced to the main SBR zone. Note that the layers are numbered such that layer 1 is near the
top, and number 9 is near the bottom.

Single Always-Mixed Prezone Setup

The Prezone 1 tab shown below is used for specifying the volume and aeration settings of the prezone for
the SBR + 1 always-mixed prezone element.

360 • Building Configurations Biowin 6 Help Manual

The Prezone 1 tab of an SBR + 1 always-mixed prezone element

You can specify the volume of the prezone using the Volume text edit field. You can set up the prezone
aeration operation by clicking the Prezone 1 aeration… button. Doing so will present you with the dialog box
shown below.

The SBR zone aeration setting dialog box for prezone 1

Biowin 6 Help Manual Building Configurations • 361

There are two methods for specifying aeration: either by a DO setpoint or by an Air flow rate. The aeration
method is specified by clicking on the appropriate radio button.
When DO setpoint is selected, the setpoint concentration must be specified. You may specify either a
Constant setpoint or a Scheduled DO setpoint pattern (clicking the Pattern… button will open the Edit DO
setpoint itinerary dialog box). You may wish to place a restriction on the minimum and maximum allowable
air flow rate that may be used to achieve the desired DO setpoint by setting a minimum or maximum
allowable airflow in the Air flow rate constraints group. This is a useful feature for investigating the ability of
air equipment to achieve desired DO setpoints.
When Air flow rate is selected, the air flow rate must be specified. You may specify either a Constant air
flow rate or a Scheduled air flow rate pattern (clicking the Pattern… button will open the Edit air flow
itinerary dialog box). Note that if you specify an air supply rate, BioWin will automatically turn on the
oxygen modeling option.
There are three methods for entering diffuser information: by a Density(%), by an ATAD, or by the Number
of Diffusers. The diffuser information is specified by clicking on the appropriate radio button.
1. If you select Density(%), the diffuser density (%) (i.e. the total area of diffusers in aeration tank /
area of aeration tank expressed as a percent) must be specified in the Density(%) text edit box.
2. If ATAD is selected, the ATAD (i.e. area of aeration tank/total area of diffusers in aeration tank) must
be specified in the edit box.
3. If Number of Diffusers is selected, the number of diffusers must be specified in the edit box.

SBR + 1 Always-Mixed Prezone SBR Zone Operation

The SBR Operation tab, shown below, allows the user to enter operating parameters for the SBR zone of an
SBR + 1 always-mixed prezone element, such as cycle patterns, decant flow rates, aeration specifications
and local temperature.

362 • Building Configurations Biowin 6 Help Manual

The SBR operation tab of an SBR + 1 always-mixed prezone element

The major operational settings of the SBR zone of the SBR + 1 always-mixed prezone are those related to
Cycle settings. The Cycle length or duration is the total time that will elapse before the cycle begins to
repeat itself. The first event to take place in the cycle is the end of the mixing phase/beginning of the
settling phase. You specify this event time with the Mix until/Start settling at: spin edit control. Note that
the dialog provides you with feedback as to the length of your settling period. The second event to take
place is the beginning of the decant phase. You specify this event time with the Decant/Draw starting at:
spin edit control. Note that the dialog provides you with feedback as to the length of your decant period.
Experimenting with these settings will reveal that settling and decanting take place simultaneously – but the
settling phase length always must be greater than the decant phase length. Finally, you may set up a cycle
offset if you wish using the Offset cycle by: control.
The Offset cycle by function is used to set up systems with multiple SBR units. The cycle offset is the "time
into the cycle" for that unit at the start of the simulation (when the reference unit - SBR 1 in the figure
below - first receives influent). In other words, at the start of the simulation, each SBR unit has to be at a
point in its cycle such that the feeding phase starts when the flow is directed to it. All other settings can be
kept at the original values of the reference SBR.
Example: The figure below shows a three SBR system in which each SBR has a cycle length of 6 hours and a
feeding phase of 2 hours.
To set up your multiple SBR system:
• The SBR getting the first influent feed is identified as the reference (SBR 1 in the figure below) and
has no “cycle offset” assigned.

Biowin 6 Help Manual Building Configurations • 363

 • Then for each of the other SBRs the question is: At time zero, how far into the cycle are we for this
SBR?
From the diagram below, we see that:
SBR 2: Four hours into the cycle (that is, at the end of the Reaction phase and the beginning of the Settling
phase)
SBR 3: Two hours into the cycle (that is, in transition from the Fill phase to the Reaction phase).
Those are the cycle offset values!

Simulation time [h]

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
SBR 1 (reference) Fill React Sett Dec Fill React Sett Dec Fill React Sett Dec Fill React Sett Dec
SBR 2 Fill React Sett Dec Fill React Sett Dec Fill React Sett Dec Fill React Sett Dec Fill React
SBR 3 Fill React Sett Dec Fill React Sett Dec Fill React Sett Dec Fill React Sett Dec Fill

Offset SBR 2

Offset
SBR 3

The next operational setting is the Decant flow rate setting. You may specify this with one of two possible
methods. If you know the flow rate you wish to decant at, then choose the At a constant rate of: option and
enter the desired value. If you wish BioWin to calculate the decant flow rate for you, select the To minimum
decant level option. The decant flow rate is calculated as follows. At the beginning of the decant period, the
simulator looks at the difference between the current liquid volume and the specified minimum decant
volume. It then calculates the necessary flow rate to decant the available liquid during the decant period.

Note: BioWin calculates the required decant flow rate based on the assumption that there is no influent or
underflow activity during the decant period (even if there is).

You can specify the SBR zone aeration settings by clicking the SBR aeration… button which will show the
following dialog box.

364 • Building Configurations Biowin 6 Help Manual

The SBR zone aeration setting dialog box

There are two methods for specifying aeration: either by a DO setpoint or by an Air flow rate. The aeration
method is specified by clicking on the appropriate radio button.
• When DO setpoint is selected, the setpoint concentration must be specified. You may specify either
a Constant setpoint or a Scheduled DO setpoint pattern (clicking the Pattern… button will open the
SBR DO setpoint itinerary dialog box). You may wish to place a restriction on the minimum and
maximum allowable air flow rate that may be used to achieve the desired DO setpoint by setting a
minimum or maximum allowable airflow in the Air flow rate constraints group. This is a useful
feature for investigating the ability of air equipment to achieve desired DO setpoints.
• When Air flow rate is selected, the air flow rate must be specified. You may specify either a
Constant air flow rate or a Scheduled air flow rate pattern (clicking the Pattern… button will open
the SBR air flow itinerary dialog box). Note that if you specify an air supply rate, BioWin will
automatically turn on the oxygen modeling option.
There are three methods for entering diffuser information: by a Density(%), by an ATAD, or by the Number
of Diffusers. The diffuser information is specified by clicking on the appropriate radio button.
1. If you select Density(%), the diffuser density (%) (i.e. the total area of diffusers in aeration tank /
area of aeration tank expressed as a percent) must be specified in the Density(%) text edit box.
2. If ATAD is selected, the ATAD (i.e. area of aeration tank/total area of diffusers in aeration tank) must
be specified in the edit box.
3. If Number of Diffusers is selected, the number of diffusers must be specified in the edit box.
A Local temperature also may be specified for an SBR + 1 always-mixed prezone element. When you click on
the check box for local temperature, the Specify temperature by radio button group is enabled. You may
then specify either a Constant or Scheduled temperature.
• If constant temperature is selected, you may enter the value in the edit box.
• If scheduled temperature is selected the Pattern… button becomes active. Clicking this button
presents you with the Edit temperature itinerary dialog box.

SBR + 1 Always-Mixed Prezone Underflow

The SBR + 1 always-mixed prezone element SBR Underflow tab shown below allows you to set up underflow
rates and patterns for the SBR zone.

Biowin 6 Help Manual Building Configurations • 365

The SBR underflow tab of an SBR + 1 always-mixed prezone element

The Underflow type may be specified as a Constant underflow or a Flow pattern by selecting the
appropriate option. If you select Constant underflow, you may enter the desired underflow rate in the edit
field. If you select Flow pattern, clicking the Pattern… button will open the Underflow rate itinerary dialog
box.
The SBR zone underflow may be used for several functions:
1. As a wastage stream;
2. A mixed liquor recycle to a mixer element in front of the SBR + 1 always-mixed prezone element;
3. As both a wastage and a recycle by placing a splitter element between the underflow and the mixer
element in front of the SBR + 1 always-mixed prezone element.

SBR + 1 Always-Mixed Prezone Initial Values

The Initial values tab, shown below, is used for setting up the initial settings for SBR + 1 always-mixed
prezone concentrations and volume.

366 • Building Configurations Biowin 6 Help Manual

The Initial values tab with the Default option selected (SBR + 1 always-mixed prezone)

Use the Initial liquid hold-up field to enter a value to specify the % of full setting. It should be noted here
that the lower and upper limits on this value are 0.02 and 99.98%, respectively.
There are two methods for setting up Initial concentrations in the SBR + 1 always-mixed prezone. The dialog
box shown above illustrates the first case where the Default option is selected. When this option is selected,
BioWin applies default seed values for all the state variables (except volume, which you specify) in the same
manner it would for other bioreactor elements in all of the zones (i.e. including the prezone).
The dialog box shown below illustrates the second case where the User defined option is selected. In this
case, an editable list of state variables is displayed in the dialog box. This allows you to enter your own seed
values for state variables in the SBR + 1 always-mixed prezone.

Biowin 6 Help Manual Building Configurations • 367

The Initial values tab with the User defined option selected (SBR + 1 always-mixed prezone)

• If you choose User defined initial concentrations then there are two conditions when the User
defined initial concentrations can be used.
• If the box labeled “Set these values now …” is checked then the concentrations specified are
inserted in the state vector as soon as the OK button is clicked.
• If the box labeled “Set these values now …” is NOT checked then the initial concentrations will be
inserted in the reactor state vector when you begin a dynamic or steady state simulation and
choose to start the simulation from seed values.

Note: If “Set these values now …” is checked, the specified values are placed in the reactor state variable
vector when you click OK overriding any existing state variable vector values. Consequently a dynamic
simulation started from this point will use the User defined initial concentrations regardless of whether you
choose to start from Seed values or Current values.

The use of this option is illustrated in the example at the end of the Variable Volume/Batch Bioreactor Initial
Values section later in this chapter.

SBR + 1 Always-Mixed Prezone Power

The Power tab, shown below, allows the user to enter power specifications.

368 • Building Configurations Biowin 6 Help Manual

The Power tab (SBR +1 always-mixed prezone)

Power can be specified on a power per unit volume basis or on a fixed basis by checking or unchecking the
Power per unit vol check box, respectively. The user can enter a constant value for power or power per unit
volume by selecting the Constant value of radio button and entering a value in the text edit box.
Alternatively, the user can enter a power or power per unit volume pattern by selecting the Scheduled radio
button. This activates the Pattern…button. Clicking this button will open the Power Itinerary editor. Power
calculated for the SBR +1 always-mixed prezone element will be grouped under the “Mixing power”
category in power charts and tables.

SBR + 1 Always-Mixed Prezone Model Options

The Model tab, shown below, allows the user to enter model-related information for an SBR + 1 always-
mixed prezone element, such as settling phase behavior; kinetic, aeration, diffuser model settings, etc.

Biowin 6 Help Manual Building Configurations • 369

The Model options and parameters tab of an SBR + 1 always-mixed prezone element

There are three Settling model options that you can specify for the settling phase of an SBR. In order from
most numerically complex (slowest simulation speed) to less numerical complexity (fastest simulation
speed), there are:
1. Reactive
2. Non-reactive
3. Fast approximate simulation
The Reactive option is the “traditional” BioWin method for modeling the settling phase in an SBR. That is,
the entire state variable list is maintained in each SBR cell, so that the complete biological model can be
active during settling. This method enables BioWin to simulate phenomena such as denitrification during the
settling phase. However, because of the complexity of simultaneously solving settling and biological
equations, there is a noticeable simulation speed decrease during the settle phase.
The Non-reactive option offers a degree of simplification compared to the Reactive option. If this option is
selected, the entire state variable list is maintained in each SBR cell, but the biological model is not active
during settling. An advantage of this option is that because the complete state variable list is maintained in
each SBR cell, the effect of any changes in SBR influent composition (i.e. either particulate or soluble state
variables) that may take place during the settling phase (e.g. for a continuous flow SBR) will be
approximated in the individual SBR cells. To take a simple example, if there is a change in the SBR feed ISS
composition during the settling phase, this will be properly accounted for in the appropriate SBR cells
because each SBR cell still has “knowledge” about the ISS state variable. With this method, there is less of a

370 • Building Configurations Biowin 6 Help Manual

simulation speed decrease during the settle phase because BioWin no longer is simultaneously solving
settling and biological equations.
The Fast approximate simulation option offers the greatest degree of simplification. If this option is
selected, state variables are “grouped” (e.g. individual particulate state variables are combined into
common particulate variables) during the settling phase so that the settling equations are required to track
fewer variables. Also, because individual state variables are no longer maintained in each SBR cell,
calculation of biological reactions is not possible. Finally, it should be noted that if the SBR feed composition
happens to change during the settling phase (i.e. either particulate or soluble state variables), this change
will only be approximated with this option active – because the individual state variables are no longer being
tracked in the SBR cells. Using this settling model method, there is even less of a simulation speed decrease
during the settle phase because BioWin is not simultaneously solving settling and biological equations, and
the settling equations involve significantly fewer variables. This option is best suited for SBRs that do not
receive feed during the settle phase. It is also useful for trouble-shooting the initial setup of SBR models (e.g.
checking of flow distribution, liquid volume levels, etc.).
You also can specify Local kinetic parameters for the activated sludge model used in the STSBR
decant/settling phase. For the mixing phase, the global model parameter values are used. If you click on the
check box for local kinetic parameters, then clicking the Edit local kinetic parameters… button opens the
Parameter editor dialog box allowing you access to the various activated sludge model kinetic parameters.
If you wish to override the project global aeration parameters with local values specific to this element only,
select the box labeled Local aeration parameters. This will activate the button labeled Edit local aeration
parameters…. Clicking this button will open the Aeration dialog box, which allows you to modify aeration
parameters.
If you wish to override the project global diffuser parameters with local values specific to this element only,
select the box labeled Local diffuser parameters. This will activate the button labeled Edit local diffuser
parameters…. Clicking this button will open the Diffuser dialog box, which allows you to modify diffuser
parameters.
To model the concentrations of the constituents of the aeration gas (e.g. oxygen, carbon dioxide, etc.),
check the box labeled Model gas phase. If this option is selected, you may also enter a percentage value for
the Gas hold-up (i.e. the percentage of the total reactor volume occupied by aeration gas).
You can also specify the aeration parameters Alpha F and Beta. You may specify either a Constant value or a
Scheduled pattern for each parameter (clicking the Pattern… button will open the Edit Alpha itinerary or
Edit Beta itinerary dialog box). If you wish to plot Alpha and/or Beta click on the graph button. This will add
a time series plot of alpha and/or beta to the BioWin Album.

SBR with Two Always-Mixed Prezones

This type of SBR provides two hydraulically linked, always-mixed zones separated from the fill/draw SBR
zone by a baffle. You may specify parameters related to the SBR dimensions, cycle operation, starting
values, and underflow rates. You also may specify operating conditions for the always-mixed prezones. For
information on monitoring parameters/variables for this element, please see the Monitoring Data section in
the “General Operation” chapter.

Biowin 6 Help Manual Building Configurations • 371

The Monitor items tab of an SBR + 2 always-mixed prezones element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

372 • Building Configurations Biowin 6 Help Manual

The Tags tab of an SBR + 2 always-mixed prezones element

SBR + 2 Always-Mixed Prezones Dimensions

The SBR Dimensions tab, shown below, allows the user to enter the physical dimensions of the SBR zone of
an SBR + 2 always-mixed prezones element.

Biowin 6 Help Manual Building Configurations • 373

The SBR dimensions tab of an SBR + 2 always-mixed prezones element

There are two methods for entering the dimensions: by Area and depth, or by Volume and depth. The
method is specified by clicking on the appropriate radio button.
• If you select by Area and depth, the SBR zone area and depth must be entered in the Area and
Depth text edit boxes.
• If you select by Volume and depth, the SBR zone volume and depth must be entered in the Volume
and Depth text edit boxes.
Regardless of the method you choose, you also must specify a Width for the SBR zone. Units are shown to
the right of the edit boxes.

374 • Building Configurations Biowin 6 Help Manual

 DECANT AND/OR
OVERFLOW

FLOW IN
1 2 3

UNDERFLOW

LENGTH

Flow distribution in the SBR zone

BioWin uses the Width parameter to calculate the length of the SBR zone. The length is then divided into
three equally sized zones. Flow enters the first zone at the level specified by the Feed layer. Underflow
leaves the SBR zone at the bottom of the third zone, and decant and/or overflow leaves the SBR zone at the
top of the third zone.
Some further explanation of how BioWin uses the SBR dimensions is warranted. When you set the
dimensions, you specify a Volume, Depth and Width (and Length is calculated). Now think of a 2-d side-on
view of the SBR with flow from left to right, as shown above.
For example, imagine the full depth is 5 m and the length is 15 m. When settling starts, this is what happens:
• The horizontal length of the SBR is divided into three equal-length subsections (each 5 m in this
case).
• The vertical direction is divided into 10 equal-depth layers. [Note: as the level goes down during
decanting - with no feed - the number of layers stays at 10, and the depth of each layer decreases].
That is, think of each length section as being 10 layers stacked on top of each other (and there are 3
sections).
• Each of the three sections is treated as a vertical settler. That is, the SBR (during settling) is 3 side-
by-side settlers, with a total of 30 cells (each completely mixed i.e. of uniform composition).
Consider the dimensions of each of the 30 cells:
• The horizontal area of each cell is Width * (Length/3) = W * 5 m here.
• The end area of each cell is Width * (Liquid Depth/10) = W * 0.5 m (0.5 m when it is full). [Note: in
this case the ratio of cell horizontal to side area is 5 : 0.5 = 10 : 1 (if tank is full - but ratio increases
when tank level drops)].
For the moment, assume that there is no inflow during decanting. Decant is removed from the top-right cell.
During decanting several things happen (apart from settling in each of the 3 sections):

Biowin 6 Help Manual Building Configurations • 375

 • Say 1 (incremental) unit of volume is removed from the top-right cell (at the composition of the top
right cell).
• Overall, the volume of each of the 30 cells must be decreased by 1 unit / 30 (the length of each cell
is fixed, so the depth must decrease).
• 29/30ths of the unit volume must get into the top right cell. That is, overall 1/30th of the volume
must be removed from each of the other 29 cells.
• The 29/30ths gets into the top right cell from the cell to the left and from the cell below it.
• The cell at the bottom left of the SBR is a special case - there is no flow into it - only outflow of
1/30th. This flow leaves via the top surface and via the right hand end surface. The flow leaving each
of the 2 surfaces is proportional to the areas of each surface.
• Flow balances around each of the other 28 cells are handled in a similar manner, doing a
simultaneous flow balance on each cell. For the typical cell, there can be:
• Flow out of the top surface;
• Flow out the right side;
• Flow in through the bottom surface; and
• Flow in through the left surface.
If there is influent flow during decanting, the flow balance is just slightly more complex, but happens in a
similar fashion.

Note: This explanation makes the process sound like a step-by-step calculation. In reality, what happens is a
whole series of simultaneous integrations with error checking.

A Minimum decant level must also be specified as a percentage of the height. This level is the lowest liquid
level that can be achieved by decanting liquid out of the top of the SBR zone. Note that it is possible to
obtain lower liquid levels in a cycle than this value, but to get lower than this level, the liquid would have to
go out via the underflow.
The Feed layer also is specified on this tab. This is the layer where liquid flow is introduced to the element.
Note that the layers are numbered such that layer 1 is near the top, and number 9 is near the bottom. The
feed flow is distributed throughout the SBR + 2 always-mixed prezones element according to the vessel
geometry.

First Always-Mixed Prezone Setup

The Prezone 1 tab shown below is used for specifying the volume and aeration settings of the first prezone
for the SBR + 2 always-mixed prezones element.

376 • Building Configurations Biowin 6 Help Manual

The Prezone 1 tab of an SBR + 2 always mixed prezone element

You can specify the volume of the first prezone using the Volume text edit field. You can set up the first
prezone aeration operation by clicking the Prezone 1 aeration… button. Doing so will present you with the
dialog box shown below.

The first prezone aeration settings dialog box

Biowin 6 Help Manual Building Configurations • 377

There are two methods for specifying aeration: either by a DO setpoint or by an Air flow rate. The aeration
method is specified by clicking on the appropriate radio button.
• When DO setpoint is selected, the setpoint concentration must be specified. You may specify either
a Constant setpoint or a Scheduled DO setpoint pattern (clicking the Pattern… button will open the
Edit DO setpoint itinerary dialog box). You may wish to place a restriction on the minimum and
maximum allowable air flow rate that may be used to achieve the desired DO setpoint by setting a
minimum or maximum allowable airflow in the Air flow rate constraints group. This is a useful
feature for investigating the ability of air equipment to achieve desired DO setpoints.
• When Air flow rate is selected, the air flow rate must be specified. You may specify either a
Constant air flow rate or a Scheduled air flow rate pattern (clicking the Pattern… button will open
the Edit air flow itinerary dialog box). Note that if you specify an air supply rate, BioWin will
automatically turn on the oxygen modeling option.
There are three methods for entering diffuser information: by a Density(%), by an ATAD, or by the Number
of Diffusers. The diffuser information is specified by clicking on the appropriate radio button.
1. If you select Density(%), the diffuser density (%) (i.e. the total area of diffusers in aeration tank /
area of aeration tank expressed as a percent) must be specified in the Density(%) text edit box.
2. If ATAD is selected, the ATAD (i.e. area of aeration tank/total area of diffusers in aeration tank) must
be specified in the edit box.
3. If Number of Diffusers is selected, the number of diffusers must be specified in the edit box.

Second Always-Mixed Prezone Setup

The Prezone 2 tab shown below is used for specifying the volume and aeration settings of the second
prezone for the SBR + 2 always-mixed prezones element.

378 • Building Configurations Biowin 6 Help Manual

The Prezone 2 tab of an SBR + 2 always mixed prezone element

You can specify the volume of the second prezone using the Volume text edit field. You can set up the
second prezone aeration operation by clicking the Prezone 2 aeration… button. Doing so will present you
with the dialog box shown below.

The second prezone aeration settings dialog box

Biowin 6 Help Manual Building Configurations • 379

There are two methods for specifying aeration: either by a DO setpoint or by an Air flow rate. The aeration
method is specified by clicking on the appropriate radio button.
• When DO setpoint is selected, the setpoint concentration must be specified. You may specify either
a Constant setpoint or a Scheduled DO setpoint pattern (clicking the Pattern… button will open the
Edit DO setpoint itinerary dialog box). You may wish to place a restriction on the minimum and
maximum allowable air flow rate that may be used to achieve the desired DO setpoint by setting a
minimum or maximum allowable airflow in the Air flow rate constraints group. This is a useful
feature for investigating the ability of air equipment to achieve desired DO setpoints.
• When Air flow rate is selected, the air flow rate must be specified. You may specify either a
Constant air flow rate or a Scheduled air flow rate pattern (clicking the Pattern… button will open
the Edit air flow itinerary dialog box). Note that if you specify an air supply rate, BioWin will
automatically turn on the oxygen modeling option.
There are three methods for entering diffuser information: by a Density(%), by an ATAD, or by the Number
of Diffusers. The diffuser information is specified by clicking on the appropriate radio button.
1. If you select Density(%), the diffuser density (%) (i.e. the total area of diffusers in aeration tank /
area of aeration tank expressed as a percent) must be specified in the Density(%) text edit box.
2. If ATAD is selected, the ATAD (i.e. area of aeration tank/total area of diffusers in aeration tank) must
be specified in the edit box.
3. If Number of Diffusers is selected, the number of diffusers must be specified in the edit box.

SBR + 2 Always-Mixed Prezones SBR Zone Operation

The SBR Operation tab, shown below, allows the user to enter operating parameters for the SBR zone of an
SBR + 2 always-mixed prezones element, such as cycle patterns, decant flow rates, aeration specifications
and local temperature.

380 • Building Configurations Biowin 6 Help Manual

The SBR operation tab of an SBR + 2 always-mixed prezones element

The major operational settings of the SBR zone of the SBR + 2 always-mixed prezones element are those
related to Cycle settings. The Cycle length or duration is the total time that will elapse before the cycle
begins to repeat itself. The first event to take place in the cycle is the end of the mixing phase/beginning of
the settling phase. You specify this event time with the Mix until/Start settling at: spin edit control. Note
that the dialog provides you with feedback as to the length of your settling period. The second event to take
place is the beginning of the decant phase. You specify this event time with the Decant/Draw starting at:
spin edit control. Note that the dialog provides you with feedback as to the length of your decant period.
Experimenting with these settings will reveal that settling and decanting take place simultaneously – but the
settling phase length always must be greater than the decant phase length. Finally, you may set up a cycle
offset if you wish using the Offset cycle by: control.
The Offset cycle by function is used to set up systems with multiple SBR units. The cycle offset is the "time
into the cycle" for that unit at the start of the simulation (when the reference unit - SBR 1 in the figure
below - first receives influent). In other words, at the start of the simulation, each SBR unit has to be at a
point in its cycle such that the feeding phase starts when the flow is directed to it. All other settings can be
kept at the original values of the reference SBR.

Example: The figure below shows a three SBR system in which each SBR has a cycle length of 6 hours and a
feeding phase of 2 hours.

To set up your multiple SBR system:

Biowin 6 Help Manual Building Configurations • 381

 • The SBR getting the first influent feed is identified as the reference (SBR 1 in the figure below) and
has no “cycle offset” assigned.
• Then for each of the other SBRs the question is: At time zero, how far into the cycle are we for this
SBR?
From the diagram below, we see that:
SBR 2: Four hours into the cycle (that is, at the end of the Reaction phase and the beginning of the Settling
phase)
SBR 3: Two hours into the cycle (that is, in transition from the Fill phase to the Reaction phase).
Those are the cycle offset values!

Simulation time [h]

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
SBR 1 (reference) Fill React Sett Dec Fill React Sett Dec Fill React Sett Dec Fill React Sett Dec
SBR 2 Fill React Sett Dec Fill React Sett Dec Fill React Sett Dec Fill React Sett Dec Fill React
SBR 3 Fill React Sett Dec Fill React Sett Dec Fill React Sett Dec Fill React Sett Dec Fill

Offset SBR 2

Offset
SBR 3

The next operational setting is the Decant flow rate setting. You may specify this with one of two possible
methods. If you know the flow rate you wish to decant at, then choose the At a constant rate of: option and
enter the desired value. If you wish BioWin to calculate the decant flow rate for you, select the To minimum
decant level option. The decant flow rate is calculated as follows. At the beginning of the decant period, the
simulator looks at the difference between the current liquid volume and the specified minimum decant
volume. It then calculates the necessary flow rate to decant the available liquid during the decant period.

Note: BioWin calculates the required decant flow rate based on the assumption that there is no influent or
underflow activity during the decant period (even if there is).

You can specify the SBR zone aeration settings by clicking the SBR aeration… button which will show the
following dialog box.

382 • Building Configurations Biowin 6 Help Manual

The SBR zone aeration setting dialog box

There are two methods for specifying aeration: either by a DO setpoint or by an Air flow rate. The aeration
method is specified by clicking on the appropriate radio button.
• When DO setpoint is selected, the setpoint concentration must be specified. You may specify either
a Constant setpoint or a Scheduled DO setpoint pattern (clicking the Pattern… button will open the
SBR DO setpoint itinerary dialog box). You may wish to place a restriction on the minimum and
maximum allowable air flow rate that may be used to achieve the desired DO setpoint by setting a
minimum or maximum allowable airflow in the Air flow rate constraints group. This is a useful
feature for investigating the ability of air equipment to achieve desired DO setpoints.
• When Air flow rate is selected, the air flow rate must be specified. You may specify either a
Constant air flow rate or a Scheduled air flow rate pattern (clicking the Pattern… button will open
the SBR air flow itinerary dialog box). Note that if you specify an air supply rate, BioWin will
automatically turn on the oxygen modeling option.
There are three methods for entering diffuser information: by a Density(%), by an ATAD, or by the Number
of Diffusers. The diffuser information is specified by clicking on the appropriate radio button.
1. If you select Density(%), the diffuser density (%) (i.e. the total area of diffusers in aeration tank /
area of aeration tank expressed as a percent) must be specified in the Density(%) text edit box.
2. If ATAD is selected, the ATAD (i.e. area of aeration tank/total area of diffusers in aeration tank) must
be specified in the edit box.
3. If Number of Diffusers is selected, the number of diffusers must be specified in the edit box.
A Local temperature also may be specified for an SBR + 2 always-mixed prezones element. When you click
on the check box for local temperature, the Specify temperature by radio button group is enabled. You may
then specify either a Constant or Scheduled temperature.
• If constant temperature is selected, you may enter the value in the edit box.
• If scheduled temperature is selected the Pattern… button becomes active. Clicking this button
presents you with the Edit temperature itinerary dialog box.

SBR + 2 Always-Mixed Prezones Underflow

The SBR + 2 always-mixed prezones SBR Underflow tab shown below allows you to set up underflow rates
and patterns for the SBR zone.

Biowin 6 Help Manual Building Configurations • 383

The SBR underflow settings tab of an SBR + 2 always-mixed prezones element

The Underflow type may be specified as a Constant underflow or a Flow pattern by selecting the
appropriate option. If you select Constant underflow, you may enter the desired underflow rate in the edit
field. If you select Flow pattern, clicking the Pattern… button will open the Underflow rate itinerary dialog
box.
The SBR zone underflow may be used for several functions:
1. As a wastage stream;
2. A mixed liquor recycle to a mixer element in front of the SBR + 2 always-mixed prezones element;
3. As both a wastage and a recycle by placing a splitter element between the underflow and the mixer
element in front of the SBR + 2 always-mixed prezones element.

SBR + 2 Always-Mixed Prezones Internal Recycle Flows

The SBR + 2 always-mixed prezones element SBR internal recycle flows tab shown below allows you to set
up recycles between the SBR zone and the second prezone, and between the second and first prezone.

384 • Building Configurations Biowin 6 Help Manual

The SBR internal recycle flows tab of an SBR + 2 always-mixed prezones element

You may have a recycle flow which goes from the second prezone to the first one. If you select Constant
recycle, you may enter the desired recycle flow rate in the edit field. If you select Recycle pattern, clicking
the Pattern… button will open the Recycle flow rate itinerary dialog box.
You also may have a recycle flow which goes from the SBR zone to the second prezone. If you select
Constant recycle, you may enter the desired recycle flow rate in the edit field. If you select Recycle pattern,
clicking the Pattern… button will open the Recycle flow rate itinerary dialog box.
Two final points should be noted with regard to internal recycle flows:
1. It is possible to have a recycle flow from the SBR zone to the first prezone by returning the SBR zone
underflow (or a portion of it) to the input of the SBR + 2 always-mixed prezones element.
2. Internal recycle flows are set to zero when the SBR zone goes into settle/decant mode.

SBR + 2 Always-Mixed Prezones Initial Values

The Initial values tab, shown below, is used for setting up the initial settings for SBR + 2 always-mixed
prezones concentrations and volume.

Biowin 6 Help Manual Building Configurations • 385

The Initial values tab with the Default option selected (SBR + 2 always-mixed prezones element)

Use the Initial liquid hold-up field to enter a value to specify the % of full setting. It should be noted here
that the lower and upper limits on this value are 0.02 and 99.98%, respectively.
There are two methods for setting up Initial concentrations in the SBR + 2 always-mixed prezones. The
dialog box shown above illustrates the first case where the Default option is selected. When this option is
selected, BioWin applies default seed values for all the state variables (except volume, which you specify) in
the same manner it would for other bioreactor elements in all of the zones (i.e. including the prezones).
The dialog box shown below illustrates the second case where the User defined option is selected. In this
case, an editable list of state variables is displayed in the dialog box. This allows you to enter your own seed
values for state variables in the SBR + 2 always-mixed prezones element.

386 • Building Configurations Biowin 6 Help Manual

The Initial values tab with the User defined option selected (SBR + 2 always-mixed prezones element)

• If you choose User defined initial concentrations then there are two conditions when the User
defined initial concentrations can be used.
• If the box labeled “Set these values now …” is checked then the concentrations specified are
inserted in the state vector as soon as the OK button is clicked.
• If the box labeled “Set these values now …” is NOT checked then the initial concentrations will be
inserted in the reactor state vector when you begin a dynamic or steady state simulation and
choose to start the simulation from seed values.

Note: If “Set these values now …” is checked, the specified values are placed in the reactor state variable
vector when you click OK overriding any existing state variable vector values. Consequently a dynamic
simulation started from this point will use the User defined initial concentrations regardless of whether you
choose to start from Seed values or Current values.

The use of this option is illustrated in the example at the end of the Variable Volume/Batch Bioreactor Initial
Values section later in this chapter.

SBR + 2 Always-Mixed Prezone Power

The Power tab, shown below, allows the user to enter power specifications.

Biowin 6 Help Manual Building Configurations • 387

The Power tab (SBR + 2 always-mixed prezones)

Power can be specified on a power per unit volume basis or on a fixed basis by checking or unchecking the
Power per unit vol check box, respectively. The user can enter a constant value for power or power per unit
volume by selecting the Constant value of radio button and entering a value in the text edit box.
Alternatively, the user can enter a power or power per unit volume pattern by selecting the Scheduled radio
button. This activates the Pattern…button. Clicking this button will open the Power Itinerary editor. Power
calculated for the SBR+2 always-mixed prezone element will be grouped under the “Mixing power” category
in power charts and tables.

SBR + 2 Always-Mixed Prezones Model

The Model tab, shown below, allows the user to enter model-related information for an SBR + 2 always-
mixed prezones element, such as settling phase behavior; kinetic, aeration, diffuser model settings, etc.

388 • Building Configurations Biowin 6 Help Manual

The Model tab of an SBR + 2 always-mixed prezones element

There are three Settling model options that you can specify for the settling phase of an SBR. In order from
most numerically complex (slowest simulation speed) to less numerical complexity (fastest simulation
speed), there are:
1. Reactive
2. Non-reactive
3. Fast approximate simulation
The Reactive option is the “traditional” BioWin method for modeling the settling phase in an SBR. That is,
the entire state variable list is maintained in each SBR cell, so that the complete biological model can be
active during settling. This method enables BioWin to simulate phenomena such as denitrification during the
settling phase. However, because of the complexity of simultaneously solving settling and biological
equations, there is a noticeable simulation speed decrease during the settle phase.
The Non-reactive option offers a degree of simplification compared to the Reactive option. If this option is
selected, the entire state variable list is maintained in each SBR cell, but the biological model is not active
during settling. An advantage of this option is that because the complete state variable list is maintained in
each SBR cell, the effect of any changes in SBR influent composition (i.e. either particulate or soluble state
variables) that may take place during the settling phase (e.g. for a continuous flow SBR) will be
approximated in the individual SBR cells. To take a simple example, if there is a change in the SBR feed ISS
composition during the settling phase, this will be properly accounted for in the appropriate SBR cells
because each SBR cell still has “knowledge” about the ISS state variable. With this method, there is less of a

Biowin 6 Help Manual Building Configurations • 389

simulation speed decrease during the settle phase because BioWin no longer is simultaneously solving
settling and biological equations.
The Fast approximate simulation option offers the greatest degree of simplification. If this option is
selected, state variables are “grouped” (e.g. individual particulate state variables are combined into
common particulate variables) during the settling phase so that the settling equations are required to track
fewer variables. Also, because individual state variables are no longer maintained in each SBR cell,
calculating biological reactions is not possible. Finally, it should be noted that if the SBR feed composition
happens to change during the settling phase (i.e. either particulate or soluble state variables), this change
will only be approximated with this option active – because the individual state variables are no longer being
tracked in the SBR cells. Using this settling model method, there is even less of a simulation speed decrease
during the settle phase because BioWin is not simultaneously solving settling and biological equations, and
the settling equations involve significantly fewer variables. This option is best suited for SBRs that do not
receive feed during the settle phase. It is also useful for trouble-shooting the initial setup of SBR models (e.g.
checking of flow distribution, liquid volume levels, etc.).
You also can specify Local kinetic parameters for the activated sludge model used in the STSBR
decant/settling phase. For the mixing phase, the global model parameter values are used. If you click on the
check box for local kinetic parameters, then clicking the Edit local kinetic parameters… button opens the
Parameter editor dialog box allowing you access to the various activated sludge model kinetic parameters.
If you wish to override the project global aeration parameters with local values specific to this element only,
select the box labeled Local aeration parameters. This will activate the button labeled Edit local aeration
parameters…. Clicking this button will open the Aeration dialog box, which allows you to modify aeration
parameters.
If you wish to override the project global diffuser parameters with local values specific to this element only,
select the box labeled Local diffuser parameters. This will activate the button labeled Edit local diffuser
parameters…. Clicking this button will open the Diffuser dialog box, which allows you to modify diffuser
parameters.
To model the concentrations of the constituents of the aeration gas (e.g. oxygen, carbon dioxide, etc.),
check the box labeled Model gas phase. If this option is selected you may also enter a percentage value for
the Gas hold-up (i.e. the percentage of the total reactor volume occupied by aeration gas).
You can also specify the aeration parameters Alpha F and Beta. You may specify either a Constant value or a
Scheduled pattern for each parameter (clicking the Pattern… button will open the Edit Alpha itinerary or
Edit Beta itinerary dialog box). If you wish to plot Alpha and/or Beta click on the graph button. This will add
a time series plot of alpha and/or beta to the BioWin Album.

SBR with Mix/Settle Prezone(s)

This type of SBR allows you to have hydraulically linked prezones that go into settling mode when the decant
zone goes into settle mode. The following SBR with mix/settle prezone combinations are available:
• SBR + 1 Prezone
• SBR + 2 Prezones
BioWin allows you to have internal recycles between the prezones and the SBR, as shown in the following
diagram.

390 • Building Configurations Biowin 6 Help Manual

 MIX/SET SBR
PREZONE ZONE

1st MIX/SET 2nd MIX/SET SBR

PREZONE PREZONE ZONE

Flow recycles and patterns that can be set up between an SBR and its prezone(s)

The following sections describe the dialog boxes for the SBR with one and two mix/settle prezone(s),
respectively.

SBR with One Mix/Settle Prezone

This type of SBR provides one hydraulically linked, mix/settle zone separated from the fill/draw SBR zone by
a baffle. You may specify parameters related to the SBR dimensions, cycle operation, starting values, and
underflow rates. You also may specify operating conditions for the mix/settle prezone. For information on
monitoring parameters/variables for this element, please see the Monitoring Data section in the “General
Operation” chapter.

Biowin 6 Help Manual Building Configurations • 391

The Monitor items tab of an SBR with one mix/settle prezone element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

392 • Building Configurations Biowin 6 Help Manual

The Tags tab of an SBR with one mix/settle prezone element

SBR + 1 Mix/Settle Prezone Dimensions

The SBR Dimensions tab, shown below, allows the user to enter the physical dimensions of the SBR zone of
an SBR + 1 mix/settle prezone element.

Biowin 6 Help Manual Building Configurations • 393

The SBR dimensions tab of an SBR with one mix/settle prezone element

There are two methods for entering the dimensions: by Area and depth, or by Volume and depth. The
method is specified by clicking on the appropriate radio button.
• If you select by Area and depth, the SBR zone area and depth must be entered in the Area and
Depth text edit boxes.
• If you select by Volume and depth, the SBR zone volume and depth must be entered in the Volume
and Depth text edit boxes.
Regardless of the method you choose, you also must specify a Width for the SBR zone. Units are shown to
the right of the edit boxes.

394 • Building Configurations Biowin 6 Help Manual

 DECANT AND/OR
OVERFLOW

FLOW IN
1 2 3

UNDERFLOW

LENGTH

Flow distribution in the SBR zone

BioWin uses the Width parameter to calculate the length of the SBR zone. The length is then divided into
three equally sized zones. Underflow leaves the SBR zone at the bottom of the third zone, and decant
and/or overflow leaves the SBR zone at the top of the third zone.
Some further explanation of how BioWin uses the SBR dimensions is warranted. When you set the
dimensions, you specify a Volume, Depth and Width (and Length is calculated). Now think of a 2-d side-on
view of the SBR with flow from left to right, as shown above.
For example, imagine the full depth is 5 m and the length is 15 m. When settling starts, this is what happens:
• The horizontal length of the SBR is divided into three equal-length subsections (each 5 m in this
case).
• The vertical direction is divided into 10 equal-depth layers. [Note: as the level goes down during
decanting - with no feed - the number of layers stays at 10, and the depth of each layer decreases].
That is, think of each length section as being 10 layers stacked on top of each other (and there are 3
sections).
• Each of the three sections is treated as a vertical settler. That is, the SBR (during settling) is 3 side-
by-side settlers, with a total of 30 cells (each completely mixed i.e. of uniform composition).
Consider the dimensions of each of the 30 cells:
• The horizontal area of each cell is Width * (Length/3) = W * 5 m here.
• The end area of each cell is Width * (Liquid Depth/10) = W * 0.5 m (0.5 m when it is full). [Note: in
this case the ratio of cell horizontal to side area is 5 : 0.5 = 10 : 1 (if tank is full - but ratio increases
when tank level drops)].
For the moment, assume that there is no inflow during decanting. Decant is removed from the top-right cell.
During decanting several things happen (apart from settling in each of the 3 sections):

Biowin 6 Help Manual Building Configurations • 395

 • Say 1 (incremental) unit of volume is removed from the top-right cell (at the composition of the top
right cell).
• Overall, the volume of each of the 30 cells must be decreased by 1 unit / 30 (the length of each cell
is fixed, so the depth must decrease).
• 29/30ths of the unit volume must get into the top right cell. That is, overall 1/30th of the volume
must be removed from each of the other 29 cells.
• The 29/30ths gets into the top right cell from the cell to the left and from the cell below it.
• The cell at the bottom left of the SBR is a special case - there is no flow into it - only outflow of
1/30th. This flow leaves via the top surface and via the right hand end surface. The flow leaving each
of the 2 surfaces is proportional to the areas of each surface.
• Flow balances around each of the other 28 cells are handled in a similar manner, doing a
simultaneous flow balance on each cell. For the typical cell, there can be:
• Flow out of the top surface;
• Flow out the right side;
• Flow in through the bottom surface; and
• Flow in through the left surface.
If there is influent flow during decanting, the flow balance is just slightly more complex, but happens in a
similar fashion. Note that this explanation makes the process sound like a step-by-step calculation. In reality,
what happens is a whole series of simultaneous integrations with error checking.
A Minimum decant level must also be specified as a percentage of the height. This level is the lowest liquid
level that can be achieved by decanting liquid out of the top of the SBR zone. Note that it is possible to
obtain lower liquid levels in a cycle than this value, but to get lower than this level, the liquid would have to
go out via the underflow.

Note: Unlike the SBR + 1 always-mixed prezone and SBR + 2 always-mixed prezones elements, you do not
specify a feed layer – the feed is input to the top of a prezone and flow leaves from the bottom of a prezone.

Single Mix/Settle Prezone Setup

The Prezone 1 tab shown below is used for specifying the volume of the prezone for the SBR + 1 mix/settle
prezone element.

396 • Building Configurations Biowin 6 Help Manual

The Prezone 1 tab of an SBR with one mix/settle prezone element

You can specify the volume of the prezone using the Volume text edit field.

SBR + 1 Mix/Settle Prezone SBR Zone Operation

The SBR Operation tab, shown below, allows the user to enter operating parameters for the SBR zone of an
SBR + 1 mix/settle prezone element, such as cycle patterns, decant flow rates, aeration specifications and
local temperature.

Biowin 6 Help Manual Building Configurations • 397

The SBR operation tab of an SBR with one mix/settle prezone element

The major operational settings of the SBR zone of the SBR + 1 mix/settle prezone are those related to Cycle
settings. The Cycle length or duration is the total time that will elapse before the cycle begins to repeat
itself. The first event to take place in the cycle is the end of the mixing phase/beginning of the settling
phase. You specify this event time with the Mix until/Start settling at: spin edit control. Note that the dialog
provides you with feedback as to the length of your settling period. The second event to take place is the
beginning of the decant phase. You specify this event time with the Decant/Draw starting at: spin edit
control. Note that the dialog provides you with feedback as to the length of your decant period.
Experimenting with these settings will reveal that settling and decanting take place simultaneously – but the
settling phase length always must be greater than the decant phase length. Finally, you may set up a cycle
offset if you wish using the Offset cycle by: control.
The Offset cycle by function is used to set up systems with multiple SBR units. The cycle offset is the "time
into the cycle" for that unit at the start of the simulation (when the reference unit - SBR 1 in the figure
below - first receives influent). In other words, at the start of the simulation, each SBR unit has to be at a
point in its cycle such that the feeding phase starts when the flow is directed to it. All other settings can be
kept at the original values of the reference SBR.
Example: The figure below shows a three SBR system in which each SBR has a cycle length of 6 hours and a
feeding phase of 2 hours.
To set up your multiple SBR system:
• The SBR getting the first influent feed is identified as the reference (SBR 1 in the figure below) and
has no “cycle offset” assigned.

398 • Building Configurations Biowin 6 Help Manual

 • Then for each of the other SBRs the question is: At time zero, how far into the cycle are we for this
SBR?
From the diagram below, we see that:
SBR 2: Four hours into the cycle (that is, at the end of the Reaction phase and the beginning of the Settling
phase)
SBR 3: Two hours into the cycle (that is, in transition from the Fill phase to the Reaction phase).
Those are the cycle offset values!

Simulation time [h]

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
SBR 1 (reference) Fill React Sett Dec Fill React Sett Dec Fill React Sett Dec Fill React Sett Dec
SBR 2 Fill React Sett Dec Fill React Sett Dec Fill React Sett Dec Fill React Sett Dec Fill React
SBR 3 Fill React Sett Dec Fill React Sett Dec Fill React Sett Dec Fill React Sett Dec Fill

Offset SBR 2

Offset
SBR 3

The next operational setting is the Decant flow rate setting. You may specify this with one of two possible
methods. If you know the flow rate you wish to decant at, then choose the At a constant rate of: option and
enter the desired value. If you wish BioWin to calculate the decant flow rate for you, select the To minimum
decant level option. The decant flow rate is calculated as follows. At the beginning of the decant period, the
simulator looks at the difference between the current liquid volume and the specified minimum decant
volume. It then calculates the necessary flow rate to decant the available liquid during the decant period.

Note: BioWin calculates the required decant flow rate based on the assumption that there is no influent or
underflow activity during the decant period (even if there is).

You can specify the SBR zone aeration settings by clicking the SBR aeration… button which will show the
following dialog box.

The SBR zone aeration setting dialog box

Biowin 6 Help Manual Building Configurations • 399

There are two methods for specifying aeration: either by a DO setpoint or by an Air flow rate. The aeration
method is specified by clicking on the appropriate radio button.
When DO setpoint is selected, the setpoint concentration must be specified. You may specify either a
Constant setpoint or a Scheduled DO setpoint pattern (clicking the Pattern… button will open the SBR DO
setpoint itinerary dialog box). You may wish to place a restriction on the minimum and maximum allowable
air flow rate that may be used to achieve the desired DO setpoint by setting a minimum or maximum
allowable airflow in the Air flow rate constraints group. This is a useful feature for investigating the ability of
air equipment to achieve desired DO setpoints.
When Air flow rate is selected, the air flow rate must be specified. You may specify either a Constant air
flow rate or a Scheduled air flow rate pattern (clicking the Pattern… button will open the SBR air flow
itinerary dialog box). Note that if you specify an air supply rate, BioWin will automatically turn on the
oxygen modeling option.
There are three methods for entering diffuser information: by a Density(%), by an ATAD, or by the Number
of Diffusers. The diffuser information is specified by clicking on the appropriate radio button.
If you select Density(%), the diffuser density (%) (i.e. the total area of diffusers in aeration tank / area of
aeration tank expressed as a percent) must be specified in the Density(%) text edit box.
If ATAD is selected, the ATAD (i.e. area of aeration tank/total area of diffusers in aeration tank) must be
specified in the edit box.
If Number of Diffusers is selected, the number of diffusers must be specified in the edit box.
You can set up the prezone aeration operation by clicking the Prezone 1 aeration… button. Doing so will
present you with the dialog box shown below.

The single mix/settle prezone aeration settings dialog box

There are two methods for specifying aeration: either by a DO setpoint or by an Air flow rate. The aeration
method is specified by clicking on the appropriate radio button.
• When DO setpoint is selected, the setpoint concentration must be specified. You may specify either
a Constant setpoint or a Scheduled DO setpoint pattern (clicking the Pattern… button will open the
SBR DO setpoint itinerary dialog box). You may wish to place a restriction on the minimum and
maximum allowable air flow rate that may be used to achieve the desired DO setpoint by setting a

400 • Building Configurations Biowin 6 Help Manual

 minimum or maximum allowable airflow in the Air flow rate constraints group. This is a useful
feature for investigating the ability of air equipment to achieve desired DO setpoints.
• When Air flow rate is selected, the air flow rate must be specified. You may specify either a
Constant air flow rate or a Scheduled air flow rate pattern (clicking the Pattern… button will open
the SBR air flow itinerary dialog box). Note that if you specify an air supply rate, BioWin will
automatically turn on the oxygen modeling option.
There are three methods for entering diffuser information: by a Density(%), by an ATAD, or by the Number
of Diffusers. The diffuser information is specified by clicking on the appropriate radio button.
1. If you select Density(%), the diffuser density (%) (i.e. the total area of diffusers in aeration tank /
area of aeration tank expressed as a percent) must be specified in the Density(%) text edit box.
2. If ATAD is selected, the ATAD (i.e. area of aeration tank/total area of diffusers in aeration tank) must
be specified in the edit box.
3. If Number of Diffusers is selected, the number of diffusers must be specified in the edit box.
A Local temperature also may be specified for an SBR + 1 mix/settle prezone element. When you click on
the check box for local temperature, the Specify temperature by radio button group is enabled. You may
then specify either a Constant or Scheduled temperature.
• If constant temperature is selected, you may enter the value in the edit box.
• If scheduled temperature is selected the Pattern… button becomes active. Clicking this button
presents you with the Edit temperature itinerary dialog box.

SBR + 1 Mix/Settle Prezone Underflow

The SBR + 1 mix/settle prezone SBR Underflow tab shown below allows you to set up underflow rates and
patterns for the SBR zone of this element.

Biowin 6 Help Manual Building Configurations • 401

The SBR underflow tab of an SBR + 1 mix/settle prezone element

The Underflow type may be specified as a Constant underflow or a Flow pattern by selecting the
appropriate option. If you select Constant underflow, you may enter the desired underflow rate in the edit
field. If you select Flow pattern, clicking the Pattern… button will open the Underflow rate itinerary dialog
box.
The SBR zone underflow may be used for several functions:
1. As a wastage stream;
2. A mixed liquor recycle to a mixer element in front of the SBR + 1 mix/settle prezone element;
3. As both a wastage and a recycle by placing a splitter element between the underflow and the mixer
element in front of the SBR + 1 mix/settle prezone element.

SBR + 1 Mix/Settle Prezone Initial Values

The Initial values tab, shown below, is used for setting up the initial settings for SBR + 1 mix/settle prezone
concentrations and volume.

402 • Building Configurations Biowin 6 Help Manual

The Initial values tab with the Default option selected (SBR + 1 mix/settle prezone element)

Use the Initial liquid hold-up field to enter a value to specify the % of full setting. It should be noted here
that the lower and upper limits on this value are 0.02 and 99.98%, respectively.
There are two methods for setting up Initial concentrations in the SBR + 1 mix/settle prezone. The dialog
box shown above illustrates the first case where the Default option is selected. When this option is selected,
BioWin applies default seed values for all the state variables (except volume, which you specify) in the same
manner it would for other bioreactor elements in all of the zones (i.e. including the prezone).
The dialog box shown below illustrates the second case where the User defined option is selected. In this
case, an editable list of state variables is displayed in the dialog box. This allows you to enter your own seed
values for state variables in the SBR + 1 mix/settle prezone.

Biowin 6 Help Manual Building Configurations • 403

The Initial values tab with the User defined option selected (SBR + 1 mix/settle prezone element)

• If you choose User defined initial concentrations then there are two conditions when the User
defined initial concentrations can be used.
• If the box labeled “Set these values now …” is checked then the concentrations specified are
inserted in the state vector as soon as the OK button is clicked.
• If the box labeled “Set these values now …” is NOT checked then the initial concentrations will be
inserted in the reactor state vector when you begin a dynamic or steady state simulation and
choose to start the simulation from seed values.

Note: If “Set these values now …” is checked, the specified values are placed in the reactor state variable
vector when you click OK overriding any existing state variable vector values. Consequently a dynamic
simulation started from this point will use the User defined initial concentrations regardless of whether you
choose to start from Seed values or Current values.

The use of this option is illustrated in the example at the end of the Variable Volume/Batch Bioreactor Initial
Values section later in this chapter.

SBR + 1 Mix/Settle Prezone Power

The Power tab, shown below, allows the user to enter power specifications.

404 • Building Configurations Biowin 6 Help Manual

The Power tab (SBR + 1 mix/settle prezone)

Power can be specified on a power per unit volume basis or on a fixed basis by checking or unchecking the
Power per unit vol check box, respectively. The user can enter a constant value for power or power per unit
volume by selecting the Constant value of radio button and entering a value in the text edit box.
Alternatively, the user can enter a power or power per unit volume pattern by selecting the Scheduled radio
button. This activates the Pattern…button. Clicking this button will open the Power Itinerary editor. Power
calculated for the SBR + 1 mix/settle prezone element will be grouped under the “Mixing power” category in
power charts and tables.

SBR + 1 Mix/Settle Prezone Model

The Model options and parameters tab, shown below, allows the user to enter model-related information
for an SBR + 1 mix/settle prezone element, such as settling phase behavior; kinetic, aeration, diffuser model
settings, etc.

Biowin 6 Help Manual Building Configurations • 405

The Model options and parameters tab of an SBR + 1 mix/settle prezone element

There are three Settling model options that you can specify for the settling phase of an SBR. In order from
most numerically complex (slowest simulation speed) to less numerical complexity (fastest simulation
speed), there are:
1. Reactive
2. Non-reactive
3. Fast approximate simulation
The Reactive option is the “traditional” BioWin method for modeling the settling phase in an SBR. That is,
the entire state variable list is maintained in each SBR cell, so that the complete biological model can be
active during settling. This method enables BioWin to simulate phenomena such as denitrification during the
settling phase. However, because of the complexity of simultaneously solving settling and biological
equations, there is a noticeable simulation speed decrease during the settle phase.
The Non-reactive option offers a degree of simplification compared to the Reactive option. If this option is
selected, the entire state variable list is maintained in each SBR cell, but the biological model is not active
during settling. An advantage of this option is that because the complete state variable list is maintained in
each SBR cell, the effect of any changes in SBR influent composition (i.e. either particulate or soluble state
variables) that may take place during the settling phase (e.g. for a continuous flow SBR) will be
approximated in the individual SBR cells. To take a simple example, if there is a change in the SBR feed ISS
composition during the settling phase, this will be properly accounted for in the appropriate SBR cells
because each SBR cell still has “knowledge” about the ISS state variable. With this method, there is less of a

406 • Building Configurations Biowin 6 Help Manual

simulation speed decrease during the settle phase because BioWin no longer is simultaneously solving
settling and biological equations.
The Fast approximate simulation option offers the greatest degree of simplification. If this option is
selected, state variables are “grouped” (e.g. individual particulate state variables are combined into
common particulate variables) during the settling phase so that the settling equations are required to track
fewer variables. Also, because individual state variables are no longer maintained in each SBR cell,
calculation of biological reactions is not possible. Finally, it should be noted that if the SBR feed composition
happens to change during the settling phase (i.e. either particulate or soluble state variables), this change
will only be approximated with this option active – because the individual state variables are no longer being
tracked in the SBR cells. Using this settling model method, there is even less of a simulation speed decrease
during the settle phase because BioWin is not simultaneously solving settling and biological equations, and
the settling equations involve significantly fewer variables. This option is best suited for SBRs that do not
receive feed during the settle phase. It is also useful for trouble-shooting the initial setup of SBR models (e.g.
checking of flow distribution, liquid volume levels, etc.).
You also can specify Local kinetic parameters for the activated sludge model used in the STSBR
decant/settling phase. For the mixing phase, the global model parameter values are used. If you click on the
check box for local kinetic parameters, then clicking the Edit local kinetic parameters… button opens the
Parameter editor dialog box allowing you access to the various activated sludge model kinetic parameters.
If you wish to override the project global aeration parameters with local values specific to this element only,
select the box labeled Local aeration parameters. This will activate the button labeled Edit local aeration
parameters…. Clicking this button will open the Aeration dialog box, which allows you to modify aeration
parameters.
If you wish to override the project global diffuser parameters with local values specific to this element only,
select the box labeled Local diffuser parameters. This will activate the button labeled Edit local diffuser
parameters…. Clicking this button will open the Diffuser dialog box, which allows you to modify diffuser
parameters.
To model the concentrations of the constituents of the aeration gas (e.g. oxygen, carbon dioxide, etc.),
check the box labeled Model gas phase. If this option is selected you may also enter a percentage value for
the Gas hold-up (i.e. the percentage of the total reactor volume occupied by aeration gas).
You can also specify the aeration parameters Alpha F and Beta. You may specify either a Constant value or a
Scheduled pattern for each parameter (clicking the Pattern… button will open the Edit Alpha itinerary or
Edit Beta itinerary dialog box). If you wish to plot Alpha and/or Beta click on the graph button. This will add
a time series plot of alpha and/or beta to the BioWin Album.

SBR with 2 Mix/Settle Prezones

This type of SBR provides two hydraulically linked, mix/settle zones separated from the fill/draw SBR zone by
a baffle. You may specify parameters related to the SBR dimensions, cycle operation, starting values, and
underflow rates. You also may specify operating conditions for the mix/settle prezones. For information on
monitoring parameters/variables for this element, please see the Monitoring Data section in the “General
Operation” chapter.

Biowin 6 Help Manual Building Configurations • 407

The Monitor items tab of an SBR with two mix/settle prezones element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

408 • Building Configurations Biowin 6 Help Manual

The Tags tab of an SBR with two mix/settle prezones element

SBR + 2 Mix/Settle Prezones Dimensions

The SBR Dimensions tab, shown below, allows the user to enter the physical dimensions of the SBR zone of
an SBR + 2 mix/settle prezones element.

Biowin 6 Help Manual Building Configurations • 409

The SBR dimensions tab of an SBR with two mix/settle prezones element

There are two methods for entering the dimensions: by Area and depth, or by Volume and depth. The
method is specified by clicking on the appropriate radio button.
• If you select by Area and depth, the SBR zone area and depth must be entered in the Area and
Depth text edit boxes.
• If you select by Volume and depth, the SBR zone volume and depth must be entered in the Volume
and Depth text edit boxes.
Regardless of the method you choose, you also must specify a Width for the SBR zone. Units are shown to
the right of the edit boxes.

410 • Building Configurations Biowin 6 Help Manual

 DECANT AND/OR
OVERFLOW

FLOW IN
1 2 3

UNDERFLOW

LENGTH

Flow distribution in the SBR zone

BioWin uses the Width parameter to calculate the length of the SBR zone. The length is then divided into
three equally sized zones. Underflow leaves the SBR zone at the bottom of the third zone, and decant
and/or overflow leaves the SBR zone at the top of the third zone.
Some further explanation of how BioWin uses the SBR dimensions is warranted. When you set the
dimensions, you specify a Volume, Depth and Width (and Length is calculated). Now think of a 2-d side-on
view of the SBR with flow from left to right, as shown above.
For example, imagine the full depth is 5 m and the length is 15 m. When settling starts, this is what happens:
• The horizontal length of the SBR is divided into three equal-length subsections (each 5 m in this
case).
• The vertical direction is divided into 10 equal-depth layers. [Note: as the level goes down during
decanting - with no feed - the number of layers stays at 10, and the depth of each layer decreases].
That is, think of each length section as being 10 layers stacked on top of each other (and there are 3
sections).
• Each of the three sections is treated as a vertical settler. That is, the SBR (during settling) is 3 side-
by-side settlers, with a total of 30 cells (each completely mixed i.e. of uniform composition).
Consider the dimensions of each of the 30 cells:
• The horizontal area of each cell is Width * (Length/3) = W * 5 m here.
• The end area of each cell is Width * (Liquid Depth/10) = W * 0.5 m (0.5 m when it is full). [Note: in
this case the ratio of cell horizontal to side area is 5 : 0.5 = 10 : 1 (if tank is full - but ratio increases
when tank level drops)].
For the moment, assume that there is no inflow during decanting. Decant is removed from the top-right cell.
During decanting several things happen (apart from settling in each of the 3 sections):
• Say 1 (incremental) unit of volume is removed from the top-right cell (at the composition of the top
right cell).

Biowin 6 Help Manual Building Configurations • 411

 • Overall, the volume of each of the 30 cells must be decreased by 1 unit / 30 (the length of each cell
is fixed, so the depth must decrease).
• 29/30ths of the unit volume must get into the top right cell. That is, overall 1/30th of the volume
must be removed from each of the other 29 cells.
• The 29/30ths gets into the top right cell from the cell to the left and from the cell below it.
• The cell at the bottom left of the SBR is a special case - there is no flow into it - only outflow of
1/30th. This flow leaves via the top surface and via the right hand end surface. The flow leaving each
of the 2 surfaces is proportional to the areas of each surface.
• Flow balances around each of the other 28 cells are handled in a similar manner, doing a
simultaneous flow balance on each cell. For the typical cell, there can be:
• Flow out of the top surface;
• Flow out the right side;
• Flow in through the bottom surface; and
• Flow in through the left surface.
If there is influent flow during decanting, the flow balance is just slightly more complex, but happens in a
similar fashion. Note that this explanation makes the process sound like a step-by-step calculation. In reality,
what happens is a whole series of simultaneous integrations with error checking.
A Minimum decant level must also be specified as a percentage of the height. This level is the lowest liquid
level that can be achieved by decanting liquid out of the top of the SBR zone. Note that it is possible to
obtain lower liquid levels in a cycle than this value, but to get lower than this level, the liquid would have to
go out via the underflow.

Note: Unlike the SBR + 1 always-mixed prezone and SBR + 2 always-mixed prezones elements, you do not
specify a feed layer – the feed is input at the top of the first prezone.

First Mix/Settle Prezone Setup

The Prezone 1 tab shown below is used for specifying the volume of the first prezone for the SBR + 2
mix/settle prezones element.

412 • Building Configurations Biowin 6 Help Manual

The Prezone 1 tab of an SBR with two mix/settle prezones element

You can specify the volume of the prezone using the Volume text edit field.

Second Mix/Settle Prezone Setup

The Prezone 2 tab shown below is used for specifying the volume of the second prezone for the SBR + 2
mix/settle prezones element.

Biowin 6 Help Manual Building Configurations • 413

The Prezone 2 tab of an SBR with two mix/settle prezones element

You can specify the volume of the prezone using the Volume text edit field.

SBR + 2 Mix/Settle Prezones SBR Zone Operation

The SBR Operation tab, shown below, allows the user to enter operating parameters for the SBR zone of an
SBR + 2 mix/settle prezones element, such as cycle patterns, decant flow rates, aeration specifications and
local temperature.

414 • Building Configurations Biowin 6 Help Manual

The SBR operation tab of an SBR with two mix/settle prezones element

The major operational settings of the SBR zone of the SBR + 2 mix/settle prezones are those related to Cycle
settings. The Cycle length or duration is the total time that will elapse before the cycle begins to repeat
itself. The first event to take place in the cycle is the end of the mixing phase/beginning of the settling
phase. You specify this event time with the Mix until/Start settling at: spin edit control. Note that the dialog
provides you with feedback as to the length of your settling period. The second event to take place is the
beginning of the decant phase. You specify this event time with the Decant/Draw starting at: spin edit
control. Note that the dialog provides you with feedback as to the length of your decant period.
Experimenting with these settings will reveal that settling and decanting take place simultaneously – but the
settling phase length always must be greater than the decant phase length. Finally, you may set up a cycle
offset if you wish using the Offset cycle by: control.
The Offset cycle by function is used to set up systems with multiple SBR units. The cycle offset is the "time
into the cycle" for that unit at the start of the simulation (when the reference unit - SBR 1 in the figure
below - first receives influent). In other words, at the start of the simulation, each SBR unit has to be at a
point in its cycle such that the feeding phase starts when the flow is directed to it. All other settings can be
kept at the original values of the reference SBR.
Example: The figure below shows a three SBR system in which each SBR has a cycle length of 6 hours and a
feeding phase of 2 hours.
To set up your multiple SBR system:
• The SBR getting the first influent feed is identified as the reference (SBR 1 in the figure below) and
has no “cycle offset” assigned.

Biowin 6 Help Manual Building Configurations • 415

 • Then for each of the other SBRs the question is: At time zero, how far into the cycle are we for this
SBR?
From the diagram below, we see that:
SBR 2: Four hours into the cycle (that is, at the end of the Reaction phase and the beginning of the Settling
phase)
SBR 3: Two hours into the cycle (that is, in transition from the Fill phase to the Reaction phase).
Those are the cycle offset values!

Simulation time [h]

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
SBR 1 (reference) Fill React Sett Dec Fill React Sett Dec Fill React Sett Dec Fill React Sett Dec
SBR 2 Fill React Sett Dec Fill React Sett Dec Fill React Sett Dec Fill React Sett Dec Fill React
SBR 3 Fill React Sett Dec Fill React Sett Dec Fill React Sett Dec Fill React Sett Dec Fill

Offset SBR 2

Offset
SBR 3

The next operational setting is the Decant flow rate setting. You may specify this with one of two possible
methods. If you know the flow rate you wish to decant at, then choose the At a constant rate of: option and
enter the desired value. If you wish BioWin to calculate the decant flow rate for you, select the To minimum
decant level option. The decant flow rate is calculated as follows. At the beginning of the decant period, the
simulator looks at the difference between the current liquid volume and the specified minimum decant
volume. It then calculates the necessary flow rate to decant the available liquid during the decant period.

Note: BioWin calculates the required decant flow rate based on the assumption that there is no influent or
underflow activity during the decant period (even if there is).

You can specify the SBR zone aeration settings by clicking the SBR aeration… button which will show the
following dialog box.

The SBR zone aeration setting dialog box

416 • Building Configurations Biowin 6 Help Manual

There are two methods for specifying aeration: either by a DO setpoint or by an Air flow rate. The aeration
method is specified by clicking on the appropriate radio button.
• When DO setpoint is selected, the setpoint concentration must be specified. You may specify either
a Constant setpoint or a Scheduled DO setpoint pattern (clicking the Pattern… button will open the
SBR DO setpoint itinerary dialog box). You may wish to place a restriction on the minimum and
maximum allowable air flow rate that may be used to achieve the desired DO setpoint by setting a
minimum or maximum allowable airflow in the Air flow rate constraints group. This is a useful
feature for investigating the ability of air equipment to achieve desired DO setpoints.
• When Air flow rate is selected, the air flow rate must be specified. You may specify either a
Constant air flow rate or a Scheduled air flow rate pattern (clicking the Pattern… button will open
the SBR air flow itinerary dialog box). Note that if you specify an air supply rate, BioWin will
automatically turn on the oxygen modeling option.
There are three methods for entering diffuser information: by a Density(%), by an ATAD, or by the Number
of Diffusers. The diffuser information is specified by clicking on the appropriate radio button.
1. If you select Density(%), the diffuser density (%) (i.e. the total area of diffusers in aeration tank /
area of aeration tank expressed as a percent) must be specified in the Density(%) text edit box.
2. If ATAD is selected, the ATAD (i.e. area of aeration tank/total area of diffusers in aeration tank) must
be specified in the text edit box.
3. If Number of Diffusers is selected, the number of diffusers must be specified in the text edit box.
You can set up the first prezone aeration operation by clicking the Prezone 1 aeration… button. Doing so will
present you with the dialog box shown below.

The first mix/settle prezone aeration settings dialog box

There are two methods for specifying aeration: either by a DO setpoint or by an Air flow rate. The aeration
method is specified by clicking on the appropriate radio button.
• When DO setpoint is selected, the setpoint concentration must be specified. You may specify either
a Constant setpoint or a Scheduled DO setpoint pattern (clicking the Pattern… button will open the
SBR DO setpoint itinerary dialog box). You may wish to place a restriction on the minimum and
maximum allowable air flow rate that may be used to achieve the desired DO setpoint by setting a

Biowin 6 Help Manual Building Configurations • 417

 minimum or maximum allowable airflow in the Air flow rate constraints group. This is a useful
feature for investigating the ability of air equipment to achieve desired DO setpoints.
• When Air flow rate is selected, the air flow rate must be specified. You may specify either a
Constant air flow rate or a Scheduled air flow rate pattern (clicking the Pattern… button will open
the SBR air flow itinerary dialog box). Note that if you specify an air supply rate, BioWin will
automatically turn on the oxygen modeling option.
There are three methods for entering diffuser information: by a Density(%), by an ATAD, or by the Number
of Diffusers. The diffuser information is specified by clicking on the appropriate radio button.
1. If you select Density(%), the diffuser density (%) (i.e. the total area of diffusers in aeration tank /
area of aeration tank expressed as a percent) must be specified in the Density(%) text edit box.
2. If ATAD is selected, the ATAD (i.e. area of aeration tank/total area of diffusers in aeration tank) must
be specified in the text edit box.
3. If Number of Diffusers is selected, the number of diffusers must be specified in the text edit box.
Clicking the Prezone 2 aeration… button allows you to specify aeration settings for the second prezone
using the same dialog boxes as those used for the first zone, shown above.
A Local temperature also may be specified for an SBR + 2 mix/settle prezones element. When you click on
the check box for local temperature, the Specify temperature by radio button group is enabled. You may
then specify either a Constant or Scheduled temperature.
• If constant temperature is selected, you may enter the value in the edit box.
• If scheduled temperature is selected the Pattern… button becomes active. Clicking this button
presents you with the Edit temperature itinerary dialog box.

SBR + 2 Mix/Settle Prezones Underflow

The SBR + 2 mix/settle prezones SBR Underflow tab shown below allows you to set up underflow rates and
patterns for the SBR zone.

418 • Building Configurations Biowin 6 Help Manual

The SBR underflow settings tab of an SBR with two mix/settle prezones element

The Underflow type may be specified as a Constant underflow or a Flow pattern by selecting the
appropriate option. If you select Constant underflow, you may enter the desired underflow rate in the edit
field. If you select Flow pattern, clicking the Pattern… button will open the Underflow rate itinerary dialog
box.
The SBR zone underflow may be used for several functions:
1. As a wastage stream;
2. A mixed liquor recycle to a mixer element in front of the SBR + 2 mix/settle prezones element;
3. As both a wastage and a recycle by placing a splitter element between the underflow and the mixer
element in front of the SBR + 2 mix/settle prezones element.

SBR + 2 Mix/Settle Prezones Internal Recycle Flows

The SBR + 2 mix/settle prezones element SBR internal recycle flows tab shown below allows you to set up
recycles between the SBR zone and the second prezone, and between the second and first prezone.

Biowin 6 Help Manual Building Configurations • 419

The SBR internal recycle flows tab of an SBR with two mix/settle prezones element

You may have a recycle flow which goes from the second prezone to the first one. If you select Constant
recycle, you may enter the desired recycle flow rate in the edit field. If you select Recycle pattern, clicking
the Pattern… button will open the Recycle flow rate itinerary dialog box.
You also may have a recycle flow which goes from the SBR zone to the second prezone. If you select
Constant recycle, you may enter the desired recycle flow rate in the edit field. If you select Recycle pattern,
clicking the Pattern… button will open the Recycle flow rate itinerary dialog box.
Two final points should be noted regarding internal recycle flows:
1. It is possible to have a recycle flow from the SBR zone to the first prezone by returning the SBR zone
underflow (or a portion of it) to the input of the SBR + 2 mix/settle prezones element.
2. Internal recycle flows are set to zero when the SBR zone goes into settle/decant mode.

SBR + 2 Mix/Settle Prezones Initial Values

The Initial values tab, shown below, is used for setting up the initial settings for SBR + 2 mix/settle prezones
concentrations and volume.

420 • Building Configurations Biowin 6 Help Manual

The Initial values tab with the Default option selected (SBR + 2 mix/settle prezones)

Use the Initial liquid hold-up field to enter a value to specify the % of full setting. It should be noted here
that the lower and upper limits on this value are 0.02 and 99.98%, respectively.
There are two methods for setting up Initial concentrations in the SBR + 2 mix/settle prezones. The dialog
box shown above illustrates the first case where the Default option is selected. When this option is selected,
BioWin applies default seed values for all the state variables (except volume, which you specify) in the same
manner it would for other bioreactor elements in all of the zones (i.e. including the prezones).
The dialog box shown below illustrates the second case where the User defined option is selected. In this
case, an editable list of state variables is displayed in the dialog box. This allows you to enter your own seed
values for state variables in the SBR + 2 mix/settle prezones.

Biowin 6 Help Manual Building Configurations • 421

The Initial values tab with the User defined option selected (SBR + 2 mix/settle prezones)

• If you choose User defined initial concentrations then there are two conditions when the User
defined initial concentrations can be used.
• If the box labeled “Set these values now …” is checked then the concentrations specified are
inserted in the state vector as soon as the OK button is clicked.
• If the box labeled “Set these values now …” is NOT checked then the initial concentrations will be
inserted in the reactor state vector when you begin a dynamic or steady state simulation and
choose to start the simulation from seed values.

Note: If “Set these values now …” is checked, the specified values are placed in the reactor state variable
vector when you click OK overriding any existing state variable vector values. Consequently a dynamic
simulation started from this point will use the User defined initial concentrations regardless of whether you
choose to start from Seed values or Current values.

The use of this option is illustrated in the example at the end of the Variable Volume/Batch Bioreactor Initial
Values section later in this chapter.

SBR + 2 Mix/Settle Prezone Power

The Power tab, shown below, allows the user to enter power specifications.

422 • Building Configurations Biowin 6 Help Manual

The Power tab (SBR +2 mix/settle prezones)

Power can be specified on a power per unit volume basis or on a fixed basis by checking or unchecking the
Power per unit vol check box, respectively. The user can enter a constant value for power or power per unit
volume by selecting the Constant value of radio button and entering a value in the text edit box.
Alternatively, the user can enter a power or power per unit volume pattern by selecting the Scheduled radio
button. This activates the Pattern…button. Clicking this button will open the Power Itinerary editor. Power
calculated for the SBR + 2 mix/settle prezone element will be grouped under the “Mixing power” category in
power charts and tables.

SBR + 2 Mix/Settle Prezones Model

The Model tab, shown below, allows the user to enter model-related information for an SBR + 2 mix/settle
prezones element, such as settling phase behavior; kinetic, aeration, diffuser model settings, etc.

Biowin 6 Help Manual Building Configurations • 423

The Model options and parameters tab of an SBR + 2 mix/settle prezones element

There are three Settling model options that you can specify for the settling phase of an SBR. In order from
most numerically complex (slowest simulation speed) to less numerical complexity (fastest simulation
speed), there are:
1. Reactive
2. Non-reactive
3. Fast approximate simulation
The Reactive option is the “traditional” BioWin method for modeling the settling phase in an SBR. That is,
the entire state variable list is maintained in each SBR cell, so that the complete biological model can be
active during settling. This method enables BioWin to simulate phenomena such as denitrification during the
settling phase. However, because of the complexity of simultaneously solving settling and biological
equations, there is a noticeable simulation speed decrease during the settle phase.
The Non-reactive option offers a degree of simplification compared to the Reactive option. If this option is
selected, the entire state variable list is maintained in each SBR cell, but the biological model is not active
during settling. An advantage of this option is that because the complete state variable list is maintained in
each SBR cell, the effect of any changes in SBR influent composition (i.e. either particulate or soluble state
variables) that may take place during the settling phase (e.g. for a continuous flow SBR) will be
approximated in the individual SBR cells. To take a simple example, if there is a change in the SBR feed ISS
composition during the settling phase, this will be properly accounted for in the appropriate SBR cells
because each SBR cell still has “knowledge” about the ISS state variable. With this method, there is less of a

424 • Building Configurations Biowin 6 Help Manual

simulation speed decrease during the settle phase because BioWin no longer is simultaneously solving
settling and biological equations.
The Fast approximate simulation option offers the greatest degree of simplification. If this option is
selected, state variables are “grouped” (e.g. individual particulate state variables are combined into
common particulate variables) during the settling phase so that the settling equations are required to track
fewer variables. Also, because individual state variables are no longer maintained in each SBR cell,
calculation of biological reactions is not possible. Finally, it should be noted that if the SBR feed composition
happens to change during the settling phase (i.e. either particulate or soluble state variables), this change
will only be approximated with this option active – because the individual state variables are no longer being
tracked in the SBR cells. Using this settling model method, there is even less of a simulation speed decrease
during the settle phase because BioWin is not simultaneously solving settling and biological equations, and
the settling equations involve significantly fewer variables. This option is best suited for SBRs that do not
receive feed during the settle phase. It is also useful for trouble-shooting the initial setup of SBR models (e.g.
checking of flow distribution, liquid volume levels, etc.).
You also can specify Local kinetic parameters for the activated sludge model used in the STSBR
decant/settling phase. For the mixing phase, the global model parameter values are used. If you click on the
check box for local kinetic parameters, then clicking the Edit local kinetic parameters… button opens the
Parameter editor dialog box allowing you access to the various activated sludge model kinetic parameters.
If you wish to override the project global aeration parameters with local values specific to this element only,
select the box labeled Local aeration parameters. This will activate the button labeled Edit local aeration
parameters…. Clicking this button will open the Aeration dialog box, which allows you to modify aeration
parameters.
If you wish to override the project global diffuser parameters with local values specific to this element only,
select the box labeled Local diffuser parameters. This will activate the button labeled Edit local diffuser
parameters…. Clicking this button will open the Diffuser dialog box, which allows you to modify diffuser
parameters.
To model the concentrations of the constituents of the aeration gas (e.g. oxygen, carbon dioxide, etc.),
check the box labeled Model gas phase. If this option is selected you may also enter a percentage value for
the Gas hold-up (i.e. the percentage of the total reactor volume occupied by aeration gas).
You can also specify the aeration parameters Alpha F and Beta. You may specify either a Constant value or a
Scheduled pattern for each parameter (clicking the Pattern… button will open the Edit Alpha itinerary or
Edit Beta itinerary dialog box). If you wish to plot Alpha and/or Beta click on the graph button. This will add
a time series plot of alpha and/or beta to the BioWin Album.

Granular Sludge Sequencing Tank

Granular Sludge Sequencing Tank
The Granular sludge sequencing tank (GSST) element simulates granular sludge in a sequencing tank reactor.
You may specify parameters related to the GSST’s dimensions, cycle operation, starting values, and wasting
rates etc. For information on monitoring parameters/variables for this element, please see the Monitoring
Data section in the “General Operation” chapter.

Biowin 6 Help Manual Building Configurations • 425

The Monitor items tab of a Granular sludge sequencing tank

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

426 • Building Configurations Biowin 6 Help Manual

The Tags tab of a Granular sludge sequencing tank element

GSST Dimensions
The Dimensions tab, shown below, allows the user to enter the physical dimensions of a GSST element.

Biowin 6 Help Manual Building Configurations • 427

The Dimensions tab of a Granular sludge sequencing tank

There are two methods for entering the dimensions: by Area and depth, or by Volume and depth. The
method is specified by clicking on the appropriate radio button.
• If you select by Area and depth, the GSST area and depth must be entered in the Area and Depth
text edit boxes.
• If you select by Volume and depth, the GSST volume and depth must be entered in the Volume and
Depth text edit boxes.
Regardless of the method you choose, you also must specify a Width for the GSST. Units are shown to the
right of the edit boxes.
Typically, in practice, the GSST is decanted by a small amount at the end of the settle/feed period, before
mixing starts to prevent overflow when aeration begins. If you wish to include a decant period then a
Decant level can be specified as a percentage of the total GSST volume. This level is the lowest liquid level
that can be achieved by decanting liquid out of the top of the GSST. Note that it is possible to obtain lower
liquid levels in a cycle than this value, but to get lower than this level, the liquid would have to go out via the
waste/underflow. See GSST Operation for configuring decant in a GSST element.

428 • Building Configurations Biowin 6 Help Manual

GSST Granules
The Granules tab, shown below, allows the user to enter characteristics of the granules in the GSST element
which are used to calculate the available granular surface area. More details can be found in Modeling
Granular Sludge Sequencing Tanks.

The Operation tab of a Granular sludge sequencing tank

• The Estimated granule diameter (mm) can be entered directly in the text edit box provided. This
sets the initial diameter of the granules at the beginning of the simulation. The actual diameter is a
simulated output and will change from the initial estimate over the duration of a simulation. See
Modeling Granular Sludge Sequencing Tanks.
• The Estimated granule settled volume (% of reactor volume) can be entered directly in the text edit
box provided. This sets the initial estimate of the reactor volume occupied by both the granules and
the intergranual voidage when they have settled to the bottom of the reactor. The actual settled
volume is a simulated output and will change from the original estimate over the duration of a
simulation. See Modeling Granular Sludge Sequencing Tanks.
• The Voidage (of settled granules) (%) can be entered directly in the text edit box provided. This sets
the percentage of the granule settled volume occupied by voidage. Although the granule diameter
and settled volume parameters are simulated and may change over the course of a simulation, the

Biowin 6 Help Manual Building Configurations • 429

 voidage percent is assumed to remain constant over the duration of a simulation. See Modeling
Granular Sludge Sequencing Tanks.

GSST Operation
The Operation tab, shown below, allows the user to enter operating parameters for a GSST element, such as
cycle patterns, decant flow rates, aeration specifications and local temperature.

The Operation tab of a Granular sludge sequencing tank

The major operational settings of the GSST are the Cycle settings. An example illustrating how the cycle
settings translate into an operational schedule is provided at the end of this section.
The Cycle length or duration is the total time that will elapse before the cycle begins to repeat itself. The
first event to take place in the cycle is the end of the mixing phase/beginning of the settling phase. You
specify this event time with the Mix until/Start settling at: spin edit control. Note that the dialog provides
you with feedback as to the length of your settling period. The second event to take place is the beginning of
the decant phase. You specify this event time with the Decant/Draw starting at: spin edit control. Note that
the dialog provides you with feedback as to the length of the decant period. Experimenting with these
settings will reveal that settling and decanting take place simultaneously – but the settling phase length
always must be greater than the decant phase length.

430 • Building Configurations Biowin 6 Help Manual

You may set up a cycle offset if you wish using the Offset cycle by: control. The Offset cycle by function is
used to set up systems with multiple GSST units; for example, a multiple GSST system where each GSST is
fed sequentially. The cycle offset is the "time into the cycle" that the simulation will start. This is further
explained in the cycle offset example below. All other settings can be kept at the original values of the
reference GSST.
Cycle offset example: The figure below shows the operation cycle for two GSSTs. Each GSST has a cycle
length of 6 hours and a feeding phase of 1 hour and 30 minutes labelled as “Feed”. The react phase is
labelled “Mix”, the settle phase is labelled “S”, “W” denotes the waste phase, and the decant phase is
labelled “D”.
• GSST 1 is identified as the reference and has no “cycle offset” assigned. Therefore, the simulation
will start at time 0 of the cycle (that is, at the beginning of the React phase).
• From the diagram below, we see that for GSST 2 we are 1.5 hours into the cycle (that is, 1.5 hours
into the mixing phase) when a 1.5-hour cycle offset is specified. Therefore, the simulation will start
at time 1.5-hour into the cycle.

The next operational setting is the Decant flow rate setting. You may specify this with one of two possible
methods. If you know the flow rate you wish to decant at, then choose the At a constant rate of: option and
enter the desired value. If you wish BioWin to calculate the decant flow rate for you, select the To minimum
decant level option. The decant flow rate is calculated as follows. At the beginning of the decant period, the
simulator looks at the difference between the current liquid volume and the specified minimum decant
volume (i.e. the Decant level specified on the Dimensions tab). It then calculates the necessary flow rate to
decant the available liquid during the decant period.

Note: BioWin assumes that there are no influent or wastage flows during the decant period and bases the
calculation for required decant flow rate on that premise.

Note: If you do not wish to decant the GSST (i.e. drop the liquid level) the decant method should be
specified as At a constant rate of: 0. When the decant flow rate is specified as zero, a time still needs to be
specified for Decant/Draw starting at:. The specified decant period however will be ignored. So long as the
GSST is operating at full liquid volume any influent flow will result in overflow.

You can specify the GSST aeration settings by clicking the GS seq. tank aeration… button which will show the
following dialog box.

Biowin 6 Help Manual Building Configurations • 431

The Aeration setting dialog box of a GSST

There are two methods for specifying aeration: either by a DO setpoint or by an Air flow rate. The aeration
method is specified by clicking on the appropriate radio button. When DO setpoint is selected, the setpoint
concentration must be specified. You may specify either a Constant setpoint or a Scheduled DO setpoint
pattern (clicking the Pattern… button will open the Edit DO Setpoint itinerary dialog box). You may wish to
place a restriction on the minimum and maximum allowable air flow rate that may be used to achieve the
desired DO setpoint by setting a minimum or maximum allowable airflow in the Air flow rate constraints
group. This is a useful feature for investigating the ability of air equipment to achieve desired DO setpoints.
When Air flow rate is selected, the air flow rate must be specified. You may specify either a Constant air
flow rate or a Scheduled air flow rate pattern (clicking the Pattern… button will open the Edit Air flow rate
itinerary dialog box). Note that if you specify an air supply rate, BioWin will automatically turn on the
oxygen modeling option.
There are three methods for entering diffuser information: by a Density(%), by an ATAD, or by the Number
of Diffusers. The diffuser information is specified by clicking on the appropriate radio button.
• If you select Density(%), the diffuser density (%) (i.e. the total area of diffusers in aeration tank /
area of aeration tank expressed as a percent) must be specified in the Density(%) text edit box.
• If ATAD is selected, the ATAD (i.e. area of aeration tank/total area of diffusers in aeration tank) must
be specified in the text edit box.
• If Number of Diffusers is selected, the number of diffusers must be specified in the text edit box.

Note: The react/mix phase in a GSST element sets the Maximum time span in which you can aerate. You
cannot have aeration occurring during the Settling/Decant phase.

A Local temperature may be specified for a GSST element. When you click on the check box for local
temperature, the Specify temperature by radio button group is enabled. You may then specify either a
Constant or Scheduled temperature.
If constant temperature is selected, you may enter the value in the edit box.
If scheduled temperature is selected the Pattern… button becomes active. Clicking this button presents you
with the Edit temperature itinerary dialog box.

432 • Building Configurations Biowin 6 Help Manual

Cycle Operation Example: The figure below illustrates an example operational cycle for a GSST element.
Note the cycle length, settling and decant periods correspond to the default settings observed when you
drop a GSST element onto the drawing board:

In this example, the cycle length/duration is 6 hours (or 360 minutes). The figure above breaks the cycle
down into 15-minute increments. The cycle offset is zero, therefore at time 0 the GSST starts in the
react/fully mixed phase. During the mix phase aeration can be specified as described above. The GSST
remains fully mixed until settling starts at 210 minutes (or 3 hours and 30 minutes) into the cycle. The GSST
remains in settle mode from 210 minutes until 360 minutes (or for 2 hours and 30 minutes) when the 6-hour
cycle resets. The designated settling period when ONLY settling occurs (i.e. no other scheduled operations
occur in conjunction with settling) is 30 minutes (from 210 minutes until 240 minutes). A 15-minute wasting
period is then specified from 240 minutes until 255 minutes. Wasting is specified via the Waste tab of the
GSST. (See GSST Waste). After the wasting event, the GSST is fed from 255 minutes until 345 minutes (or for
1.5 hours). An influent element can be set-up with a variable input type to allow feeding to occur only during
the scheduled operating feed time. After feeding the GSST is decanted for 15 minutes (from 345 minutes
until 360 minutes) to decrease the liquid level.

Note: Feed can enter the GSST at any time in the cycle. The feed flow is controlled by upstream elements
which must be appropriately configured to ensure that flow only reaches the GSST at the desired times.

From the operational schedule above, we can see that the GSST is wasted, fed and decanted all while the
GSST is in settle mode. The figure below illustrates a flow schematic of the GSST in settle mode.

Biowin 6 Help Manual Building Configurations • 433

The following points summarize key aspects of GSST operation:
• When the GSST goes into settle mode, the granules instantaneously settle to the bottom of the tank
and occupy the granule settled volume which includes a voidage volume. Granules may not be lost
due to “poor settling”.
• The remaining bulk volume is divided vertically into “n” equal-depth layers (See GSST Model Options
for a description of how “n” is set).
• A one-dimensional (in the vertical direction) settling model in Model Reference section) is applied to
model the settling of bulk solids in the vertically divided bulk volume.
• If wastage is specified during settling, thickened mixed-liquor is removed from the bottom layer i.e.
the nth layer.
• As the liquid level decreases during wasting – with no feed – the number of layers stays at n, and the
depth of each layer decreases by the same proportional amount.
• Feed enters the GSST unit from the bottom and flows through the voidage of the settled granule
volume. The voidage volume is assumed to be completely mixed (i.e. not plug or semi-plug flow).
• The feed displaces liquid upward into the settled layers of bulk above the granule settled volume.
• Decant or overflow leaves the GSST from the top layer.

434 • Building Configurations Biowin 6 Help Manual

 • If the GSST is decanted down to a certain level, as the liquid level goes down during decanting – with
no feed – the number of layers stays at n, and the depth of each layer decreases. For a more
detailed description of the GSST element see Modeling Granular Sludge Sequencing Tanks.

GSST Waste
The GSST Waste tab shown below allows you to set up wastage/underflow rates and patterns for the GSST
element. Note only mixed liquor solids will be wasted from a GSST element; granules cannot be wasted.

The wastage settings tab of a GSST

The Wastage type may be specified as a Constant flow or a Flow pattern by selecting the appropriate
option. If you select Constant flow, you may enter the desired wastage flow rate in the edit field. If you
select Flow pattern, clicking the Pattern… button will open the Edit Wasting rate itinerary dialog box.
The GSST waste/underflow may be used for several functions:
1. As a mixed liquor wastage stream;
2. A mixed liquor recycle to a mixer element in front of the GSST;
3. As both a wastage and a recycle of mixed liquor by placing a splitter element between the
underflow and the mixer element in front of the GSST.

Biowin 6 Help Manual Building Configurations • 435

Note: While the GSST is in settle mode, the wastage stream will be drawn from the bottom settled layer (i.e.
the nth layer) of the bulk volume where the mixed liquor solids concentration is the highest. If the GSST is
wasted during mixing, the wastage stream will be representative of the fully mixed bulk solids
concentration. See GSST Operation|topic=GSST Operation for a flow schematic of the GSST in settle mode.

GSST Initial Values (mixed mode bulk)

The Initial values (mixed mode bulk) tab, shown below, is used for setting up the initial settings of the GSST
element’s bulk concentrations and volume.

The Initial values tab with the Default option active (GSST)

Use the Initial liquid hold-up field to enter a value to specify the % of full setting. It should be noted here
that the lower and upper limits on this value are 0.02 and 99.98%, respectively.
There are two methods for setting up Initial concentrations for the bulk in the GSST. The dialog box shown
above illustrates the first case where the Default option is selected. When this option is selected, BioWin
applies default seed values for all the state variables (except volume, which you specify) in the same manner
it would for other bioreactor elements.

436 • Building Configurations Biowin 6 Help Manual

The dialog box shown below illustrates the second case where the User defined option is selected. In this
case, an editable list of state variables is displayed in the dialog box. This allows you to enter your own seed
values for state variables in the bulk of the GSST.

The Initial values tab with the User defined option active (GSST)

• If you choose User defined initial concentrations, then there are two conditions when the User
defined initial concentrations can be used.
• If the box labeled “Set these values now …” is checked then the concentrations specified are
inserted in the state vector as soon as the OK button is clicked.
• If the box labeled “Set these values now …” is NOT checked then the initial concentrations will be
inserted in the reactor state vector when you begin a dynamic simulation and choose to start the
simulation from seed values.

Note: If “Set these values now …” is checked, the specified values are placed in the reactor state variable
vector when you click OK overriding any existing state variable vector values. Consequently, a dynamic
simulation started from this point will use the User defined initial concentrations regardless of whether you
choose to start from Seed values or Current values.

Biowin 6 Help Manual Building Configurations • 437

The use of this option is illustrated in the example at the end of the Variable Volume/Batch Bioreactor Initial
Values section.

GSST Power Options

The Power tab, shown below, allows the user to enter power specifications for mechanical mixing in the
GSST.

The Power tab (GSST)

Power can be specified on a power per unit volume basis or on a fixed basis by checking or unchecking the
Power per unit vol check box, respectively. The user can enter a constant value for power or power per unit
volume by selecting the Constant value of radio button and entering a value in the text edit box.
Alternatively, the user can enter a power or power per unit volume pattern by selecting the Scheduled radio
button. This activates the Pattern…button. Clicking this button will open the Power Itinerary editor. Power
calculated for the GSST element will be grouped under the “Mixing power” category in power charts and
tables.

438 • Building Configurations Biowin 6 Help Manual

GSST Model Options

The Model tab, shown below, allows the user to enter model-related information for a GSST element, such
as settling phase behavior; kinetic, aeration and diffuser model settings, etc.

The Model options and parameters tab of a GSST

You can specify Local kinetic parameters and/or Local biofilm parameters for the activated sludge model
used in the GSST. If you click on the check box for local kinetic parameters and/or local biofilm parameters,
then clicking the Edit local kinetic parameters… or Edit local biofilm parameters button opens the
Parameter editor dialog box allowing you access to the various activated sludge model kinetic/biofilm
parameters.
If you wish to override the project global aeration parameters with local values specific to this element only,
select the box labeled Local aeration parameters. This will activate the button labeled Edit local aeration
parameters…. Clicking this button will open the Aeration dialog box, which allows you to modify aeration
parameters.
If you wish to override the project global diffuser parameters with local values specific to this element only,
select the box labeled Local diffuser parameters. This will activate the button labeled Edit local diffuser

Biowin 6 Help Manual Building Configurations • 439

parameters…. Clicking this button will open the Diffuser dialog box, which allows you to modify diffuser
parameters.
To model the concentrations of the constituents of the aeration gas (e.g. oxygen, carbon dioxide, etc.),
check the box labeled Model gas phase. If this option is selected, you may also enter a percentage value for
the Gas hold-up (i.e. the percentage of the total reactor volume occupied by aeration gas).
If you wish to specify Local settling parameters for bulk settling in the GSST (i.e. settling model parameters
that are different from those specified under the Project|Parameters… menu), click on the check box for
local settling parameters, then click the Edit local settling parameters… button to open the Model
parameter editor dialog box.
You can also specify the aeration parameters Alpha F and Beta. You may specify either a Constant value or a
Scheduled pattern for each parameter (clicking the Pattern… button will open the Edit Alpha itinerary or
Edit Beta itinerary dialog box). If you wish to plot Alpha and/or Beta click on the graph button. This will add
a time series plot of alpha and/or beta to the BioWin Album.
The Granule model options area allows the user to specify the number of internal layers (through the
granule) to use when modeling the biofilm associated with the granules. The boundary layer thickness can
also be specified. For more information, see Modeling Fixed Film Processes and Modeling Granular Sludge
Sequencing Tanks.
The Number of layers used to model bulk settling in the GSST can be modified using the spin edit box. The
minimum number of layers allowed for the model is 5, the default is 10. Increasing the number of layers will
improve the resolution of the predicted settler profile. Increasing the number of layers will also increase the
computational difficulty of the simulation, potentially resulting in reduced simulation speed. In most cases
this parameter should be left at the default value of 10 layers.

Note: when you drop a GSST element onto the drawing board, several “local” options are checked by
default, including Local kinetic parameters, Local biofilm parameters, Local diffuser parameters, and Local
settling parameters. This has been done based on EnviroSim’s experience with calibrating the GSST to a
variety of systems, and may help to reduce calibration effort. Further background is provided in Modeling
Granular Sludge Sequencing Tanks.

Thermal Hydrolysis Unit

The thermal hydrolysis unit is used to simulate the breakdown of particulate components in a sludge stream
into various soluble components. The unit allows for simulation of potential impacts of sludge pre-treatment
technologies on process performance such as biogas production in downstream digesters and nutrient
content in recycle streams. A picture of the thermal hydrolysis unit in a BioWin flowsheet is shown below:

440 • Building Configurations Biowin 6 Help Manual

A BioWin flowsheet incorporating a thermal hydrolysis unit

For information on monitoring parameters/variables for this element, please see the Monitoring Data
section in the “General Operation” chapter.

The Monitor items tab of the thermal hydrolysis unit

Biowin 6 Help Manual Building Configurations • 441

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

The Tags tab of the thermal hydrolysis unit

Thermal Hydrolysis Unit Operation

The Operation tab, allows the user to specify temperature for the thermal hydrolysis unit.

442 • Building Configurations Biowin 6 Help Manual

The Operation tab of a thermal hydrolysis unit

You may specify either a Constant or Scheduled temperature. If constant temperature is selected, you may
enter the value in the edit box. If scheduled temperature is selected the Pattern… button becomes active.
Clicking this button presents you with the Edit temperature itinerary dialog box.

Thermal Hydrolysis Unit Power

The Power tab, allows the user to specify mechanical power requirements for the thermal hydrolysis unit.

Biowin 6 Help Manual Building Configurations • 443

The Power tab of a thermal hydrolysis unit

The user can choose to include mechanical power in power calculations by clicking the Uses mechanical
power check box. This activates the Mechanical power specification group. Power can be specified on a
power per unit flow basis or on a fixed basis by checking or unchecking the Power per unit flow to this
element check box, respectively. The user can enter a constant value for power or power per unit flow by
selecting the Constant value of radio button and entering a value in the text edit box. Alternatively, the user
can enter a power or power per unit flow pattern by selecting the Scheduled radio button. This activates the
Pattern…button. Clicking this button will open the the Power Itinerary editor.

Thermal Hydrolysis Unit Heating

The Heating tab, allows the user to specify heating methods and heat recovery options for the thermal
hydrolysis unit.

444 • Building Configurations Biowin 6 Help Manual

The Heating tab of a thermal hydrolysis unit

The heating power requirement is determined for Thermal Hydrolysis flowsheet elements. Typically, the
main component of the heating power is the amount of energy required to heat an influent stream to the
desired operating temperature specified in the Thermal Hydrolysis Unit. The heating power requirement is
provided from the following two choices:
1. Electrical heating which will incur an electricity cost, or
2. Heating via an external fuel source used in a boiler (i.e. natural gas, heating oil, diesel, or a custom
fuel) which will incur a cost for fuel.
To specify the Boiler (Fuel) heating method select the Boiler (Fuel) ratio button. This activates the Boiler
options group. Users can select the desired fuel source using the drop-down menu provided. An efficiency
for the boiler can also be entered in the Boiler Efficiency text edit box. To specify electrical heating select
the Electrical radio button. This activates the Electrical heating options group. An efficiency for electrical
heating can be entered in the Electrical heating efficiency text box.
The user can also choose to model heating power recovery in the form of a heat exchanger (H/X) by
checking the Heat exchanger on inflow/outflow check box

Note : When the option to include a heat exchanger is specified, BioWin assumes that the hot Thermal
Hydrolysis Unit output stream is used to heat the cool incoming stream in a counter-current heat exchanger.

A value for Exchanger efficiency and H/X Hot Stream Exit T – H/X Cold Stream Entry T (i.e. the difference in
temperature between the heat exchanger’s hot exit stream and cold entry stream) can be entered directly

Biowin 6 Help Manual Building Configurations • 445

into the appropriate text edit boxes. A schematic representing the difference in temperature between the
hot exit and cold entry streams for the heat exchanger is shown below.

Schematic illustrating H/X Hot Stream Exit T – H/X Cold Stream Entry T

Note: This section provides information on specifying heating methods and power recovery in a thermal
hydrolysis unit. Detailed information on the calculation of heating power and power recovery from heat
exchangers in a Thermal Hydrolysis unit is provided in the Heating Power and Power Recovery section of the
Power in BioWin chapter.

Thermal Hydrolysis Unit Model

The Model tab, allows the user to access and edit hydrolysis parameters for the thermal hydrolysis unit.

446 • Building Configurations Biowin 6 Help Manual

The Model tab of a thermal hydrolysis unit

The Hydrolysis parameters interface allows the users to define the fate of particulate components of a
sludge stream:
Users can specify whether or not major particulate components of sludge VSS (e.g. biomass, endogenous
residue [ZE], biodegradable particulate COD [XSP], unbiodegradable particulate COD [XI]) will be affected by
the thermal hydrolysis process. For example, a setting of 1 for the Fraction of biomass converted parameter
means that all of the incoming biomass will be converted. Furthermore, users can specify the fate of a
converted component. For example, a setting of 0.2 for the Fraction of converted biomass going to endog.
residue (remainder to XSP) means that 20% of the incoming biomass will be converted to endogenous
residue, and 80% will be converted to biodegradable particulate COD (XS).

Note: By inputting non-zero values for Fraction of endogenous converted and Fraction of unbiodegradable
particulate converted (all to XSP) fractions, it is possible to convert components of sludge VSS that BioWin
normally considers to be unbiodegradable into a biodegradable form.

Biowin 6 Help Manual Building Configurations • 447

Aerobic Digester
The aerobic digester simulates the aerobic digestion process in a CSTR. You may specify parameters related
to the operation and control of the aerobic digester element. For information on monitoring
parameters/variables for this element, please see the Monitoring Data section in the “General Operation”
chapter.

The Monitor items tab of an aerobic digester element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

448 • Building Configurations Biowin 6 Help Manual

The Tags tab of an aerobic digester element

Aerobic Digester Dimensions

The Dimensions tab, shown below, allows the user to enter the physical dimensions of an aerobic digester
element.

Biowin 6 Help Manual Building Configurations • 449

The Dimensions tab of an aerobic digester element

There are two methods for entering the dimensions: by Area and depth, or by Volume and depth. The
method is specified by clicking on the appropriate radio button.
• If you select by Area and depth, the aerobic digester area and depth must be entered in the Area
and Depth text edit boxes.
• If you select by Volume and depth, the aerobic digester volume and depth must be entered in the
Volume and Depth text edit boxes.
Regardless of the method you choose, you also must specify a Width for the element. Units are shown to
the right of the edit boxes. The element name and type, and a picture of the element also are shown.

Aerobic Digester Operation

The Operation tab, shown below, allows the user to enter operating parameters for an aerobic digester
element, such as aeration and diffuser specifications, as well as local temperature.

450 • Building Configurations Biowin 6 Help Manual

The Operation tab of an aerobic digester element

There are two methods for specifying aeration: either by a DO setpoint or by an Air flow rate. The aeration
method is specified by clicking on the appropriate radio button.
• When DO setpoint is selected, the setpoint concentration must be specified. You may specify either
a Constant setpoint or a Scheduled DO setpoint pattern (clicking the Pattern… button will open the
Edit DO setpoint itinerary dialog box). You may wish to place a restriction on the minimum and
maximum allowable air flow rate that may be used to achieve the desired DO setpoint by setting a
minimum or maximum allowable airflow in the Air flow rate constraints group. This is a useful
feature for investigating the ability of air equipment to achieve desired DO setpoints.
• When Air flow rate is selected, the air flow rate must be specified. You may specify either a
Constant air flow rate or a Scheduled air flow rate pattern (clicking the Pattern… button will open
the Edit air flow itinerary dialog box). Note that if you specify an air supply rate, BioWin will
automatically turn on the oxygen modeling option.
There are three methods for entering diffuser information: by a Density(%), by an ATAD, or by the Number
of Diffusers. The diffuser information is specified by clicking on the appropriate radio button.
1. If you select Density(%), the diffuser density (%) (i.e. the total area of diffusers in aeration tank /
area of aeration tank expressed as a percent) must be specified in the Density(%) text edit box.
2. If ATAD is selected, the ATAD (i.e. area of aeration tank/total area of diffusers in aeration tank) must
be specified in the text edit box.
3. If Number of Diffusers is selected, the number of diffusers must be specified in the text edit box.

Biowin 6 Help Manual Building Configurations • 451

A Local temperature also may be specified for an aerobic digester element. When you click on the check box
for local temperature, the Specify temperature by radio button group is enabled. You may then specify
either a Constant or Scheduled temperature.
• If constant temperature is selected, you may enter the value in the edit box.
• If scheduled temperature is selected the Pattern… button becomes active. Clicking this button
presents you with the Edit temperature itinerary dialog box.

Note: You do not input a VSS destruction directly into the digester element as an operating parameter.
Rather, the digester element will predict the VSS destruction as a result of operating conditions (e.g.
retention time), kinetics (e.g. particulate material hydrolysis rates), and other factors [e.g. composition of
sludge feed stream(s)]. The predicted VSS destruction can be viewed in the summary pane by pointing at a
digester in the flowsheet, or it can be plotted in the BioWin Album.

Aerobic Digester Power

The Power tab, shown below, allows the user to enter power specifications for mechanical mixing in an
Aerobic Digester element.

The Power tab of an Aerobic Digester element

Power can be specified on a power per unit volume basis or on a fixed basis by checking or unchecking the
Power per unit vol check box, respectively. The user can enter a constant value for power or power per unit
volume by selecting the Constant value of radio button and entering a value in the text edit box.
Alternatively, the user can enter a power or power per unit volume pattern by selecting the Scheduled radio

452 • Building Configurations Biowin 6 Help Manual

button. This activates the Pattern…button. Clicking this button will open the Power Itinerary editor. Power
calculated for the Aerobic Digester element will be grouped under the “Mixing power” category in power
charts and tables.

Aerobic Digester Model

The Model tab, shown below, allows the user to change local model parameters.

The Model tab of an Aerobic Digester element

You can specify Local kinetic parameters for the activated sludge model used in the Aerobic Digester
element. If you click on the check box for local kinetic parameters, then clicking the Edit local kinetic
parameters… button opens the Parameter editor dialog box allowing you access to the various activated
sludge model kinetic parameters.
If you wish to override the project global aeration parameters with local values specific to this element only,
select the box labeled Local aeration parameters. This will activate the button labeled Edit local aeration
parameters…. Clicking this button will open the Aeration dialog box, which allows you to modify aeration
parameters.
If you wish to override the project global diffuser parameters with local values specific to this element only,
select the box labeled Local diffuser parameters. This will activate the button labeled Edit local diffuser
parameters…. Clicking this button will open the Diffuser dialog box, which allows you to modify diffuser
parameters.

Biowin 6 Help Manual Building Configurations • 453

To model the concentrations of the constituents of the aeration gas (e.g. oxygen, carbon dioxide, etc.),
check the box labeled Model gas phase. If this option is selected, you may also enter a percentage value for
the Gas hold-up (i.e. the percentage of the total reactor volume occupied by aeration gas).
You can also specify the aeration parameters Alpha F and Beta. You may specify either a Constant value or a
Scheduled pattern for each parameter (clicking the Pattern… button will open the Edit Alpha itinerary or
Edit Beta itinerary dialog box). If you wish to plot Alpha and/or Beta click on the graph button. This will add
a time series plot of alpha and/or beta to the BioWin Album.

Anaerobic Digester
The anaerobic digester simulates the anaerobic digestion process in a CSTR. You may specify parameters
related to the operation and control of the anaerobic digester element. For information on monitoring
parameters/variables for this element, please see the Monitoring Data section in the “General Operation”
chapter.

The Monitor items tab of an Anaerobic digester element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

454 • Building Configurations Biowin 6 Help Manual

The Tags tab of an Anaerobic digester element

Anaerobic Digester Dimensions

The Dimensions tab, shown below, allows the user to enter the physical dimensions of an Anaerobic
digester element.

Biowin 6 Help Manual Building Configurations • 455

The Dimensions tab of an Anaerobic digester element

There are two methods for entering the dimensions: by Area and depth, or by Volume and depth. The
method is specified by clicking on the appropriate radio button.
• If you select by Area and depth, the anaerobic digester area and depth must be entered in the Area
and Depth text edit boxes.
• If you select by Volume and depth, the anaerobic digester volume and depth must be entered in the
Volume and Depth text edit boxes.
Regardless of the method you choose, you also must specify a Width for the element. Units are shown to
the right of the edit boxes. The element name and type, and a picture of the element also are shown.
You must also enter the Head space volume and the Head space pressure (in terms of absolute pressure) for
the anaerobic digester. The head space pressure is used in the determination of the volumetric gas flowrate.

Anaerobic Digester Operation

The Operation tab, shown below, allows the user to specify a local temperature.

456 • Building Configurations Biowin 6 Help Manual

The Operation tab of an Anaerobic digester element

A Local temperature may be specified for an anaerobic digester element. When you click on the check box
for local temperature, the Specify temperature by radio button group is enabled. You may then specify
either a Constant or Scheduled temperature.
If constant temperature is selected, you may enter the value in the edit box.
If scheduled temperature is selected the Pattern… button becomes active. Clicking this button presents you
with the Edit temperature itinerary dialog box.
• The digester temperature is used in the determination of the volumetric gas flowrate.

Note: You do not input a VSS destruction directly into the digester element as an operating parameter.
Rather, the digester element will predict the VSS destruction as a result of operating conditions (e.g.
retention time), kinetics (e.g. particulate material hydrolysis rates), and other factors [e.g. composition of
sludge feed stream(s)]. The predicted VSS destruction can be viewed in the summary pane by pointing at a
digester in the flowsheet, or it can be plotted in the BioWin Album.

Anaerobic Digester Outflow

The anaerobic digester element Outflow tab, shown below, is used to specify the overflow behavior. The
overflow behavior can be generalized as follows:
• Whenever the anaerobic digester element is full, it overflows at the influent rate, regardless of the
overflow setting.

Biowin 6 Help Manual Building Configurations • 457

 • Whenever the anaerobic digester element is empty and the outflow rate is set higher than the
influent rate, the anaerobic digester element will only have an outflow equal to the influent flow, so
as not to have negative volume. If the outflow rate is set lower than the influent rate, then the
anaerobic digester element will begin to fill up.
• If the Constant volume (i.e. outflow=inflow) option is checked, then the entire liquid volume entered
on the Dimensions tab is used and the volume will be constant.

Note: Remember for steady state simulations, the initial liquid hold-up volume will be used for calculations.

The following is a description of the behavior of the three outflow settings:

• Overflow only – the Anaerobic digester element fills up, and then overflows at the influent flow rate.
• Constant outflow – the outflow always tries to attain the specified constant rate, except when
physically constrained (i.e. when the Anaerobic digester element is full or empty)
• Flow pattern – the outflow always tries to attain the current specified pattern rate, except when
physically constrained (i.e. when the Anaerobic digester element is full or empty). To specify a
pattern, click the Pattern… button when it becomes active. For more information, see the Liquid
outflow itinerary section in the “General Operation” chapter.

The Outflow tab of an Anaerobic digester element

458 • Building Configurations Biowin 6 Help Manual

Anaerobic Digester Initial Values
The Initial values tab, shown below, is used for specifying the initial settings for anaerobic digester element
concentrations and volume.

The Initial values tab with the Default option active (Anaerobic digester element)

Use the Initial liquid hold-up field to enter a value to specify the % of full setting. This initial liquid hold-up
volume will be used for steady state calculations. It should be noted here that the lower and upper limits on
this value are 0.02 and 99.98%, respectively. This reflects the fact that this is the liquid volume, and allows
for small differences between liquid volume and reactor volume for inlet and outlet pipes.
There are two methods for setting up Initial concentrations in the anaerobic digester element. The dialog
box shown above illustrates the first case where the Default option is selected. When this option is selected,
BioWin applies default seed values for all the state variables (except volume, which you specify) in the same
manner it would for bioreactor elements.
The dialog box shown below illustrates the second case where the User defined option is selected. In this
case, an editable list of state variables is displayed in the dialog box. This allows you to enter your own seed
values for state variables in the anaerobic digester element.

Biowin 6 Help Manual Building Configurations • 459

The Initial values tab with the User defined option active (Anaerobic digester element)

• If you choose User defined initial concentrations then there are two conditions when the User
defined initial concentrations can be used.
• If the box labeled “Set these values now …” is checked then the concentrations specified are
inserted in the state vector as soon as the OK button is clicked.
• If the box labeled “Set these values now …” is NOT checked then the initial concentrations will be
inserted in the reactor state vector when you begin a dynamic or steady state simulation and
choose to start the simulation from seed values.

Note: If “Set these values now …” is checked, the specified values are placed in the reactor state variable
vector when you click OK overriding any existing state variable vector values. Consequently a dynamic
simulation started from this point will use the User defined initial concentrations regardless of whether you
choose to start from Seed values or Current values.

The use of this option is illustrated in the example at the end of the Variable Volume/Batch Bioreactor Initial
Values section later in this chapter.

Anaerobic Digester Power

The Power tab, shown below, allows the user to enter mechanical mixing power specification for the
anaerobic digester element.

460 • Building Configurations Biowin 6 Help Manual

The Power tab of an Anaerobic digester element

Mixing power can be specified on a power per unit volume basis or on a fixed basis by checking or
unchecking the Power per unit vol check box, respectively. The user can enter a constant value for power or
power per unit volume by selecting the Constant value of radio button and entering a value in the text edit
box. Alternatively, the user can enter a power or power per unit volume pattern by selecting the Scheduled
radio button. This activates the Pattern…button. Clicking this button will open the Power Itinerary editor.

Anaerobic Digester Gas use

The Gas use tab, shown below, allows the user to specify the fate of gas generated in the Anaerobic Digester
element.

Biowin 6 Help Manual Building Configurations • 461

The Gas Use tab of an Anaerobic digester element with CHP specified

Using the radio buttons provided, users can choose between three options for specifying how to use the gas
generated in the Anaerobic Digester: CHP, Boiler (heating influent), and Flare/Sell all. See Heating Power
for an illustration of the gas use options available.
If the CHP radio button is selected, the CHP Options group will become visible. Users can specify the Percent
CHP engine to power and the Percent CHP engine to heat by entering a value directly in the text edit boxes
provided. BioWin will calculate the Percent CHP engine exhaust/waste by difference. By default, when CHP
is selected the option to use the heat generated via CHP towards the digester input stream is switched on by
checking the Use CHP heat for digester input stream check box. Users can specify the efficiency of using this
heat by entering a value in the Efficiency of heat use text edit box.
The fate of the energy (e.g. whether it is all used onsite with any excess being sold back to the grid or it is all
sold back to the grid) produced by the CHP unit is specified in Project|Cost/Energy|Combined Heat and
Power (CHP)…. Detailed information on specifying CHP parameters is provided in the Specifying Project
Combined Heat and Power (CHP) section of the Managing BioWin Projects chapter. See Combined Heat and
Power (CHP) and Heating Power Equations with CHP for more information on CHP specification and
calculation in BioWin.
Selecting the Boiler (heating influent) radio button, shown below, allows the gas generated in the Anaerobic
Digester to be used as a fuel source for the boiler for heating the digester and digester influent stream. This
activates the Boiler (heating digester and influent stream) group where users can specify the efficiency of
using the gas by entering a value in the Efficiency of gas use text edit box. Users also have an option to sell
any excess gas remaining by selecting the Sell excess gas (all gas if “Flare/Sell all” selected) check box.

462 • Building Configurations Biowin 6 Help Manual

When this option is selected, any excess gas not used for heating will be sold at the Biogas sale price [$/GJ]
specified under Project|Costs/Energy|Fuel/Chemical…on the Heating fuel/Chemical Costs tab.

The Gas Use tab of an Anaerobic digester element with Boiler (heating influent) specified

Selecting the Flare/Sell all radio button, shown below, allows all of the gas generated in the Anaerobic
Digester to be flared off or sold. This activates the Sell excess gas (all gas if “Flare/Sell all” selected) check
box. When this option is unchecked, all of the gas generated in the Anaerobic Digester will be flared off.
When this option is checked, all of the gas generated in the Anaerobic Digester will be sold. Gas is sold at the
Biogas sale price [$/GJ] specified under Project|Costs/Energy|Fuel/Chemical…on the Heating
fuel/Chemical Costs tab.

Biowin 6 Help Manual Building Configurations • 463

The Gas Use tab of an Anaerobic digester element with Flare/Sell all specified

See Heating Power for more information on how the above parameters influence heating power and heat
recovery calculations for the Anaerobic Digester element.

Anaerobic Digester Heating/heat loss

The Heating/heat loss tab, shown below, allows users to enter options for heating, heat loss and heat
recovery for the Anaerobic Digester.

464 • Building Configurations Biowin 6 Help Manual

The Heating/heat loss tab of an Anaerobic digester element

The heating power requirement is determined for anaerobic digester flowsheet elements. Typically, the
main component of the heating power is the amount of energy required to heat an influent stream to the
desired operating temperature specified in the digester. Additional heating power may be required in an
anaerobic digester element to overcome a specified digester heat loss. The heating power requirement is
provided from the following two choices:
1. Electrical heating which will incur an electricity cost, or
2. Heating via an external fuel source used in a boiler (i.e. natural gas, heating oil, diesel, or a custom
fuel) which will incur a cost for fuel.
Daily heat loss can be specified in the Heat loss group. Users can specify a constant heat loss by selecting the
Constant value of radio button and entering a value in the text edit box. Alternatively, users can specify a
scheduled heat loss by selecting the Scheduled radio button. This activates the Pattern…button. Clicking this
button will open the Heat loss itinerary editor.
Heating and heat recovery options can be entered in the Digester heating and heat recovery options group.
By default, the heating method in the anaerobic digester element is specified as Boiler (Fuel). The user can
choose a fuel source (i.e. Natural gas, Heating oil, Diesel or Custom fuel) in the Boiler options group using
the drop down list provided. Users can also specify the efficiency of the boiler in the Boiler efficiency text
edit box. Note: when the Boiler (Fuel) heating method is specified heating power in the Anaerobic Digester
will be zero since electricity is not consumed. Instead BioWin will calculate the amount of fuel required to
meet heating demands and the associated fuel costs.

Biowin 6 Help Manual Building Configurations • 465

Alternatively, users can choose to provide heat electrically by selecting the Electrical radio button in the
Heating Method group. This activates the Electrical heating options group. The efficiency of electrical
heating can be specified in the Electrical heating efficiency text edit box. Note: when the Electrical heating
method is specified a value for heating power will be included in power consumption calculations unless a
heat recovery option can sufficiency provide enough heat for the Anaerobic Digester.
Heat recovery options can be entered in the Heat recovery options group. Users can specify to use a heat
exchanger on inflow/outflow by checking the Heat exchanger on inflow/outflow checkbox. When the
option to include a heat exchanger is specified, BioWin assumes that the hot Anaerobic Digester output
stream is used to heat the cool incoming stream in a counter-current heat exchanger. Users can enter the
efficiency of the exchanger in the Exchanger efficiency text edit box as well as the temperature difference
between the heat exchanger’s hot exit stream and cold entry stream in the H/X Hot Stream Exit T – H/X
Cold Stream Entry T text edit box. A schematic representing the difference in temperature between the hot
exit and cold entry streams for the heat exchanger is shown below.

Schematic illustrating H/X Hot Stream Exit T – H/X Cold Stream Entry T

See Heating Power for more information on how the above parameters are used to calculate heating power
and heat recovery for the Anaerobic Digester element.

Anaerobic Digester Model options

The Model options tab, shown below, allows the user to specify pH options and also change local kinetic
model parameters.

466 • Building Configurations Biowin 6 Help Manual

The Model tab of an Anaerobic digester element

You can select Local kinetic parameters and click the Edit local kinetic parameters… button in order to
specify kinetic parameters for the anaerobic digester that are different from the configuration global
parameters.
You can select whether you want BioWin to Calculate tank pH or you can Use a specified value if you wish.

Pipes
The Pipe line options tab, shown below, allows the user to specify pipe display options. You can access this
dialog box by double-clicking a pipe arrowhead on the drawing board or right clicking a pipe arrowhead and
choosing Properties... from the resulting popup menu.
Note that in some cases it may be useful to name pipes in your flowsheet, in case you want to (a) display
names for them on the drawing board, or (b) include them in a table of an Excel-based report.

Biowin 6 Help Manual Building Configurations • 467

The Pipe line options tab

There are five pipe styles from which you can select by clicking the appropriate radio button:
1. Open box
2. Straight
3. Step
4. Step (middle) – this is the default pipe style
5. U-shape
An example of the selected option is shown in the picture on the lower part of the tab. Pipes must start from
and end at an element. Clicking once on a pipe will reveal that it has “tag” points (denoted by small circles
on the pipe). If a circle is red, then it may be moved. The various pipe styles differ in how these points may
be moved by dragging them around the drawing board.

Open Box Pipe Style

The Open Box style has two points which may be moved. This makes the Open Box style the most flexible of
the available styles. This flexibility is useful in avoiding pipes crossing over one another and going through
elements in complex configurations with internal recycles. The first point (i.e. the point closest to the pipe's
beginning) is free to move up and down in the vertical direction, as shown in the picture below.

468 • Building Configurations Biowin 6 Help Manual

The first point for an open box pipe can move in the vertical direction

The second point (i.e. the middle point of the three) is free to move about in the horizontal direction, as
shown in the picture below.

The second point for an open box can move in the horizontal direction

Straight Pipe Style

The Straight style has two points as shown in the picture below. Neither of these points may be moved – the
pipe simply is a straight line drawn between the two elements.

Biowin 6 Help Manual Building Configurations • 469

A straight pipe's point may not be moved about the drawing board

Step Pipe Style

The Step style has one point which may be moved. The first point (i.e. the point closest to the pipe's
beginning) may be moved about in the horizontal direction, as shown in the picture below.

A step pipe has one point which may be moved horizontally

Step Middle Pipe Style

The Step (middle) style has three points as shown in the picture below. None of these points may be moved
– the pipe automatically forms a step at the point halfway between the elements.

470 • Building Configurations Biowin 6 Help Manual

A step (middle) pipe has no moveable points

U-Shape Pipe Style

The U-shape style has one point which may be moved. The first point (i.e. the point closest to the pipe's
beginning) may be moved about in the vertical direction, as shown in the picture below.

A U-shape has one point which may be moved vertically

You can change line or arrow properties for individual pipes so that they are different from the settings you
have chosen in Project|Current Project Options… or Project|New Project Options….
You can change the Color, Width, and Style of the lines used to represent pipes on the drawing board. You
may increase the arrow size on the lines used to represent pipes. The arrow angle also can be changed.

Note: The “arrow angle” refers to the acute angle between the arrow side and the pipe line. For example, if
you want arrows with “flat” bases, set the arrow side angle to the maximum of 60 degrees.

Biowin 6 Help Manual Building Configurations • 471

For information on tags for the pipe element, please see the Customizing the Project Appearance subsection
in the Customizing BioWin section in the “General Operation” chapter. Note that for pipes, only mass rates
will be displayed in tags.

The Tags tab of a pipe element

Tanks
Grit Removal Tank
The grit removal tank element is used to simulate the removal of sand and other inerts in a system. You may
specify details regarding the physical specifications, flow split method, and solids separation operation of
the grit tank. For information on monitoring parameters/variables for this element, please see the
Monitoring Data section in the “General Operation” chapter.

472 • Building Configurations Biowin 6 Help Manual

The Monitor items tab of a Grit removal tank element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

Biowin 6 Help Manual Building Configurations • 473

The Tags tab of a Grit removal tank element

Grit Removal Tank Dimensions

The Dimensions tab, shown below, allows the user to enter the physical dimensions of a grit removal tank
element.

474 • Building Configurations Biowin 6 Help Manual

The Dimensions tab of a Grit removal tank element

There are two methods for entering the dimensions: by Area and depth, or by Volume and depth. The
method is specified by clicking on the appropriate radio button.
• If you select by Area and depth, the grit removal tank area and depth must be entered in the Area
and Depth text edit boxes.
• If you select by Volume and depth, the grit removal tank volume and depth must be entered in the
Volume and Depth text edit boxes.
Regardless of the method you choose, you also must specify a Width for the element. Units are shown to
the right of the edit boxes. The element name and type, and a picture of the element also are shown.

Grit Removal Tank Operation

The Operation tab, shown below, allows you to specify the amount of grit removed by the grit removal tank
element.

Biowin 6 Help Manual Building Configurations • 475

The Operation tab of a Grit removal tank element

There are two edit boxes on this tab. The Percentage grit removal may be entered in the first edit box. This
is the average percentage grit removal, and may differ from the instantaneous percentage removal
observed in a dynamic simulation.
The second edit box is provided for specifying the Grit zone volume fraction; this is the grit zone fraction of
a unit volume. The concentration of the underflow (grit stream) can be modified by adjusting this fraction.

Grit Removal Tank Split Method

The Flow split tab, shown below, allows the user to specify the flow split method for a grit removal tank.

476 • Building Configurations Biowin 6 Help Manual

The Flow split tab of a grit removal tank element

The method of specifying the flow split for a grit removal tank may be selected from a number of options.
You can specify the flow using a Ratio, Fraction, or Underflow rate by clicking on the corresponding radio
button. If you specify an underflow rate (denoted by the symbol U), it will result in a constant underflow out
the bottom of the grit removal tank. Note that when the grit removal tank is operating in this mode, if the
influent flow is less than the set Underflow rate, then all of the influent flow will be sent to the underflow. If
you specify either the Ratio or Fraction split method, then the underflow will be calculated using the
corresponding formula based on the overflow rate (denoted by the symbol O) and the underflow rate U.
Next to the split method radio group is an edit box; if the split method is selected from the radio group, the
value may be entered in the edit box. Units are shown adjacent to the edit box (where applicable) and the
label of the edit box changes to indicate the chosen split method.
The split method group also contains a Constant check box; if the flow split does not vary with time this box
should be checked. It should be noted that this check box applies only to the split methods listed in the radio
group and is checked by default. If the Constant check box is unchecked, the Pattern… button becomes
active so you can enter a time-varying pattern for the flow split. Clicking this button presents you with the
Edit split itinerary dialog box.
The underflow rate also can be Paced with an influent stream. To select the flow paced option, click on the
Paced at check box. The percentage of the influent flow rate may then be specified, and the influent stream
for flow pacing may be selected from the drop list box which shows all influent streams available for your
system.

Biowin 6 Help Manual Building Configurations • 477

Grit Removal Tank Power
The Power tab, shown below, allows the user to enter mechanical power specifications for the grit removal
tank element.

The Power tab of a Grit removal tank element

Power can be specified on a power per unit flow basis or on a fixed basis by checking or unchecking the
Power per unit flow for this element check box, respectively. The user can enter a constant value for power
or power per unit flow by selecting the Constant value of radio button and entering a value in the text edit
box. Alternatively, the user can enter a power or power per unit flow pattern by selecting the Scheduled
radio button. This activates the Pattern…button. Clicking this button will open the Power Itinerary editor.

Equalization Tank
The Equalization Tank is a completely mixed vessel in which there is no reaction. You may change aspects of
the Equalization Tank’s dimensions and operation. For information on monitoring parameters/variables for
this element, please see the Monitoring Data section in the “General Operation” chapter.

478 • Building Configurations Biowin 6 Help Manual

The Monitor items tab for an Equalization Tank element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

Biowin 6 Help Manual Building Configurations • 479

The Tags tab of an Equalization Tank element

Equalization Tank Dimensions

The Dimensions tab, shown below, allows the user to enter the physical dimensions of an Equalization Tank
element.

480 • Building Configurations Biowin 6 Help Manual

The Dimensions tab of an Equalization Tank element

There are two methods for entering the dimensions: by Area and depth, or by Volume and depth. The
method is specified by clicking on the appropriate radio button.
• If you select by Area and depth, the tank area and depth must be entered in the Area and Depth text
edit boxes.
• If you select by Volume and depth, the tank volume and depth must be entered in the Volume and
Depth text edit boxes.
Regardless of the method you choose, you also must specify a Width for the element. Units are shown to
the right of the edit boxes. The element name and type, and a picture of the element also are shown.

Equalization Tank Operation

The Operation tab, shown below, allows the user to enter operating parameters for an Equalization Tank
element.

Biowin 6 Help Manual Building Configurations • 481

The Operation tab of an Equalization Tank element

You may specify Equalization tank mode (either a constant or variable liquid volume) by clicking on the
appropriate radio button. If the Constant liquid volume mode is selected, the outflow rate is equal to the
inflow rate, and no other operating data are required; the liquid volume is equal to the volume entered in
the dimensions tab.
If the Variable liquid volume mode is selected, the Outflow rate and Initial liquid hold-up (as a percentage
of the full volume) must be specified. Edit boxes are provided for entering the outflow rate and initial liquid
hold-up; flow units are shown adjacent to these.

Equalization Tank Power

The Power tab, shown below, allows the user to specify mechanical mixing power for an Equalization Tank
element.

482 • Building Configurations Biowin 6 Help Manual

The Power tab of an Equalization Tank element

Power can be specified on a power per unit volume basis or on a fixed basis by checking or unchecking the
Power per unit vol check box, respectively. The user can enter a constant value for power or power per unit
volume by selecting the Constant value of radio button and entering a value in the text edit box.
Alternatively, the user can enter a power or power per unit volume pattern by selecting the Scheduled radio
button. This activates the Pattern…button. Clicking this button will open the the Power Itinerary editor.
Power calculated for the Equalization Tank element will be grouped under the “Mixing power” category in
power charts and tables.

Clarifiers
Ideal Primary Settling Tank

Note: With the release of BioWin 4.1, there is no longer an “activated” primary settling tank. The ideal
primary settling tank now has the ability to incorporate biological modeling if desired (e.g. to simulate a
primary sludge fermenter). When you open a file created in a previous version of BioWin that may have
contained activated primary settling tank elements, these will automatically be replaced with the updated
BioWin 4.1 ideal primary settling tank. It should also be noted that if a flowsheet created in a previous
version of BioWin incorporated “old” ideal primary settling tank elements, these will not be automatically
replaced. If the updated ideal primary settling tank element functionality available as of BioWin 4.1 is
desired, then the “old” ideal primary settling tank elements will need to be replaced.

Biowin 6 Help Manual Building Configurations • 483

The Ideal primary settling tank element is used to model settlement of particulate material in a wastewater
stream which does not contain activated sludge mixed liquor (e.g. a raw influent stream). You may specify
the physical characteristics, the flow split method, and the solids separation operation of the primary
settler. For information on monitoring parameters/variables for this element, please see the Monitoring
Data section in the “General Operation” chapter.

The Monitor items tab of an Ideal primary settling tank element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

484 • Building Configurations Biowin 6 Help Manual

The Tags tab of an Ideal primary settling tank element

Ideal Primary Settling Tank Dimensions

The Dimensions tab, shown below, allows the user to enter the physical dimensions of an ideal primary
settling tank element.

Biowin 6 Help Manual Building Configurations • 485

The Dimensions tab of an Ideal primary settling tank element

There are two methods for entering the dimensions: by Area and depth, or by Volume and depth. The
method is specified by clicking on the appropriate radio button.
• If you select by Area and depth, the ideal primary settler area and depth must be entered in the
Area and Depth text edit boxes.
• If you select by Volume and depth, the ideal primary settler volume and depth must be entered in
the Volume and Depth text edit boxes.
Regardless of the method you choose, you also must specify a Width for the element. Units are shown to
the right of the edit boxes. The element name and type, and a picture of the element also are shown.

Ideal Primary Settling Tank Operation

The Operation tab, shown below, allows the user to enter configuration specifications for an ideal primary
settling tank element, as well as specify a local temperature.

486 • Building Configurations Biowin 6 Help Manual

The Operation tab of an Ideal primary settling tank element

There are three input areas on this tab. The first edit box is used to enter the Fraction of settler height that
is occupied by the sludge blanket. The solids captured by the ideal primary settling tank are reported to the
portion of the total settler volume defined by this fraction.
The second input area allows users to specify the base Percent removal of particulate state variables. A
Constant value or a Scheduled pattern can be entered. If the Scheduled button is clicked, a Percent
removal itinerary editor is available:

Biowin 6 Help Manual Building Configurations • 487

The Ideal primary settling tank element percent removal itinerary editor

The third input area allows users to specify modified removals for selected particulate state variables as a
multiplication factor applied to the base percent removal. Checking the box to the left of a particulate state
variable allows the user to input a multiplication factor for that variable:

Changing the base percent removal multiplication factor for a particulate state variable

488 • Building Configurations Biowin 6 Help Manual

Setting a variable’s multiplication factor to a value greater than zero and less than 1 will result in a net
capture rate lower than the base percent removal for that variable. Setting a variable’s multiplication factor
to a value greater than 1 will result in a net capture rate higher than the base percent removal for that
variable.
To edit a multiplication factor that has been changed from 1 (e.g. screen shot below), the user can double-
click on the changed factor:

If a check box for a changed state variable multiplication factor is un-checked, the previously entered
multiplication factor will no longer be applied to the base percent removal (if the check box is re-checked
either immediately or later, the user will be presented with a base factor of 1 to edit).
The ideal primary settling tank now displays the % capture for TSS, COD, and BOD in the summary pane
when you point at it in the drawing board area:

Biowin 6 Help Manual Building Configurations • 489

These percent removals, as well as percent removals for TKN and TP may also be plotted directly as either
current value or time series under the Settlers group of the Element specific list:

Using this functionality users can rapidly develop plots to show percent removals across primary settling
tanks:

490 • Building Configurations Biowin 6 Help Manual

A Local temperature may be specified for an ideal primary settling tank. When you click on the check box for
local temperature, the Specify temperature by radio button group is enabled. You may then specify either a
Constant or Scheduled temperature.
If constant temperature is selected, you may enter the value in the edit box.
If scheduled temperature is selected the Pattern… button becomes active. Clicking this button presents you
with the Edit temperature itinerary dialog box.

Ideal Primary Settling Tank Split Method

The Flow split tab, shown below, allows the user to specify the flow split method for an ideal primary
settling tank element.

Biowin 6 Help Manual Building Configurations • 491

The Flow split tab of an Ideal primary settling tank element

The method of specifying the flow split for an ideal primary settling tank element may be selected from a
number of options. You can specify the flow using a Ratio, Fraction, or Underflow rate by clicking on the
corresponding radio button. If you specify an underflow rate (denoted by the symbol U), it will result in a
constant underflow out the bottom of the ideal primary settling tank. Note that when the ideal primary
settling tank is operating in this mode, if the influent flow is less than the set Underflow rate, then all of the
influent flow will be sent to the underflow. If you specify either the Ratio or Fraction split method, then the
underflow will be calculated using the corresponding formula based on the overflow rate (denoted by the
symbol O) and the underflow rate U.
Next to the split method radio group is an edit box; if the split method is selected from the radio group, the
value may be entered in the edit box. Units are shown adjacent to the edit box (where applicable) and the
label of the edit box changes to indicate the chosen split method.
The split method group also contains a Constant check box; if the flow split does not vary with time this box
should be checked. It should be noted that this check box applies only to the split methods listed in the radio
group and is checked by default. If the Constant check box is unchecked, the Pattern… button becomes
active so you can enter a time-varying pattern for the flow split. Clicking this button presents you with the
Edit split itinerary dialog box.
The underflow rate also can be Paced with an influent stream. To select the flow paced option, click on the
Paced at check box. The percentage of the influent flow rate may then be specified, and the influent stream
for flow pacing may be selected from the drop list box which shows all influent streams available for your
system.

492 • Building Configurations Biowin 6 Help Manual

Ideal Primary Settling Tank Power
The Power tab, shown below, allows the user to enter mechanical power specifications for the Ideal primary
settling tank element.

The Power tab of an Ideal Primary Settling Tank element

Power can be specified on a power per unit flow basis or on a fixed basis by checking or unchecking the
Power per unit flow to this element check box, respectively. The user can enter a constant value for power
or power per unit flow by selecting the Constant value of radio button and entering a value in the text edit
box. Alternatively, the user can enter a power or power per unit flow pattern by selecting the Scheduled
radio button. This activates the Pattern…button. Clicking this button will open the Power Itinerary editor.

Ideal Primary Settling Tank Model

The Model tab, shown below, allows the user to specify parameters impacting the model used in the ideal
primary settling tank element (such as pH) and also specify local model parameters.

Biowin 6 Help Manual Building Configurations • 493

The Model tab of an Ideal primary settling tank element

To activate the biological model within an ideal primary settling tank, the user must check the Biological
reaction box on the Model tab. This activates the Local kinetic parameters check box. You can select Local
kinetic parameters and click the Edit local kinetic parameters… button in order to specify kinetic
parameters for the activated primary settling tank element that are different from the configuration global
parameters. If the Local kinetic parameters box is not checked then the Edit local kinetic parameters…
button remains greyed out. The user also can select whether to have BioWin Calculate tank pH or Use a
specified value.

Ideal Clarifier
The Ideal (secondary) clarifier element is used to model settlement of particulate material in a wastewater
stream containing activated sludge mixed liquor based on an idealized solids separation model. You may
specify the physical characteristics, the flow split method, the solids separation operation, and biological
reaction of the Ideal clarifier element. For information on monitoring parameters/variables for this element,
please see the Monitoring Data section in the “General Operation” chapter.

494 • Building Configurations Biowin 6 Help Manual

The Monitor items tab of an Ideal clarifier element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

Biowin 6 Help Manual Building Configurations • 495

The Tags tab of an Ideal clarifier element

Ideal Clarifier Dimensions

The Dimensions tab, shown below, allows the user to enter the physical dimensions of an Ideal clarifier
element.

496 • Building Configurations Biowin 6 Help Manual

The Dimensions tab of an Ideal clarifier element

There are two methods for entering the dimensions: by Area and depth, or by Volume and depth. The
method is specified by clicking on the appropriate radio button.
• If you select by Area and depth, the ideal clarifier area and depth must be entered in the Area and
Depth text edit boxes.
• If you select by Volume and depth, the ideal clarifier volume and depth must be entered in the
Volume and Depth text edit boxes. Units are shown to the right of the edit boxes. The element
name and type, and a picture of the element also are shown.

Ideal Clarifier Operation

The Operation tab, shown below, allows the user to enter settling behavior specifications for an Ideal
clarifier element, as well as specify a local temperature.

Biowin 6 Help Manual Building Configurations • 497

The Operation tab of an Ideal clarifier element

There are two edit boxes on this tab. The first edit box is used to enter the Percentage solids removal for
the ideal clarifier (you may either have a constant or scheduled capture rate); the Sludge blanket height
may be specified using the second box. Sludge blanket height is expressed as a fraction of the total settler
height
A Local temperature also may be specified for an ideal clarifier. When you click on the check box for local
temperature, the Specify temperature by radio button group is enabled. You may then specify either a
Constant or Scheduled temperature.
• If constant temperature is selected, you may enter the value in the edit box.
• If scheduled temperature is selected the Pattern… button becomes active. Clicking this button
presents you with the Edit temperature itinerary dialog box.

Ideal Clarifier Split Method

The Flow split tab, shown below, allows the user to specify the flow split method for an ideal clarifier
element.

498 • Building Configurations Biowin 6 Help Manual

The Flow split tab of an Ideal clarifier element

The method of specifying the flow split for an Ideal clarifier element may be selected from a number of
options. You can specify the flow using a Ratio, Fraction, or Underflow rate by clicking on the corresponding
radio button. If you specify an underflow rate (denoted by the symbol U), it will result in a constant
underflow out the bottom of the ideal secondary settler. Note that when the ideal clarifier is operating in
this mode, if the influent flow is less than the set Underflow rate, then all of the influent flow will be sent to
the underflow. If you specify either the Ratio or Fraction split method, then the underflow will be calculated
using the corresponding formula based on the overflow rate (denoted by the symbol O) and the underflow
rate U.
Next to the split method radio group is an edit box; if the split method is selected from the radio group, the
value may be entered in the edit box. Units are shown adjacent to the edit box (where applicable) and the
label of the edit box changes to indicate the chosen split method.
The split method group also contains a Constant check box; if the flow split does not vary with time this box
should be checked. It should be noted that this check box applies only to the split methods listed in the radio
group and is checked by default. If the Constant check box is unchecked, the Pattern… button becomes
active so you can enter a time-varying pattern for the flow split. Clicking this button presents you with the
Edit split itinerary dialog box.
The underflow rate also can be Paced with an influent stream. To select the flow paced option, click on the
Paced at check box. The percentage of the influent flow rate may then be specified, and the influent stream
for flow pacing may be selected from the drop list box which shows all influent streams available for your
system.

Biowin 6 Help Manual Building Configurations • 499

Ideal Clarifier Power
The Power tab, shown below, allows the user to enter mechanical power specifications for the Ideal clarifier
element.

The Power tab of an Ideal clarifier element

Power can be specified on a power per unit flow basis or on a fixed basis by checking or unchecking the
Power per unit flow to this element check box, respectively. The user can enter a constant value for power
or power per unit flow by selecting the Constant value of radio button and entering a value in the text edit
box. Alternatively, the user can enter a power or power per unit flow pattern by selecting the Scheduled
radio button. This activates the Pattern…button. Clicking this button will open the Power Itinerary editor.

ldeal Clarifier Model

The ideal clarifier Model tab, shown below, allows the user to specify whether biological reactions in the
clarifier are modeled, and if so, model options such as local kinetic parameters.

500 • Building Configurations Biowin 6 Help Manual

The Model tab of an Ideal clarifier element

If you wish to model biological reactions in the ideal clarifier, click on the check box for Biological reaction;
this switches on the activated sludge processes and enables the Local kinetic parameters check box.
If you wish to specify Local kinetic parameters for the ideal clarifier (i.e. kinetic parameters that are
different from those specified under the Project|Parameters… menu), click on the check box for local
kinetic parameters, then click the Edit local kinetic parameters… button to open the Parameter editor
dialog box which allows you to access the various activated sludge model kinetic parameters.

Point Clarifier
The Point (secondary) clarifier element is similar to the Ideal clarifier element and is used to model
settlement of particulate material in a wastewater stream containing activated sludge mixed liquor based on
an idealized solids separation model. The distinctive feature of this element is that it has no volume. You
may specify the flow split method and the solids removal percentage - because the element has no volume,
biological reactions may not be modeled. For information on monitoring parameters/variables for this
element, please see the Monitoring Data section in the “General Operation” chapter.

Biowin 6 Help Manual Building Configurations • 501

The Monitor items tab of a Point clarifier element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

502 • Building Configurations Biowin 6 Help Manual

The Tags tab of a Point clarifier element

Point Clarifier Operation

The Operation tab, shown below, allows the user to enter configuration specifications for a point clarifier
element.

Biowin 6 Help Manual Building Configurations • 503

The Operation tab of a Point clarifier element

There is an edit box on this tab that is used to enter the Percent solids removal for the point clarifier
element.

Point Clarifier Split Method

The Flow split tab, shown below, allows the user to specify the flow split method for a point clarifier
element.

504 • Building Configurations Biowin 6 Help Manual

The Flow split tab of a Point clarifier element

The method of specifying the flow split for a point clarifier element may be selected from a number of
options. You can specify the flow using a Ratio, Fraction, or Underflow rate by clicking on the corresponding
radio button. If you specify an underflow rate (denoted by the symbol U), it will result in a constant
underflow out the bottom of the point clarifier element. Note that when the point clarifier is operating in
this mode, if the influent flow is less than the set Underflow rate, then all of the influent flow will be sent to
the underflow. If you specify either the Ratio or Fraction split method, then the underflow will be calculated
using the corresponding formula based on the overflow rate (denoted by the symbol O) and the underflow
rate U.
Next to the split method radio group is an edit box; if the split method is selected from the radio group, the
value may be entered in the edit box. Units are shown adjacent to the edit box (where applicable) and the
label of the edit box changes to indicate the chosen split method.
The split method group also contains a Constant check box; if the flow split does not vary with time this box
should be checked. It should be noted that this check box applies only to the split methods listed in the radio
group and is checked by default. If the Constant check box is unchecked, the Pattern… button becomes
active so you can enter a time-varying pattern for the flow split. Clicking this button presents you with the
Edit split itinerary dialog box.
The underflow rate also can be Paced with an influent stream. To select the flow paced option, click on the
Paced at check box. The percentage of the influent flow rate may then be specified, and the influent stream
for flow pacing may be selected from the drop list box which shows all influent streams available for your
system.

Biowin 6 Help Manual Building Configurations • 505

Point Clarifier Power/Costs
The Power/Costs tab, shown below, allows the user to enter specifications for power consumption and
costs for a point clarifier element.

The Power/Costs tab of a Point clarifier element

Checking the Include this unit in power/cost calculation check box activates the Options (for power/cost
calculation) group. To enter power consumption for the point clarifier element, check the Power checkbox.
This activates the Power specification group. Power can be specified on a power per unit flow basis or on a
fixed basis by checking or unchecking the Power per unit flow to this element check box, respectively. The
user can enter a constant value for power or power per unit flow by selecting the Constant value of radio
button and entering a value in the text edit box. Alternatively, the user can enter a power or power per unit
flow pattern by selecting the Scheduled radio button. This activates the Pattern…button. Clicking this button
will open the Power Itinerary editor. To enter a cost for the point clarifier element, check the
Chemicals/other checkbox and enter a value in the text edit box.

Model Clarifier
The Model (secondary) clarifier element is used to model settlement of particulate material in a wastewater
stream containing activated sludge mixed liquor based on a one-dimensional flux model. You may specify
the physical characteristics, the flow split method, and the solids separation operation of the Model clarifier
element. For information on monitoring parameters/variables for this element, please see the Monitoring
Data section in the “General Operation” chapter.

506 • Building Configurations Biowin 6 Help Manual

The Monitor items tab of a Model clarifier element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

Biowin 6 Help Manual Building Configurations • 507

The Tags tab of a Model clarifier element

Common Feature: Locate a Specified Suspended Solids Concentration. A very powerful feature of both
settling models is that a user can specify a suspended solids concentration and the model will locate and
plot the height of that suspended solids concentration within the settler profile.

For example, if a user has measured the concentration of the sludge blanket in a secondary settling tank to
be 2,500 mg/L the model can locate the height of this concentration within its profile, and plot it with time.
This gives users a tool to track the approximate location of the sludge blanket.

Model Clarifier Dimensions

The Dimensions tab, shown below, allows the user to enter the physical dimensions of a model clarifier
element.

508 • Building Configurations Biowin 6 Help Manual

The Dimensions tab of a Model clarifier element

There are two methods for entering the dimensions: by Area and depth, or by Volume and depth. The
method is specified by clicking on the appropriate radio button.
• If you select by Area and depth, the Model secondary clarifier area and depth must be entered in
the Area and Depth text edit boxes.
• If you select by Volume and depth, the Model clarifier volume and depth must be entered in the
Volume and Depth text edit boxes. Units are shown to the right of the edit boxes. The element
name and type, and a picture of the element also are shown.

Model Clarifier Operation

The model clarifier element Operation tab, shown below, allows the user to specify local temperature.

Biowin 6 Help Manual Building Configurations • 509

The Operation tab of a Model clarifier element

A Local temperature also may be specified for a model clarifier element. When you click on the check box
for local temperature, the Specify temperature by radio button group is enabled. You may then specify
either a Constant or Scheduled temperature.
• If constant temperature is selected, you may enter the value in the edit box.
• If scheduled temperature is selected the Pattern… button becomes active. Clicking this button
presents you with the Edit temperature itinerary dialog box.

Model Clarifier Split Method

The Flow split tab, shown below, allows the user to specify the flow split method for a Model clarifier
element.

510 • Building Configurations Biowin 6 Help Manual

The Flow split tab of a Model clarifier element

The method of specifying the flow split for a model clarifier element may be selected from a number of
options. You can specify the flow using a Ratio, Fraction, or Underflow rate by clicking on the corresponding
radio button. If you specify an underflow rate (denoted by the symbol U), it will result in a constant
underflow out the bottom of the model clarifier. Note that when the model clarifier is operating in this
mode, if the influent flow is less than the set Underflow rate, then all of the influent flow will be sent to the
underflow. If you specify either the Ratio or Fraction split method, then the underflow will be calculated
using the corresponding formula based on the overflow rate (denoted by the symbol O) and the underflow
rate U.
Next to the split method radio group is an edit box; if the split method is selected from the radio group, the
value may be entered in the edit box. Units are shown adjacent to the edit box (where applicable) and the
label of the edit box changes to indicate the chosen split method.
The split method group also contains a Constant check box; if the flow split does not vary with time this box
should be checked. It should be noted that this check box applies only to the split methods listed in the radio
group and is checked by default. If the Constant check box is unchecked, the Pattern… button becomes
active so you can enter a time-varying pattern for the flow split. Clicking this button presents you with the
Edit split itinerary dialog box.
The underflow rate also can be Paced with an influent stream. To select the flow paced option, click on the
Paced at check box. The percentage of the influent flow rate may then be specified, and the influent stream
for flow pacing may be selected from the drop list box which shows all influent streams available for your
system.

Biowin 6 Help Manual Building Configurations • 511

Model Clarifier Power
The model clarifier element Power tab, shown below, allows the user to enter mechanical power
specifications.

The Power tab of a Model clarifier element

Power can be specified on a power per unit flow basis or on a fixed basis by checking or unchecking the
Power per unit flow to this element check box, respectively. The user can enter a constant value for power
or power per unit flow by selecting the Constant value of radio button and entering a value in the text edit
box. Alternatively, the user can enter a power or power per unit flow pattern by selecting the Scheduled
radio button. This activates the Pattern…button. Clicking this button will open the Power Itinerary editor.

Model Clarifier Model

The Model tab, shown below, allows the user to enter settling model specifications, as well as specify
whether biological reactions in the clarifier are modeled, and if so, model options such as local kinetic
parameters.

512 • Building Configurations Biowin 6 Help Manual

The Model tab of a Model clarifier element

If you wish to model biological reactions in the ideal clarifier, click on the check box for Biological reaction;
this switches on the activated sludge processes and enables the Local kinetic parameters check box.
If you wish to specify Local kinetic parameters for the ideal clarifier (i.e. kinetic parameters that are
different from those specified under the Project|Parameters… menu), click on the check box for local
kinetic parameters, then click the Edit local kinetic parameters… button to open the Parameter editor
dialog box which allows you to access the various activated sludge model kinetic parameters.
If you wish to specify Local settling parameters for the model clarifier (i.e. settling model parameters that
are different from those specified under the Project|Parameters… menu), click on the check box for local
settling parameters, then click the Edit local settling parameters… button to open the Model parameter
editor dialog box.
The Number of layers used to model the secondary settler can be modified using the spin edit box. The
minimum number of layers allowed for the model is 5, the default is 10. Increasing the number of layers will
improve the resolution of the predicted settler profile.
You also may specify the Top feed layer and the Number of feed layers using spin edit boxes. The feed layer
refers to the layer into which the applied solids loading is placed. Feed points are not allowed in the top or
bottom layers.

Dewatering Unit
The Dewatering unit element is used to simulate the separation of liquid and solids in an influent stream to
increase the solids concentration. You may specify details regarding the flow split method and the solids

Biowin 6 Help Manual Building Configurations • 513

separation operation of the Dewatering unit. For information on monitoring parameters/variables for this
element, please see the Monitoring Data section in the “General Operation” chapter.

The Monitor items tab of a Dewatering unit element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

514 • Building Configurations Biowin 6 Help Manual

The Tags tab of a Dewatering unit element

Dewatering Unit Operation

The Operation tab, shown below, allows you to specify the degree of thickening obtained by the dewatering
unit element.

Biowin 6 Help Manual Building Configurations • 515

The Operation tab of a Dewatering unit element

The edit box on this tab is used to enter the Percent solids removal.

Dewatering Unit Split Method

The Flow split tab, shown below, allows the user to specify the flow split method for a Dewatering unit
element.

516 • Building Configurations Biowin 6 Help Manual

The Flow split tab of a Dewatering unit element

The method of specifying the flow split for a dewatering unit element may be selected from a number of
options. You can specify the flow using a Ratio, Fraction, or Underflow rate by clicking on the corresponding
radio button. If you specify an underflow rate (denoted by the symbol U), it will result in a constant
underflow out the bottom of the dewatering unit. Note that when the dewatering unit is operating in this
mode, if the influent flow is less than the set Underflow rate, then all of the influent flow will be sent to the
underflow. If you specify either the Ratio or Fraction split method, then the underflow will be calculated
using the corresponding formula based on the overflow rate (denoted by the symbol O) and the underflow
rate U.
Next to the split method radio group is an edit box; if the split method is selected from the radio group, the
value may be entered in the edit box. Units are shown adjacent to the edit box (where applicable) and the
label of the edit box changes to indicate the chosen split method.
The split method group also contains a Constant check box; if the flow split does not vary with time this box
should be checked. It should be noted that this check box applies only to the split methods listed in the radio
group and is checked by default. If the Constant check box is unchecked, the Pattern… button becomes
active so you can enter a time-varying pattern for the flow split. Clicking this button presents you with the
Edit split itinerary dialog box.
The underflow rate also can be Paced with an influent stream. To select the flow paced option, click on the
Paced at check box. The percentage of the influent flow rate may then be specified, and the influent stream
for flow pacing may be selected from the drop list box which shows all influent streams available for your
system.

Biowin 6 Help Manual Building Configurations • 517

Dewatering Unit Power/Costs
The Power/Costs tab, shown below, allows you to specify power and cost information for the dewatering
unit.

The Power/Costs tab of a Dewatering unit element

Checking the Include this unit in power/cost calculation check box will activate the Options (for power/cost
calculation) group. To specify power for the dewatering unit, check the Power check box which activates the
Power specifications group. Power can be specified on a power per unit flow basis or on a fixed basis by
checking or unchecking the Power per unit flow to this element check box, respectively. The user can enter
a constant value for power or power per unit flow by selecting the Constant value of radio button and
entering a value in the text edit box. Alternatively, the user can enter a power or power per unit flow
pattern by selecting the Scheduled radio button. This activates the Pattern…button. Clicking this button will
open the Power Itinerary editor. Power specified for the Dewatering unit will be included in the
“Solid/liquid separation/Disinfection Power” category in charts and tables. To specify costs for the
Dewatering unit, check the Chemicals/other check box and entering a value in the text edit box.

Splitter
Splitters divide a stream on a mass / flow (constant density) basis. You may specify physical characteristics of
the splitter and the method used by the Splitter element to split the influent flow. For information on
monitoring parameters/variables for this element, please see the Monitoring Data section in the “General
Operation” chapter.

518 • Building Configurations Biowin 6 Help Manual

The Monitor items tab of a Splitter element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

Biowin 6 Help Manual Building Configurations • 519

The Tags tab of a Splitter element

Splitter Flow Split

The Flow split tab, shown below, allows the user to specify the type of splitter and the flow specifications.

520 • Building Configurations Biowin 6 Help Manual

The Flow split tab of a Splitter element

There are four different splitter types, each of which may be configured from this tab. These are:
1. Conventional
2. Flow paced
3. Router
4. Bypass
A conventional splitter can operate on a constant or pattern basis. To operate in the constant mode, select
the box labeled Constant. Next you must select a method used to split the flow using the Specify split
method radio button group (Ratio, Fraction, Rate in side, or Rate in main). Once you have chosen a split
method, you must enter the value for the ratio, fraction, or flow in the text edit area that will be labeled
according to the choice you have made. If you specify a maximum rate in the side or main output stream
(denoted by the symbols S and M, respectively), it will result in a constant flow to the stream. Note that
when these methods are used, if the influent flow is less than the specified rate, then all of the influent flow
will be sent to the stream for which the rate was specified. If you specify either the Ratio or Fraction split
method, then the output stream flows will be calculated using the corresponding formula based on the side
and main output stream flows.
If the Constant check box is unchecked, the Pattern… button becomes active so you can enter a time-
varying pattern for the flow split. Use the Specify split method radio button group (Ratio, Fraction, Rate in
side, or Rate in main) to choose the split method that you want to set a pattern for. Next, click the Pattern…
button to access the Edit split itinerary dialog box which you may use to enter your pattern.

Biowin 6 Help Manual Building Configurations • 521

Options for a flow paced splitter are found in the Flow pacing group. Select the Paced at check box. You may
now specify the remaining two items required for a flow paced splitter. Enter a number in the text edit area
labeled % of, and then select an influent element as the basis for flow pacing from the drop list box of
influent elements in the configuration. Note that when you select to use a flow paced splitter, the side
stream output is paced as a percentage of the selected influent.
Options for a router are located in the Routing group. Select the Flow router check box. Click on the Routing
pattern… button which will now be enabled to open the Edit router itinerary dialog box. Note that when
you select to use a router, you are using a timed pattern to switch between a fraction of 0 and 1. That is, all
flow goes either to the main or side output stream according to the time interval pattern you specify.
Options for a bypass splitter are located in the Bypass group. Select the Bypass weir check box. When you
do this, you will be able to enter a value in the Flow text edit area. This value will set the maximum
allowable flow in the main output stream. Any flow in excess of this value will bypass the main output
stream and be directed to the side output stream.

Microscreen
For information on monitoring parameters/variables for this element, please see the Monitoring Data
section in the “General Operation” chapter.

The Monitor items tab of a microscreen element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

522 • Building Configurations Biowin 6 Help Manual

The Tags tab of a microscreen element

Microscreen Operation
The Operation tab, shown below, allows the user to specify the solids removal performance of the
microscreen element.

Biowin 6 Help Manual Building Configurations • 523

The Operation tab of a Microscreen element

The Microscreen element applies a % solids capture to all types of solids in the microscreen influent stream.
This capture rate may be a Constant value or Scheduled values; if the Scheduled option is selected then a
Pattern… button becomes active.
You may also specify an Additional % capture of volatile particulate inerts (XI) that is applied only to XI
material in addition to the general % solids capture that is applied to all solids in the microscreen influent.
For example, if a general solids capture of 5% and an XI solids capture of 40% are specified, then 5% (on a
mass rate basis) of all incoming solids types will be retained by the microscreen (e.g. XE, XSP, organisms) and
45% (on a mass rate basis) of all incoming XI will be retained by the Microscreen element.

Microscreen Flow Split

The Flow split tab, shown below, allows the user to specify the flow division leaving the Microscreen
element.

524 • Building Configurations Biowin 6 Help Manual

The Flow split tab of a Microscreen element

The method of specifying the flow split for a microscreen element may be selected from a number of
options. You can specify the flow using a Ratio, Fraction, or Underflow rate by clicking on the corresponding
radio button. If you specify an underflow rate (denoted by the symbol U), it will result in a constant
underflow out the bottom of the microscreen. Note that when the microscreen is operating in this mode, if
the influent flow is less than the set Underflow rate, then all of the influent flow will be sent to the
underflow. If you specify either the Ratio or Fraction split method, then the underflow will be calculated
using the corresponding formula based on the overflow rate (denoted by the symbol O) and the underflow
rate U.
Next to the split method radio group is an edit box; if the split method is selected from the radio group, the
value may be entered in the edit box. Units are shown adjacent to the edit box (where applicable) and the
label of the edit box changes to indicate the chosen split method.
The split method group also contains a Constant check box; if the flow split does not vary with time this box
should be checked. It should be noted that this check box applies only to the split methods listed in the radio
group and is checked by default. If the Constant check box is unchecked, the Pattern… button becomes
active so you can enter a time-varying pattern for the flow split. Clicking this button presents you with the
Edit split itinerary dialog box.
The underflow rate also can be Paced with an influent stream. To select the flow paced option, click on the
Paced at check box. The percentage of the influent flow rate may then be specified, and the influent stream
for flow pacing may be selected from the drop list box which shows all influent streams available for your
system.

Biowin 6 Help Manual Building Configurations • 525

Microscreen Power/Costs
The Power/Costs tab, shown below, allows you to specify power and costs for the microscreen.

The Costs tab of a Microscreen element

Checking the Include this unit in power/cost calculation check box will activate the Options (for power/cost
calculation) group. To specify a Power for the microscreen element check the Power check box. This
activates the Power specifications group. Power can be specified on a power per unit flow basis or on a fixed
basis by either checking or unchecking the Power per unit flow to this element check box, respectively. The
user can enter a constant value for power or power per unit flow by selecting the Constant value of radio
button and entering a value in the text edit box. Alternatively, the user can enter a power or power per unit
flow pattern by selecting the Scheduled radio button. This activates the Pattern…button. Clicking this button
will open the Power Itinerary editor. Power specified for the Microscreen will be included in the “Solid/liquid
separation/Disinfection Power” category in charts and tables. To specify costs for the Microscreen element
check the Chemicals/other check box and entering a value into the text edit box.

Cyclone
For information on monitoring parameters/variables for this element, please see the Monitoring Data
section in the “General Operation” chapter.

526 • Building Configurations Biowin 6 Help Manual

The Monitor items tab of a Cyclone element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

Biowin 6 Help Manual Building Configurations • 527

The Tags tab of a Cyclone element

Cyclone Operation
The Operation tab, shown below, allows the user to specify the solids removal performance of the Cyclone
element.

528 • Building Configurations Biowin 6 Help Manual

The Operation tab of a Cyclone element

There are two input areas on this tab. The first input area allows users to specify the base Percent removal
of particulate state variables. A Constant value or a Scheduled pattern can be entered. If the Scheduled
button is clicked, a Percent removal itinerary editor is available:

The cyclone element percent removal itinerary editor

Biowin 6 Help Manual Building Configurations • 529

The second input area allows users to specify modified removals for selected particulate state variables as a
multiplication factor applied to the base percent removal. Checking the box to the left of a particulate state
variable allows the user to input a multiplication factor for that variable:

Changing the base percent removal multiplication factor for a particulate state variable

Setting a variable’s multiplication factor to a value greater than zero and less than 1 will result in a net
capture rate lower than the base percent removal for that variable. Setting a variable’s multiplication factor
to a value greater than 1 will result in a net capture rate higher than the base percent removal for that
variable.
To edit a multiplication factor that has been changed from 1, the user can double-click on the changed
factor. If a check box for a changed state variable multiplication factor is un-checked, the previously entered
multiplication factor will no longer be applied to the base percent removal (if the check box is re-checked
either immediately or later, the user will be presented with a base factor of 1 to edit).

Cyclone Flow Split

The Flow split tab, shown below, allows the user to specify the flow division leaving the Cyclone element.

530 • Building Configurations Biowin 6 Help Manual

The Flow split tab of a Cyclone element

The method of specifying the flow split for a cyclone element may be selected from a number of options.
You can specify the flow using a Ratio, Fraction, or Underflow rate by clicking on the corresponding radio
button. If you specify an underflow rate (denoted by the symbol U), it will result in a constant underflow out
the bottom of the cyclone. Note that when the cyclone is operating in this mode, if the influent flow is less
than the set Underflow rate, then all of the influent flow will be sent to the underflow. If you specify either
the Ratio or Fraction split method, then the underflow will be calculated using the corresponding formula
based on the overflow rate (denoted by the symbol O) and the underflow rate U.
Next to the split method radio group is an edit box; if the split method is selected from the radio group, the
value may be entered in the edit box. Units are shown adjacent to the edit box (where applicable) and the
label of the edit box changes to indicate the chosen split method.
The split method group also contains a Constant check box; if the flow split does not vary with time this box
should be checked. It should be noted that this check box applies only to the split methods listed in the radio
group and is checked by default. If the Constant check box is unchecked, the Pattern… button becomes
active so you can enter a time-varying pattern for the cyclone element flow split. Clicking this button
presents you with the Edit split itinerary dialog box.
The underflow rate also can be Paced with an influent stream. To select the flow paced option, click on the
Paced at check box. The percentage of the influent flow rate may then be specified, and the influent stream
for flow pacing may be selected from the drop list box which shows all influent streams available for your
system.

Biowin 6 Help Manual Building Configurations • 531

Cyclone Power/Costs
The Power/Costs tab, shown below, allows you to specify power and costs for the cyclone.

The Power/Costs tab of a Cyclone element

Checking the Include this unit in power/cost calculation check box will activate the Options (for power/cost
calculation) group. To specify a Power for the Cyclone element, check the Power check box. This activates
the Power specification group. Power can be specified on a power per unit flow basis or on a fixed basis by
checking or unchecking the Power per unit flow to this element check box, respectively. The user can enter
a constant value for power or power per unit flow by selecting the Constant value of radio button and
entering a value in the text edit box. Alternatively, the user can enter a power or power per unit flow
pattern by selecting the Scheduled radio button. This activates the Pattern…button. Clicking this button will
open the Power Itinerary editor. Power specified for the Cyclone will be included in the “Solid/liquid
separation/Disinfection Power” category in charts and tables. To specify costs for the Cyclone element,
check the Chemicals/other check box and entering a value into the text edit box.

ISS Cyclone
For information on monitoring parameters/variables for this element, please see the Monitoring Data
section in the “General Operation” chapter.

532 • Building Configurations Biowin 6 Help Manual

The Monitor items tab of an ISS cyclone element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

Biowin 6 Help Manual Building Configurations • 533

The Tags tab of an ISS cyclone element

ISS Cyclone Operation

The Operation tab, shown below, allows the user to specify the solids removal performance of the ISS
cyclone element.

534 • Building Configurations Biowin 6 Help Manual

The Operation tab of an ISS cyclone element

The ISS cyclone element applies a % solids capture of inert suspended solids (ISS) to only ISS in the ISS
cyclone influent stream; the mass rate of other particulate state variables is split according to the flow split.
This capture rate may be a Constant or Scheduled value; if the Scheduled option is selected then a Pattern…
button becomes active.

ISS Cyclone Flow Split

The Flow split tab, shown below, allows the user to specify the flow division leaving the ISS cyclone element.

Biowin 6 Help Manual Building Configurations • 535

The Flow split tab of an ISS cyclone element

The method of specifying the flow split for an ISS cyclone element may be selected from a number of
options. You can specify the flow using a Ratio, Fraction, or Underflow rate by clicking on the corresponding
radio button. If you specify an underflow rate (denoted by the symbol U), it will result in a constant
underflow out the bottom of the ISS cyclone. Note that when the ISS cyclone element is operating in this
mode, if the influent flow is less than the set Underflow rate, then all of the influent flow will be sent to the
underflow. If you specify either the Ratio or Fraction split method, then the underflow will be calculated
using the corresponding formula based on the overflow rate (denoted by the symbol O) and the underflow
rate U.
Next to the split method radio group is an edit box; if the split method is selected from the radio group, the
value may be entered in the edit box. Units are shown adjacent to the edit box (where applicable) and the
label of the edit box changes to indicate the chosen split method.
The split method group also contains a Constant check box; if the flow split does not vary with time this box
should be checked. It should be noted that this check box applies only to the split methods listed in the radio
group and is checked by default. If the Constant check box is unchecked, the Pattern… button becomes
active so you can enter a time-varying pattern for the flow split. Clicking this button presents you with the
Edit split itinerary dialog box.
The underflow rate also can be Paced with an influent stream. To select the flow paced option, click on the
Paced at check box. The percentage of the influent flow rate may then be specified, and the influent stream
for flow pacing may be selected from the drop list box which shows all influent streams available for your
system.

536 • Building Configurations Biowin 6 Help Manual

ISS Cyclone Power/Costs
The Power/Costs tab, shown below, allows you to specify power and costs for the ISS Cyclone.

The Power/Costs tab of an ISS Cyclone element

Checking the Include this unit in power/cost calculation check box will activate the Options (for power/cost
calculation) group. To specify a Power for the ISS Cyclone element, check the Power check box. This
activates the Power specification group. Power can be specified on a power per unit flow basis or on a fixed
basis by checking or unchecking the Power per unit flow to this element check box, respectively. The user
can enter a constant value for power or power per unit flow by selecting the Constant value of radio button
and entering a value in the text edit box. Alternatively, the user can enter a power or power per unit flow
pattern by selecting the Scheduled radio button. This activates the Pattern…button. Clicking this button will
open the Power Itinerary editor. Power specified for the ISS Cyclone will be included in the “Solid/liquid
separation/Disinfection Power” category in charts and tables. To specify costs for the ISS Cyclone element,
check the Chemicals/other check box and entering a value into the text edit box.

Mixers
Side Stream Mixer
The side stream mixer combines two streams into a single stream. You may specify details regarding the
physical characteristics of the mixer element. For information on monitoring parameters/variables for this
element, please see the Monitoring Data section in the “General Operation” chapter.

Biowin 6 Help Manual Building Configurations • 537

The Monitor items tab of a Side stream mixer element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

538 • Building Configurations Biowin 6 Help Manual

The Tags tab of a Side stream mixer element

General Mixer
The general mixer combines multiple streams into a single stream. You may specify details regarding the
physical characteristics of the mixer element. For information on monitoring parameters/variables for this
element, please see the Monitoring Data section in the “General Operation” chapter.

Biowin 6 Help Manual Building Configurations • 539

The Monitor items tab of a General mixer element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

540 • Building Configurations Biowin 6 Help Manual

The Tags tab of a General mixer element

Plug Flow Channel

The plug flow channel element allows you to specify the mixing intensity at the metal dosing point. It is
intended to be used in conjunction with metal addition elements. The mixing intensity sets the number of
active adsorption sites on the hydrated metal oxides (HMOs) onto which soluble PO4-P adsorbs. For
information on monitoring parameters/variables for this element, please see the Monitoring Data section in
the “General Operation” chapter.
Important note about the updated chemical phosphorus removal model in BioWin 6.0: This model
requires that metal streams must be added to elements that have volume. It is no longer applicable to add
a metal input stream to a mixing node element. If you want to simulate adding a metal stream to a channel
at your plant, you should use the new Plug Flow Channel element. The Plug Flow Channel element should be
sized appropriately; e.g. it should have a linear flow velocity of between 0.3 and 0.5 m/s, and likely an HRT
on the order of a few minutes. It also may be necessary to increase the velocity gradient in the first zone of
the plug flow channel to reflect turbulent mixing conditions. You can also add a metal input stream directly
to a bioreactor; BioWin will use the velocity gradient it calculates based on factors such as flow through the
reactor, air flow rates, and specified mixing intensity in the chemical phosphorus model calculations.

Biowin 6 Help Manual Building Configurations • 541

The Monitor items tab of a Plug Flow Channel element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

542 • Building Configurations Biowin 6 Help Manual

The Tags tab of a Plug Flow Channel element

Plug Flow Channel Dimensions

The Dimensions tab, shown below, allows the user to enter the physical dimensions of a plug flow channel
element.

Biowin 6 Help Manual Building Configurations • 543

The Dimensions tab of a Plug Flow Channel element

The Length, Width and Liquid depth are entered into the appropriate text edit boxes. The Volume is then
calculated. Units are shown to the right of the edit boxes. The element name and type, and a picture of the
element also are shown.

Note: these dimensions should be set to result in reasonable horizontal flow velocities (e.g. 0.5 m/s or 1.6
ft/s) and retention times since these properties will have a significant impact on the effectiveness of metal
dosing.

Plug Flow Channel Operation

The Operation tab, shown below, allows the user to specify the velocity gradient at the addition point.

544 • Building Configurations Biowin 6 Help Manual

The Operation tab of a Plug Flow Channel element

The Plug Flow Channel element applies a Velocity gradient at addition point. This velocity gradient may be a
Constant or Scheduled value; if the Scheduled option is selected then a Pattern… button becomes active.
Clicking the Pattern… button presents you with the Edit Velocity gradient at addition point itinerary dialog
box.

Pumps
For information on monitoring parameters/variables for this element, please see the Monitoring Data
section in the “General Operation” chapter.

Biowin 6 Help Manual Building Configurations • 545

The Monitor items tab of a Pump element

For information on tags for this element, please see the Customizing the Project Appearance subsection in
the Customizing BioWin section in the “General Operation” chapter.

546 • Building Configurations Biowin 6 Help Manual

The Tags tab of a Pump element

Pumping Power Options

The Pumping power options tab, shown below, allows the user to specify the pumping power options.

Biowin 6 Help Manual Building Configurations • 547

The Pumping power options tab of a Pump element

The method of specifying the pumping power options for a pump element may be selected from a number
of options. You can allow BioWin to determine the pumping power required (Calculate Power) or specify a
Constant power or a Scheduled power by clicking on the corresponding radio button.
If you specify to calculate power, the Pipe & pump specifications button becomes active so you can enter
pump and pipe specifications for calculating power. Clicking this button presents you with the Pump and
pipe specifications dialog box, shown below, where the user can enter the static head, pipe length and pipe
inside diameter into the respective text edit boxes.

The Pump and pipe specifications dialog box

Clicking the Pump efficiency… button opens the Pump efficiency dialog box, shown below, where the user
can specify the constants ‘A’, ‘B’, and ‘C’ in the overall pump efficiency equation. Values can be entered

548 • Building Configurations Biowin 6 Help Manual

directly into the text edit boxes. Note that if you want one efficiency applied over the entire range of
discharge flows, then the ‘B’ and ‘C’ coefficients can be set to zero.

The Pump efficiency dialog box

Clicking the Pipe/configuration details… in the Pump and pipe specifications dialog box presents you with
the Pipe Roughness and fittings dialog box, shown below, where the user can specify parameters for pipe
roughness and fittings.

The Pipe roughness and fittings dialog box

The method of specifying the pipe roughness for the length of pipe specified in the Pump and pipes
specifications dialog box may be selected from a number of pipe material options. You can specify pipe
material and thereby the roughness by clicking on the corresponding material radio button (i.e. PVC/HDPE,
Riveted steel, etc.). Selecting the Custom radio button activates the pipe roughness text edit box so a pipe
roughness value can be entered directly into the text edit box.
The roughness factor for the fittings (i.e. K(fittings)) can either be specified directly or calculated. If the
roughness factor for the fittings is known, it can be directly entered into the K(fittings) – Total minor losses
text edit box. To calculate K(fittings), enter the number of each type of fitting (i.e. Pipe entrance

Biowin 6 Help Manual Building Configurations • 549

(bellmouth), 90o bend, etc.) along the specified pipe length directly into the respective text edit boxes. Then
click the Calculate total K for fittings button. This changes the K(fittings) – Total minor losses text edit box
to show the calculated value.

Note: This section details the use of the pump element for specifying parameters for pumping power
calculations. For technical information about pumping power equations, please see the Power in BioWin
chapter.

If you specify a constant power than the value for power can be entered into the text edit box. If you specify
a scheduled power, the Pattern… button becomes active so you can enter a time-varying pattern for the
power. Clicking this button presents you with the Edit pump power supply itinerary dialog box.

Note: When the power is user specified (i.e. for each of the last two options) BioWin does not calculate the
flow based on the power you have input. It is assumed that the required flow can be delivered by the pump.
The last two options are for the scenario of keeping track of the power consumed by existing pumps at a
wastewater treatment facility.

550 • Building Configurations Biowin 6 Help Manual

Running Simulations

Running Simulations in BioWin

This section provides detailed information about the menu commands available in the Simulate menu of the
main simulator window.

Note: For systems that are difficult to solve, see the Tips for Systems that are Difficult to Solve section in this
chapter.

Check Simulate Data

Use this command to ensure that you have properly specified data for all the elements in your configuration,
and that all the elements in the configuration are connected with pipes. If you have elements in your
configuration that are not connected with pipes, the other commands in the Simulate menu will be grayed
out, and when you choose Check simulate data, the following dialog box will appear to notify you which
elements are not properly connected. The elements that are not connected will be listed in the Incomplete
pipe connections list, and if you click on an element in this group, the missing connection will be displayed
in the Missing connection(s) list.

Dialog box used for checking simulation data

Biowin 6 Help Manual Running Simulations • 551

Note: Invoking this command also shows you the Data not specified for list which contains the names of
elements that you have not yet specified physical and operating parameters for. Even if you wish to use the
default values, you must acknowledge this by viewing the properties of the element if you wish to remove
them from the list. You could do this by closing the dialog box, and accessing the properties for the
elements in the list from the drawing board. However, a quicker method is to double-click on element
names in the Data not specified for list. This will open the properties dialog box for the element you
double-clicked on. Once the properties dialog is closed, you will be returned to the Check simulate data
dialog box and the element that you double-clicked on will have been removed from the list.

Once you have specified data and pipe connections for all elements, all lists in the Check simulate data
dialog box will be empty. You may then invoke other commands in the Simulate menu.

Flow Balance
This command will open the flow solver dialog box, seen below. Note that if you have not specified physical
and operating data for the elements in your configuration, you will be presented with the Check simulation
data dialog box – you can bypass this warning by clicking the Accept button.

Simulator controls and information display for flow balance

• Clicking the Pause button will suspend the flow balance solver at the current time shown.
• Clicking the Play button either begins the flow balance solver or resumes it if the Pause button has
been clicked.
• Clicking the Stop button will terminate the flow balance solver at the current time shown.
• Clicking the Details button shows / hides the flow balance solver information. The information
displayed consists of the iteration number of the two most recent solver iterations, the error of each
iteration (i.e. the maximum difference between the current iteration values and the steady state
solution values), and the time that has elapsed between the two most recent iterations.

Steady State Balance

This command will open the steady state solver dialog box, seen below. Note that if you have not specified
physical and operating data for the elements in your configuration, you will be presented with the Check
simulation data dialog box – you can bypass this warning by clicking the Accept button.

552 • Running Simulations Biowin 6 Help Manual

Simulator controls and information display for steady state analysis

• Clicking the Pause button will suspend the steady state solver at the current time shown.
• Clicking the Play button either begins the steady state solver or resumes it if the Pause button has
been clicked.
• Clicking the Stop button will terminate the steady state solver at the current time shown.
• Clicking the Details button shows / hides the steady state solver information. The information
displayed consists of the iteration number of the two most recent solver iterations, the error of each
iteration (i.e. the maximum difference between the current iteration values and the steady state
solution values), and the time that has elapsed between the two most recent iterations.
The Start from group contains three options for controlling the starting conditions that the steady state
solver uses in obtaining a solution. If you select Seed values, BioWin will use its seeding algorithm to place
numerical seed values in all the elements of a configuration. The seeding algorithm is based on various
factors including the influent loading and the seed sludge age specified on the Numerical Parameters tab
accessed via the Project|Current Project Options… menu command. If you select Current values, whatever
numerical values exist in a configuration’s elements will be used as steady state solver starting values, i.e.
BioWin will not use its seeding algorithm. This option can be useful if you have already solved a steady state
on a complex system and a minor change requiring a new solution has been made. If you have previously
obtained a steady state solution, BioWin will present the option for starting from Last steady state. Quite
often starting from a steady state rather than re-seeding will result in a quick solution.
Note: For more information about the Numerical Parameters tab, please see the Numerical Parameters
section of the “General Operation” chapter.
If the Use complex seed is selected, the following sequence of events takes place:
• The configuration is seeded using the average loading conditions and the user-specified seed sludge
age.
• BioWin begins to run a dynamic simulation using the average loading conditions. Two progress bars
display information about the dynamic simulation – the top bar shows the progress towards the
maximum dynamic simulation time of 20 days, and the bottom bar indicates the “stability” of the
dynamic simulation.
• When one of these criteria is met, the BioWin steady state solver will begin its solution routine using
the current values for seeding. Note that the user may interrupt this process and force the steady
state solver to begin with whatever current values are present before one of the two criteria has
been met.

Biowin 6 Help Manual Running Simulations • 553

Note: The left portion of the main simulator window status bar contains information about whether or not a
steady state solution has been found for the current configuration.

Dynamic Simulation
This command will open the dynamic simulation dialog box, seen below. Note that if you have not specified
physical and operating data for the elements in your configuration, you will be presented with the Check
simulation data dialog box – you can bypass this warning by clicking the Accept button.

Simulator controls and information display

Clicking the Pause button will suspend the dynamic simulation at the current time shown.
Clicking the Play button either begins a dynamic simulation or continues one if the simulator has been
paused (either by pressing the Pause button or by reaching the end of a previous dynamic simulation). If the
Play button is clicked to begin a dynamic simulation, the following dialog box will be seen:

Dialog used to begin a dynamic simulation

554 • Running Simulations Biowin 6 Help Manual

In the Simulate start group, you choose the time at which the dynamic simulation will begin:
• If you select Simulate from project start date then 12:00 AM on the day that you specified as the
simulation start date on the Project information tab accessed from the Project|Info menu command
will be used.
• If you select Continue from then the time at which the previous dynamic simulation was stopped
will be used.
• If you select Simulate from, then you may specify the exact day (using the calendar that appears
when the drop arrow is clicked) and time (using the spin edit box) at which the dynamic simulation
will start. Note that if this option is chosen, then any time series in charts will be cleared or “saved”
in the album depending on your settings. BioWin gives you the option of keeping the time series
plots if the “Display option to store previous time series…” was selected on the Chart options tab of
the Chart master dialog box (Select Tools|Chart master … to access the Chart master).
In the Simulation stop group, there are two methods for specifying the length of the dynamic simulation:
• If you select Simulate for, then you may specify the length of the dynamic simulation in days.
• If you select Simulate until, then you may specify the exact length of the dynamic simulation by
choosing the day (using the calendar that appears when the drop arrow is clicked) and time on that
day (using the spin edit box) at which the dynamic simulation will end.
The Simulate start conditions group contains options that pertain to numerical seeding at the start of the
dynamic simulation:
• If you select Seed values, the simulator will be seeded with default state variable values.
• If you select Current values, then the simulator will be seeded with the current values of state
variables.
• If you select Last steady state (if a steady state solution has been previously obtained), then the
simulator will be seeded with the values of state variables obtained from that previous steady state
solution.
Clicking Start will begin the dynamic simulation using your specified choices.
If the Play button is clicked to restart a dynamic simulation after the simulator has been paused, the
following dialog box will be seen:

Dialog used to continue a dynamic simulation

In the Simulation duration group, you can specify the ending time of the dynamic simulation:

Biowin 6 Help Manual Running Simulations • 555

 • If you select Continue for, then you may specify the length of the dynamic simulation in days. If you
want the simulation to end at the time you specified at the beginning of the simulation (i.e. you
simply want to continue after pausing mid-simulation), do not change this value.
• If you select Continue until, then you may specify the exact length of the dynamic simulation by
choosing the day (using the calendar that appears when the drop arrow is clicked) and time on that
day (using the spin edit box) at which the dynamic simulation will end. If you want the simulation to
end at the time you specified at the beginning of the simulation (i.e. you simply want to continue),
do not change this value.
Clicking Continue will resume your dynamic simulation.

Tips for Complex Systems

By default BioWin uses an adaptive hybrid solver to search for a steady state solution. This solver uses a
combination of a modified Newton-Raphson method and a Decoupled Linear Search algorithm. Typically the
solver will find a solution in less than 15 iterations, although for complex systems this might take longer.

Note: After a system has been solved to a steady state solution it is almost always easier for the solver to
converge on the solution from current values rather than from seed. If a particular organism type is
“washed-out” in a steady state solution then starting from current values may bias the solver against them
and it may be better to start from seed.

If the solver is experiencing difficulties in finding a solution, the parameters used in the solver are adapted
automatically, nevertheless there may be situations where either the solver is still unable to determine the
solution, or the user wishes to change the solver parameters to improve performance. [The solver does not
improve the error value for more than 20-30 iterations, or becomes very slow.] If you are experiencing
difficulties in determining the steady state solution for a particular configuration you have a number of
options.
1. Check that volumes, flows, DO settings, influent concentrations are all valid. Try matching the seed
sludge age of the system. If you are using SRT control, try fixed wastage flow first.
2. Try using the complex seeding method (non SRT control systems). Start your simulation. [Press F6 or
select Simulate|Steady State] This will open the Steady State solver dialog box, check the Use
Complex seed checkbox before pressing the Run button (as shown below).

Press the play button to begin the simulation. BioWin opens a dialog which shows the progress of the
complex seeding. This dialog is shown below.

556 • Running Simulations Biowin 6 Help Manual

The complex seeding essentially performs a dynamic simulation at the steady state conditions. The dialog
box will close automatically when the Dynamic time target is achieved. Generally it is not necessary to wait
for the dialog box to close automatically as a short period of dynamic seeding will usually be sufficient to
improve the performance and the user can press the Try Now! button at any time to start the main solver.
3. A third approach is to try using more conservative settings for the solver. BioWin provides a set of
Conservative parameter defaults (see Steady State Solver Optionsabove) or you can enter your own
selection of parameter values.

Note: Using the conservative values forces the solver to make smaller adjustments which usually increases
the number of iterations but also stops very bad adjustments. These values are stored with the project file,
and do not affect other simulations.

Note: The BioWin default conservative values are particularly applicable to systems in which spontaneous
chemical precipitation (HDP, Struvite) is probable as these reactions have extremely rapid reaction rates.

4. For certain systems it may be better to use only one of the solution techniques. That is rather than
using the hybrid method, use either the Modified Newton-Raphson method or the Decoupled Linear
Search algorithm. The Numerical Parameters tab allows you to select any one of these methods.

Note: For more information about the Numerical Parameters tab, please see the Numerical Parameters
section of the “General Operation” chapter.

Note: The double exponential settler model is generally not well behaved for the Modified Newton-Raphson
method.

5. Simplify the model.

Simplify the model by turning off one (or more) of the options on the Project|Current Project
Options…|Model tab; namely
• pH inhibition for activated sludge kinetics.
• pH calculations.
• Oxygen modeling.
• Chemical precipitations.

Biowin 6 Help Manual Running Simulations • 557

 • Metal precipitation chemistry.
Now try to solve the system, if a solution is achieved then you may start turning the options back on and
resolving starting from the Current values.
6. For very complex configurations with difficulties finding a solution a general step-wise method may
be useful:
• Simulate with pH modeling, limitation, etc. turned off.
• Enable pH modeling, simulate from current values.
• Enable pH limitation, simulate from current values.
• Enable Struvite, Ca-phosphates modeling (if required), simulate from current values.
• Enable metal precipitation modeling (if required), simulate from current values.
Repeat this step-wise method with conservative solver settings, or using only one of the solver methods.
7. If a configuration does not converge in spite of trying the methods described above:
• Consider simplifying the configuration if at all possible.
• Send the configuration (*.bwc file) with the description of the problem (exact steps) for support
to support@envirosim.com)

Note: Under some circumstances merely stopping and then restarting the solver from Current values will
assist the solver. This essentially resets the solver parameters, but provides different seed values.

Note: The Solution not found message is displayed when the solver has:

• Identified a singular matrix – in which case you may be able to solve selecting the Decoupled Linear
Search option on the Numerical Parameters tab.
• Exceeded the maximum number of iterations allowed – you should probably try one of the methods
described above.
• Experienced numerical instability or range problems – you should probably try one of the methods
described above.

Note: For more information about the Numerical Parameters tab, please see the Numerical Parameters
section of the “General Operation” chapter.

If a dynamic simulation is proceeding very slowly, then certain of the tips above also may be applicable. For
example, it may be possible to simplify the model by turning certain model options off – not all model
options are necessary all the time. In the specific case of a model incorporating chemical phosphorus
removal and use of one or more channel elements with very small volumes relative to other flowsheets, in
some cases there may be benefit in switching from the default BDF dynamic simulation method to the
BWHeun method.

558 • Running Simulations Biowin 6 Help Manual

Stopping a Steady State Simulation
If a system is not converging to a steady state solution, you may want to stop the simulation. To do this, click
the “stop” button on the steady state control dialogue box:

Click the “stop” button to stop the steady state solver.

In some cases, BioWin may display the following message:

Message displayed by BioWin when attempting to stop a steady state solution.

If possible, you should wait for this message to close itself – this will happen when BioWin successfully
terminates the computer CPU thread dedicated to the solver. In rare cases, BioWin may have difficulty
closing the thread; in these cases, you can click the “abort” button. In these cases, you should save your file
and restart BioWin.

Biowin 6 Help Manual Running Simulations • 559

Data Output (charts, tables, reports)

BioWin Album
The BioWin Album provides users with a powerful tool for displaying results of simulations and imported
data in a variety of manners. You may display your results in a numerical format using customizable or pre-
configured tables or as charts in a variety of rich graphical formats.
Because these charting capabilities are so powerful, there are three major sections of the manual devoted
to them. For information related to creating charts, please see Creating Charts & Adding Series. For
information on chart formatting, please see Chart Formatting Procedures. Finally, Series Formatting
Procedures contains information detailing the various formatting options for different series styles.
The BioWin album is accessed from the main simulator window via the menu choice View|Album. Note that
once you have set up the album to appear as you desire, closing it will not result in a loss of your changes.
The album and the information it contains are saved along with the BioWin configuration file (.bwc).
The BioWin Album consists of three main parts:
1. Menus
2. Album pages and panes
3. Toolbar
The following sections give an outline of each part.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 561

The BioWin album

Album Menus
The various menus available in the BioWin Album are located at the top of the window. The menus available
are:
• Album
• Database
• View
Each menu may be accessed with either of two methods:
1. Click on the text of the menu, or;
2. Hold down the Alt key on your keyboard and press the letter on the keyboard corresponding to the
underlined letter in the menu title. For example, Alt+A will access the Album menu.

Album pages and panes

Pages are used as “containers” for panes in the BioWin Album. You may have as many pages as you desire in
the album. Only one page at a time may be viewed; you may select a page for viewing by clicking on its tab.
Each page can contain up to four panes, and BioWin offers a number of different pane layouts on any page
as shown in the picture below.

562 • Data Output (charts, tables, reports) Biowin 6 Help Manual

BioWin album page layout gallery

In most cases, the panes on a page are resizable to offer further flexibility. Panes are used as “containers”
for the various information displays in the BioWin Album, i.e.:

• For information related to charts, please see Creating Charts & Adding Series, Chart Formatting
Procedures and Series Formatting Procedures.
• For information on table displays (Table, Rates table, Power table & Cost table) please see Album
Table Displays
• For information on Element Info displays in please see Element Info - Pre-defined Table in Album
Next, several common procedures related to album pages and panes will be covered.

Add a Page to the Album

1. Click Album|Add Page… (you also can access this command by right-clicking on an existing album
page's tab, or clicking the Add page button in the Album toolbar located just below the Album tabs).
2. Click on the pane layout for the page from the gallery of available choices.
3. If you want a page name different from the default given, enter a name for the new page in the New
album page name: text edit area. This is the text that appears in the page tab.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 563

 4. Click OK to finish adding the page.

Duplicate a Page in the Album

1. Select the tab of the album page that you wish to duplicate and right-click.
2. Select Duplicate page from the resulting popup menu.
3. A copy of the page with the same title and a number in parentheses will be placed immediately
following the source page.

Note: You can also do this by clicking the Duplicate page button on the Album Toolbar located just below
the page tabs. The ability to duplicate pages allows you to create charts more rapidly; once you have a chart
set up and formatted as you like you can duplicate it and simply delete its old series and add new ones.

Move a Page in the Album

1. Right-click the tab of the album page that you wish to move (i.e. change order of).
2. Select Move page from the resulting popup menu and you will be presented with the dialog box
shown below.

3. Dialog box used to move pages around in the album

4. The dialog box will list the other pages currently contained in the album. Select the page that you
want to place the page you are moving in front of, and click OK.

Note: If you double-click on a page name listed in the Move page dialog box, the page you are moving will
be placed in front of that page before you click OK. You can use this feature to quickly "try out" several
locations for the page you are moving.

Delete a Page from the Album

1. Click on the tab of the album page you want to delete to make it is the current page.
2. Right-click on the tab of the page you wish to delete and select Delete page (you can also click the
Delete page button in the Album toolbar located just below the Album tabs).

Rename an Album Page

1. Click on the tab of the album page you wish to rename to make it the current page.

564 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 2. Right-click on the tab of the page you wish to rename and select the Rename page… menu item (or
by clicking the Rename page button in the Album toolbar located just below the Album tabs).

Switch Display Types

1. Right-click on the album chart, table, or element information display that you wish to replace with
another type.
2. If you right-click on a chart and select the Chart option you will be presented with the menu shown
below.

Menu option used to switch from chart to table or element information display

3. From the sub-menu, select one of the possible two other types.
4. If you right-click on a table or element information display you will be presented with the menu
shown below.

Menu option used to switch to chart and element information display

5. From the sub-menu, select one of the possible two other types.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 565

Delete a Display
Right-click on the album chart, table, or element information display that you wish to delete.
• If you are deleting a table or element information display, select the Delete Current… option from
the resulting popup menu as shown below.

Menu used to delete current table

• If you are deleting a chart, select the Chart option from the resulting popup, then select Delete
Current Chart…from the resulting flyout.

Menu used to delete current chart

Resize Panes
Hold the mouse cursor over a dividing line adjacent to the album pane that you wish to resize.
• If the dividing line is vertical, your cursor will change to the horizontal resize cursor ( ). Click the
mouse button and drag the dividing line to change to horizontal size of the pane.
• If the dividing line is horizontal, your cursor will change to the vertical resize cursor ( ). Click the
mouse button and drag the dividing line to change the vertical size of the pane.

566 • Data Output (charts, tables, reports) Biowin 6 Help Manual

Note: The panes in the layout that consists of four equally sized panes on a page may not be resized. This is
the only layout where resizing of panes is not permitted.

Printing Album Pages

The Album|Print pages command from the main menu bar should be used when you want to print multiple
or all of the album pages. Selecting this command will present you with the dialog box shown below.

Dialog box used for printing multiple or all of the album pages

The Album pages to print section allows you to choose between printing All X pages (X changes according to
the number of pages in the current album), or a Range of pages (when the option is selected, you may enter
text in the from and to spin edit boxes).
Once you have selected the album pages that you want to print, you can choose between one of four Album
page layout options:
1. The top left option will result in the contents of each album page being printed on an entire page.
For example if an album page contains only one chart, that chart will be printed on an entire page. If
an album page contains two panes with a chart on each, then the two charts will be printed on an
entire page.
2. The top right option will print the contents of each album page to one horizontal half of a page. Each
printed page will contain two BioWin Album pages.
3. The bottom left option will print the contents of each album page to one vertical half of a page in
the report. Each printed page will contain two BioWin Album pages.
4. The bottom right option will print the contents of each album page to one quarter of a page in the
report. Each printed page will contain four BioWin Album pages.
The General section contains a number of generic printing options. You can select your page Orientation to
be Landscape or Portrait. You can specify the Number of copies of each page that you would like to print.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 567

The Printer setup… button will open the printer setup dialog box which will allow you to access the printer’s
properties, set paper size, page orientation, and a number of other printer options (the options presented to
you will be dependent on the printer you have).
Once you are satisfied with your layout settings, click the OK button to print.

Album Toolbar
The Album Toolbar, located at the bottom of the album just below the page tabs, provides short cuts
buttons for many of the page management options described above. It also provides additional
functionality such as rearranging the tab layout, launching simulations from within the Album, and closing
the Album.

Album Table Displays

To allow users more flexibility for displaying information about elements, BioWin also offers the
functionality of creating customized tables for display in the album. In these tables, it is possible to include
all or any combination of the elements in the current configuration. You also may choose the compounds
and/or variables included in the table. Once you have added a table, you may add more elements to it or
remove existing ones if you wish. You also can resize the columns in the table.
A two-pane album page with example tables is shown below.

An album page showing two example tables

Add a Table Display (Concentrations and/or mass rates)

1. Right-click on the blank album pane where you wish to place the table.

568 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 2. Select Table from the resulting popup menu.
3. The Table Editor dialog will open.

Tab used to choose elements for table display

4. From the Elements tree view, select the element(s) that you wish to include in the table.
• You can expand individual element groups, select specific elements, click on them and push the
right-pointing arrow to move them to the Selected elements list; or move entire element groups
over at once by clicking on the element group (e.g. Bioreactor) and clicking the right-pointing
arrow.

Note: If the element you have selected has multiple outputs (e.g. a secondary clarifier), all outputs are
added to the Selected elements list by default. If you do not want one of the outputs (e.g. the underflow of
a secondary clarifier), simply click on the entry in the Selected elements list and press the Delete key on your
keyboard.

• If you want to change the order in which the Selected elements will appear in the table, move
the elements around by clicking on them and clicking the up/down arrows. You can change the
order of a group of elements, by using the Ctrl or Shift key to select the group and then clicking
the up or down arrow. Finally, you can move a selection directly to the top or bottom of the list
by holding the Ctrl key while you click the up or down arrow.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 569

 5. Choose the variables you want to include in the table from the Element specific, Water Chemistry,
State variables, or Combined lists. If you want to add more than one variable from a given group,
you may do so: To select a contiguous group, click the first variable of the group, and while holding
the Shift key, click the last variable of the group. To select non-contiguous variables, hold the Ctrl
key and click the desired variables in succession. You may also simultaneously select variables from
multiple lists.
6. Once you have selected the variables you want in the table, move them to the Selected variables list
by clicking the right-pointing arrow.
• If you want to change the order in which the Selected variables will appear in the table, move
the variables up or down by clicking on them and clicking the up/down arrows. You can change
the order of a group of variables, by using the Ctrl or Shift key to select the group and then
clicking the up or down arrow. Finally, you can move a selection directly to the top or bottom of
the list by holding the Ctrl key while you click the up or down arrow.
7. If you wish to re-add certain variables, place a check in the box labeled Duplicates, and re-add the
variables.
8. Select whether you want to display Concentrations, Mass rates, or Both in your table.
9. If you want to add a blank line between table entries, click the Add blank line button. The blank line
will show as a short dashed line in the Selected elements list. The blank line can be moved up or
down in the list just like other elements. Multiple lines may be added to the list.
10. If you want BioWin to display the total of a table’s columns, click the Add total so far button. The
word “Total” will be added to the Selected elements list. The Total can be moved up or down in the
list just like other elements. Multiple totals may be added to the list; if a total will always totalize
the rows preceding it.
11. If you want to arrange the table so that the selected flowsheet elements are arranged in columns
and the selected variables are in rows, check the box labelled Transpose table.
12. Click OK to finish.

Add a Table Display (Process rates)

1. Right-click on the blank album pane where you wish to place the table.
2. Select Rates table from the resulting popup menu.
3. The Table Editor dialog will open.

570 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 Tab used to choose elements and rates for table display

4. From the Elements list select the element(s) that you wish to include in the table.
5. Once you have selected the elements you want to plot, move them to the Selected elements list by
clicking the right-pointing arrow.
• If you want to change the order in which the Selected elements will appear in the table, move
the elements up or down by clicking on them and clicking the up/down arrows. You can change
the order of a group of elements, by using the Ctrl or Shift key to select the group and then
clicking the up or down arrow. Finally, you can move a selection directly to the top or bottom of
the list by holding the Ctrl key while you click the up or down arrow.
6. Choose a rate or selection of rates from the Process rate names list. To select a contiguous group,
click the first rate of the group, and while holding the Shift key, click the last rate of the group. To
select non-contiguous rates, hold the Ctrl key and click the desired rates in succession.
7. Once you have selected the rates you want in included in the table, move them to the Selected
process rates list by clicking the right-pointing arrow.
• If you want to change the order in which the Selected process rates will appear in the table,
move the rate name up or down by clicking on them and clicking the up/down arrows. You can
change the order of a group of variables, by using the Ctrl or Shift key to select the group and
then clicking the up or down arrow. Finally, you can move a selection directly to the top or
bottom of the list by holding the Ctrl key while you click the up or down arrow.
8. You can add duplicate rates to a table if the box labeled Duplicates is checked.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 571

 9. Click Close to finish.

Add a Table Display (Pre-defined Power table)

1. Right-click on the blank album pane where you wish to place the table.
2. Select Power Table from the resulting popup menu.

3. The Table Editor dialog will open.

572 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 4. Choose the element(s) you want to include in the table. By default, all of the elements appear in the
Selected lists for each of the power categories (i.e. blowers, mixing power, mechanical power etc.).
To remove an element(s) from the Selected list select the element(s) and click the left pointing
arrow. To remove all of the elements from the Selected list, click the double left pointing arrows.
You may also double click on an element to move from one list to another.
5. In the Options group specify if you would like to Show total (of displayed) and Show costs.
6. In the System wide display options group specify if you would like to Show total this activates
options to Show HVAC and Show CHP engine power. If you specify to Show costs and Show total,
then you can also choose to Show service charge and Show peak demand charge.
7. Click the Ok button to create the table and exit the table editor.

Add a Table Display (Pre-defined Cost table)

1. Right-click on the blank album pane where you wish to place the table.
2. Select Cost Table from the resulting popup menu.

3. A Cost Table summarizing the costs associated with each of the cost categories (i.e. power costs,
chemical costs, Fuel (Heating and/or Sale), and sludge costs) will be automatically generated and
added to the Album.

Add a Table Display (Pre-defined Air Supply group table)

1. Right-click on the blank album pane where you wish to place the table.
2. Select Air supply group table from the resulting popup menu.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 573

 3. An Air supply group table summarizing the blower Power and the Intake Pressure, Discharge
Pressure and Intake Airflow used in the calculation of blower power will be automatically generated
and added to the Album.

Edit Table Entries

1. In the album, double-click on any row of the table, or right-click and select Edit Table… from the
resulting popup menu.
2. This returns you to the Table Editor dialog, where you can change the parameters displayed in the
table, change the elements shown in the table, etc.

Resize Table Columns

You can resize columns in a table in one of two ways:
1. Open the album page containing the table you want to resize columns for. Hold your cursor over the
right dividing line of the column you want to resize in the column heading row. When you do this,
your cursor will change to the horizontal resize cursor ( ). Click the mouse and drag the column
dividing line until the column is the desired size.
2. To size a column so that it fits the widest value displayed in that column, simply click on the column
heading. Note that this will undo any resizing you have done with the first method as it sets the
other columns to a “standard” width.

Note: you can change the default width of table columns, so that you do not need to adjust them all the
time. Use the Tools|Customize menu command, and go to the Explorer options. Set the Default width of
the columns to a larger number (e.g. 200), and the alignment of the data using the Align drop list box.

Element Info - Pre-defined Table in Album

BioWin has two preset element information displays for viewing in the album. They provide a quick means
of displaying information about a particular element in your configuration. Like any other information
display, these may be added to any pane on a page.
The two types of element information display are State variable and Summary. Both types of display are
divided into two main sections. The State variable display lists information about all the state variables for
the selected element, including their concentrations and mass flow rates in the left section. The Summary
display lists information about various compounds (e.g. Volatile Suspended Solids, Chemical Oxygen
Demand, etc.) for the selected element, including their concentrations and mass flow rates in the left
section. In the bottom section of the display, element specific information is displayed.

Note: Element specific information includes parameters that are relevant only to certain types of elements.
For example, Solids Loading Rate only applies to settlers, Oxygen Utilization Rate applies only to aerated
bioreactors, etc.

In the right section, both types of display show general information about the selected element such as the
element name, the location in the element from where the compound / state variable data are obtained
(i.e. Output, Underflow), and where appropriate, physical data such as element dimensions and
temperature. You may control the location in the element from where the compound / state variable data
are obtained by clicking the Options button. Note that this may not be appropriate for all element types

574 • Data Output (charts, tables, reports) Biowin 6 Help Manual

since for certain elements (e.g. effluent) the location is irrelevant. For splitters, if you want to see data for
the side stream, you should select the Options|Alt. output option.
Both types of display also allow you to resize the columns in the left section where names, concentrations,
and mass flow rates of state variables / compounds are listed. Also, you can change the space allocated in
the pane for each section by holding your mouse over the vertical or horizontal line which divides the two
sections of the display until the resize cursor appears, and dragging the vertical line.
Example element information displays are shown below.

A "summary" element information display

Biowin 6 Help Manual Data Output (charts, tables, reports) • 575

A "state variable" element information display

Add an Element Info Display From The Album

To add an Element Info display to the BioWin Album starting from an empty album pane:
1. Right-click on the album pane where you want to place an element information display.
2. Select Element info… from the resulting popup menu.
3. In the Elements drop list box, select the element that you want to display information for.
4. In the View type radio button group, select State variable view or Summary view.
5. Click Close to finish.

576 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 Tab used for creation of element information displays

Add an Element Info Display From the Drawing Board

You can also add an Element Info display directly from the drawing board:
1. Click on the element selection tool ( ) from the configure toolbar.
2. Move the cursor over the element on the drawing board for which you wish to add an element
information display. When you do so, the cursor will change to the element selection cursor ( ).
3. Right-click on the element, and select Add to album from the resulting popup menu.
4. From the resulting flyout menu, select either Element info (Summary) or Element info (State
variables). A new page will be added to the album for the element information display you have
selected.

Drawing Board Table Displays

Certain tables only may be added via an element on the drawing board. This section provides details on this
type of table.

Add a Biofilm Reactor Details Table Display

1. Right-click on the media bioreactor that you want to add a details table for.
2. Click on Add to album and choose Details from the resulting pop-out menu.
3. Open the Album, and the biofilm reactor details table will have been added to a new page after any
pages currently in the Album.
4. A biofilm reactor details table shows the concentration of all state variables in each biofilm layer and
the bulk phase. An example of a biofilm details table is shown below:

Biowin 6 Help Manual Data Output (charts, tables, reports) • 577

A biofilm reactor details table added via the drawing board.

Album Chart Sub-Menu

This section provides information about the menu commands available in the Chart sub-menu of the popup
menu that results from right-clicking on a chart in the BioWin album. Note that some of these commands
also may be accessed by right-clicking on a table or element information display, but in this case, they will be
accessible directly from the resulting popup menu as opposed to a sub-menu.

Chart sub-menu

578 • Data Output (charts, tables, reports) Biowin 6 Help Manual

Copy
Use this command to place a copy of the current display (i.e. chart, table, element summary, aeration table)
on the Windows clipboard. This will make the display available for pasting into another application such as a
word processor.

Add To Notes
When this command is invoked for an element information display, table, or aeration table display, BioWin
will place a tab-delimited text version of the table into the Simulation Notes editor. If this command is
invoked for a chart display, you will be prompted to save the chart file in a graphics file format of your
choice, and the file location path will be placed into the Simulation Notes editor for your reference.

Print…
This command will invoke the album display print dialog box, shown below:

Dialog box used for printing album charts, tables, or element information displays

Use the Printer drop list box to select the printer you want to use for printing. The Printer Setup… button
will open the printer setup dialog box which will allow you to access the printer’s properties, set paper size,
page orientation, and a number of other printer options. The Print button will send the print job to the
printer and the printout will match the preview which is shown. The Close button closes this dialog box and
returns you to the album.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 579

Using the Paper Orientation group, specify whether you want the printing to be done on a Portrait or
Landscape page. The print preview gives you an idea of what the printout will look like under each format.
If you do not wish to see the size of the margins for your print job, you may de-select the box labeled View
Margins. You can control the margins using three different methods:
1. Using the Margins (%) Spin Edits, you can adjust each margin as you like. The four Spin Edit boxes
each control the margin that shares its position, that is, the top Spin Edit controls the top margin,
the bottom Spin Edit controls the bottom margin, and so on. When you change a value, you will see
changes in the print preview accordingly.
2. You may drag each margin using the mouse. Position the mouse cursor over the margin you wish to
adjust until the horizontal ( ) or vertical ( ) resize cursor appears. Click the mouse button, hold it,
and drag the margin to the position you wish it to occupy. Notice that when you finish dragging it,
the values in the Margins (%) Spin Edits will have been updated.
3. By moving the object to be printed around on the page. When the mouse cursor takes the form of a
hand ( ), you may click and drag the entire object around on the page until it is in the desired
position. Notice that when you finish dragging it, the values in the Margins (%) Spin Edits will have
been updated.
If after applying any one of these methods of adjusting margins you wish to reset the margins to the default
values, you may do so by clicking the Reset Margins button.
You can use the Chart Detail scroll bar to adjust the text size on your print job. Sliding the scroll towards
More decreases the size of text on your chart and gives greater prevalence to the chart on the printout.
Sliding the scroll towards Normal increases the size of the text on your chart and gives less prevalence to the
chart on the printout.

Note: If you are having trouble with a table print preview not fitting into the margins, ensure that you have a
True Type font (font styles with a TT after their name) selected in your Project | Current Project Options -
Drawing board options tab.

Export…
This command opens the Export tab of the chart editor.

Change to Table…
This command will change the current display from a chart or an element summary to a table (or a new
table if the current display is already a table). Values from the current chart, element summary, or table will
not be placed in the table; this command is simply for changing the type of display in the current pane.

Change to Element info…

This command will change the current display from a Chart or Table to an Element summary (or a different
type of element summary if the current display is already an Element summary). Values from the current
Chart, Element summary, or Table will not be placed in the Element summary; this command is simply for
changing the type of display in the current pane.

580 • Data Output (charts, tables, reports) Biowin 6 Help Manual

Change to Chart
This command will change the current display from a Table or Element summary to a Chart. Values from the
current Element summary or Table will not be placed in the Chart; this command is simply for changing the
type of display in the current pane.

Delete current…
This command will delete the current display from an album pane. This command is useful if you wish to
delete one information display from a multi-pane album page without deleting or changing the displays on
the other panes of the page.

Creating Charts & Adding Series

Charts in BioWin
Charts are used in BioWin to display various types of series. It is possible to change the formatting of certain
chart properties. For more information see Chart Formatting Procedures.

Add a Chart To The Album

1. Open the album by selecting View|Album in the BioWin main window.
2. Add a new page to the album by selecting Album|Add page…
3. From the Select new album page gallery, select the desired layout.
4. Right-click on the pane that you want the chart to occupy.
5. Choose Chart from the resulting popup menu.
6. Alternatively if you would like to add a time series or current value chart directly to the Album
choose Add time series chart… or Add current value chart… from the resulting popup menu.

Series Styles in BioWin

A series may be any one of a variety of styles including:
• Line
• Fast Line
• Point
• Bar (Horizontal and Vertical)
• Area
• Pie
• Surface
Users will find that certain series styles are best suited to specific series types. For example, applying the Pie
series style to time series data is probably not as effective as using the Line or Fast Line series style. Each
series style has its own set of unique formatting options. For further information on changing these
formatting options, see “Series Formatting Procedures”.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 581

Series Available from the Album
BioWin offers users a number of different series types that may be used to plot data. This section outlines
information and procedures related to series types that may be added to a chart from the album.

Time Series (Album)

This series type is used for time series analysis of data. This tab can be used to add multiple Time Series
plots. For example, you quickly can generate a group of series that show the ammonia concentration in each
bioreactor.

Add a Time Series from the Album

1. Right-click on an album chart and click Add Series in the resulting popup menu (if starting from a
blank Album page and the option to add a Chart is selected the “click Add Series” step is bypassed
automatically).

The time series (from album) dialog box

2. On the Time series tab, select the element you wish to plot a variable for from the Elements list at
the bottom of the tab.

582 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 3. You can expand individual element groups, select specific elements, click on them and push the
right-pointing arrow to move them to the Selected elements list; or move entire element groups
over at once by clicking on the element group (e.g. Bioreactor) and clicking the right-pointing arrow.
4. Note that if the element you have selected has multiple outputs (e.g. a secondary clarifier), all
outputs are added to the Selected elements list by default. If you do not want one of the outputs
(e.g. the underflow of a secondary clarifier), simply click on the entry in the Selected elements list
and press the Delete key on your keyboard.
5. If you want to change the order in which the Selected elements will appear in the plot, move the
elements around by clicking on them and clicking the up/down arrows. You can change the order of
a group of elements, by using the Ctrl or Shift key to select the group and then clicking the up or
down arrow. Finally, you can move a selection directly to the top or bottom of the list by holding
the Ctrl key while you click the up or down arrow.
6. Choose a parameter to plot from the Element specific, Water Chemistry, State variables, or
Combined lists. If you want to add more than one variable from a given group, you may do so. To
select a contiguous group, click the first variable of the group, and while holding the Shift key, click
the last variable of the group. To select non-contiguous variables, hold the Ctrl key and click the
desired variables in succession. You may also simultaneously select variables from multiple lists.
Once you have selected the variables you want to plot, move them to the Selected variables list by
clicking the right-pointing arrow. If you want to change the order in which the Selected variables
will appear in the multi time series plot, move the variables up or down by clicking on them and
clicking the up/down arrows. You can change the order of a group of variables, by using the Ctrl or
Shift key to select the group and then clicking the up or down arrow. Finally, you can move a
selection directly to the top or bottom of the list by holding the Ctrl key while you click the up or
down arrow.
7. Specify whether you want the plot to show Concentrations, Flows…, Mass Rates, Composite
Samples, or a Surface plot by clicking the appropriate option button.
8. A preview of the type of series that will be plotted is shown to the left of the Plot selected button. If
you wish to change to another series type, click the preview to open the Time series gallery and
choose the desired series style that you wish to apply. If you want your chart to have a three-
dimensional appearance, ensure that the box labeled 3D is checked and click OK.
9. Click the Plot selected button.
10. Click the Close button to finish.

Note: You can customize BioWin so that the Element specific, Water Chemistry, State variables, and
Combined lists appear in alphabetical order. This can make it easier to find the variable you want to plot. To
do this, check the Sort… boxes on the Chart options tab of the Tools|Chart Master menu. You can also
rapidly locate a variable in any of the lists by clicking in the list and typing the first character/few characters
of the variable name (e.g. click in the State variables list and type “n” to quickly locate the Nitrate N
variable).

Biowin 6 Help Manual Data Output (charts, tables, reports) • 583

Adding a Composite Time Series
Composite series are added via the Time Series interface. The regular steps for adding a time series are
followed, but prior to pressing the Plot selected button, the Composite Samples option button is clicked.
Doing so makes the composite series options available, as shown below.

The time series (from album) dialog box for plotting a Composite samples series.

A composite sample series can be used to plot composite sampling data for a given parameter in one or
more elements. You may specify the sampling period (e.g. a daily composite, a weekly composite, etc.), any
offsets that will take place in the sampling period, and whether you want the data to be flow weighted
average or a simple average.
An important concept is the Composite period. Concentrations (and flows) are monitored by BioWin at the
user-specified plotting interval and the composite of these samples is calculated and plotted at the end of
the Composite period. For example, if you have a 1 day composite period (i.e. a daily composite), and
BioWin is set up to plot or monitor concentrations at a one hour interval, then the composite sample will be
based on 24 “measurements” and will be plotted at the end of each 24 hour period. Note that the sampling
period must be greater than the database data interval, otherwise the sample will not be a composite.
Another important concept is the Offset. This is the amount by which you step into the composite period
when you start simulating.

584 • Data Output (charts, tables, reports) Biowin 6 Help Manual

Note: It should be noted that composite sampling data are not added to BioWin's database.

You may choose to plot flow weighted averages of your samples, or simple averages. If you choose to have
flow weighted average values plotted, the following formula will be used for n points (where Q is flow and C
is concentration):

∑𝑛𝑖=1 𝑄𝑖 𝐶𝑖
𝐹. 𝑊. 𝐴𝑣𝑔. =
∑𝑛𝑖=1 𝑄𝑖
If you choose to have simple average values plotted, then the following formula will be used:
∑𝑛𝑖=1 𝐶𝑖
𝐴𝑣𝑔. =
𝑛

Adding a Surface Series

Surface series can be used for spatial profiles of a given variable. For example, say you have a configuration
with three bioreactors, and you want to show the ammonia profile over the bioreactors. The ammonia
concentration would be plotted on the Y (vertical) axis, the bioreactor number would be plotted on the X
(horizontal) axis, and time would be plotted on the Z axis.
Surface series are added via the Time Series interface. The regular steps for adding a time series are
followed, but prior to pressing the Plot selected button, the Surface Plot option button is clicked. Doing so
makes the surface series options available, as shown below.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 585

The time series (from album) dialog box for plotting a surface series.

The following points describe the two pieces of information you can specify for your surface plot:
• Select the horizontal axis that you want time to be recorded on. If you check the box labeled Time
on Z axis, then time will be recorded on the Z axis (the axis that goes into the screen). If this box is
left unselected, then time will be recorded on the X axis (the horizontal axis).
• Set your Plot resolution. If you want a fine grid, decrease the value in the spin edit box. If you want a
coarse grid, increase the value. Note that fine grids look better, but will increase demand on system
resources.
After pushing the Plot selected… button, the chart needs to be switched to a 3D chart: To do so right-click
on the chart, select Edit options… from the menu and go to the Chart|3D tab. Checking the 3 Dimensions
box switches to a 3-dimensional chart. Increasing the value for 3D % increases the depth of the chart.

Note: The maximum grid size for a surface plot is 2000.

586 • Data Output (charts, tables, reports) Biowin 6 Help Manual

Current Value (Album)
For a group of selected elements (or a single element), a current value series will show the most recent (with
respect to simulation start time) value of a chosen compound. During a dynamic simulation, the series will
be updated and redrawn after each data interval. For a steady-state simulation, the series is updated for
each step of the simulation and, if a steady state solution is found, will represent the final steady-state
values.
Current value plots are best suited to a specific group of the available series styles, such as Bar, Pie, and
Area. As such, the choice of styles in the gallery is limited to these.

Note: It is also possible to plot current values of Mass Rates.

Add a Current Value Series

Right-click on an album chart and click Add Series in the resulting popup menu (if starting from a blank
Album page and the option to add a Chart is selected, the “click Add Series” step is bypassed automatically).
1. Click on the Current value tab of the Add Series dialog box.
2. In the Elements tree view list, select the element(s) that you wish to include in the current value
plot.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 587

 The current value series dialog

• If you wish to include all the elements from a group (for example, all the bioreactors), click
on the group heading and then click the right-pointing arrow to move them all to the
Selected elements list.
• If you wish to include only certain elements from a group (or groups), then click on the plus
sign (+) next to the group heading to expand it, click on the specific element you want to
include, and then click the right-pointing arrow to move it to the Selected elements list.
3. If you want to change the order in which the Selected elements will appear in the current value
plot, move the elements around by clicking on them and clicking the up/down arrows. You can
change the order of a group of elements, by using the Ctrl or Shift key to select the group and then
clicking the up or down arrow. Finally, you can move a selection directly to the top or bottom of the
list by holding the Ctrl key while you click the up or down arrow.
4. Choose a parameter to plot from the Element specific, Water Chemistry, State variables, or
Combined lists. If you want to add more than one parameter from a given group, you may do so. To
select a contiguous group, click the first parameter of the group, and while holding the Shift key,
click the last parameter of the group. To select non-contiguous parameters, hold the Ctrl key and
click the desired parameters in succession. You may also simultaneously select parameters from

588 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 multiple lists. Once you have selected the parameters you want to plot, move them to the Selected
variables list by clicking the right-pointing arrow. If you want to change the order in which the
Selected variables will appear in the plot, move the variables up or down by clicking on them and
clicking the up/down arrows. You can change the order of a group of parameters, by using the Ctrl
or Shift key to select the group and then clicking the up or down arrow. Finally, you can move a
selection directly to the top or bottom of the list by holding the Ctrl key while you click the up or
down arrow.
5. Specify whether you want the plot to show Concentrations/Flows or Mass Rates by clicking the
appropriate option button.
6. A preview of the type of series that will be plotted is shown to the left of the Plot selected button. If
you wish to change to another series type, click the preview to open the Current value series gallery
and choose the desired series style that you wish to apply. If you want your chart to have a three-
dimensional appearance, ensure that the box labeled 3D is checked and click OK.
7. Click the Plot selected button.
8. Click the Close button to finish.

Note: You can customize BioWin so that the Element specific, Water Chemistry, State variables, and
Combined lists appear in alphabetical order. This can make it easier to find the variable you want to plot. To
do this, check the Sort… boxes on the Chart options tab of the Tools|Chart Master menu. You can also
rapidly locate a variable in any of the lists by clicking in the list and typing the first character/few characters
of the variable name (e.g. click in the State variables list and type “n” to quickly locate the Nitrate N
variable).

Special Series (Album)

BioWin comes with some plots that are generated semi-automatically. These include Process volume
fractions, Total suspended solids Mass fractions, and retention time (SRT, HRT plots). For Process volume
fraction and TSS Mass fraction plots, you only are required to select the elements that you want included in
the plots. BioWin then performs the necessary calculations and generates the plot.
For dynamic SRT plots, you can select from one of the calculated SRTs as previously defined on the
Calculators tab. You then may customize the appearance of the chart using BioWin's powerful chart and
series formatting tools.

Add a Special Series From the Album

If you want to add a process volume or mass fraction series:
1. Right-click on an album chart and click Add Series in the resulting popup menu.
2. Click on the Special tab of the Add Series dialog box.
3. In the Elements tree view, select the element(s) that you wish to include in the special plot.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 589

 The special series (from album) dialog

• If you wish to include all the elements from a group (for example, all the bioreactors), click
on the group heading and then click the right-pointing arrow to move them all to the
Selected elements list.
• If you wish to include only certain elements from a group (or groups), then click on the plus
sign (+) next to the group heading to expand it, click on the specific element you want to
include, and then click the right-pointing arrow to move it to the Selected elements list.
4. If you want to change the order in which the Selected elements will appear in the special plot, move
the elements around by clicking on them and clicking the up/down arrows.
5. When you are satisfied with the order of the included elements, click on the Plot volume pie button
to generate a pie series showing the volume fraction of each selected element, or click on the Plot
mass pie button to generate a pie series showing the mass fraction of each selected element.
6. Click the Close button to finish.

590 • Data Output (charts, tables, reports) Biowin 6 Help Manual

If you want to add a time series plot of a calculated retention time (SRT, HRT):

Note that an SRT or HRT calculation has been defined. Please see SRT Calculation or HRT Calculation for
instructions.

7. Right-click on an album chart and click Add Series… in the resulting popup menu.
8. Click on the Special tab of the Add Series dialog box.
9. In the Retention time calculators group of the Other plots section, select the calculated SRT or HRT
that you want to plot, and click the Plot… button.
10. From the Time series gallery, choose the desired series style that you wish to apply. If you want
your chart to have a three-dimensional appearance, ensure that the box labeled 3D is checked and
click OK.
11. Click the Close button to finish.

Power/Energy consumption (Album)

Power/Energy consumption plots can be generated semi-automatically in BioWin. These include:
Power Demand Distribution plots
• Pie plot of instantaneous power demand
• Bar plot of instantaneous power demand
• Bar plot of Monthly peak demand
Time Series plots
• Instantaneous power by category
• Total and net instantaneous power
• Energy consumption (Daily)
• Energy consumption (Monthly)
• Energy consumption (Yearly)
• Energy consumption
For power demand distribution and time series plots, you are only required to select the elements that you
want included in the plots. BioWin then performs the necessary calculations and generates the plot. You
then may customize the appearance of the chart using BioWin's powerful chart and series formatting tools.
The Monthly peak demand chart gets generated automatically. This chart shows past current values for the
monthly peak demand history and will move forward in time if a dynamic simulation is selected.

Adding a Power/Energy consumption Plot to the Album

If you want to add a Current Power Distribution plot:
1. Right-click on an album chart and click Add Series in the resulting popup menu.
2. Click on the Power/Energy consumption tab of the Add parameters for plotting dialog box.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 591

 The Power/Energy consumption (from album) dialog

3. Choose the element(s) you want to include in the plot. By default, all of the elements appear in the
Selected lists for each of the power categories (i.e. blowers, mixing power, mechanical power etc.).
Note the power categories displayed in the Power/Energy consumption tab will vary depending on
your specific configuration.
4. To remove an element(s) from the Selected list of a power category select the element(s) and click
the left pointing arrow. To remove all of the elements from the Selected list, click the double left
pointing arrows. If all of the elements are removed from the Selected list of a power category the
respective category will not be included in the plot.
5. In the Power Demand Distribution group, you can choose a Pie or a Bar plot by selecting the
appropriate radio button.

592 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 6. Use the Labels (marks) radio button group to specify if the distribution plot labels should show
Name and kW or Name and %.
7. When you are satisfied with the list of selected elements and the plot and label type, click the
Instantaneous power distribution button to generate a pie or bar chart illustrating the current
power demand distribution for the project.
8. Click the Close button to finish.

Note: If the option to Include HVAC power is checked HVAC will also appear as a category in the Power
Distribution plots

If you want to add a Monthly peak demand plot:

9. Right-click on an album chart and click Add Series in the resulting popup menu.
10. Click on the Power/Energy consumption tab of the Add parameters for plotting dialog box.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 593

 The Power/Energy consumption (from album) dialog

11. Choose the Monthly peak demand button.

12. Click the Close button to finish.

Note: This plot shows the peak 15-minute power demand for each month over the most recent 12 months
of simulation; this facilitates calculating and checking demand charges for the subsequent month. Although
a current value bar plot is shown indicating the past monthly current values of the peak demand, this plot
will move forward in time during a dynamic simulation. After a month of simulation, a new bar will appear
indicating the last month’s peak demand. It can also be re-formatted to take the form of a line plot if
desired.

594 • Data Output (charts, tables, reports) Biowin 6 Help Manual

If you want to add one of the time series power/energy consumption plots [Instantaneous power
consumption (by category), Total instantaneous power, Net instantaneous power, Energy consumption (i.e.
daily, monthly, yearly, and total)]:
13. Right-click on an album chart and click Add Series… in the resulting popup menu.
14. Click on the Power/Energy consumption tab of the Add Parameters for plotting dialog box.

The Power/Energy consumption (from album) dialog

15. Choose the element(s) you want to include in the plot. By default, all of the elements appear in the
Selected lists for each of the power categories (i.e. blowers, mixing power, mechanical power etc.).
Note the power categories displayed in the Power/Energy consumption tab will vary depending on
your specific configuration.
16. To remove an element(s) from the Selected list of a power category select the element(s) and click
the left pointing arrow. To remove all of the elements from the Selected list, click the double left

Biowin 6 Help Manual Data Output (charts, tables, reports) • 595

 pointing arrows. If all of the elements are removed from the Selected list of a power category the
respective category will not be included in the plot.
17. In the Time series plots group, select which Axis you would like to plot the time series on (e.g. left)
by choosing either the Left or Right radio button.
18. To generate a time series of the instantaneous power in each power category click the
Instantaneous power by category button.
19. To generate a time series for the total and net instantaneous power, select the appropriate axis (e.g.
left) and click the Total and net instantaneous power button. Note the net power deviates from the
total power only when CHP is specified in the Anaerobic Digester element and the user chooses to
use the power generated through CHP onsite (See Plotting Power with CHP example).
20. To track the total amount of power consumed per day or the daily energy consumption, select the
appropriate axis (e.g. right) and click the Energy consumption (Daily) button.
21. To track the total amount of power consumed per month or the monthly energy consumption,
select the appropriate axis (e.g. right) and click the Energy consumption (Monthly) button. Note this
will add a series that plots the accumulated energy consumption each day of the month. This series
will automatically reset at the start of each month.
22. To track the total amount of power consumed per year or the yearly energy consumption, select the
appropriate axis (e.g. right) and click the Energy consumption (Yearly) button. Note this will add a
series that plots the accumulated energy consumption each day of the year. This series will
automatically reset at the start of each year.
23. To track the total amount of power consumed over time or the energy consumption, select the
appropriate axis (e.g. right) and click the Energy consumption button. Note this will add a series that
plots the accumulated energy consumption over time.
24. When you are satisfied with your time series selection click the Close button to finish.

Note: If the option to Include HVAC power is checked HVAC will also appear as a category in the Power
Distribution plots.

Costs (Album)
Costing plots are also generated automatically in BioWin. These include:
Steady state/current value Cost Distribution plots
• Pie plot of current cost distribution
• Bar plot of current cost distribution
Dynamic Time Series plots
• Energy costs
• Consumption charge
• Service charge
• Peak demand charge
• Total cost (consumption + demand + service)

596 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 • Cumulative total cost (Yearly)
Additional Plots
• Energy consumption charge ($/kwh)
• Sludge disposal costs
• Instantaneous sludge disposal costs
• Cumulative sludge disposal costs (Yearly)
• Chemical costs
• Instantaneous chemical costs
• Cumulative chemical costs (Yearly)
• CHP power credit
• Instantaneous CHP power credit
• Cumulative CHP power credit (Yearly)
• Fuel costs
• Instantaneous fuel costs
• Cumulative fuel costs (Yearly)
• Total costs
• Instantaneous total operating cost
• Cumulative total operating cost (Yearly)
For cost distribution and time series plots, you are only required to select the chart options or the series you
want included in the plots. BioWin then performs the necessary calculations and generates the plot. You
may customize the appearance of the chart using BioWin's powerful chart and series formatting tools.

Add a Costs Plot or Series to the Album

If you want to add a Cost Distribution plot:
1. Right-click on an album chart and click Add Series in the resulting popup menu.
2. Click on the Costs tab of the Add parameters for plotting dialog box.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 597

 The Costs (from album) dialog

3. In the Cost Distribution group, you can choose a Pie or a Bar plot by selecting the appropriate radio
button from the Plot type options.
4. Use the Labels (marks) radio button group to specify if the distribution plot labels should show
Name and value or Name and %.
5. When you are satisfied with the plot and label type, click on the Current cost distribution button to
generate a pie or bar chart illustrating the current cost distribution for the project.
6. Click the Close button to finish.
If you want to add a time series plot of energy costs, sludge disposal costs, chemical costs, CHP power
credit, Fuel costs, Additional plots, or Total costs:
7. Right-click on an album chart and click Add Series… in the resulting popup menu.

598 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 8. Click on the Costs tab of the Add Parameters for plotting dialog box.

The Costs (from album) dialog

9. In the Time series plots group, select the series you would wish to plot.
Energy costs
• To generate a time series for energy consumption ($/hour), click the Consumption charge
button. The energy consumption series represents the product of the total power demand (kW)
and the specified Electricity costs ($/kwh).
• To track the service charge ($), click the Service charge button. This plots the Service charge
specified under Project|Costs/Energy|Electricity… in the Other Charges tab. Note the service
charge gets automatically plotted to the right axis.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 599

 • To track the peak demand charge ($), click the Peak demand charge button. For the first month
(until a month boundary is crossed) of simulation, this series plots the product of the Peak
demand charge and the Base Demand specified under Project|Costs/Energy|Electricity… in the
Other Charges tab. For the subsequent months of operation, the base demand is determined
from the peak demand observed in the previous month (the simulator samples the power
demand every 15 minutes to determine the peak demand). The peak demand history can be
plotted by selecting the Monthly peak demand button on the Power/Energy consumption tab
of the Add parameters for plotting dialog box. The Peak demand charge is automatically plotted
to the right axis.
• To generate a time series of the Total energy costs ($/hour), click the Total cost (consumption +
demand + service) button. This plots the sum of the Consumption charge, the Service charge
and the Peak demand charge. The Service charge and Peak demand charge are converted from
($/month) to ($/hour).
• To track the total cost of power over a year or the yearly energy consumption cost, click the
Cumulative total cost (Yearly) button. This will add a series, plotted to the right axis, which
accumulates the cost of energy consumption each day of the year. This series will automatically
reset at the start of a new year.
Additional plots
• To generate a time series illustrating the specified electricity consumption charge, click the
Energy consumption charge ($/kwh) button.
• If you wish to show the electricity consumption charge for the most recent day only, select the
Scrolling (One day only) checkbox and click the Energy consumption charge ($/kwh) button.
Sludge disposal costs
• To generate a time series of the instantaneous sludge disposal costs, click the Instantaneous
sludge disposal costs button.
To track the total cost of sludge disposal per year, click the Cumulative sludge disposal costs (Yearly)
button. This will add a series, plotted to the right axis, which accumulates the cost of sludge disposal each
day of the year. This series will automatically reset at the start of a new year.
Chemical costs
• To generate a time series of the instantaneous chemical costs, click the Instantaneous chemical
costs button.
To track the total cost of chemicals per year, click the Cumulative chemical costs (Yearly) button. This will
add a series, plotted to the right axis, which accumulates the sludge disposal cost each day of the year. This
series will automatically reset at the start of a new year.
CHP Power credit
• To generate a time series of the instantaneous CHP power credit costs, click the Instantaneous
CHP power credit button.
• To track the total power credit costs over a year, click the Cumulative CHP power credit (Yearly)
button. This will add a series, plotted to the right axis, which accumulates the power credit each
day of the year. This series will automatically reset at the start of a new year.

600 • Data Output (charts, tables, reports) Biowin 6 Help Manual

Note: CHP power credit costs only apply when the user chooses to Sell all CHP Engine power generated. This
is specified under Project|Costs/Energy|Combined Heat and Power (CHP)…

Fuel costs
• To generate a time series of the instantaneous fuel costs, click the Instantaneous fuel costs
button.
• To track the total fuel costs over a year, click the Cumulative fuel costs (Yearly) button. This will
add a series, plotted to the right axis, which accumulates the fuel costs each day of the year.
This series will automatically reset at the start of a new year.

Note: Fuel costs only apply when heating is required in an Anaerobic Digester and/or Thermal Hydrolysis
unit and the Boiler (Fuel) heating method is specified. Fuel costs include the cost of the required heating
fuel and the cost of selling the biogas generated in an Anaerobic Digester if the Sell excess gas (all gas if
“Flare/Sell all” selected) is specified.

Total costs
• To generate a time series of the instantaneous total operating costs, click the Instantaneous
total operating cost button.
• To track the total operating cost over a year, click the Cumulative total operating cost (Yearly)
button. This will add a series, plotted to the right axis, which accumulates the total operating
costs each day of the year. This series will automatically reset at the start of a new year.
10. When you are satisfied with your time series selection click the Close button to finish.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 601

Function Series (Album)
This section gives an overview of the general concept behind a Function series, outlines the basic procedure
for adding a Function series to a chart, and gives detailed descriptions of the Function series types available
in BioWin.
A function is a series type available from the album that uses one or more existing series in a chart as its
data source in order to perform a functional operation. For example, if you have two line series ‘A' and ‘B’
and you apply the ADD function to those series, a third series ‘C’ will be generated which has the sum of
series ‘A’ and ‘B’ values as its data source. Note that some of the functions available are able to use multiple
series as inputs (e.g. the multiply function), while other functions may not have multiple series as inputs
(e.g. the momentum function). Once a Function series has been added to a chart, it can be formatted and
manipulated just like a regular series.
If a Function series uses a single series as its data source then it may allow the user to specify a Period. The
period refers to the repetition period of the chosen function behavior. There are two ways in which the
period may be specified, namely; Number of points and Time range (Time series). The period is used to
control how the function is applied. For example, say you have a series with data for an entire year. The
average of all points for the year will yield one value (the year’s average) that may be displayed as a flat line
across the chart.

To do this you can select a period of 0 points or a Time range of One Year. If you are interested in the
monthly average, then it is easiest to use a Time range of One Month.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 603

It is possible to approximate this using the Number of points method by determining the approximate
number of sampling points in the month. For example, if you were using an hourly data interval you could
plot a 30 day average by choosing 720 (24x30) points.
If you choose the Number of points option then setting the period to a value of 0 means that all points in
the series will be used and the function will only be calculated once. Setting the period to a value of 1
means that each point in the series will be used and the function will be calculated n times for n points.
Setting the period to a value of 2 means that the function will be calculated on each successive group of two
points so that the function will be calculated n/2 times for n points. In general, setting the period to a value
of p for n points means that the function will be calculated n/p times.
If you choose the Time range (Time series) option then you can select from the BioWin “pre-defined” time
periods to get daily, monthly, or yearly averages. However you must take care to ensure that the data
interval is smaller than the “range” that you select because the function is based on the source series and
gets all of its information from that series (as opposed to simulation results). For example, if your data
interval is 6 hours and you choose a Time range of Two Hours for the period then the results are not
meaningful as shown below.

Add a Function Series

1. Right-click on the chart and click Add Series in the resulting popup menu.
2. On the Functions tab, click the New Function… button.

604 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 The function series dialog (Selection of New Function…)

3. Choose the function that you wish to apply from the BioWin Functions gallery and click the OK
button.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 605

 The Function gallery

4. From the Available list, select the series that you wish to use as the function series data source and
move them to the Selected list in one of the following ways:
• You may move all of the series by clicking on the button marked with two right-pointing
chevrons.
• You may move contiguous multiple series by clicking on the first desired series, and while
holding down the Shift key, double-clicking the last desired series.
• You may move non-contiguous multiple series by holding the Ctrl key, clicking on the desired
series, and double-clicking on the last desired series.
• You may move series one at a time by either double clicking on each series or clicking on each
series and then clicking the button marked with one right-pointing chevron.
You may also use all of these techniques for removing series from the Selected list, using the buttons
marked with left-pointing chevrons.

606 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 The function series dialog (Selection of Series)

5. For certain function types, you may be presented with other options such as Period, Fitted Curve
Order, Weighted, or Weight %. Set these to the appropriate value. For more information on these
parameters, refer to the section regarding the specific function you have chosen.
6. If you wish, you may enter a name for the function series in the Series Name text edit area.
7. When you are satisfied with your function series settings, click the Close button to finish. At any
point before this final step you may change the type of function you are applying using the Function
drop list box.

Detailed Description of Functions

Add function

This function adds data from one or more series.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 607

If only one series is defined for the add function, only values for that series will be used in function
calculations. For example, if you have a series ‘A’ and you apply the add function to it with a period of 0,
then the resulting function series will be a flat line representing the total of all the values for series ‘A’.
If two or more series are defined for the add function, values for all the series defined will be used in
function calculations. For example, if you have two series ‘A’ and ‘B’ and you apply the add function to
them, the resulting function series will be a line with points corresponding to the sum of each pair of ‘A’ and
‘B’ values.

Add a constant function

This function allows you to add a specified constant value to one or more series. If there is only one source
series with n data points and period p, then:
𝑛

if 𝑝 = 0 then 𝐹 = 𝑐 + ∑ 𝑌𝑖
𝑖=1

if 𝑝 = 1 then 𝐹𝑖 = 𝑐 + 𝑌𝑖
𝑝−1

if 𝑝 > 1 then 𝐹𝑖 = 𝑐 + ∑ 𝑌𝑖∙𝑝−𝑗

𝑗=0

and when 𝑝 <> 0 then 𝑖 = 1 … (𝑛⁄𝑝)

where

𝐹𝑖 = the function value at point 𝑖

𝑐 = the specified constant
𝑌𝑘 = the 𝑌 value of the source series at point 𝑘
𝑝 = the specified period

If there is more than one source series then the function will have 𝑛 values according to the following
formula:
𝑚

𝐹𝑖 = 𝑐 + ∑ 𝑌(𝑗,𝑖)
𝑗=1

where

𝐹𝑖 = the function value at point 𝑖

𝑐 = the specified constant
𝑚 = the number of source series specified
𝑌(𝑗,𝑖) = the 𝑌 value of the source series 𝑗 at point 𝑖x

Average function

608 • Data Output (charts, tables, reports) Biowin 6 Help Manual

The average function takes the numerical average of values for one or more series.
If only one series is defined for the average function, only values for that series will be used in function
calculations.
∑𝑝𝑖=1 𝑌
if 𝑝 ≠ 0 then 𝑌̅ =
𝑝
∑𝑛𝑖=1 𝑌
if 𝑝 = 0 then 𝑌̅ =
𝑛
where 𝑝 = number of points in the defined period 𝑎𝑛𝑑
𝑛 = number of points in the series

For example, if you have a series ‘A’ and you apply the average function to it with a period of 0, then the
resulting function series will be a flat line representing the average of all the values for series ‘A’.
If two or more series are defined for the average function, values for all the series defined will be used in
function calculations. For example, if you have two series ‘A’ and ‘B’ and you apply the average function to
them, then the resulting function series will be a line with points corresponding to the average of each pair
of ‘A’ and ‘B’ values.

Divide function

The divide function divides data in one series by data from another series.
This function requires at least two input series. The second series defined for the function is the
denominator; therefore the order in which the series are placed in the Selected list is important. For
example, if you have two series ‘A’ and ‘B’ defined for the divide function in that order, the resulting
function series will be a line with points corresponding to the division of each pair of (‘A’ / ‘B’) values.
If you add more than two series then the first series will be divided by the second, then that result is divided
by the third, and so on.

Count function
The count function returns the number of points in an input data series. This function does not apply to
multiple input series. If more than one series is placed in the Selected list, only the first will be used. Note
also that since the function needs to look at each point in the input series, no choice is given as to what the
period is set to.
For example, say that a series ‘A’ with 100 data points is the selected series for the count function. The
resulting function series will be a flat line across the chart originating at 100 on the vertical axis.

Cumulative function

The cumulative function adds each point of an input data series in succession to give a total cumulative
value for the input series values. Since this function needs to look at each data point in the input series, no
choice is given as to what the period is set to.
For example, say a series ‘A’ is selected for the cumulative function. The resulting cumulative function series
will be a line originating at the same location as the first point in series ‘A’ with each successive point
representing the “running total” of series ‘A’.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 609

If more than one series is selected, then each point of the cumulative function represents the sum of the
“running totals” for each series.

Curve fit function

The curve fit function performs a polynomial Gaussian calculation on the input series data and draws a
smooth curve over the input series points. Note that you are not asked to define a period for the curve
fitting function, as the function requires that all points be used in order to perform a proper fit. Also, this
function does not apply to multiple series.
You must specify the Fitted Curve Order that you wish to apply to your data. This is the order of the
polynomial that will be fit to the data. For example, entering a value of 2 for this parameter means that a
quadratic polynomial will be fit to the data. Entering 3 will attempt to fit a cubic polynomial, and so on. Note
that the maximum curve order calculated by BioWin is 15.

Note: The “order” of a polynomial may also be referred to as its “degree”.

Exponential average function

This function calculates an exponentially weighted moving average according to the following formula:
̅𝑖 = 𝑌̅𝑖−1 ∙ (1 − 𝑤) + 𝑌𝑖 ∙ 𝑤
𝑌
where
̅𝑖 = the average at series point 𝑖
𝑌
𝑌̅𝑖−1 = 𝑡ℎ𝑒 average calculated using the (𝑖 − 1) points
𝑤 = the specified weighting factor
𝑌𝑖 = the current value of the series
High weighting factors give more weight to recent series values, and low weight factors give more weight to
historical series points.

High function

The high function picks out the maximum value of one or more series.
If two or more series are defined for the high function, values for all the series defined will be used in
function calculations at each period point. For example, if you have two series ‘A’ and ‘B’ and you apply the
high function to them, then the resulting function series will be a line with points corresponding to the
maximum of each pair of ‘A’ and ‘B’ values.

Low function

The low function picks out the minimum value of one or more series.
If two or more series are defined for the low function, values for all the series defined will be used in
function calculations at each period point. For example, if you have two series ‘A’ and ‘B’ and you apply the
low function to them, then the resulting function series will be a line with points corresponding to the
minimum of each pair of ‘A’ and ‘B’ values.

Moving average function

610 • Data Output (charts, tables, reports) Biowin 6 Help Manual

A p period moving average function provides a calculated average value for the current and preceding (p-1)
points according to the following formula:
𝑝
1
̅𝑖 = ∑ 𝑌𝑖−𝑗+1
𝑌
𝑝
𝑗=1

where
̅𝑖 = the moving average of the 𝑌 values at series point 𝑖
𝑌
𝑝 = the specified moving average period
𝑌𝑘 = the 𝑌 value of the series at point 𝑘
You also are given the option to calculate a weighted moving average, according to the following formula:
∑𝑝𝑗=1 𝑌𝑖−𝑗+1 ∙ 𝑋𝑖−𝑗+1
̅𝑖 =
𝑌
∑𝑝𝑗=1 𝑋𝑖−𝑗+1
where
̅𝑖 = the moving average at series point 𝑖
𝑌
𝑋𝑖 = the current 𝑋 value of the series
𝑝 = the specified moving average period
𝑌𝑘 = the 𝑌 value of the series at point 𝑘
In contrast to the ordinary moving average where all of the preceding data points are weighted equally, for
the weighted average the most recent points are weighted more heavily and on the basis of the value of X
rather than on the number of points. This may be useful for calculating a moving average on imported data
series in which the X values are not evenly spaced.

Multiply function

The multiply function multiplies data for as many series as you like.
If two or more series are defined for the multiply function, values for all the series defined will be used in
function calculations. For example, if you have two series ‘A’ and ‘B’ and you apply the multiply function to
them, then the resulting function series will be a line with points corresponding to the product of each pair
of ‘A’ and ‘B’ values.

Subtract function
The subtract function subtracts data in one series from another series.
This function requires two input series. The second series defined for the function will be subtracted from
the first, so the order in which the source series are placed in the Selected list is important. For example, if
you have two series ‘A’ and ‘B’ defined for the subtract function in that order, the resulting function series
will be a line with points corresponding to the subtraction of each pair of ‘A’ and ‘B’ values.

Trend function

The trend function fits a trend line to data points. This function does not apply to multiple series, so if more
than one series is placed in the Selected list, a trend line will be fit to the first in the list. Also, since this

Biowin 6 Help Manual Data Output (charts, tables, reports) • 611

function requires that each point in the input data series be used, no choice is given as to what the period
may be.

Multiply with a Constant

This function allows you to multiply a series or a number of series by a specified constant value.
If there is only one source series with 𝑛 data points and period, 𝑝 then:
𝑛

if 𝑝 = 0 then 𝐹 = 𝑐 × ∑ 𝑌𝑖
𝑖=1

if 𝑝 = 1 then 𝐹𝑖 = 𝑐 × 𝑌𝑖
𝑝−1

if 𝑝 > 1 then 𝐹𝑖 = 𝑐 × ∑ 𝑌𝑖∙𝑝−𝑗

𝑗=0

and when 𝑝 <> 0 then 𝑖 = 1 … (𝑛⁄𝑝)

where
𝐹𝑖 = the function value at point 𝑖
𝑐 = the specified constant
𝑌𝑘 = the 𝑌 value of the source series at point 𝑘
𝑝 = the specified period

If there is more than one source series then the function will have 𝑛 values according to the following
formula:
𝑚

𝐹𝑖 = 𝑐 × ∏ 𝑌(𝑗,𝑖)
𝑗=1

where
𝐹𝑖 = the function value at point 𝑖
𝑐 = the specified constant
𝑚 = the number of source series specified
𝑌(𝑗,𝑖) = the 𝑌 value of the source series 𝑗 at point 𝑖

Multiply and offset

This function allows you to multiply a series or a number of series by a specified constant value and “offset”
the results by adding a specified constant value.
If there is only one source series with 𝑛 data points and period 𝑝, then:
𝑛

if 𝑝 = 0 then 𝐹 = 𝑠 + 𝑐 × ∑ 𝑌𝑖
𝑖=1

612 • Data Output (charts, tables, reports) Biowin 6 Help Manual

if 𝑝 = 1 then 𝐹𝑖 = 𝑠 + 𝑐 × 𝑌𝑖

𝑝−1

if 𝑝 > 1 then 𝐹𝑖 = 𝑠 + 𝑐 × ∑ 𝑌𝑖∙𝑝−𝑗

𝑗=0

and when 𝑝 <> 0 then 𝑖 = 1 … (𝑛⁄𝑝)

where
𝐹𝑖 = the function value at point 𝑖
𝑐 = the specified constant
𝑠 = 𝑡ℎ𝑒 𝑠𝑝𝑒𝑐𝑖𝑓𝑖𝑒𝑑 𝑜𝑓𝑓𝑠𝑒𝑡
𝑌𝑘 = the 𝑌 value of the source series at point 𝑘
𝑝 = the specified period
If there is more than one source series then the function will have 𝑛 values according to the following
formula:
𝑚

𝐹𝑖 = 𝑠 + 𝑐 × ∑ 𝑌(𝑗,𝑖)
𝑗=1

where
𝐹𝑖 = the function value at point 𝑖
𝑐 = the specified constant
𝑠 = 𝑡ℎ𝑒 𝑠𝑝𝑒𝑐𝑖𝑓𝑖𝑒𝑑 𝑜𝑓𝑓𝑠𝑒𝑡
𝑚 = the number of source series specified
𝑌(𝑗,𝑖) = the 𝑌 value of the source series 𝑗 at point 𝑖

Imported Series (Album)

BioWin offers the functionality of plotting imported data. This is useful particularly for comparing simulation
results to observed data (if you are calibrating BioWin, for example). There are two types of series you can
plot using imported data:
1. Final value
2. Time series (X-Y)
A Final value series allows you to plot the last value from the column(s) of data that you select. Therefore,
this series type is similar to a current value series for imported data and is suited to styles such as bar and
pie series.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 613

A Time series allows you to plot all of the values in an imported data column against all of the values in
another imported data column (usually the imported time column). Therefore, this series type is best suited
to styles such as line and point series.

Add an Imported Series

1. Right-click on an album chart and click Add Series in the resulting popup menu.
2. Click on the Imported tab of the Add Series dialog box.
3. Using the Imported Name(s) drop list box, select the name of a file or block of data (from the
clipboard) you have already imported to the database.

The imported series dialog

5. If you want to import a new file to the database from this dialog box, you may do so by clicking the
Import… button. For more information on importing data from a file, please see Importing Data.
If you select a Final value series:

614 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 5. From the Y Value column(s) list, select the columns that you want to plot the final value of. To
select a contiguous group of columns, click the first column of the group, and while holding the Shift
key, click the last column of the group. To select non-contiguous columns, hold the Ctrl key and click
the desired columns in succession.
6. Click the Plot selected button.
7. From the General series gallery, choose the desired series style that you wish to apply. If you want
your chart to have a three-dimensional appearance, ensure that the box labeled 3D is checked and
click OK.
8. Click the Close button to finish.
If you select a Time series:
9. From the X Value column list, select the column that you want to use as the independent variable in
the plot. If you have selected a column containing time values, then checking the box labeled Add
simulation start date/time to X values will synchronize the imported time values to the original
database time values. This option will allow you to plot a time series generated using imported data
on the same axes as a time series that uses non-imported data. You should select this option if your
imported data has a “relative” time column, that is, the time column in the imported data
represents the number of days rather the actual date. If you import data with an actual date
column then this must be in the standard windows format for dates, that is, 8:00 AM on January 1st,
2010 would be represented as 40179.33.

Note: Checking the box labeled Add simulation start date/time to X values will add the Project start date to
your data. This option should be selected if your imported data starts at time zero.

10. From the Y Value column(s) list, select the columns that you want to plot. To select a contiguous
group of columns, click the first column of the group, and while holding the Shift key, click the last
column of the group. To select non-contiguous columns, hold the Ctrl key and click the desired
columns in succession. Each column that you select will yield a series on the chart.
11. Click the Plot selected button.
12. From the General series gallery, choose the desired series style that you wish to apply. If you want
your chart to have a three-dimensional appearance, ensure that the box labeled 3D is checked and
click OK.
13. Click the Close button to finish.

Process rate (Album)

BioWin can plot the value of any of the ASDM kinetic process rates either as a current value plot or as a time
series. Process rate plots are limited to “reactive” elements.

Add a Process Rate Series

1. Right-click on an album chart and click Add Series in the resulting popup menu (if starting from a
blank Album page, the “click Add Series” step is bypassed automatically).
2. Click on the Process rate tab of the Add Series dialog box.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 615

 3. Elements for which process rate information is available are listed in the Elements list. Select the
element(s) that you wish to include in the process rate plot.

The Process rate tab

4. If you want to change the order in which the Selected elements will appear in the current value
plot, move the elements around by clicking on them and clicking the up/down arrows. You can
change the order of a group of elements, by using the Ctrl or Shift key to select the group and then
clicking the up or down arrow. Finally, you can move a selection directly to the top or bottom of the
list by holding the Ctrl key while you click the up or down arrow.
5. Choose any number of processes from the Process rate names list. If you want to add more than
one parameter at a time, you may do so. To select a contiguous group, click the first parameter, and
while holding the Shift key, click the last parameter that you wish to select. To select non-
contiguous parameters, hold the Ctrl key and click the desired parameters in succession. Once you
have selected the parameters you want to plot, move them to the Selected process rates list by
clicking the right-pointing arrow. If you want to change the order in which the Selected process
rates will appear in the plot, move the process names up or down by clicking on them and clicking
the up/down arrows. You can change the order of a group of parameters, by using the Ctrl or Shift
key to select the group and then clicking the up or down arrow. Finally, you can move a selection
directly to the top or bottom of the list by holding the Ctrl key while you click the up or down arrow.
6. If you wish to plot a time series of the selected process rates, click the Plot time series …

616 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 7. From the Time series gallery, choose the desired series style that you wish to apply. If you want
your chart to have a three-dimensional appearance, ensure that the box labeled 3D is checked and
click OK.
8. If you wish to plot the current value of the process rates, click the Plot bar series … button.
9. From the Current value series gallery, choose the desired series style that you wish to apply. If you
want your chart to have a three-dimensional appearance, ensure that the box labeled 3D is checked
and click OK.
10. Click the Close button to finish.

Note: Double clicking on a process rate name will add it to the Selected process rates list.

General Plot (Album)

This tab can be used to plot current value series or X-Y “scatter” plots. It is unique in that the user may
specify the element location (i.e. Input, Output, Underflow) from which data for the series are obtained.
From this tab you may also plot element-specific information (e.g. Solids Loading Rate for settling tank
elements, Oxygen Utilization Rates for bioreactor elements, etc.) in either a “current value” or “X-Y scatter”
type plot.

Note: Parameters selected for plotting will automatically be added to the list of “Monitored” items.

Add a General “Current Value” Series from the Album

1. Right-click on an album chart and click Add Series in the resulting popup menu.
2. On the General Plot tab, select the element you wish to plot a variable for from the Element name
drop list box.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 617

 The General Current Value plot (from album) dialog box

3. Select the location in the element where you wish to obtain the plotting data from (i.e. Input,
Output (overflow), Underflow) using the Location radio button group.
4. Choose a variable to plot from the Element specific, Water Chemistry, State variables, or Combined
list boxes. If you want to add more than one variable from a given group, you may do so. To select a
contiguous group, click the first parameter of the group, and while holding the Shift key, click the
last parameter of the group. To select non-contiguous parameters, hold the Ctrl key and click the
desired parameters in succession.
5. Click the Add selected ------> button.
6. The item(s) that you have selected are listed in the Selected components for plotting list box. You
can change the order of the parameters using the “up” and “down” arrows on the right of the list
box, and delete a variable by selecting it and then hitting the Del key.
7. To add additional variables for the selected element repeat steps 3 through 6. To add variables for a
different element repeat steps 2 through 6.

618 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 8. Type a name for the series in the edit box directly below the Selected components for plotting list
box.
9. Make sure that the Current values plot box is checked.
10. Press the Plot selected … button.
11. From the General series gallery, choose the desired series style that you wish to apply. If you want
your chart to have a three-dimensional appearance, ensure that the box labeled 3D is checked and
click OK.
12. To add another Current value series repeat steps 2 through 11.
13. Click the Close button to finish.

Note: You may only select multiple variables for one element and location at a time. If you want to plot
variables for several elements and locations, you must repeat steps 3-6 for each element/location.

Some features of the dialog box described above will only appear for certain elements. For example, the
underflow location option only will appear for elements that have underflows (such as settling tank
elements). Also, the element specific list box only will appear for elements that have unique data types (such
as bioreactors).

Add a General “X-Y Scatter” Series from the Album

1. Right-click on an album chart and click Add Series in the resulting popup menu.
2. On the General Plot tab make sure that the Current values plot box is NOT checked.
3. In an X-Y scatter plot the first variable selected is plotted on the X axis and the second variable is
plotted on the Y axis. Any other variables listed in the Selected components for plotting list box are
not used! You can switch X and Y axis by using the “up” and “down” arrows on the right of the list
box, and delete a variable by selecting it and then hitting the Del key.
4. Select the element you wish to plot a variable for from the Element name drop list box.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 619

 The General X-Y Scatter plot (from album) dialog box

5. Select the location in the element where you wish to obtain the plotting data from (i.e. Input,
Output (overflow), Underflow) using the Location radio button group.
6. Choose a variable to plot from the Element specific, Water Chemistry, State variables, or Combined
list boxes.
7. Click the Add selected → button.
8. To add a second variable for the selected element repeat steps 5 through 7. To add a variable for a
different element repeat steps 4 through 7.
9. The items that you have selected are listed in the Selected components for plotting list box (the axis
that will be used for each parameter is shown to the left of the variable.
10. Type a name for the series in the edit box directly below the Selected components for plotting list
box.
11. Press the Plot selected … button.

620 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 12. From the General series gallery, choose the desired series style that you wish to apply. If you want
your chart to have a three-dimensional appearance, ensure that the box labeled 3D is checked and
click OK.
13. To add another X-Y scatter plot series repeat steps 4 through 12.
14. Click the Close button to finish.

Note: In an X-Y scatter plot a time history of both variables is required, so when you first add the series
there may not be any data to show. Since the variables involved in the scatter plot are automatically
monitored the plot will show when a dynamic simulation is run.

N2O Emissions (Album)

The N2O emissions tab offers a wide variety of options for plotting N2O emissions calculated in BioWin,
including options for carbon dioxide equivalent units, average emissions, and emissions as a fraction of the
total influent nitrogen.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 621

The N2O Emissions tab (from album) dialog box

On the left hand side of the tab there are three selection groups that allow you to select the elements to
include as Influents, Reactors, and Effluents … for the N2O emissions plot. In the Influents group, the COD,
BOD, and state variable influent elements, are all automatically preselected. The elements listed in the
Selected box of the Influents group are used to determine the Influent Total N mass rate for this plot.

Note: Methanol and metal influent elements are not automatically preselected, since they do not contain
nitrogen.

In the Reactors group, all reactor-type elements (with the exception of anaerobic digester elements which
may be added manually) are automatically preselected. The elements listed in the Selected box of the
Reactors group are used to determine the gas phase emissions (both N2O and CH4) for this plot.

Note: Process carbon dioxide emissions can be plotted through the normal time series and current value
tabs. Generally only a fraction of the carbon dioxide emissions would be considered for Green House Gas
(GHG) inventory purposes.

In the Effluents and wastage group, all effluent and sludge elements are automatically preselected. The
elements listed in the Selected box of the Effluents and wastage group are used to determine the mass of
dissolved gas phase components (N2O and CH4) leaving the system for this plot.
To delete an element from any of the Selected boxes above, click on the item and press the delete key. This
will move the item back into the Available box. To move an item from the Available box to the Selected box,
double click on the appropriate item. You can also move a selection of items from any of the Available boxes
to the Selected boxes by clicking on the appropriate right pointing arrow.

Note: The user can generate any number of N2O emissions plots. This means that emissions from individual
trains/areas may be plotted separately.

The Options group box allows you to select options that apply to both current value and time series plots. In
the options area you can specify a prefix string for the series about to be plotted by entering text in the Start
series names with field. This may be most useful if the emissions from multiple trains are to be considered
separately. The Options group allows you to decide which mass rate plots should be displayed: N2O mass
rates (in N units, CO2e units or both), methane mass rates (in CO2e units) and influent total nitrogen mass
rate (N units).

Note: Process methane emissions can be plotted through the normal time series and current value tabs if
non-CO2e units are required.

Carbon dioxide equivalence (CO2e) of nitrous oxide and methane are specified in
Project|Parameters|Aeration/Mass transfer…on the Emission factors tab, as shown below.

622 • Data Output (charts, tables, reports) Biowin 6 Help Manual

Dialog for specifying CO2e

The Time series options group box allows you to select options (applying only to time series plots)
controlling the calculation display of the average emissions, e.g. whether averages are calculated on a daily,
weekly, monthly, or yearly basis.

Add an N2O emissions plot

1. Right-click on a chart in the album and click Add Series in the resulting popup menu (if starting from
a blank Album page, the “click Add Series” step is bypassed automatically).
2. Click on the N2O Emissions tab of the Add Series dialog box.
3. Review/modify the Selected elements and Options.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 623

 The N2O Emissions charting tab

4. You may plot the dynamic N2O emissions as either a time series (press Plot selected as time series)
or as a current (instantaneous) value plot (Press Plot selected as current values). The series style is
automatically selected to match the chosen series type.

Series Available from the Drawing Board

In the previous section, procedures for adding series to charts from the album view were outlined. This
section covers procedures related to charts created directly from the drawing board by right-clicking on
elements, and the specialized series that result.
When you add a series from the drawing board, a page with a chart in which to plot the series will be added
automatically to the album (even if the album is closed or in the background at the time). If the album was
last closed or placed in the background with a page already containing a chart selected, BioWin will ask you
if you want to plot the series you are adding from the drawing board in the existing chart. You may agree to
this, or by declining choose to have BioWin add a new page with a chart in which to plot the series. Note

624 • Data Output (charts, tables, reports) Biowin 6 Help Manual

that if the last selected album page contains multiple panes (where at least one of the panes contains a
chart), a chart must have been selected (i.e. clicked on) before the album was closed in order for BioWin to
give you the option of adding the drawing board-generated series to that chart. If the chart was not
selected upon closing the album, you will not be offered the option of adding the drawing board series to it
– BioWin will add a new page with a chart for the drawing board-generated series.

Time Series (Drawing Board)

You can also add a time series to the BioWin Album directly from the drawing board. The procedure is
identical to that for adding a time series from the album, except that the element is “pre-selected” in the
dialog box.

Add a Time Series from the Drawing Board

1. In the drawing board, right-click on the element that you wish to create a time series for.
2. From the resulting popup menu, select Add to album. Next, select Chart… from the resulting flyout.
If you had previsouly closed the Album while viewing a chart, you will be presented with the choice
of adding the series to that chart or creating a new one.
3. Check the Selected elements list; the element that you right-clicked on should be there. Note that if
the element has multiple outputs (e.g. a clarifier as shown in the sample picture below), they all are
added automatically – you can delete the ones that you don’t want. To do this click on the entry in
the Selected elements list and press the Delete key on your keyboard. If you want to change the
order in which the Selected elements will appear in the plot, move the elements around by clicking
on them and clicking the up/down arrows. You can change the order of a group of elements, by
using the Ctrl or Shift key to select the group and then clicking the up or down arrow. Finally, you
can move a selection directly to the top or bottom of the list by holding the Ctrl key while you click
the up or down arrow.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 625

 The time series (from drawing board) dialog

4. Choose a parameter to plot from the Element specific, Water Chemistry, State variables, or
Combined list boxes. If you want to add more than one parameter from a given group, you may do
so. To select a contiguous group, click the first parameter of the group, and while holding the Shift
key, click the last parameter of the group. To select non-contiguous parameters, hold the Ctrl key
and click the desired parameters in succession. You may also simultaneously select parameters from
multiple lists. Once you have selected the parameters you want to plot, move them to the Selected
variables list by clicking the right-pointing arrow. If you want to change the order in which the
Selected variables will appear in the multi time series plot, move the variables up or down by
clicking on them and clicking the up/down arrows. You can change the order of a group of
parameters, by using the Ctrl or Shift key to select the group and then clicking the up or down
arrow. Finally, you can move a selection directly to the top or bottom of the list by holding the Ctrl
key while you click the up or down arrow.
5. Specify whether you want the plot to show Concentrations/Flows, Mass Rates, Composite Samples,
or a Surface plot by clicking the appropriate option button.
6. A preview of the type of series that will be plotted is shown to the left of the Plot selected button. If
you wish to change to another series type, click the preview to open the Time series gallery and
choose the desired series style that you wish to apply. If you want your chart to have a three-
dimensional appearance, ensure that the box labeled 3D is checked and click OK.

626 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 7. Click the Plot selected button.
8. Click the Close button to finish.

Note: You can customize BioWin so that the Element specific, Water Chemistry, State variables, and
Combined lists appear in alphabetical order. This can make it easier to find the variable you want to plot. To
do this, check the Sort… boxes on the Chart options tab of the Tools|Chart Master menu. You can also
rapidly locate a variable in any of the lists by clicking in the list and typing the first character of the variable
name (e.g. click in the State variables list and type “n” to quickly locate the Nitrate N variable).

Special Series (Drawing Board)

BioWin comes with a collection of special series that are generated automatically. You simply choose the
type of special series and BioWin performs the necessary calculations to generate the data required. You
may then format the series and chart as you wish. Note that these series are a special form of current value
series – that is they display the most recent data with respect to simulation start time.
The available special series are listed here with a description:

Special Series Description

All nitrogen concentrations Displays the current concentration of all nitrogen

species for the selected element.
Soluble nitrogen concentrations Displays the current concentration of all soluble
nitrogen species for the selected element.
Biomass concentrations Displays the current concentration of all organisms
and endogenous residue for the selected element.
COD concentrations Displays the current COD concentrations (including
biomass expressed in terms of COD) for the
selected element.
COD concentrations excluding biomass Displays the current COD concentrations (excluding
biomass expressed in terms of COD) for the
selected element.
Add a Special Series from the Drawing Board
1. In the drawing board, right-click on the element that you wish to create a special series for.
2. From the resulting popup menu, select Add to album. Next, select Chart… from the resulting flyout.
If you are presented with the choice of adding the series to an existing chart, click Yes or No.
3. On the Special tab, click the radio button next to the special series you want.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 627

 The Special series (from drawing board) dialog

4. Click the Plot selected button.

5. From the Current value series gallery, choose the desired series style that you wish to apply. If you
want your chart to have a three-dimensional appearance, ensure that the box labeled 3D is checked
and click OK.
6. Click the Close button to finish.

Note: You may add more than one special series to a chart by repeating steps 3-5. Keep in mind that this
will not work well for Pie series since they are drawn over top of one another.

SOTE (%) Series (Drawing Board)

A SOTE (Standard Oxygen Transfer Efficiency) series is useful for comparing alternate aeration system
designs. It allows you to quickly plot SOTE (%) as a function of air flow rate per diffuser for the current
reactor diffuser coverage (the area of diffusers divided by the area of the tank). In addition, you may plot
SOTE (%) as a function of air flow rate per diffuser for alternate diffuser coverage to compare a number of
different design scenarios.

628 • Data Output (charts, tables, reports) Biowin 6 Help Manual

Note: An Album Template Page (“SOTE data in Metric/US units.xls”) with typical SOTE (%) numbers has
been provided in the BioWin Templates directory.

If an SOTE plot is generated for an SBR element that incorporates prezones, the plot information applies to
the main SBR zone only. The information on the plot does not apply to the prezone(s).

Add a SOTE (%) Series

1. In the drawing board, right-click on the element that you wish to create a SOTE (%) series for.
2. From the resulting popup menu, select Add to album. Next, select Chart… from the resulting flyout.
If you are presented with the choice of adding the series to an existing chart, click Yes or No.
3. On the SOTE(%) tab, select the cases you would like to plot SOTE for (i.e. for the current diffuser
coverage and alternate coverage that you may specify using the %coverage spin edit boxes).

The SOTE(%) series dialog

Biowin 6 Help Manual Data Output (charts, tables, reports) • 629

 4. You may change the number of points that will be plotted in each series using the Number of points
per curve setting. Increasing this value tends to result in smoother curves.
5. Click the Plot selected… button to plot the series. Click Close to close the dialog box. You may now
open the album and look at your SOTE plot.

Process rate (Drawing Board)

You can also add a process rate series to the BioWin Album directly from the drawing board. The procedure
is identical to that for adding a process rate series from the album, except that the element is “pre-selected”
in the dialog box.

The Process rate series dialog

SBR Profile Series (Drawing Board)

A SBR profile series is useful for viewing how a variable changes with depth over the length of a sequencing
batch reactor. The resulting plot is a three-dimensional chart that shows SBR length along either the X-axis
(horizontal axis) or the Z-axis (axis going into the screen), depending on the option you choose.
Concentration of the various variables will be plotted on the Y-axis (vertical axis), and the third axis will be
assigned to SBR depth.

630 • Data Output (charts, tables, reports) Biowin 6 Help Manual

Add a SBR Profile Series
1. In the drawing board, right-click on the SBR element that you wish to create a SBR profile series for.
2. From the resulting popup menu, select Add to album. Next, select Profile plot… from the resulting
flyout. If you are presented with the choice of adding the series to an existing chart, click Yes or No.
3. Using the dialog box shown below, select the Orientation of the profile plot by choosing to plot SBR
length on the X-axis (Length on X) or SBR length on the Z-axis (Length on Z).

The SBR profile series dialog box

4. From the State variables and Combined lists, choose the variables you wish to plot and click the Plot
selected button. Note that you can plot multiple parameters on one chart by repeating this step
before clicking the Close button to finish.

Trickling Filter Profile Series (Drawing Board)

A trickling filter profile series is useful for viewing how a variable changes over both the height of the
trickling filter (i.e. top, middle, and bottom sections) and within the biofilm thickness and the bulk liquid
phase within each section. These plots may either take the form of current value (i.e. steady-state type) or
time series (i.e. dynamic type) plots.

Add a Trickling Filter Profile Series

1. In the drawing board, right-click on the Trickling Filter element that you wish to create a profile
series for.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 631

 2. From the resulting popup menu, select Add to album. Next, select Profile plot… from the resulting
flyout. If you are presented with the choice of adding the series to an existing chart, click Yes or No.
3. From the State variables and Combined lists, choose the variables you wish to plot. You can select
the parameters you want from the list and move them to the Selected variables list by either
double-clicking the variable in its list or clicking on it and then clicking the right-pointing arrow.
4. Next, select the series type (Current value or Time series) and the orientation (Concentration on X
or Concentration on Y). Finally, click the Plot selected… button to add your chart to the BioWin
Album.

The Trickling Filter profile series dialog box

Settling Tank State Point Chart (Drawing Board)

State Point Analysis (SPA) is a useful tool applied by engineers to gain insight into the current or anticipated
operating regime of a secondary settling tank, with respect to whether the settling tank is safely, critically,
or over loaded.
With a few mouse clicks, BioWin can generate a SPA chart for a given set of sludge settleability
characteristics. BioWin takes SPA charts beyond the traditional desktop analysis typically performed by
engineers because it is able to illustrate the changes of the secondary settling tank operating regime under
dynamic loading conditions. For example, the square points in the chart below show the different state
point locations over one day’s simulation under varying flow and load to the plant.

632 • Data Output (charts, tables, reports) Biowin 6 Help Manual

A state point analysis chart created in BioWin, showing the state point movements under dynamic flow and load conditions.

The following points should be noted regarding state point charts:

• The gravity flux is traditionally drawn using Vesilind model settling parameters. The parameter
values used are shown below the state point chart in red text, as shown in the picture above.
• In keeping with tradition, the state point chart is not “restricted” in any way, e.g. by the settling
velocity clarification switch, maximum sludge compactability, etc. The “unmodified” Vesillind
relationship is used to construct the gravity flux curve.
• It is possible to construct a state point chart for an ideal secondary settling tank (i.e. a non-model
settling tank). In this case, the Vesilind model parameters are used to construct the gravity flux
curve, and the ideal secondary settling tank area, underflow, etc. are used in all the calculations.
This approach is useful for alerting to possibly critical or overloaded secondary settling tank
conditions that the ideal settling tank would not normally indicate to the user directly, without the
additional complexity of a model secondary settling tank.
• Because the chart itself does not know the unit system (i.e. SI or US imperial), the label that BioWin
initially applies to the vertical flux axis shows units for both systems. The user can edit out the unit
system that does not apply. The unit label on the vertical axis does not impact the actual values
plotted in the chart; these plotted values will be in the correct units.

Add a Settling Tank State Point Analysis Chart

1. In the drawing board, right-click on the secondary settling tank element that you wish to create a
state point chart for.
2. From the resulting popup menu, select Add to album. Next, select Chart… from the resulting flyout.
If you are presented with the choice of adding the series to the current chart or creating a new
chart, click Current or New.
3. Select the State point tab.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 633

 The add state point chart dialog

4. Check the boxes for the various lines you want to show on the state point chart. By default, all are
checked except the Plot dynamic state point history option. You can select the Plot dynamic state
point history option if you want to see points that track the movement of the state point during
dynamic simulations under varying flow, load, and recycle for the secondary settling tank. This is a
very useful feature.
5. Once the Plot dynamic state point history option is selected, you can choose to Limit state point
history to place a limit on the number of “historical” state points that are drawn. You may then
specify the maximum number of state points.

634 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 6. Click the Plot selected… button.

Settling Tank Profile Series (Drawing Board)

A settling tank profile series is useful for viewing how a parameter changes over the depth of a settling tank
element (or other separator-type elements such as grit removal tanks, dewatering units, and ideal primary
clarifiers). There are two different types of profile series:
1. Current value
2. Time series (surface)
A Current value settling tank profile series shows the most recent (with respect to simulation start time)
values of the chosen parameter(s) over the depth of the settling tank. During a dynamic simulation, the
settling tank profile series will be updated and redrawn after each data interval. For a steady-state
simulation, the settling tank profile series will represent the final steady-state values.
A Time series (surface) settling tank profile series shows the history of a parameter changing over the depth
of a settling tank. This history is illustrated as a surface where the leading edge represents the most recent
profile.

Add a Settling Tank Profile Series

1. In the drawing board, right-click on the settling tank element that you wish to create a profile series
for.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 635

 2. From the resulting popup menu, select Add to album. Next, select Profile plot… from the resulting
flyout. If you are presented with the choice of adding the series to an existing chart, click Yes or No.
3. Select the Profile type.
If you select a Current value settling tank profile:

The Current values Settling tank profile series dialog

4. From the Orientation radio button group, select whether you want to plot Concentration on X, or
Concentration on Y. In making this choice you are specifying whether you want the concentration
of the variable you are plotting on the vertical (Y) or horizontal (X) axis. The settling tank depth will
be plotted on the axis you do not select.
5. Select the variable you want to plot the profile of from the State variables or Combined list boxes.
6. Click the Plot selected button.
7. To choose and change the default desired series style click the sample chart to show the General
series gallery. If you want your chart to have a three-dimensional appearance, ensure that the box
labeled 3D is checked and click OK.
8. Click the Close button to finish.
If you select a Time series (surface) settling tank profile:

636 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 The Time series (surface) settling tank profile series dialog

9. From the Orientation radio button group, select whether you want to plot Time on X, or Time on Z.
In making this choice you are specifying whether you want the time history of the parameter you
are plotting to go along the horizontal (X) or Z (going into the screen) axis. Settling tank depth will
be plotted on the axis you do not select, and for surface profiles concentration of the variable you
are plotting always is assigned to the vertical (Y) axis.
10. Select the variable you want to plot the profile of from the State variables or Combined list boxes.
11. Set your Plot resolution. If you want a fine grid, decrease the value in the spin edit box. If you want
a coarse grid, increase the value. Note that fine grids look better, but will increase demand on
system resources.
12. Click the Plot selected button.
13. Click the Close button to finish.
14. To show the third dimension, the chart needs to be switched to a 3D chart: To do so right-click on
the chart, select Edit options… from the menu and go to the Chart|3D tab. Checking the 3
Dimensions box switches to a 3-dimensional chart. Increasing the value for 3D % increases the
depth of the chart.

Chart Formatting Procedures

One of BioWin’s helpful charting features is that changes you make to a chart are displayed “on the fly” as
you make them. This is an excellent way to learn the functionality of the chart editing/formatting controls
since you immediately see the results of clicking various buttons, spin edit boxes, and other dialog box
controls in the background.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 637

In many instances entering a value of "0" in a chart formatting field means that BioWin will resort to a
default value for the selected property (e.g. the increment of an axis scale).

Chart Axis Procedures

This section outlines the basic procedure you need to know in order to change and manipulate chart axis
properties, and also gives a number of specific related procedures. The section is structured such that the
order of its sub-topics follows the order of the sub-tabs on the Axis main tab. In general, most axis
manipulations are done via the following procedure:
1. Right-click on the chart to open the Edit menu, and then click Edit Axes….
2. Select the axis (i.e. Left, Right, Top, Bottom, Depth) that you want to change from the Axes list.
3. Select one of the six sub-tabs to change general axis properties such as Scales, Title, Labels, Axis,
Ticks, Grid, Position, Items.
4. Make the desired specific changes to the axis you have specified using the options on the sub-tabs.

Axis Scale Procedures

This section contains procedures that can be executed from the Scales sub-tab of the Axis tab. The topics all
are related to controlling the numerical properties of the chart axes such as scale increment, scale maximum
and minimums, and the type of axis (i.e. logarithmic, inverted).

The axis scales editor sub-tab

Remove a Chart Axis

1. Right-click on the chart to open the Edit menu, and then click Edit Axes….
2. In the Axes list, select the axis you want to remove.
3. In the Scales|Options sub-tab, un-check the box labeled Visible.
4. Click the Close button to finish.

638 • Data Output (charts, tables, reports) Biowin 6 Help Manual

Note: To remove another axis, repeat steps 1-3.

Set Axis Scale Maximum and Minimum Values

1. Right-click on the chart to open the Edit menu, and then click Edit Axes….
2. Select the axis you wish to set scale maximum and/or minimum values for using the Axes list.
3. If you want BioWin to set the scale maximum and minimum automatically, in the Scales|Options
sub-tab, check the box labeled Automatic and go to step 8. If you want to manually set one or both
of the values, go to Step 4.
4. In the Scales|Options sub-tab, un-check the box labeled Automatic.
5. In the Scales|Minimum and/or Scales|Maximum sub-tab, uncheck Auto button for the value (i.e.
maximum or minimum) you wish to manually set and click the Change button.
6. Enter your desired value in the resulting dialog box and click OK.
• If you have set the axis to Date/Time Format, then the dialog box will allow you to set the
desired maximum or minimum in date/time formats.
• If you would like to set the remaining value (i.e. maximum or minimum) manually, repeat Step 5.
To have BioWin automatically set the remaining value, check the box labeled Auto for that
value.
7. Click the Close button to finish.

Note: If you do not see the series you expect to when you first look at a chart, in the Scales|Options sub-
tab, check the box labeled Automatic to ensure that all series are contained within the axes boundaries.

Set Axis Scale Increment

1. Right-click on the chart to open the Edit menu, and then click Edit Axes….
2. Select the axis you wish to set scale increment for using the Axes list.
3. In the Scales|Increment sub-tab, click the Change... button.
4. Enter your desired increment in the resulting dialog box and click OK.
• If you have set the axis to Date/Time Format, then the dialog box will allow you to set the
desired increment in time units.
5. Click the Close button to finish.

Note: Entering a value of "0" in the Axis Increment field will result in BioWin determining the axis increment
automatically.

Set Axis Scale Type

1. Right-click on the chart to open the Edit menu, and then click Edit Axes….
2. Select the axis you wish to set the scale type for using the Axes list.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 639

 • If you want the selected axis to have a logarithmic scale, in the Scales|Options sub-tab, check
the box labeled Logarithmic and select the Log Base.
• If you want the axis scale inverted (i.e. minimum value at the top of a vertical axis), in the
Scales|Options sub-tab, check the box labeled Inverted.
3. Click the Close button to finish.

Axis Title Procedures

This section contains procedures that can be executed from the Title sub-tab of the Axis tab. The topics
covered all are related to creating and formatting chart axis titles, including adding a title, changing the axis
title font, changing the axis title area size, and changing the axis title angle.

The axis title style editor sub-tab

Add an Axis Title

1. Right-click on the chart to open the Edit menu, and then click Edit Axes….
2. Select the axis you wish to add a title to using the Axes list.
3. Click the Title|Style sub-tab.
4. In the text edit area labeled Title, enter the text for your title.
5. Click the Close button to finish.

Change the Axis Title Area Size

1. Right-click on the chart to open the Edit menu, and then click Edit Axes….
2. Select the axis you wish to change the title area size for using the Axes list.
3. Click the Title|Style sub-tab.
4. If you have not already done so, enter the text for your title in the text edit area labeled Title.

640 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 5. Click the spin edit box labeled Size to change the title area size by 1-point increments, or enter a
value using the keyboard.
6. Click the Close button to finish.

Note: Entering a value of "0" in the Axis Title Area Size field will result in BioWin determining the size
automatically.

Change the Axis Title Angle

1. Right-click on the chart to open the Edit menu, and then click Edit Axes….
2. Select the axis you wish to change the title angle for using the Axes list.
3. Click the Title|Style sub-tab.
4. If you have not already done so, enter the text for your title in the text edit area labeled Title.
5. Click the spin edit box labeled Angle to change the title angle by 90-degree increments, or enter a
value using the keyboard.
6. Click the Close button to finish.

Change the Axis Title Font

The axis title text editor sub-tab

1. Right-click on the chart to open the Edit menu, and then click Edit Axes….
2. Select the axis you wish to change the title font for using the Axes list.
3. Click the Title|Style sub-tab.
4. If you have not already done so, enter the text for your title in the text edit area labeled Title.
5. Click the Format|Font sub-tab to display the font properties.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 641

 6. Click the Edit… button to display the Font Properties dialog box and select the Font (e.g. Arial, Times
New Roman, etc.), the Font Style (e.g. Italic, Bold, etc.), Size, and Color until the Sample Text has
the appearance you want.
7. Click the OK button to close the Font Properties dialog box.
8. In the Title|Format|Font|Shadow|Format sub-tab, click the Color… button to display the Color
dialog box and select from the Basic Colors or Define Custom Colors to add a shadow to your text if
desired.
9. Click the OK button to close the Color dialog box.
10. Click the spin edit boxes in the Size group to adjust the horizontal and vertical aspects of the shadow
or enter a value from the keyboard.
11. In the Title|Format|Font|Options sub-tab, click the Inter-char spacing spin edit box to adjust the
character spacing or enter a value from the keyboard.
12. Click the Close button to finish.

Change the Axis Title Border

A Title border introduces a border around the characters and numbers of your title.

The axis title border editor dialog box

1. Right-click on the chart to open the Edit menu, and then click Edit Axes….
2. Select the axis you wish to change the title font border for using the Axes list.
3. If you have not already done so, click the Title|Style sub-tab and enter the text for your title in the
text edit area labeled Title.
4. Click the Format|Font sub-tab to display the font properties.
5. Click the Outline sub-tab to access the border properties and select the Style, Color and Width of
the font border you require around the title.

642 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 6. Click the Close button to finish.

Axis Label Procedures

This section contains procedures that can be executed from the Labels sub-tab of the Axis tab. The topics
covered include procedures for changing the axis label font, position, and style.

The tick labels editor sub-tab

Change the Axis Tick Label Options

1. Right-click on the chart to open the Edit menu, and then click Edit Axes….
2. Select the axis you wish to change the label font for using the Axes list.
3. Click the Labels|Style sub-tab.
4. Ensure that the box labeled Visible is checked.
5. Click the spin edit box labeled Size to change the amount of space between the axis title and the axis
labels by 1-point increments, or enter a value using the keyboard.
6. Click the spin edit box labeled Angle to change the label angle by 90-degree increments, or enter a
value using the keyboard.
7. Click the spin edit box labeled Min Separation % to change the space between axis labels in 10
percent increments, or enter a value using the keyboard.
8. Check the box labeled Multi-line to word wrap your axis label.
9. Check the box labeled Round First to round multi-decimal labels to one decimal point. Note this
option only works with certain Styles (e.g. Auto and Value).
10. Check the box labeled Label on Axis to include or exclude the first and last axis labels.
11. Click the Close button to finish.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 643

Change the Axis Label Style

1. Right-click on the chart to open the Edit menu, and then click Edit Axes….
2. Select the axis you wish to change the label font for using the Axes list.
3. Click the Labels|Style sub-tab.
4. Ensure that the box labeled Visible is checked.
5. Use the drop down list labeled Style to adjust the display of the axis values (e.g. Text, Label, Value).
6. Click the Close button to finish.

Change the Axis Label Format

The axis label format dialog box

1. Right-click on the chart to open the Edit menu, and then click Edit Axes….
2. Select the axis you wish to change the label font for using the Axes list.
3. Click the Labels sub-tab.
4. Ensure that the box labeled Visible is checked.
5. Click the Options sub-tab.
6. Use the drop-down list labeled Values Format to adjust the display of the axis values or see the
sections BioWin Number Formats and BioWin Date / Time Formats.
7. Click the Close button to finish.

BioWin Number Formats

This section contains an overview of the various number formats that are available in BioWin. Although this
information is applicable elsewhere, it has been included here since it will most likely be needed in relation
to chart axis labeling.

644 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 Specifier Description

0 Digit placeholder. If the value being formatted has a digit in the position where the ‘0’
appears in the format string, then that digit is copied to the output string. Otherwise, a
‘0’ is stored in that position in the output string.
# Digit placeholder. If the value being formatted has a digit in the position where the ‘#’
appears in the format string, then that digit is copied to the output string. Otherwise
nothing is stored in that position in the output string.
. Decimal point. The first ‘.’ character in the format string determines the location of the
decimal separator in the formatted value; any additional ‘.’ characters are ignored. The
actual character used as a decimal separator in the output string is specified in the
Number Format of the International section of the Windows Control Panel.
, Thousand separator. If the format string contains one or more ‘,’ characters, the output
will have thousand separators inserted between each group of three digits to the left of
the decimal point. The placement and number of ‘,’ characters in the format string does
not affect the output, except to indicate that thousand separators are wanted. The actual
character used as a thousand separator in the output string is specified in the Number
Format of the International section of the Windows Control Panel.
E+ Scientific notation. If any of the strings ‘E+’, ‘E-’, ‘e+’, or ‘e-’ are contained in the format
string, the number is formatted using scientific notation. A group of up to four ‘0’
characters can immediately follow the ‘E+’, ‘E-’, ‘e+’, or ‘e-’ to determine the minimum
number of digits in the exponent. The ‘E+’ or ‘e+’ formats cause a plus sign to be output
for positive exponents and a minus sign to be output for negative exponents. The ‘E-’ and
‘e-’ formats output a sign character only for negative exponents.
'xx'/"xx" Characters enclosed in single or double quotes are output as-is, and do not affect
formatting.
; Separates sections for positive, negative, and zero numbers in the format string.
The locations of the leftmost ‘0’ before the decimal point in the format string and the rightmost ‘0’ after the
decimal point in the format string determine the range of digits that are always present in the output string.
The number being formatted is always rounded to as many decimal places as there are digit placeholders
(‘0’ or ‘#’) to the right of the decimal point. If the format string contains no decimal point, the value being
formatted is rounded to the nearest whole number.
If the number being formatted has more digits to the left of the decimal separator that there are digit
placeholders to the left of the ‘.’ character in the format string, the extra digits are output before the first
digit placeholder.
To allow different formats for positive, negative, and zero values, the format string can contain between one
and three sections separated by semicolons:
1. One section: The format string applies to all values;
2. Two sections: The first section applies to positive values and zeros, and the second section applies
to negative values;

Biowin 6 Help Manual Data Output (charts, tables, reports) • 645

 3. Three sections: The first section applies to positive values, the second applies to negative values,
and the third section applies to zeros.
If the section for negative values or the section for zero values is empty, that is there is nothing between the
semicolons that delimit the section, the section for the positive values is used instead.
If the section for positive values is empty, or if the entire format string is empty, the value is formatted using
general floating-point formatting with 15 significant digits. General floating-point formatting is also used if
the value has more than 18 digits to the left of the decimal point and the format string does not specify
scientific notation.
The following table shows some sample formats and the results produced when the formats are applied to
different values:

Format String 1234 -1234 0.5 0

None Specified 1234 -1234 0.5 0

0 1234 -1234 1 0
0.00 1234.00 -1234.00 0.50 0.00
#.## 1234 -1234 .5
#,##0.00 1,234.00 -1,234.00 0.50 0.00
#,##0.00;(#,##0.00) 1,234.00 (1,234.00) 0.50 0.00
#,##0.00;;Zero 1,234.00 -1,234.00 0.50 Zero
0.000E+00 1.234E+03 -1.234E+03 5.000E-01 0.000E+00
#.###E-0 1.234E3 -1.234E3 5E-1 0E0

BioWin Date / Time Formats

This section contains an overview of the various date/time formats that are available in BioWin. Although
this information is applicable elsewhere, it has been included here since it will most likely be needed in
relation to chart axis labeling.

Specifier Description

C Displays the date followed by the time.

D Displays the day as a number without a leading zero (1-31).
dd Displays the day as a number without a leading zero (01-31).
ddd Displays the day as an abbreviation (Sat-Sun).
dddd Displays the day as a full name (Saturday-Sunday).
ddddd Displays the date in a short format.
dddddd Displays the date in a long format.

646 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 M Displays the month as a number without a leading zero (1-12). If the ‘m’ specifier
immediately follows an ‘h’ or ‘hh’ specifier, the minute rather than the month is
displayed.
mm Displays the month as a number with a leading zero (01-12). If the ‘mm’ specifier
immediately follows an ‘h’ or ‘hh’ specifier, the minute rather than the month is
displayed.
mmm Displays the month as an abbreviation (Jan-Dec).
mmmm Displays the month as a full name (January-December).
yy Displays the year as a two-digit number (00-99).
yyyy Displays the year as a four-digit number (0000-9999).
H Displays the hour as a number without a leading zero (0-23).
hh Displays the hour as a number with a leading zero (00-23).
N Displays the minute as a number without a leading zero (0-59).
nn Displays the minute as a number with a leading zero (00-59).
S Displays the second as a number without a leading zero (0-59).
ss Displays the second as a number with a leading zero (00-59).
T Displays the time using a short format.
Tt Displays the time using a long format.
am/pm Uses the 12-hour clock for the preceding ‘h’ or ‘hh’ specifier, and displays ‘am’ for
any hour before noon, and ‘pm’ for any hour after noon. The am/pm specifier can
use lower, upper, or mixed case, and the result is displayed accordingly.
a/p Uses the 12-hour clock for the preceding ‘h’ or ‘hh’ specifier, and displays ‘a’ for
any hour before noon, and ‘p’ for any hour after noon.
Ampm Uses the 12-hour clock for the preceding ‘h’ or ‘hh’ specifier, and displays a default
am string for any hour before noon, and a default pm string for any hour after
noon.
/ Displays the date separator character.
: Displays the time separator character.
'xx'/"xx" Characters enclosed in single or double quotes are displayed as-is, and do not
affect formatting.
Format specifiers may be written in upper case as well as lower case letters - both produce the same result.
If the string given by the format parameter is empty, the date and time is formatted as if a ‘c’ format
specifier had been given.

Change the Axis Label Font

Biowin 6 Help Manual Data Output (charts, tables, reports) • 647

 The axis label text editor dialog box

1. Right-click on the chart to open the Edit menu, and then click Edit Axes….
2. Select the axis you wish to change the label font for using the Axes list
3. Click the Labels|Style sub-tab.
4. Ensure that the box labeled Visible is checked.
5. Click the Format|Font|Font sub-tab to display the font properties.
6. Click the Edit… button to display the Font Properties dialog box and select the Font (e.g. Arial, Times
New Roman, etc.), the Font Style (e.g. Italic, Bold, etc.), Size, and Color until the Sample Text has
the appearance you want.
7. Click the OK button to close the Font Properties dialog box.
8. Click the Color button in the Labels|Format|Font|Shadow|Format subtab to display the Color
dialog box and select from the Basic Colors to add a shadow to your text if desired.
9. Click the OK button to close the Color dialog box.
10. Click the spin edit boxes to adjust the horizontal and vertical aspects of the shadow or enter a value
from the keyboard.
11. In the Labels|Format|Font|Options subtab, click the Inter-char spacing spin edit box to adjust the
character spacing or enter a value from the keyboard.
12. Click the Close button to finish.

Change the Axis Label Border

A Label border introduces a border around the characters and numbers of your labels.

648 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 The axis title border editor dialog box

1. Right-click on the chart to open the Edit menu, and then click Edit Axes….
2. Select the axis you wish to change the title font for using the Axes list.
3. Click the Labels|Style sub-tab and ensure that the box labeled Visible is checked.
4. Click the Labels|Format|Font|Font sub-tab to display the font properties.
5. In the Labels|Format|Font|Outline sub-tab select the Style, Color and Width of border you require
around the characters of your title.
6. Click the Close button to finish.

Tick Formatting Procedures

This section contains procedures that can be executed from the Axis, Ticks and Grid sub-tabs of the Axis tab.
The topics covered include procedures for specifying the appearance of the chart axes, grid, and axes ticks.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 649

The tick formatting editor sub-tab

Change the Chart Axis Formatting

1. Right-click on the chart to open the Edit menu, and then click Edit Axes….
2. Select the axis you wish to change the formatting for using the Axes list.
3. Click the Axis|Format sub-tab.
4. Make sure that the box labeled Visible is checked.
5. Select the axis width you want from the Width slider.
6. To change the axis color, select the Color... button to open the color selection dialog box.
7. Click on the axis color you want and then click OK to close the color selection dialog box.
8. Click the Close button to finish.

Change the Chart Major Grid Formatting

1. Right-click on the chart to open the Edit menu, and then click Edit Axes….
2. Select the axis you wish to change the formatting for using the Axes list.
3. Click the Grid|Border|Format sub-tab.
4. Make sure that the box labeled Visible is checked.
5. Select the grid width you want from the Width slider.
6. To change the grid color, select the Color... button to open the color selection dialog box.
7. Click on the grid color you want and then click OK to close the color selection dialog box.
8. Select the grid style you want from the Style sub-tab.
9. Click the Close button to finish.

650 • Data Output (charts, tables, reports) Biowin 6 Help Manual

Change the Axis Major Tick Formatting

1. Right-click on the chart to open the Edit menu, and then click Edit Axes….
2. Select the axis you wish to change the formatting for using the Axes list.
3. Click the Ticks|Outer|Format sub-tab.
4. Make sure that the box labeled Visible is checked.
5. Select the major tick width you want from the Width slider.
6. To change the major tick color, select the Color... button to open the color selection dialog box.
7. Click on the major tick color you want and then click OK to close the color selection dialog box.
8. Select the major tick style you want from the Style sub-tab.
9. If you only want the major ticks where labels are, ensure that the box labeled At Labels Only is
checked.
10. If you want to increase the length of the major ticks, use the Length spin edit box.
11. Click the Close button to finish.

Change the Axis Inner Tick Formatting

1. Right-click on the chart to open the Edit menu, and then click Edit Axes….
2. Select the axis you wish to change the formatting for using the Axes list.
3. Click the Ticks|Inner|Format sub-tab.
4. Make sure that the box labeled Visible is checked.
5. Select the inner tick width you want from the Width slider.
6. To change the inner tick color, select the Color... button to open the color selection dialog box.
7. Click on the inner tick color you want and then click OK to close the color selection dialog box.
8. Select the inner tick style you want from the Style sub-tab.
9. Click the Close button to finish.

Change the Axis Minor Tick Formatting

Biowin 6 Help Manual Data Output (charts, tables, reports) • 651

 The tick formatting editor sub-tab

1. Right-click on the chart to open the Edit menu, and then click Edit Axes….
2. Select the axis you wish to change the formatting for using the Axes list.
3. Click the Ticks|Minor|Format sub-tab.
4. Make sure that the box labeled Visible is checked.
5. Select the minor tick width you want from the Width slider.
6. To change the minor tick color, select the Color... button to open the color selection dialog box.
7. Click on the minor tick color you want and then click OK to close the color selection dialog box.
8. Select the minor tick style you want from the Style sub-tab.
9. If you want to increase the size of the minor ticks, use the Length spin edit box.
10. If you want to increase the number of minor ticks, use the Count spin edit box.
11. Click the Close button to finish.

Change the Chart Minor Grid Formatting

1. Right-click on the chart to open the Edit menu, and then click Edit Axes….
2. Select the axis you wish to change the formatting for using the Axes list.
3. Click the Grid|Minor|Format sub-tab.
4. Make sure that the box labeled Visible is checked.
5. Select the grid width you want from the Width slider.
6. To change the grid color, select the Color... button to open the color selection dialog box.
7. Click on the grid color you want and then click OK to close the color selection dialog box.
8. Select the grid style you want from the Style sub-tab.

652 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 9. Click the Close button to finish.

Chart Title Procedures

This section contains procedures that can be executed from the Edit Title tab. Note that in BioWin charting
terminology, a chart title may be either a Title at the top of the chart, or Footer at the bottom of the chart.
It is possible to have both on the same chart, as well as a Subtitle and Subfooter. This section includes
procedures for adding a chart title, changing a title’s font and alignment, adding a frame to a title, and
adding a fill pattern, gradient or shadow to the title frame.

The chart title text editor tab

Add a Chart Title

1. Right-click on the chart to open the Edit menu, and then click Edit Titles….
2. If you want the title above the chart, select Title in the drop list box. If you want the title below the
chart, select Foot.
3. In the Options sub-tab, ensure that the box labeled Visible is checked.
4. In the Text edit area of the Text sub-tab; change the default text to the title you desire.
5. Click the Close button to finish.

Note: If no chart title is desired, un-check the box labeled Visible. If titles above and below the chart are
desired, perform the above procedure twice, i.e. once for the Title and once for the Foot. A Subtitle and
Subfooter can be added in the same way.

Change the Chart Title Alignment

1. Specify which title you want to change in the drop-down list box.
2. In the Text alignment drop list box of the Text sub-tab, select Left, Center, or Right.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 653

 3. Click the Close button to finish.

Change the Chart Title Position

The chart title position editor tab

1. Specify which title you want to change in the drop-down list box.
2. Select the Position sub-tab.
3. Check the Custom box.
4. Adjust the Left and Top measurements by clicking the spin edit boxes or type in a value from the
keyboard.
5. Click the Close button to finish.

654 • Data Output (charts, tables, reports) Biowin 6 Help Manual

Add a Frame to the Chart Title

The chart title format editor tab

1. Specify which title you want to change in the drop-down list box.
2. Select the Format|Format sub-tab.
3. Make sure that the Transparent check box is unchecked.
4. Select the Border|Frame sub-tab to open the Border Editor.
5. Make sure that the box labeled Visible is checked in the Format sub-tab.
6. Select the frame width you want from the Width slider.
7. To change the frame color, select the Color... button to open the color selection dialog box.
8. Click on the frame color you want and then click OK to close the color selection dialog box.
9. Select the frame style you want from the Style sub-tab.
10. Click the Close button to finish.

Add a Fill Pattern and Color to a Chart Title Frame

1. Specify which title you want to change in the drop-down list box.
2. Select the Format|Pattern sub-tab to open the fill pattern editor.
3. Select the fill style you want from the sub-tabs provided.
4. To change the fill color, select the Color... button to open the color selection dialog box.
5. Click on the color you want and then click OK to close the color selection dialog box.
6. Click the Close button to finish.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 655

Add an Image to a Chart Title Frame
1. Specify which title you want to change in the drop-down list box.
2. Select the Format|Pattern sub-tab to open the Pattern Editor.
3. To add an image, select the Browse... button in the Custom sub-tab, to open the file selection dialog
box.
4. Choose the graphic image you want and then click OK to close the file selection dialog box.
5. Click the Close button to finish.

Change the Chart Title Font Properties

The chart title text editor tab

1. Specify which title you want to change in the drop-down list box.
2. Click the Format|Font sub-tab to display the font properties.
3. Click the Edit… button in the Font subtab, to display the Font Properties dialog box and select the
Font (e.g. Arial, Times New Roman, etc.), the Font Style (e.g. Italic, Bold, etc.), Size, and Color until
the Sample Text has the appearance you want.
4. Click the OK button to close the font properties dialog box.
5. Click the Color button in the Shadow|Format sub-tab to display the Color dialog box and select from
the Basic Colors to add a shadow to your text if desired.
6. Click the OK button to close the Color dialog box.
7. Click the spin edit boxes to adjust the horizontal and vertical aspects of the shadow or enter a value
from the keyboard.

656 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 8. In the Format|Font|Options sub-tab, click the Inter-char spacing spin edit box to adjust the
character spacing or enter a value from the keyboard.
9. In the Format|Font|Outline sub-tab select the Style, Color and Width of border you require around
the characters of your title.
10. Click the Close button to finish.

Add a Gradient to a Chart Title Frame

The chart title gradient editor tab

1. Specify which title you want to change in the drop-down list box.
2. Select the Format|Pattern|Gradient sub-tab.
3. Ensure the Visible box is checked.
4. Select a direction (e.g. Left Right, Top Bottom) for the gradient from the Direction drop-down list.
5. In the Colors sub-tab, use the Start, Middle and End buttons to select the colors for the gradient. If
no middle color is required, check the No Middle box.
6. To reverse the start and end colors, use the Swap button.
7. Click the Close button to finish.

Note: In order to see the gradient, you must make sure that the Transparent check box on the
Format|Format tab is unchecked.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 657

Add a Shadow to a Chart Title Frame

The chart title shadow editor tab

1. Specify which title you want to change in the drop-down list box.
2. Select the Format|Shadow|Format sub-tab.
3. Click the Color button to display the Color dialog box and select from the Basic Colors to add a
shadow to your text if desired.
4. Click the OK button to close the Color dialog box.
5. Click the Size slider to adjust the depth of the shadow or enter a value from the keyboard.
6. Click the Close button to finish.

Chart Legend Procedures

This section contains topics covering procedures that can be executed from the Edit Legend… tab. The
procedures outlined include a variety of chart legend formatting options such as outlines, three-dimensional
appearance, position and fonts. The list below contains some general legend tips:
• To have no legend, uncheck the box labeled Visible.
• To reverse the order in which series are placed in the legend, check the box labeled Inverted.
• To add check boxes beside each item in the legend, select Check boxes from the drop list box. This
feature allows an easy selection of series to be shown in the chart.
• To change the color of the text in the legend to match the series in the graph, check the box labeled
Font Series Color.

658 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 The chart legend style editor tab

Legend Styles
This section gives descriptions of the various legend styles that may be applied to chart legends in BioWin.
Generally, the Automatic style is the Legend Style best suited for most series types.
There are two attributes that control the appearance of legends in BioWin. The Legend Style determines
the possible content of the legend. The Text Style determines the layout of the legend content. The table
below describes the possible legend styles.

Style Description

Automatic Generally, if there is only one series on your chart, this style shows the
series values. If there are two or more series, this style will show the
names of the various series.
Series Names Shows the names of all series in a chart. Since only names are shown
in the legend, Text Styles do not apply.
Series Values The legend shows information for only the first series in the chart.
Last Values The legend shows information for the last point of each series in the
chart.

Tip: To control the numeric format of your legend entries, change the series Label Number Format. To do
this:

1. Right-click the chart and select Edit Series….

2. Select the series corresponding to the legend entry you want to change the numeric formatting of.
3. Click on the General tab.
4. Click on the Options sub-tab
5. In the Formats group, change the Values or Percents formatting to the style you want.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 659

 6. Click OK to finish.

Legend Text Styles

This section gives examples of the various legend text styles that may be applied to BioWin chart legends.
The table below provides a simple example of the available legend text styles.

Style Example

Plain Unaerated
Right Value Unaerated 37, 970.173
Left Value 37, 970.173 Unaerated
Right Percent Unaerated 26.6 %
Left Percent 26.6 % Unaerated
X Value 0
Value 37, 970.173
Percent 26.6 %
X and Value 0 37, 970.173
X and Percent 0 26.6 %
For example, consider the process mass plot shown below. The legend shown in this picture has the Left
Percent legend text style applied.

660 • Data Output (charts, tables, reports) Biowin 6 Help Manual

Process mass plot with Left Percent Legend Text Style applied to legend

Some of the legend text styles mentioned above refer to series "points". In BioWin charts, a point can refer
to a bar of a bar series, or a pie slice of a pie series. Note that time series (e.g. Line and point series) points
do not have names.

Tip: To control the numeric format of your legend entries, change the series Label Number Format. To do
this:

1. Right-click the chart and select Edit Series….

2. Select the series corresponding to the legend entry you want to change the numeric formatting of
from the left pane.
3. Click on the General tab.
4. Click on the Options sub-tab
5. In the Formats group, change the Values or Percents formatting to the style you want.
6. Click OK to finish.

Note: When you apply a Legend Text Style that involves percent, the individual point percentages are
calculated as follows. The total sum of the point values is calculated. Then each individual point percentage
is calculated by dividing the point value by the total sum of the points.

Change the Chart Legend Vertical Spacing

1. Right-click on the chart to open the Edit menu, and then click Edit Legend….
2. Select the legend spacing you want from the Vert. Spacing spin edit box in the Style sub-tab.
3. Click the Close button to finish.

Add Dividing Lines to a Legend

1. Right-click on the chart to open the Edit menu, and then click Edit Legend….
2. Click the Lines|Format sub-tab.
3. Make sure that the box labeled Visible is checked.
4. Select the dividing line width you want from the Width slider.
5. To change the dividing line color, select the Color... button to open the color selection dialog box.
6. Click on the dividing line color you want and then click OK to close the color selection dialog box.
7. Select the dividing line style you want from the Style sub-tab.
8. Click the Close button to finish.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 661

Change the Legend Position

Chart legend position dialog box

1. Right-click on the chart to open the Edit menu, and then click Edit Legend….
2. Click the Position sub-tab.
3. Make sure that the box labeled Resize Chart is checked, so that the chart will reposition itself
according to the legend position you select.
4. In the Position group, use the radio buttons to choose Left, Right, Top or Bottom.
5. Adjust the amount of space between the legend and the chart using the Margin spin edit box.
6. Fine-tune the position of the legend using the Position Offset % spin edit box.
7. Set up a custom location by checking the box labeled Custom and adjusting the Left and Top spin
edit boxes.
8. Click the Close button to finish.

662 • Data Output (charts, tables, reports) Biowin 6 Help Manual

Change the Appearance of Legend Symbols

Chart legend symbols dialog box

1. Right-click on the chart to open the Edit menu, and then click Edit Legend….
2. Click the Symbols|Size sub-tab.
3. Adjust the size of the legend symbols using the Width spin edit box.
4. Choose between Percent and Pixels in the Width Units drop-down list.
5. Position the symbols on the Left or Right of the legend text with the Position drop-down list in the
Options sub-tab.
6. Remove the space between symbols by checking the box labeled Continuous. Note this option is
only effective if the legend is located on the left or right of the chart.
7. Click the Close button to finish.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 663

Change the Chart Legend Background Color and Pattern

Chart legend format dialog box

1. Right-click on the chart to open the Edit menu, and then click Edit Legend….
2. Click the Format|Format sub-tab.
3. Select the Color... button to open the color selection dialog box to change the legend background
color.
4. Click on the legend background color you want and then click OK to close the color selection dialog
box.
5. If a background pattern is required, select the Pattern sub-tab to open the Pattern Editor.
6. Select the fill style you want from the provided sub-tabs.
7. To change the background pattern fill color, select the Color... button to open the color selection
dialog box.
8. Click on the color you want and then click OK to close the color selection dialog box.
9. Click the Close button to finish.

Add a Frame to the Chart Legend

1. Right-click on the chart to open the Edit menu, and then click Edit Legend….
2. Click the Format|Border|Frame sub-tab to open the Border Editor.
3. Make sure that the box labeled Visible is checked on the Format sub-tab.
4. Select the frame width you want from the Width slider.
5. To change the frame color, select the Color... button to open the color selection dialog box.
6. Click on the frame color you want and then click OK to close the color selection dialog box.

664 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 7. Select the frame style you want from the Style sub-tab.
8. If a rounded box is required, check the box labeled Round Frame in the Format|Border|Corners
sub-tab.
9. If a three-dimensional effect is required, select Raised or Lowered from the Style radio button group
in the Format|Border|Bevel sub-tab. The depth of this effect can be adjusted with the Size spin edit
box.
10. Click the Close button to finish.

Change the Chart Legend Font

Chart legend text dialog box

1. Right-click on the chart to open the Edit menu, and then click Edit Legend….
2. Click the Format|Font|Font sub-tab.
3. Click the Edit... button to open the font properties dialog box.
4. Specify the Font (e.g. Arial, Times New Roman, etc.), the Font Style (e.g. Italic, Bold, etc.), Size, and
Color until the Sample Text has the appearance you want.
5. Click the OK button to close the font properties dialog box.
6. Click the Color button in the Format|Font|Shadow|Format sub-tab to display the Color dialog box
and select from the Basic Colors to add a shadow to your text if desired.
7. Click the OK button to close the Color dialog box.
8. Click the spin edit boxes to adjust the horizontal and vertical aspects of the shadow or enter a value
from the keyboard.
9. In the Format|Font|Options sub-tab, click the Inter-char spacing spin edit box to adjust the
character spacing or enter a value from the keyboard.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 665

 10. Click the Close button to finish.

Add a Color Gradient to the Chart Legend

Chart legend gradient dialog box

1. Right-click on the chart to open the Edit menu, and then click Edit Legend….
2. Select the Format|Pattern|Gradient sub-tab.
3. Ensure the Visible box is checked.
4. Select a direction (e.g. Left Right, Top Bottom) for the gradient from the Direction drop-down list.
5. In the Colors section of the dialog box, use the Start, Middle and End buttons to select the colors for
the gradient. If no middle color is required, check the No Middle box.
6. To reverse the start and end colors, use the Swap button.
7. Click the Close button to finish.

666 • Data Output (charts, tables, reports) Biowin 6 Help Manual

Add a Shadow to the Chart Legend Frame

Chart legend shadow dialog box

1. Right-click on the chart to open the Edit menu, and then click Edit Legend….
2. Select the Format|Shadow|Format sub-tab.
3. Click the Color button to display the Color dialog box and select from the Basic Colors to add a
shadow to your legend frame if desired.
4. Click the OK button to close the Color dialog box.
5. Click the Size slider to adjust the depth of the shadow or enter a value from the keyboard.
6. Click the Close button to finish.

Other Chart Options and Procedures

This section consists of procedures and options that change the general appearance of charts. All of these
procedures can be executed after right clicking on the chart to open the Edit menu, then clicking Edit
Options….

Chart Options
This section consists of procedures that can be executed from the Chart tab of the Edit Options… menu
choice.

Change the Series Order

Biowin 6 Help Manual Data Output (charts, tables, reports) • 667

Chart series options dialog box

1. Right-click on the chart to open the Edit menu, and then click Edit Options….
2. Select the Series branch from the left pane tree menu.
3. Click on the series that needs to be moved in the series list on the right pane.

4. Click the or button to change the order of the selected item in the list.
5. Click the Close button to finish.

Note: Use the check boxes beside the series to temporarily remove them from the chart display. This dialog
box can also be used to Delete the selected series and edit the Title… text.

Change the Series Type

1. Right-click on the chart to open the Edit menu, and then click Edit Options….
2. Select the Series branch from the left pane tree menu.
3. Click on the series that needs to be moved in the series list on the right pane.
4. Click the Change… button to display the general series gallery dialog box.

668 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 General series type dialog box

5. Check the box labeled 3D to display three dimensional chart types if required.
6. Click any chart type that you would like to use for the series.
7. Click OK to close the series type dialog box.
8. Click the Close button to finish.

Chart Panel Options

This section consists of procedures that can be executed from the Chart|Panel sub-tab in the Edit Options…
menu choice. It includes procedures for changing the background appearance and border options for your
chart.

Changing the Chart Background Color

1. Right-click on the chart to open the Edit menu, and then click Edit Options….
2. Select the Chart branch from the left pane tree menu.
3. Click the Panel sub-tab to access the panel options.
4. Click the Colour sub-tab.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 669

 Chart panel Background dialog box

5. Click the Color… button to display the Color dialog box and select from the Basic Colors to add a
color to the chart background.
6. Click the OK button to close the Color dialog box.
7. Click the Close button to finish.

Note: This option can also be used to add an image to the chart background using the Browse… button in
the Image|Options sub-tab. This opens a file selection dialog box from which you can choose a graphic
image (such as a company logo) to place behind the chart. Once an image is chosen, options from the Style
radio button list in the Image|Bounds sub-tab are available to control the display of the image. Choose
between Stretch, Tile and Center.

Adding a Border to the Chart

1. Right-click on the chart to open the Edit menu, and then click Edit Options….
2. Select the Chart branch from the left pane tree menu
3. Click the Panel sub-tab to access the panel options.
4. Click the Borders|Border|Format sub-tab.

670 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 Chart panel Borders dialog box

5. Click the check box labeled Visible to add a single line around the entire chart.
6. In the Borders|Bevel sub-tab, use the drop down lists in the Bevel Inner and Bevel Outer sections to
add or remove Lowered or Raised bevel effects.
7. Adjust the width of the bevel effects using the Width spin edit boxes.
8. Click the Close button to finish.
Below is an example of a chart with the effects chosen in the dialog box above:

Biowin 6 Help Manual Data Output (charts, tables, reports) • 671

An example of a chart with beveled inner and outer borders

Adding a Gradient to the Chart Background

1. Right-click on the chart to open the Edit menu, and then click Edit Options….
2. Select the Chart branch from the left pane tree menu
3. Click the Panel sub-tab to access the panel options.
4. Click the Gradient sub-tab.

672 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 Chart panel Gradient dialog box

5. Ensure the Visible box is checked.

6. Select a direction (e.g. Left Right, Top Bottom) for the gradient from the Direction drop-down list.
7. In the Colors section of the dialog box, use the Start, Middle and End buttons to select the colors for
the gradient. If no middle color is required, check the No Middle box.
8. To reverse the start and end colors, use the Swap button.
9. Click the Close button to finish.

Adjust the Appearance of Chart Walls

1. Right-click on the chart to open the Edit menu, and then click Edit Options.
2. Select the Chart branch from the left pane tree menu.
3. Click the Walls sub-tab to access the wall display options.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 673

 Chart Walls dialog box

4. If you want the walls of the chart to be transparent, un-check the box labeled Visible. If you want to
see them, make sure that this box is checked.

To change the color of a three-dimensional wall:

1. Select the desired wall by clicking on the appropriate sub-tab (Left, Right, Bottom or Back)
2. In the Format sub-tab, select the Color... button to open the color selection dialog box.
3. Click on the wall color you want
4. Click OK to close the color selection dialog box.

To change the border of a three-dimensional wall:

1. Select the desired wall by clicking on the appropriate sub-tab (Left, Right, Bottom or Back)
2. Select the Border|Frame|Format sub-tab, click the Color…button to open the border color editor.
3. Make sure that the box labeled Visible is checked.
4. Select the wall border width you want from the Width slider.
5. Select the wall border style you want from the Style sub-tab.

To change the wall border color:

1. Select the Color... button to open the color selection dialog box.
2. Click on the wall border color you want and then click OK to close the color selection dialog box.
3. Click OK to close the border color editor.

674 • Data Output (charts, tables, reports) Biowin 6 Help Manual

To change the Pattern of a three-dimensional wall:
1. Select the desired wall by clicking on the appropriate sub-tab (Left, Right, Bottom or Back)
2. Select the Pattern sub-tab to open the pattern selection options.
3. Click on the wall pattern you want from the sub-tabs provided.
4. Click OK to close the pattern selection dialog box.

To change the gradient of a three-dimensional wall:

1. Select the desired wall by clicking on the appropriate sub-tab (Left, Right, Bottom or Back)
2. Select the Pattern|Gradient sub-tab button to open the gradient selection options.
3. Ensure the Visible box is checked.
4. Select a direction (e.g. Left Right, Top Bottom) for the gradient from the Direction drop-down list.
5. In the Colors section of the dialog box, use the Start, Middle and End buttons to select the colors for
the gradient. If no middle color is required, check the No Middle box.
6. To reverse the start and end colors, use the Swap button.
7. Click OK to close the gradient selection dialog box.

To change the size of a three-dimensional wall:

1. Select the desired wall by clicking on the appropriate sub-tab (Left, Right, Bottom or Back)
2. Adjust the value in the Size spin edit box in the Options sub-tab.
3. To remove any of these options from an individual wall, click the appropriate sub-tab (Left, Right,
Bottom or Back), and remove the check from the box labeled Visible.
4. Click the Close button to finish.

Adjust Chart Three-Dimensional Appearance

1. Right-click on the chart to open the Edit menu, and then click Edit Options….
2. Select the Chart branch from the left pane tree menu.
3. Click the 3D sub-tab to access the 3D display options.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 675

 Chart 3D dialog box

4. If you want your chart to have a three-dimensional appearance, ensure that the box labeled 3
Dimensions is checked.
5. If you do not want your chart to have a three-dimensional appearance, ensure that the box labeled
3 Dimensions is cleared.
To adjust the three-dimensional depth of the chart:
1. Increase or decrease the value under the 3 Dimensions check-box using the slider provided.
2. Checking the Orthogonal check box and increasing or decreasing the value in the Angle spin edit box
can further adjust the three-dimensional appearance.
To adjust the size of the chart on the page :
1. Drag the point in the section labeled Zoom.
To rotate the chart on the page :
1. Uncheck the box labeled Orthogonal
2. Drag the point in the section labeled Rotation.
To change the elevation of the chart on the page :
1. Uncheck the box labeled Orthogonal
2. Drag the point in the section labeled Elevation.
3. The chart can be moved to the left or right on the page by dragging the point in the section labeled
Horiz. Offset.
4. The chart can be moved up or down on the page by dragging the point in the section labeled Vert.
Offset.

676 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 5. Click the Close button to finish.

Series Options
For information on the procedures that can be executed from the Series tab of the Edit Options… menu
choice, please see Series Formatting Procedures.

Tools Options
This section consists of procedures that can be executed from the Tools tab of the Edit Options menu
choice. It includes procedures for customizing your graph including hand-drawn lines, annotations and page
numbering.

Adding a Tool

1. Right-click on the chart to open the Edit menu, and then click Edit Options….
2. Select the Tools tree branch from the left pane.
3. Click the Add… button to access the tools list

Chart Tools Gallery dialog box

4. Click on the tool you would like to use from the Series, Axis or Other tabs (e.g. Annotation in the
Other tab).

Biowin 6 Help Manual Data Output (charts, tables, reports) • 677

 5. Click the Add button to finish.
Repeat these steps as necessary to add the tools you would like to use to the Tools dialog box. Once a tool
has been added numerous new tabs will appear in the Chart editor which can be used to edit and customize
the newly added tool. For example, you can modify the text, font, position, color, border, background,
shadow, etc. of an annotation. Or you can modify the color, style, width, etc. of a color band. Positioning the
Chart editor away from the added tool on the chart will allow you to see any modifications to the chart tool
as they are selected.

Disabling a Chart Tool

1. Right-click on the chart to open the Edit menu, and then click Edit Options….
2. Select the Tools tab.
3. Choose the tool you want to disable from the list.
4. Remove the check from the box labeled Active.
5. Click the Close button to finish.

Export Options
This section contains procedures for exporting your chart to other programs and includes a discussion of the
different file types that are available, as well as sending your chart through email.

Exporting Charts

This option allows exporting charts in different formats. The files will not include the underlying data.
1. Right-click on the chart to open the Edit menu, and then click Edit Options….
2. Select the Export tree branch from the left pane.

678 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 Export Picture dialog box

3. Select the Picture sub-tab.

4. Choose the file format you want to use (Metafile, Bitmap, GIF or JPEG) in the Format box.
5. Adjust specific file format options for export by selecting the Options sub-tab and applying the
desired settings. Note that the options available vary with the file format selected.
6. Adjust the width and height of the exported chart by selecting the Size sub-tab and increasing or
decreasing the values in the Width and Height spin edit boxes. To keep the chart size in
perspective, check the box labeled Keep aspect ratio.

Export Chart Series Data

This option can be used to export the underlying data of a BioWin chart into other software (e.g. MS Excel).
1. Right-click on the chart to open the Edit menu, and then click Edit Options….
2. Select the Export branch from the left pane.
3. Select the Data sub-tab.

Export Data dialog box

4. Select the data series you wish to export using the drop-down list labeled Series.
5. Choose the file format for the data series (Text, XML or HTML-Table) using the radio buttons in the
Format section.
6. Include the point index, point labels and header information by checking the boxes in the sub-tab
labeled Include.

Exporting as Email Attachment

Biowin 6 Help Manual Data Output (charts, tables, reports) • 679

 1. Right-click on the chart to open the Edit menu, and then click Edit Options….
2. Select the Export branch from the left pane.
3. Select the export settings required using the Picture and Data sub-tabs.
4. Click the Send… button to open your email client. You may be asked to provide a password.
5. Your Email program will create a new email message and attach the file. Complete the message and
send it. Close your Email program when finished.

Exporting to a File

1. Right-click on the chart to open the Edit menu, and then click Edit Options….
2. Select the Export branch from the left pane.
3. Select the export settings required using the Picture and Data sub-tabs.
4. Click the Save… button to open the Save As dialog box.
5. Enter a filename for the file and choose the storage location.
6. Click the Save button.
7. Click the Close button to finish.

Print Options
This section contains procedures for printing your charts, including options for printer setup, printer
selection and page setup.

Print Preview the Chart

1. Right-click on the chart to open the Edit menu, and then click Edit Options….
2. Select the Print branch from the left pane.

680 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 Print preview dialog box

3. This dialog box can be used to:

• Select your printer from the Printer drop-down list.
• Choose your paper orientation (Portrait or Landscape) from the Orientation radio buttons.
• Adjust the margins by dragging the margin lines on the previewed page.
• Dragging the pointer in the section called Detail between More and Normal will scale the chart
text sizes. Smaller text (More detail) generally looks better when printing.
• Change your printer setup options (such as paper size, paper source) using the Setup… button.
• Print the previewed page using the Print button.
4. Click the Close button to finish.

Changing the Paper Orientation

1. Right-click on the chart to open the Edit menu, and then click Edit Options….
2. Select the Print branch from the left pane.
3. Change between Landscape and Portrait orientation using the radio buttons in the Orientation
section.
4. Click the Close or Print button to finish.

Selecting a Printer

1. Right-click on the chart to open the Edit menu, and then click Edit Options….
2. Select the Print branch from the left pane.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 681

 3. Using the drop-down list labeled Printer, select the printer required.
4. Click the Print button to finish.

Adjusting the Chart Size

1. Right-click on the chart to open the Edit menu, and then click Edit Options….
2. Select the Print branch from the left pane.
3. To adjust the chart margins and resize the chart, point the mouse at the dashed lines in the print
preview area of the print dialog box and drag them to the desired position. The print preview
window will automatically display the adjusted chart
4. To adjust the level of detail, drag the pointer in the section labeled Detail between More and
Normal.
5. Click the Close or Print button to finish.

Adjusting the Chart Position

1. Right-click on the chart to open the Edit menu, and then click Edit Options….
2. Select the Print branch in the left pane.
3. Position the mouse over the graph in the print preview area. The mouse pointer will change to an
image of a hand.
4. Drag the chart into the desired location.
5. Click the Close or Print button to finish.

Changing the Paper Size or Source

1. Right-click on the chart to open the Edit menu, and then click Edit Options.
2. Select the Print branch in the left pane.
3. Click on the Setup… button to open the print setup dialog box.
4. Select the paper size (e.g. Legal, A4, Executive) from the drop-down list labeled Size.
5. Select the paper feed source for the printout (e.g. Lower, Upper, Manual Feed) from the drop-down
list labeled Source.
6. Click the OK button to close the print setup dialog box.
7. Click the Print or Close button to finish.

Series Formatting Procedures

One of BioWin’s helpful series formatting features is that changes you make to a series are displayed “on the
fly” as you make them. This is an excellent way to learn the functionality of the series editing controls since
you immediately see the results of clicking various buttons, spin edit boxes, and other dialog box controls in
the background.

682 • Data Output (charts, tables, reports) Biowin 6 Help Manual

Common Series Procedures
This section covers procedures that are accessible from the Series tab of the Edit Series… command (it is
also accessible through Edit Options…|Series).

Tab used for series format manipulation

Change a Series Style

1. Right-click on the chart to open the Edit menu, and then click Edit Series… or Edit Options…
command.
2. In the Series list box on the right pane, select the series you want to change the style of.
3. Click the Change... button.
4. Select the new series style from the Series Gallery. If a 3D style is required, ensure the 3D box is
checked. Click the OK button when done.
5. Click the Close button to finish.

Note: To change the style of another series, repeat steps 2-4.

Rename a Series
1. Right-click on the chart to open the Edit menu, and then click Edit Series… or Edit Options…
command.
2. In the Series list box on the right pane, select the series you want to rename.
3. Click the Title... button.
4. Enter the new name in the Change Series Title dialog box, and click OK.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 683

 5. Click the Close button to finish.

Note: To rename another series, repeat steps 2-4.

Delete a Series From a Chart

1. Right-click on the chart to open the Edit menu, and then click Edit Series… or Edit Options…
command.
2. In the Series list box on the right pane, select one or multiple series you want to delete.
3. Click the Delete button.
4. If you are sure you want to delete this/these series, click Yes in the confirmation box.
5. Click the Close button to finish.

Note: To delete another series, repeat steps 2-4.

Add/Remove a Series in the Legend

1. Right-click on the chart to open the Edit menu, and then click Edit Series… or Edit Options…
command.
2. Select the desired series in the left pane.
3. Click the General|Legend sub-tab.
4. Add or remove the check from the box labeled Visible.
5. Click the Close button to finish.

Note: To add/remove another series, repeat steps 2-4.

Change Axis Position for a Series

1. Right-click on the chart to open the Edit menu, and then click the Edit Series… or Edit Options…
command.
2. Select the series you want to control in the left pane.
3. Click the General|Options sub-tab.
4. Choose the position that you want the series plotted on (Top, Bottom or Top and Bottom) from the
drop-down list in the section labeled Horizontal Axis.
5. If you want this axis to have date/time formats, check the box labeled Date Time.
6. In the Vertical Axis drop-down list select the vertical axis (Left, Right or Left and Right) that you
want the series to be plotted on.
7. If you want this axis to have date/time formats, check the box labeled Date Time.
8. Click the Close button to finish.

684 • Data Output (charts, tables, reports) Biowin 6 Help Manual

Note: To change the axis for another series, repeat steps 2-8.

Series Labeling Procedures

This section outlines the various methods for changing the appearance of series labels, known as marks,
including border, color, font, and style.

Dialog box used for manipulating series marks

Adding Labels to a Chart

1. Right-click on the chart to open the Edit menu, and then click Edit Series… or Edit Options…
command.
2. Select the series you want to control in the left pane.
3. Click the Marks sub-tab.
4. Make sure that the box labeled Visible is checked on the Style sub-tab.
5. Click the Close button to finish.

Series Label Styles

This section gives an outline and examples of the various series label styles that are available in BioWin.

Style Example

Value 1234
Percent 12 %

Biowin 6 Help Manual Data Output (charts, tables, reports) • 685

 Label Mass
Label & Percent Mass 25 %
Label & Value Mass 1234
Legend Depends on Legend Text Style
Percent Total 12 % of 1234
Label & Percent Total Mass 12 % of 1234
Xvalue 4321

Change the Series Label Style

1. Right-click on the chart to open the Edit menu, and then click Edit Series… or Edit Options…
command.
2. Select the series you want to control in the left pane.
3. Click the Marks sub-tab.

Dialog box used to manipulate the style of chart marks

4. Make sure that the box labeled Visible is checked on the Style sub-tab.
5. In the Style drop-down list on the Text|Options sub-tab, select the label style that you want for the
series.
6. Click the Close button to finish.

Note: To change the label style for another series, repeat steps 2-5.

686 • Data Output (charts, tables, reports) Biowin 6 Help Manual

Change the Series Label Number Format
1. Right-click on the chart to open the Edit menu, and then click Edit Series… or Edit Options…
command.
2. Select the series you want to control in the left pane.
3. Click the General sub-tab.
4. Click the Options sub-tab.
5. In the Formats group, change the Values or Percents formatting to the style you want. Refer to the
Number Formats in BioWin topic below for more information.
6. Click OK to finish.

Number Formats in BioWin

This section contains an overview of the various number formats that are available in BioWin. Although this
information is applicable elsewhere, it has been included here since it will most likely be needed in relation
to chart labeling.

Specifier Description

0 Digit placeholder. If the value being formatted has a digit in the position where the
‘0’ appears in the format string, then that digit is copied to the output string.
Otherwise, a ‘0’ is stored in that position in the output string.
# Digit placeholder. If the value being formatted has a digit in the position where the
‘#’ appears in the format string, then that digit is copied to the output string.
Otherwise nothing is stored in that position in the output string.
. Decimal point. The first ‘.’ character in the format string determines the location
of the decimal separator in the formatted value; any additional ‘.’ characters are
ignored. The actual character used as a decimal separator in the output string is
specified in the Number Format of the International section of the Windows
Control Panel.
, Thousand separator. If the format string contains one or more ‘,’ characters, the
output will have thousand separators inserted between each group of three digits
to the left of the decimal point. The placement and number of ‘,’ characters in the
format string does not affect the output, except to indicate that thousand
separators are wanted. The actual character used as a thousand separator in the
output string is specified in the Number Format of the International section of the
Windows Control Panel.
E+ Scientific notation. If any of the strings ‘E+’, ‘E-’, ‘e+’, or ‘e-’ are contained in the
format string, the number is formatted using scientific notation. A group of up to
four ‘0’ characters can immediately follow the ‘E+’, ‘E-’, ‘e+’, or ‘e-’ to determine
the minimum number of digits in the exponent. The ‘E+’ or ‘e+’ formats cause a
plus sign to be output for positive exponents and a minus sign to be output for
negative exponents. The ‘E-’ and ‘e-’ formats output a sign character only for
negative exponents.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 687

 'xx'/"xx" Characters enclosed in single or double quotes are output as-is, and do not affect
formatting.
; Separates sections for positive, negative, and zero numbers in the format string.
The locations of the leftmost ‘0’ before the decimal point in the format string and the rightmost ‘0’ after the
decimal point in the format string determine the range of digits that are always present in the output string.
The number being formatted is always rounded to as many decimal places as there are digit placeholders
(‘0’ or ‘#’) to the right of the decimal point. If the format string contains no decimal point, the value being
formatted is rounded to the nearest whole number.
If the number being formatted has more digits to the left of the decimal separator that there are digit
placeholders to the left of the ‘.’ character in the format string, the extra digits are output before the first
digit placeholder.
To allow different formats for positive, negative, and zero values, the format string can contain between one
and three sections separated by semicolons:
1. One section: The format string applies to all values;
2. Two sections: The first section applies to positive values and zeros, and the second section applies
to negative values;
3. Three sections: The first section applies to positive values, the second applies to negative values,
and the third section applies to zeros.
If the section for negative values or the section for zero values is empty, that is there is nothing between the
semicolons that delimit the section, the section for the positive values is used instead.
If the section for positive values is empty, or if the entire format string is empty, the value is formatted using
general floating-point formatting with 15 significant digits. General floating-point formatting is also used if
the value has more than 18 digits to the left of the decimal point and the format string does not specify
scientific notation.
The following table shows some sample formats and the results produced when the formats are applied to
different values:

Format String 1234 -1234 0.5 0

None Specified 1234 -1234 0.5 0

0 1234 -1234 1 0
0.00 1234.00 -1234.00 0.50 0.00
#.## 1234 -1234 .5
#,##0.00 1,234.00 -1,234.00 0.50 0.00
#,##0.00;(#,##0.00) 1,234.00 (1,234.00) 0.50 0.00
#,##0.00;;Zero 1,234.00 -1,234.00 0.50 Zero
0.000E+00 1.234E+03 -1.234E+03 5.000E-01 0.000E+00
#.###E-0 1.234E3 -1.234E3 5E-1 0E0

688 • Data Output (charts, tables, reports) Biowin 6 Help Manual

Change the Series Label Frame
1. Right-click on the chart to open the Edit menu, and then click Edit Series… or Edit Options…
command.
2. Select the series you want to control in the left pane.
3. Click the Marks|Style sub-tab.
4. Make sure that the box labeled Visible is checked.
5. Click the Marks|Text|Format|Border|Frame|Format sub-tab.

Dialog box used for formatting marks

6. Make sure that the box labeled Visible is checked.

7. Select the label frame width you want from the Width slider.
8. Select the label frame style you want from the Style sub-tab.
To change the label frame color:
9. In the Marks|Text|Format|Border|Frame|Format sub-tab, select the Color... button to open the
Color selection dialog box.
10. Click on the label frame color you want
11. Click OK to close the Color selection dialog box.
12. Click the Close button to finish.

Note: To change the label frame for another series, repeat steps 2-13. If you don't want series labels to
extend beyond the chart axis boundaries, check the box labeled Clipped in the Marks|Style sub-tab.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 689

Change the Series Label Color
1. Right-click on the chart to open the Edit menu, and then click Edit Series… or Edit Options…
command.
2. Select the series you want to control in the left pane.
3. Click the Marks|Style sub-tab.
4. Make sure that the box labeled Visible is checked.
5. Click the Marks|Text|Format|Format sub-tab.

Dialog box used for formatting marks

6. Click the Color... button to open the Color selection dialog box.
7. Click on the label color you want and then click OK to close the Color selection dialog box.
8. Click the Close button to finish.

Note: To change the label color for another series, repeat steps 2-8. If you want the series labels to be
clear, make the label color white.

To change the series label pattern:

9. Right-click on the chart to open the Edit menu, and then click Edit Series… or Edit Options…
command.
10. Select the series you want to control from the left pane.
11. Click the Marks|Style sub-tab.
12. Make sure that the box labeled Visible is checked.
13. Click the Marks|Text|Format|Pattern sub-tab to open the Pattern Editor tabs.

690 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 Dialog box used for formatting marks

14. Select the pattern style you want using the provided tabs.

Change the Pattern Color:

1. Select the Color... button to open the Color selection dialog box.
2. Click on the pattern color you want
3. Click OK to close the Color selection dialog box.
4. Click the Close button to finish.

Note: To change the label pattern for another series, repeat steps above.

Change the Series Label Font

1. Right-click on the chart to open the Edit menu, and then click Edit Series… or Edit Options…
command.
2. Select the series you want to control from the left pane.
3. Click the Marks|Style sub-tab.
4. Make sure that the box labeled Visible is checked.
5. Click the Marks|Text|Format|Font|Font sub-tab.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 691

 Dialog box used for manipulating the text of series marks

6. Click the Edit... button to open the Font properties dialog box.
7. Specify the Font (e.g. Arial, Times New Roman, etc.), the Font Style (e.g. Italic, Bold, etc.), Size, and
Color until the Sample Text has the appearance you want.
8. Click the OK button to close the Font properties dialog box.
To add an outline effect to the font :
9. Click the Outline… button to open the Border Editor tabs.
10. Make sure that the box labeled Visible is checked.
11. Choose the Color, Style and Width for the outline you require.
To adjust the amount of white space between the characters:
12. Increase or decrease the value in the Inter-char spacing spin edit box in the Options sub-tab.
13. Click the Close button to finish.

Note: To change the label font for another series, repeat steps above.

Change the Series Label Gradient

1. Right-click on the chart to open the Edit menu, and then click Edit Series… or Edit Options…
command.
2. Select the series you want to control from the left pane.
3. Click the Marks|Style sub-tab.
4. Make sure that the box labeled Visible is checked.

692 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 5. Click the Marks|Text|Format|Pattern|Gradient sub-tab.

Dialog box used to add a gradient to series marks

6. Ensure the Visible box is checked.

7. Select a direction (e.g. Left Right, Top Bottom) for the gradient from the Direction drop-down list.
8. In the Colors section of the dialog box, use the Start, Middle and End buttons to select the colors for
the gradient. If no middle color is required, check the No Middle box.
9. To reverse the start and end colors, use the Swap button.
10. Click the Close button to finish.

Note: To change the label gradient for another series, repeat steps 2-9.

Change the Series Label Shadow

1. Right-click on the chart to open the Edit menu, and then click Edit Series… or Edit Options…
command.
2. Select the series you want to control in the left pane.
3. Click the Marks|Style sub-tab.
4. Make sure that the box labeled Visible is checked.
5. Select the Marks|Text|Format|Shadow|Format sub-tab.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 693

 Dialog box used to add a shadow to series marks

6. Make sure that the box labeled Visible is checked.

7. Click the Color button to display the Color dialog box and select from the Basic Colors to add a
shadow to your text if desired.
8. Click the OK button to close the Color dialog box.
9. Click and drag the Size slider to adjust the depth of the shadow or enter a value from the keyboard.
10. Click the Close button to finish.

Note: To change the label shadow for another series, repeat steps 2-9.

Edit the Series List

This section describes a number of ways to manipulate the series that are plotted on a chart. Right-clicking
on a chart and selecting Edit Series… from the resulting popup menu will open the following dialog box.

694 • Data Output (charts, tables, reports) Biowin 6 Help Manual

The Edit Series Chart|Series list dialog box

Hide/Show a Series
This dialog box allows you to turn the display of a series in a chart on or off. Note that this does not remove
the series from the chart; rather it simply toggles a series' visibility. To show or hide a series in a chart,
check or uncheck the check box beside the series name in the dialog box. If you want to remove a series,
click on the series and press the Delete key on your keyboard.

Change the Series Plotting Order

You can use this dialog box to change the order in which series are plotted on a chart. To do this, click on a
series name so that it is highlighted, and then click the up or down arrow. Note that when you do this, the
order in which series are listed in the legend changes accordingly.

Change a Series Color

The color of each series is shown next to its name in the series list. Double-clicking on the color will open up
the Color selection dialog box. You can then use this dialog box to change the color of the series.

Fast Line Series Procedures

This section is an overview of formatting procedures that can be executed from the Series|Format sub-tab
of the Edit Series… menu for a Fast Line series.
Fast Line series can be used for traditional engineering X-Y plots, time series analysis, etc. In BioWin they
particularly are useful for displaying dynamic simulation results. Fast Line series have fewer display options

Biowin 6 Help Manual Data Output (charts, tables, reports) • 695

than the regular Line series, but they draw quicker and therefore are useful if you are plotting several series
at once. The Fast Line series style trades display options for speed of execution.

Fast Line series formatting options

Change the Fast Line Series Appearance

1. Right-click on the chart to open the Edit menu, and then click Edit Series….
2. In the left pane, select the fast line series you want to change the appearance of.
3. Click the Format|Format sub-tab.

696 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 Fast line series formatting options

4. Ensure that the box labeled Visible is checked.

5. Change the width of the line using the Width slider.
6. Click the Color... button to open the Color selection dialog box.
7. Click on the fast line series color you want and then click OK to close the Color selection dialog box.
8. Change the line style using the Style sub-tab. Note that this option is not available if the line width
is greater than one due to screen resolution restrictions.
9. Click the Close button to finish.

Line Series Procedures

This is an overview of formatting procedures that can be executed from the Format and Point sub-tabs of
the Edit Series tab for a Line Series.
Line series can be used for traditional engineering X-Y plots, time series analysis, etc. In BioWin they
particularly are useful for displaying dynamic simulation results.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 697

Line series line formatting options

Line series point formatting options

Change the Line Series Color

1. Right-click on the chart to open the Edit menu, and then click Edit Series….

698 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 2. In the left pane, select the line series you want to change the appearance of.
3. Click the Format|Format sub-tab.

Line series line formatting options

4. Click the Color... button to open the Color selection dialog box.
5. Click on the line series color you want and then click OK to close the Color selection dialog box.
6. Click the Close button to finish.

Change the Line Series Border

1. Right-click on the chart to open the Edit menu, and then click Edit Series….
2. In the left pane, select the line series you want to change the appearance of.
3. Click the Format|Border|Format sub-tab.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 699

 Line series line formatting options

4. Make sure that the box labeled Visible is checked.

5. Select the line series border width you want from the Width slider.
6. Select the line series border style you want from the Style sub-tab.

To change the line series border color:

7. Select the Color... button in the Format sub-tab to open the Color selection dialog box.
8. Click on the line series border color you want and then click OK to close the Color selection dialog
box.
9. Click OK to close the Border Editor.
10. Click the Close button to finish.

Change the Line Series Pattern and Mode

1. Right-click on the chart to open the Edit menu, and then click Edit Series….
2. In the left pane, select the line series you want to change the pattern or mode of.
3. Click the Format|Pattern sub-tab.
4. Use the sub-tabs provided to change the line series pattern.
5. If you want each instance of the chosen pattern to have a unique color, check the box labeled Color
Each in the Format|Format sub-tab.

700 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 6. If you want the Line Mode to be such that the line is drawn in a stair-step manner between your
data points, check the box labeled Stairs in the Format|Options sub-tab. To invert the stair-step
pattern, check the box labeled Inverted.
7. Click the Close button to finish.

Change the Line Series Point General Appearance

1. Right-click on the chart to open the Edit menu, and then click Edit Series….
2. In the left pane, select the line series you want to change point general appearance of.
3. Click the Point|Format sub-tab.

Line series point formatting options

• Ensure that the box labeled Visible is checked.

• Change the size of the points using the Width and Height spin edit boxes in the Size sub-tab. To
adjust the axes to accommodate the point size, check the box labeled Inflate Margins.
• To change the point marker, use the Style sub-tab.
4. Click the Close button to finish.

Change the Line Series Point Color

1. Right-click on the chart to open the Edit menu, and then click Edit Series….
2. In the left pane, select the line series you want to change point general appearance of.
3. Click the Point|Format sub-tab.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 701

 4. Ensure that the box labeled Visible is checked.
5. Click the Pattern sub-tab to access the pattern formatting tools.
6. Click the Color… button on the Solid sub-tab to open the Color selection dialog box.
7. Click on the line series point color you want and then click OK to close the Color selection dialog box.
8. Click the Close button to finish.

Change the Line Series Point Border

1. Right-click on the chart to open the Edit menu, and then click Edit Series….
2. In the left pane, select the line series you want to change point general appearance of.
3. Click the Point|Format sub-tab.

Line series point formatting options

4. Ensure that the box labeled Visible is checked.

5. Click the Border sub-tab.
6. Make sure that the box labeled Visible is checked.
7. Select the line series point border width you want from the Width slider.
8. Select the line series point border style you want from the Style sub-tab.

To change the line series point border color:

9. Select the Color... button to open the Color selection dialog box.

702 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 10. Click on the line series point border color you want and then click OK to close the Color selection
dialog box.
11. Click OK to close the Border Editor.
12. Click the Close button to finish.

Point Series Procedures

This is an overview of formatting procedures that can be executed from the Series|Format sub-tab of the
Edit Series… menu for a Point Series.
Point series are useful for X-Y plots, especially if the data are scattered or irregular. Quite often they are
used to represent experimental data on a plot comparing observed and predicted results.

Point series formatting options

Change the Point Series General Appearance

1. Right-click on the chart to open the Edit menu, and then click Edit Series….
2. In the left pane, select the point series you want to change the appearance of.
3. Click the Format|Format sub-tab.
4. Ensure that the box labeled Visible is checked.
5. Change the size of the points using the Width and Height spin edit boxes in the Size sub-tab. To
adjust the axes to accommodate the point size, check the box labeled Inflate Margins.

To change the point marker:

6. Use the Style sub-tab to choose a point marker.
7. If you want each point in the series to have a random, different color, check the box labeled Color
Each in the Format sub-tab.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 703

 8. Click the Close button to finish.

Change the Point Series Pattern

1. Right-click on the chart to open the Edit menu, and then click Edit Series….
2. In the left pane, select the point series you want to change the color of.
3. Click the Format|Format sub-tab.
4. Ensure that the box labeled Visible is checked.
5. Click the Pattern sub-tab.
6. Use the sub-tabs to choose the pattern you want. Click on the Color... button to open the Pattern
Color Editor dialog box.
7. Click on the color you want and then click OK to close the Pattern Color Editor dialog box.
8. Click the Close button to finish.

Change the Point Series Border

1. Right-click on the chart to open the Edit menu, and then click Edit Series….
2. In the left pane, select the point series you want to change the border of.
3. Click the Format|Format sub-tab.
4. Ensure that the box labeled Visible is checked.
5. Click the Border sub-tab to access the border tools.
6. Make sure that the box labeled Visible is checked.
7. Select the point border width you want from the Width spin edit box.
8. Select the point border style you want from the Style sub-tab.
To change the point border color :
9. Select the Color... button in the Format sub-tab to open the Color selection dialog box.
10. Click on the point border color you want
11. Click OK to close the Color selection dialog box.
12. Click the Close button to finish.

Bar Series Procedures

This is an overview of formatting procedures that can be executed from the Series|Format sub-tab of the
Edit Series… menu for a Bar Series (Vertical and Horizontal).
Note that when adding a new bar series to a chart, BioWin assumes that the bar series will consist of vertical
bars. If this is not suitable for your chart, then you may change the bar series so that it uses horizontal bars
by using the Change… option.
Bar series are useful for current value plots and displaying steady-state simulation results. Multiple bar
series can be "stacked" to illustrate proportional differences.

704 • Data Output (charts, tables, reports) Biowin 6 Help Manual

Bar series formatting options

Change the Bar Series Color

1. Right-click on the chart to open the Edit menu, and then click Edit Series….
2. In the left pane, select the bar series you want to change the color of.
3. Click the Format|Options sub-tab.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 705

 Bar series formatting options

4. If you want each bar in the series to have a random, different color, check the box labeled Color
Each.
5. If you want all the bars to have the same color, click the Color... button to open the color selection
dialog box.
6. Click on the bar color you want and then click OK to close the color selection dialog box.
7. If your bar series is three-dimensional and you want to have a shadow effect on the three-
dimensional face, check the box labeled Dark.
8. Click the Close button to finish.

Change the Bar Series Border

1. Right-click on the chart to open the Edit menu, and then click Edit Series.
2. In the left pane, select the bar series you want to change the border of.
3. Click the Format|Border|Format|Format sub-tab.

706 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 Bar series formatting options

4. Make sure that the box labeled Visible is checked.

5. Select the bar border width you want from the Width slider.
6. Select the bar border style you want from the Style sub-tab.

To change the bar border color:

7. Select the Color... button to open the Color selection dialog box.
8. Click on the bar border color you want
9. Click OK to close the Color selection dialog box.
10. Click the Close button to finish.

Change the Bar Series Pattern

1. Right-click on the chart to open the Edit menu, and then click Edit Series….
2. In the left pane, select the bar series you want to change the pattern of.
3. Click the Format|Pattern sub-tab.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 707

 Bar series formatting options

4. Select the pattern style you want from the available tabs.

To change the pattern color:

5. Select the Color... button to open the color selection dialog box.
6. Click on the pattern color you want and then click OK to close the Color selection dialog box.
7. Click the Close button to finish.

Change the Bar Series Shapes and Positions

1. Right-click on the chart to open the Edit menu, and then click Edit Series….
2. In left pane, select the bar series you want to change the shape and/or position of.
3. Click the Format sub-tab.
• To change the shape of the bars in your bar series, use the Style sub-tab to choose from a
variety of shapes.
• You can change the amount of space between the bars in a series by changing the value in the %
Bar Width: spin edit box in the Size sub-tab. Increasing the value increases the width of the
bars, thus decreasing the space between them.
• You can shift the position of the bars in a series using the % Bar Offset: spin edit box in the Size
sub-tab. This property especially is useful when plotting multiple bar series on the same chart.
• If you want margins between the bars in a series and the chart boundaries, check the box
labeled Bar Side Margins.

708 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 • If you are labeling the bars in a series you can reduce the amount that labels will overwrite each
other by checking the box labeled Auto Mark Position.
4. Click the Close button to finish.

Control Bar Placement for Multiple Bar Series

1. Right-click on the chart to open the Edit menu, and then click Edit Series….
2. In the left pane, select one of the bar series. In this special case of series formatting, selecting one
bar series also will result in changes to the other bar series.
3. Click the Stack sub-tab.

Bar series stack options

4. In the drop list box or icon box choose one of the following options for bar placement:
• None: This will place corresponding bars in each series in front of one another. However, if your
chart is three-dimensional you will be able to see portions of all the series.
• Side: This will place corresponding bars in each series beside one another.
• Stacked: This will place corresponding bars in each series on top of one another.
• Stacked 100%: This will place corresponding bars in each series on top of one another showing
the relative size of each bar on a 100 % scale.
• Side All: This will place each complete series side by side.
• To have bar bottoms for a series start at the zero coordinate, check the box labeled Use Origin.
• To have them begin at a different ordinate value, uncheck this box and input the desired starting
value.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 709

 5. Click the Close button to finish.

Pie Series Procedures

This is an overview of formatting procedures that can be executed from the Series|Format sub-tab of the
Edit Series… menu for a Pie Series.
Pie series are useful for displaying proportional or fractional data when you desire to show the size of the
portions relative to each other. For example, pie series may be used to display wastewater characteristic
fractions, plant sludge mass fractions, plant volume fractions, etc. They also are a good method for
displaying results in current value plots.

Pie series formatting options

Change the Pie Series General Appearance

1. Right-click on the chart to open the Edit menu, and then click Edit Series….
2. In the left tab, select the pie series you want to change the appearance of.
3. Click the Circled sub-tab.

710 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 Pie series circled options

• If you want your pie series to be circular in shape, check the box labeled Circled.
• To rotate the pie chart, use the Rotation slider.
• If you want to have an elliptical pie series, adjust the dimensions using the Horizontal and
Vertical spin edit boxes in the Radius sub-tab. To let BioWin determine your elliptical radii,
check the boxes labeled Auto.
4. Click the Close button to finish.

Change the Pie Series Color and Pattern

1. Right-click on the chart to open the Edit menu, and then click Edit Series….
2. In the left pane, select the pie series you want to change the appearance of.
3. Click the Format|Options sub-tab.
4. If you would rather have patterns as opposed to solid color fills for your pie slices, check the box
labeled Patterns.
5. Click the Close button to finish.

Change the Pie Series Border

1. Right-click on the chart to open the Edit menu, and then click Edit Series….
2. In left pane, select the pie series you want to change the border of.
3. Click the Format|Border|Border sub-tab.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 711

 Pie series formatting options

4. Click the Format sub-tab.

5. Make sure that the box labeled Visible is checked.
6. Select the pie series border width you want from the Width slider.
7. Select the pie series border style you want from the Style sub-tab.

To change the pie series border color:

8. Select the Color... button to open the Color selection dialog box.
9. Click on the pie series border color you want
10. Click OK to close the Color selection dialog box.
11. Click the Close button to finish.

Change the Pie Series Three-Dimensional Appearance

1. Right-click on the chart to open the Edit menu, and then click Edit Series….
2. In left pane, select the pie series you want to change the three-dimensional appearance of.
3. Click the Circled|Options sub-tab.

712 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 Pie series circled options

4. If you want your pie series to be three-dimensional, check the box labeled 3 Dimensions.

Note: If you want the three-dimensional pie face to have a slightly darker tint than the top of the pie series,
check the box labeled Dark 3D on the Format|Options tab.

To have a darker shadow effect on the three-dimensional pie face:

5. Increase the value in the Horiz. Size and Vert. Size spin edit boxes in the Circled|Shadow|Format
sub-tab.
To change the shadow color:
6. Click the Color... button in the Circled|Shadow|Format sub-tab.
7. This will open the Color selection dialog box
8. Select the shadow color you want,
9. Click OK to close the Color selection dialog box
10. Click the Close button to finish.

Arrange the Pie Series Slices

1. Right-click on the chart to open the Edit menu, and then click Edit Series….
2. In the left pane, select the pie series you want to rearrange the pie series slices appearance of.
3. Click the Format|Options sub-tab.
• If you want to place emphasis on the largest pie slice, use the Explode biggest spin edit box to
separate the largest slice from the rest of the pie.
• You can combine all pie slices below a specified value or percentage into a single slice. To do
this:
4. Use the Style drop list box in the Format|Group Slices|General sub-tab to choose the criteria
(below a certain value or percent) you want to use to group slices.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 713

 5. In the Value text edit area, enter the cut-off value. All pie slices below this value will be combined
into one pie.
6. You can label the grouped slices. Click the Marks|Style sub-tab and ensure that Visible is checked.
Now click back on the Format|Group Slices|General sub-tab and enter your text in the Label text
edit area at the bottom of the dialog box.

Area Series Procedures

This is an overview of formatting procedures that can be executed from the Series|Format and
Series|Points sub-tabs of the Edit Series… menu for an Area Series.
Area series are somewhat of a combination of a line chart and a bar chart. They provide a richer way of
displaying line chart data in three dimensions, and offer some of the stacking properties of multiple bar
series to illustrate proportional differences. As such they are useful for displaying results in current value
charts.

Area series formatting options

Area series point formatting options

714 • Data Output (charts, tables, reports) Biowin 6 Help Manual

Change the Area Series General Appearance
1. Right-click on the chart to open the Edit menu, and then click Edit Series….
2. In the left pane, select the area series you want to change the appearance of.
3. Click the Format sub-tab.

Area series format options

• If you want a pattern (drawn in black lines) on the face of your area series, use the Pattern sub-
tab to select the one you desire.
• To have the points that define the area series joined in a “stair-step” pattern, check the box
labeled Stairs in the Format|Options sub-tab.
4. Click the Close button to finish.

Change the Area Series Color

1. Right-click on the chart to open the Edit menu, and then click Edit Series….
2. In the left pane, select the area series you want to change the color of.
3. Click the Format|Options sub-tab.
4. If you want each area segment in the series to have a random, different color, check the box labeled
Color Each.
5. If you want all the area segments to have the same color, click the Color... button to open the Color
selection dialog box.
6. Click on the area color you want and then click OK to close the Color selection dialog box.
7. Click the Close button to finish.

Change the Area Series Border

1. Right-click on the chart to open the Edit menu, and then click Edit Series….

Biowin 6 Help Manual Data Output (charts, tables, reports) • 715

 2. In left pane, select the area series you want to change the border of.
3. Click the Format sub-tab.
4. Click the Border|Format sub-tab.
5. Make sure that the box labeled Visible is checked.
6. Select the area border width you want from the Width slider.
7. Select the area border style you want from the Style sub-tab.
To change the area border color:
8. Select the Color... button to open the Color selection dialog box.
9. Click on the area border color you want
10. Click OK to close the Color selection dialog box.
11. Click the Close button to finish.

Change the Area Series Lines Format

1. Right-click on the chart to open the Edit menu, and then click Edit Series….
2. In the left-pane, select the area series you want to change the lines format of.
3. Click the Format sub-tab.

Area series format options

4. Click the Area Lines|Format sub-tab.

5. Make sure that the box labeled Visible is checked.
6. Select the area line width you want from the Width slider.
7. Select the area line style you want from the Style sub-tab.
To change the area line color:
8. Select the Color... button to open the Color selection dialog box.

716 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 9. Click on the area line color you want and then click OK to close the Color selection dialog box.
10. Click the Close button to finish.

Control Area Placement for Multiple Area Series

1. Right-click on the chart to open the Edit menu, and then click Edit Series….
2. In the left pane, select one of the area series. In this special case of series formatting, selecting one
area series also will result in changes to the other area series.
3. Click the Format|Stack sub-tab.

Area series format options

4. In the Multiple Areas: radio button group choose one of the following options for area series
placement:
• None: This will place each area series in front of one another. However, if your chart is three-
dimensional you will be able to see portions of all the series.
• Stacked: This will place each area series on top of one another.
• Stacked 100%: This will place each area series on top of one another showing the relative size of
each area on a 100 % scale.
5. Click the Close button to finish.

Change the Area Series Point General Appearance

1. Right-click on the chart to open the Edit menu, and then click Edit Series….
2. In the left pane, select the area series you want to change the point general appearance of.
3. Click the Point|Format sub-tab. Area series point options
• Ensure that the box labeled Visible is checked.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 717

 • In the Size sub-tab, change the size of the points using the Width and Height spin edit boxes. To
adjust the axes to accommodate the point size, check the box labeled Inflate Margins.
• To change the point marker in the Style sub-tab.
4. Click the Close button to finish.

Change the Area Series Point Pattern

1. Right-click on the chart to open the Edit menu, and then click Edit Series….
2. In the left pane, select the area series you want to change the point color of.
3. Click the Point|Format sub-tab.
4. Ensure that the box labeled Visible is checked.
5. Click the Pattern sub-tab to select the area series point pattern you want using the available sub-
tabs.
6. Click the Close button to finish.

Change the Area Series Point Border

1. Right-click on the chart to open the Edit menu, and then click Edit Series….
2. In left pane, select the area series for which you want to change the point border.
3. Click the Point|Format sub-tab.
4. Ensure that the box labeled Visible is checked.
5. Click the Border|Format sub-tab.
6. Make sure that the box labeled Visible is checked.
7. Select the area series point border width you want from the Width slider.
8. Select the area series point border style you want from the Style sub-tab.
To change the area series point border color:
9. Select the Color... button to open the Color selection dialog box.
10. Click on the area series point border color you want
11. Click OK to close the Color selection dialog box.
12. Click the Close button to finish.

Surface Series Procedures

This is an overview of formatting procedures that can be executed from the Series|Format and Series|Grid
3D sub-tabs of the Edit Series… menu for a Surface Series.
Surface series can be used for spatial profiles of a given compound. For example, say you have a
configuration with three bioreactors, and you want to show the ammonia profile over the bioreactors. The
ammonia concentration would be plotted on the Y (vertical) axis, the bioreactor number would be plotted
on the X (horizontal) axis, and time would be plotted on the Z axis. They also are useful for displaying time-
histories of secondary settler depth - concentration profiles.

718 • Data Output (charts, tables, reports) Biowin 6 Help Manual

Surface series formatting options

Surface series Grid 3D options

Surface Series Gridline Appearance

1. Right-click on the chart to open the Edit menu, and then click Edit Series….
2. In the left pane, select the surface series you want to change the gridlines of.
3. Click the Format sub-tab.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 719

 Surface series formatting options

4. Click the Border|Format sub-tab.

• To turn the gridlines on or off, check or uncheck the box labeled Visible.
• To change the gridline thickness, increase or decrease the value in the Width slider.
• To change the gridline color, click the Color button to open the Color selection dialog box.
• To change the line style (e.g. solid, dashed, etc.) used to draw the gridlines, select a style from
the Style sub-tab. Note that you may not have a Width greater than 1 with any style other than
Solid.
5. Click the Close button to finish.

Surface Series Drawing Mode

1. Right-click on the chart to open the Edit menu, and then click Edit Series….
2. In the left pane, select the surface series you want to change the drawing mode of.
3. Click the Format|Options sub-tab.

720 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 Surface series formatting options

4. From the Drawing Mode radio button group, choose from the following:
• To have a colored surface, choose Solid mode.
• To have a surface with only the gridlines showing, choose WireFrame mode.
• To have your surface drawn with a series of small dots, choose DotFrame mode. Note that this
mode may be difficult to see with some color combinations.
5. When you are satisfied with the appearance of your surface series, click the Close button to finish.

Surface Series Color Mode

1. Right-click on the chart to open the Edit menu, and then click Edit Series….
2. In the left pane, select the surface series you want to change the color mode of.
3. Click the Grid 3D sub-tab.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 721

 Surface series Grid 3D options

4. From the Grid 3D tab choose from the following sub-tab:

• To have one color for the entire surface, choose Single sub-tab. Click on the Color… button next
to this option to open the Color selection dialog box if you want to change the color.
• To have a gradient color fill for the surface, choose Range sub-tab. Click on the Start…, Middle…,
and End… buttons to change the colors used. The Start… “Range” color box is used for points
with the highest Y-values (high on the surface), the Middle… color box is used for intermediate
Y-values and the End… color box for points with the lowest Y-values (i.e. the "low" points in the
surface).
• To have a stepped color fill for the surface, choose Palette sub-tab. The value in the Steps spin
edit box determines the range of colors used in the surface fill, and the height of each point in
the surface determines its assigned color from that range.
5. The “Grid size” group allows you to adjust the appearance of the depth aspect of a surface plot. The
“Depth” spin edit allows you to change the perceived depth of the surface plot. The parameters “X”
and “Z” are determined automatically based on your selections when setting up the series initially
(and, for time series, from the current number of points in time).
6. When you are satisfied with the appearance of your surface, click Close to finish.

BioWin Explorer
The Explorer provides a means to display information about the elements that make up a configuration. You
access the Explorer from the main simulator window via the menu choice View|Explorer. From the
Explorer, you may return to the main simulator window or open the album using the respective menu
commands View|Main and View|Album. The Explorer window is split into two main panes, as shown in the
picture below. The left pane displays an expandable/collapsible outline of the elements that make up the
current configuration. The right pane displays information related to the selected node of the outline.

722 • Data Output (charts, tables, reports) Biowin 6 Help Manual

The Explorer

Note: The information contained in the right pane will be updated each time you click on any branch of the
expandable/collapsible outline in the left pane. Since the information displayed in the Explorer is not
updated automatically, you should always click on the branch that you are viewing to ensure that the
information is current before recording or reporting it.

Navigating in the Explorer

There are different ways to move about in the Explorer; the method you choose is a matter of preference
only as the various techniques accomplish the same goals. A small box beside a node indicates that node
contains sub-nodes. If there is a “+” sign in the box, this indicates that the node may be expanded to display
its sub-nodes. To expand the node, you may either click on the “+” sign, or double-click the node title (i.e.
the text immediately to the right of the box). If there is a “-” sign in the box, this indicates that the node
currently is expanded and displaying all its sub-nodes. To collapse the node, you may either click on the “-”
sign or double-click the node title.
When the Explorer initially is opened, the top node entitled “Elements” is displayed in the left pane. In the
first column of the right pane, all the elements that make up the current configuration are listed, grouped by

Biowin 6 Help Manual Data Output (charts, tables, reports) • 723

element type and sorted within each group alphabetically. The remaining columns in the right pane contain
the current values of a number of compounds and variables (the information displayed here can be changed
– see Explorer Options). Double-clicking on a row in this list will open up the properties dialog box for the
element in question and allow you to edit physical, operational, and monitoring settings. This is equivalent
to right-clicking the element on the drawing board and choosing Properties… from the resulting popup
menu, or double-clicking the element icon on the drawing board.
Expanding the “Elements” node shows all of its sub-nodes; these consist of a node for each of the different
element types in the configuration. Clicking on an element-type node causes the right pane to display a list
of the elements of that type that currently are in the configuration in the first column, with current values of
a number of compounds and variables in subsequent columns. Double-clicking on a row in this list will have
the same effect as described above.
Clicking on an individual element node causes the right pane to display current values of a number of
compounds and variables for that element. Double-clicking this row will allow you to access the element's
properties. Expanding an individual element node will display the State variables node and, if appropriate,
the Parameters node.
Clicking on the State variables node for an element causes the right pane to display a list of the current
values of all state variables for that element, as well as the mass rate for each. Clicking on the Parameters
node for an element causes the right pane to display a row of the local model parameters for that element.
Double-clicking this row will open the Model parameter editor to allow these local model parameter values
to be edited.

Explorer Appearance
You can adjust the width of the explorer columns in the right pane in two ways:
• Hold your cursor over the right dividing line of the column you want to resize in the column heading
row. When you do this, your cursor will change to the horizontal resize cursor ( ). Click the mouse
and drag the column dividing line until the column is the desired size
• To size a column so that it fits the widest value displayed in that column, simply click on the column
heading. Note that this will undo any resizing you have done with method (1) as it sets the other
columns to a “standard” width.
It also is possible to change the relative width of the two main explorer panes. When you hold your cursor
over the vertical bar that separates the left and right panes, you will see the horizontal resize cursor appear.
If you click and hold the mouse button, you will be able to drag the bar to the left or right, which will change
the relative widths of the left and right panes.

Mass Balance Window

BioWin provides mass balances of chemical oxygen demand (COD), nitrogen (N) and phosphorus (P) over
any particular element. This window allows the user to select the material of interest (COD, N or P) and view
the mass flow rates in and out of the vessel. At steady state conditions the mass balance should be zero, for
each of these items, that is the amount of COD, N or P flowing in should be the same as the amount flowing
out of the vessel. The figure below shows an example of a mass balance window for a bioreactor at steady
state conditions.

724 • Data Output (charts, tables, reports) Biowin 6 Help Manual

Note: Different elements may have slightly differing layouts for the mass balance window. For example a
clarifier element (which has no gas input) uses the list box below the element icon to represent the
Underflow instead of the Influent gas.

Mass balance window for a bioreactor at steady state conditions

The list box on the left represents the liquid input to the vessel and the list box on the right the output from
the vessel. The gas phase is represented by the list boxes above and below the graphic.

Note: If the gas phase is not modeled then BioWin reports the amount transferred to or from the liquid
phase rather than the actual gases stripped from the liquid phase (in COD units). In the figure below the gas
phase was modeled and consequently the oxygen reported in the lower list box represent the entire oxygen
content of the gas, and the majority of the oxygen is also reported in the exit gas (top list box).

Biowin 6 Help Manual Data Output (charts, tables, reports) • 725

Mass balance window for a bioreactor at steady state conditions with gas phase modeled

In each of the list boxes, any state variables that contribute to the material selected (COD, N or P) are listed
and the mass flow rate for each given. You will notice that although the figure above shows the mass
balance for COD the nitrate (NO3-N) state variable is listed in both the input and output list boxes and that it
is negative. This is because nitrate can be used as an electron acceptor. The mass balance window takes this
into account and therefore reports NO3-N as a negative number. The mass balance window also accounts for
the oxygen demand associated with ammonia so it too is reported in the list box.

Note: If the COD mass balance is selected then all items in the list box (including nitrogen components) are
reported on COD units.

Note: If nitrogen precipitates are present they may also be listed in the mass balance window for COD and
N.

Rather than closing these windows, it may be more useful to minimize them, so they can be looked at later
using the View|Other windows… command. This command opens up a list of available windows; the
windows can be re-invoked by double-clicking on the desired window in the list. To close the list, click the
“X” in the upper right corner (note this does not clear the list; the list can be re-opened at any time with the
View|Other windows… command). To remove a window from the list, that window must be closed by
clicking the red “X” in its upper right corner.

726 • Data Output (charts, tables, reports) Biowin 6 Help Manual

Using the Windows list to keep track of minimized mass balance windows.

Rates Window
BioWin allows the user to view the rates of reactions in bioreactor vessels. In the left pane of this window,
the calculated process rates are shown with units of mg/L/d. In the right pane of this window, the net
conversion rates (i.e. reaction term) for each of the State Variables are shown with units of mg/L/d * m 3.
These conversion rates are a function of the process rates, the model stoichiometry and the reactor volume
and are equivalent to the difference between the mass rate into and out of the reactor.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 727

Rates window

The rates window of the Granular Sludge Sequencing Tank element allows you to select the location of the
displayed reaction rates. The reaction rates may be displayed in the Bulk, Granules layer or Settler layer. To
display a specific granular layer or settler layer you can either use the up/down arrows or type directly into
the field.

728 • Data Output (charts, tables, reports) Biowin 6 Help Manual

Rates window for the GSST element

The Settler layer rates are only available during settling mode. If the Settler layer is selected when the GSST
is currently mixed, a note will appear to indicate this and the process rates and reaction terms will appear
blank.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 729

Note: The units of the reaction term are always in mg/L/d * m3 regardless of your current project unit
selection.

Rather than closing these windows, it may be more useful to minimize them, so they can be looked at later
using the View|Other windows… command. This command opens up a list of available windows; the
windows can be re-invoked by double-clicking on the desired window in the list. To close the list, click the
“X” in the upper right corner (note this does not clear the list; the list can be re-opened at any time with the
View|Other windows… command). To remove a window from the list, that window must be closed by
clicking the red “X” in its upper right corner.

730 • Data Output (charts, tables, reports) Biowin 6 Help Manual

Using the Windows list to keep track of minimized mass balance windows.

It is possible to get more detail about the processes contributing to the conversion rates of the individual
State Variables using information from the Rates window and the Calculated Stoichiometry for the Model:
• Right-click on a bioreactor in BioWin and open the Rates... window.
• Right-click on a column heading and select Copy from the pop-up menu to copy the table of the
calculated Process Rates to the Windows clipboard. Next, switch to an empty spreadsheet and paste
the information near the upper left-hand cell (say in cell A3). Give the worksheet a descriptive name,
e.g. “Rates”.
• Switch back to BioWin and open up Project | Current Project Options…|Model and push the Show
calculated stoichiometry... button.
• Right-click on a column heading and select Copy from the pop-up menu to copy the stoichiometry
matrix to the Windows clipboard. Next, switch to an empty worksheet in excel and paste the
information near the upper left-hand cell (say in cell A3). Give the worksheet a descriptive name,
e.g. “Stoichiometry”.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 731

 • Create a third Worksheet in the spreadsheet program and name it “Calculated Conversion Rates”.
• In the first column of the “Calculated Conversion Rates” worksheet, copy the names of the process
rates from the “Stoichiometry” Worksheet. In the first row, copy the names of the State Variables
also from the “Stoichiometry” Worksheet.
• In the first open cell of the “Calculated Conversion Rates” worksheet, enter a formula to determine
the product of the first calculated stoichiometry matrix entry and the first calculated process rate.
For example, the conversion rate for “Aer. growth of OHO on SBSC” is equal to the “Stoichiometry”
for that process and state variable multiplied by the rate for that process. If you have been following
the placement of information into your worksheets exactly as described in the steps above, the
equation entered into the first cell will be:
“='Stoichiometry'!B4*'Rates'!C4”.
Adjust this to fix the rates column so that it reads:
“='Stoichiometry'!B4*'Rates'!$C4”.

Calculating Conversion Rates (mg/L/d) due to individual Processes

• Copy this equation across the entire Matrix.

• At this point it may be useful to add a few extra rows at the top of the Worksheet along with the
details of the BioWin file, Bioreactor ID and Bioreactor Volume under investigation.
• The net conversion rate for each of the State Variables can next be calculated as the sum of the
Conversion Rates due to each of the individual processes multiplied by the Volume of the
bioreactor.

732 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 Calculating Net Conversion Rates (kg/d) as a function of volume and sum of individual conversion rates

• This value is equivalent to the reaction term calculated for each state variable in the right pane of
the "Rates" window for a BioWin flowsheet element, but offers the added benefit of being able to
identify which processes are contributing to the net conversion rate for each State Variable.

Note: There may be some slight difference between the Conversion Rates as calculated using this
spreadsheet method and those presented in the Rates window. This is due to rounding errors associated
with the number of significant figures used to calculate the rates.

Creating Project Reports

You can create a full summary of your BioWin simulation project in a Word document or Excel spreadsheet
via the File|Report to Word and File|Report to Excel menu commands. The information that is included in
reports may be specified using the Report options tab accessed via the Tools|Customize menu command.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 733

Report options dialog

The various options for Excel and Word reports are discussed in the Report Options section of the
Customizing BioWin section.

Creating a Word Report

Once you have specified the information that you want to be included in your Word report, select the
File|Report to WordTM command to begin the document generation process. This command will generate a
report in Microsoft WordTM document format. BioWin opens and communicates with Microsoft WordTM to
generate the report so to use this option Microsoft WordTM must be installed on the computer. During this
time your cursor likely will take the Windows "hourglass" form and, depending on the complexity of the
report and speed of computer, this process could take minutes to complete. When the report is complete,
the Microsoft WordTM Save As dialog box will open. An example of the dialog box is shown below
(appearance may vary according to Windows system settings).

734 • Data Output (charts, tables, reports) Biowin 6 Help Manual

WordTM Save As dialog box

Give your report document a meaningful name, and make sure you note the location you save it to (you may
navigate to any folder, just as you would saving any document).

Note: The report must be given a unique name. You may not "save over" an existing file. This behavior may
vary depending on the version of Word that you are using.

Note: It is important not to attempt to perform any other operations while the report is being generated.
BioWin and Word make heavy use of the Windows clipboard during this operation, so any attempts to copy
/ paste may cause problems in the report generation process.

Note: If WordTM is open when you start your report you may see material being placed in WordTM. You
should not attempt to edit the report while it is being created by BioWin.

Once you press “Save” or “Cancel” in the dialog above the report is complete and you may print it out, add
your own text to it, copy sections of it into your company report documents, etc.

Creating an Excel™ Report

Once you have specified the information that you want to be included in your Excel report, select the
File|Report to Excel command to begin the report generation process. BioWin will present you with a

Biowin 6 Help Manual Data Output (charts, tables, reports) • 735

dialogue to change the Excel report file name and location if you wish (the default report name and location
will be the same as the BioWin file).
Due to compatibility issues across Excel versions, the report templates that ship with BioWin are saved in
XLS format. This may result in compatibility warning and/or slight differences in appearance if the final
generated report is viewed in different versions of Excel. However, once the final generated report is
saved in the user’s version of Excel these warnings should stop.

BioWin’s “Save As” dialog box for choosing the name and location of your Excel report

Note that if you elected to include Album contents in your report (by placing a check in the Album charts
and/or Album tabular information check boxes of the Report options tab accessed via the Tools|Customize
menu command), BioWin will create separate Excel files containing this information and they also will be
saved to the location you select. Note this information will also be contained inside your report if you place
a check in the Merge output files box.

Introduction to Excel Report Templates

The content, organization, and formatting of BioWin’s Excel reports are all controlled by Excel templates.
Users can choose one or more template files by clicking the Select templates… button on the Report
options tab reached from the Tools|Customize command.
Example templates have been shipped with BioWin, and the following sections contain some introductory
information and examples of the syntax that they use. The following points are worth noting:
The templates are completely customizable. Customization can be as simple as changing the order
of/removing sheets that will appear in the final report; it can be as advanced as creating completely new
sheets with user-designed output tables.

736 • Data Output (charts, tables, reports) Biowin 6 Help Manual

It is possible to use more than one template, and have BioWin merge the results into one final Excel report
file.
It is also possible to include a spreadsheet that contains no “BioWin report syntax” as a report template.
BioWin can merge this spreadsheet into its generated Excel report file. For example, if you have a
spreadsheet that contains various design calculations, loading information, etc. that you would like included
in the final BioWin Excel report, simply choose this spreadsheet as one of your templates.
The following sections contain introductory information and examples that can be used to create or
customize BioWin Excel report templates. Note that this information is not exhaustive; more detail can be
found on the TMS Software website in their FlexCel documentation section. The following sections of the
BioWin manual may include text from this section – copyright of TMS Software is gratefully acknowledged:
http://www.tmssoftware.biz/flexcel/doc/vcl/guides/reports-designer-guide.html

Excel Report Template Formatting

This section documents some basic concepts for creating and/or customizing BioWin Excel report templates.
It should be noted that this section discusses the basic concepts used to create the example templates that
ship with BioWin; however, more advanced information and functionality is documented on the TMS
Software web site for their FlexCel product at:
http://www.tmssoftware.biz/flexcel/doc/vcl/guides/reports-designer-guide.html
There is a range of customized formatting that can be applied to the template files used to generate BioWin
Excel reports. Users can modify templates shipped with BioWin and save their own versions, or create their
own from scratch. Modifications to the templates shipped with BioWin could be as simple as deleting a few
unwanted sheets from the template, changing the order of sheets, or simple format changes. However,
more advanced modifications or the creation of new user-defined templates requires some familiarity with
important components used by BioWin’s report generation tool. These three important components are:
• Tags
• Named ranges
• Configuration sheets

Tags
In most cases, a tag is text that you place in a cell of the template that will be replaced by a different value in
the generated report. The general form of a tag is <#TagName>. In most cases tags are used to retrieve
information from BioWin, either from a report variable or table (or dataset). For example, in the BioWin
Report.xls example template file that ships with BioWin, there is a tab named Tags<#delete sheet> that
serves as a reference to several tags (report variables) that are recognized by BioWin, and will be written to
the cell of the final report if that tag is placed in a cell. For example, if a cell within a sheet of a report
template contains the tag <#PlantName;Not Available>, then the same cell on the same sheet will contain
the text from the Plant name field of BioWin’s Project|Info… dialogue box, or return the text “Not
Available” if that field is left blank in BioWin.
Tags are also commonly used to insert the correct unit text throughout a report template. For example, in
the BioWin Report.xls file the Tags<#delete sheet> tab contains a list of unit text tags along with their SI and
US Imperial equivalents. For example, if the tag <#MassRateUnits> is used in a report template, it will be

Biowin 6 Help Manual Data Output (charts, tables, reports) • 737

replaced with the text “kg/d” if the BioWin project units are SI-based or “lb/d” if the BioWin project units
are US Imperial-based.
Tags can also be used to replace placeholder images. An example of this usage can be seen in the example
BioWin Report.xls file on the Project Summary tab. The flowsheet image on this tab is actually a tagged
placeholder. Clicking on the image and examining the workbook Names box reveals that the image is
actually a tag <#ImgFlowsheet;Not Available> (as shown in the screen grab below), meaning that this
placeholder flowsheet image will be replaced with the actual flowsheet image when the report is generated
from BioWin.

Tag used as an image placeholder

Any text in a report template that is not typed using the tag formatting syntax will appear “as is”. For
example, if the text “This Text” is typed in a cell of a report with certain formatting applied to it, that text
will appear with the same formatting (i.e. font color and size, etc.) in the final generated report.
Tags can be used to execute “commands”. These can be Excel functions, expressions defined on the Config
sheet or visual basic functions. There is also a large range of defined tags. For example, in the example
BioWin Report.xls template file on the “Tankage Summary” sheet in cell G1 the tag text is:
<#if(<#volGT.#RowCount>=0;<#delete range(volGTSummary;__)>;)>

738 • Data Output (charts, tables, reports) Biowin 6 Help Manual

This uses several defined tags as well as the table named “VolGT”. The syntax if the “If” tag is
<#If(Condition; Result_If_True; Result_If_False)>
The parameters “Condition”, “Result_If_True” and “Result_If_False” can themselves be tags. In this case, if
there are 0 rows in the volGT table then the tag <#delete range(volGTSummary;__) will be executed
removing the range named “volGTSummary” and shifting the cells up. A full description of the predefined
tags and their syntax can be found at:
http://www.tmssoftware.biz/flexcel/doc/vcl/guides/reports-tag-reference.html
Finally, tags can be used to query tables of data that are generated internally in BioWin, and output the
results to the report. A reference list of tags will be provided at the end of this section. This is a powerful
way to create dynamic tables, which will be introduced in the next section discussing Named Ranges.

Named Ranges
Tags can be used to “fill in the blanks” for certain components of a report. While these are useful for non-
repetitive information (e.g. the plant name for a project), a more powerful application involves the
combined use of tags and a “band” of cells that are defined using Excel Named Ranges. In concept, a “band”
is a range of cells that is repeated to generate rows and/or columns in a table. It may be helpful to think of
the name that is used to define a band as the name of the table being created. This concept is best
illustrated with examples.
For the first example, consider the sheet named Sludge in the example BioWin Report.xls template file (a
screen shot is shown below, but it may be helpful to open the file in Excel while reading this section). For all
sludge output elements in a BioWin flowsheet, the table template discussed below will summarize flow and
concentration / mass rates for several parameters (e.g. TSS, TKN), and also perform several calculations that
are not done by BioWin. This is done by using a combination of tags and Excel formulae within a horizontal
band of cells defined as a named range, as follows:
The horizontal range of cells from B8 to P8 are defined as a named range “__Sludge__”. Note the “__” (i.e.
two underscore characters) at the beginning and end of the range name. This indicates to BioWin’s report
tool that this is a horizontal range that inserts full rows moving downward. Named ranges are defined using
Excel’s “Name Manager” tool, which is typically found on the “Formula” toolbar of most Excel versions.
Several cells inside the named range (i.e. B8:K8) contain tags. The syntax used here is along the lines of
<#Sludge.Name>, <#Sludge.Flow>, <#Sludge.TKNt_C>, <#Sludge.TKNt_MR>. The first part of these tags
“#Sludge” instructs the report tool to query a BioWin internal table of sludge elements named “Sludge”. The
second part of these tags (e.g. “.Name”, “.Flow”) extracts those parameters from the internal BioWin table,
and writes them to the final report.
Several cells inside the named range (i.e. L8:P8) contain standard Excel formulae that perform operations on
other cells in the named range. For example, cell L8 contains a formula that divides VSS by TSS (if there are
values) and formats the result as a percentage.
Because the tags and formulae are within the named range “__Sludge__”, they will be repeated, row by row
moving downward, for all of the sludge elements in the BioWin file for which the report is being generated.
Any text, formula(e), or tags below the named range will be pushed down as the rows are inserted. For
example, rows 10 and 12 that contain formulae for calculating the average and/or total for certain columns
will be moved down automatically as the named range “__Sludge__” is filled in by the report generator. Any
text, formula, or tags above the named range will stay in their current relative row. For example, row 6
contains static column heading text that will appear the same in the final report table; row 7 contains a

Biowin 6 Help Manual Data Output (charts, tables, reports) • 739

mixture of static units (e.g. mg/L) and tag-based units (e.g. <#MassRateUnits>). An example of a table from
a completed report is shown below.

Example template for creating a sludge element output report table that expands row by row downward

Final sludge element table from generated report for BioWin file with multiple sludge elements

Another type of named range can be created to form a vertical band that will be expanded column by
column, moving from left to right as the report is generated. This is illustrated by examining a second
example from the example BioWin Report.xls template file, on the Streams by Column-Mass Rates tab. For
all pipes on a BioWin flowsheet, the table template discussed below will summarize flow and mass rates for
several parameters (e.g. COD, BOD, TSS, TKN). This is done by using tags within a vertical band of cells
defined as a named range, as follows:
The vertical range of cells from D28 to D48 are defined as a named range “II_ColMRPipes_II”. Note the “II_”
(i.e. two capital I characters followed by one underscore character) at the beginning and end of the range
name. This indicates to BioWin’s report tool that this is a vertical range that inserts full columns moving to
the right. Named ranges are defined using Excel’s “Name Manager” tool, which is typically found on the
“Formula” toolbar of most Excel versions.
Several cells inside the named range (e.g. D28, D30, D32) contain tags. The syntax used here is along the
lines of <#ColMRPipes.Name>, <#ColMRPipes.Flow>, <#ColMRPipes.CODt_MR>. The first part of these tags
“#ColMRPipes” instructs the report tool to query a BioWin internal table of pipe elements for information
(in fact, BioWin’s internal table is named “Pipes”, but the naming convention used here will be outlined in
the next section discussing template Configuration Sheets). The second part of these tags (e.g. “.Name”,
“.Flow”) extracts those parameters from the internal BioWin table, and writes them to the final report.
Several cells inside the named range (e.g. D31, D33) are blank and serve only as “spacer rows” for aesthetic
purposes. However, as in the previous example, these could also contain formulae, static text, or other tags.

740 • Data Output (charts, tables, reports) Biowin 6 Help Manual

Because the tags and blank cells are within the named range “II_ColMRPipes_II”, they will be repeated,
column by column moving to the right, for all of the pipe elements on a BioWin flowsheet. Any text of
formula to the right of the named range will be pushed over as the columns are inserted. Any text, formula,
or tags to the left of the named range will stay in their current relative column. For example, column B
contains static row heading text that will appear the same in the final report table; column C contains tag-
based units (e.g. <#MassRateUnits>) that will stay in column B. An example of a table from a completed
report is shown below.
More detailed discussion of Named Ranges and their various applications in report template files can be
found in the TMS Software FlexCel documentation
(http://www.tmssoftware.biz/flexcel/doc/vcl/guides/reports-designer-guide.html).

Example template for creating a pipe mass rates table that expands column by column to the right

Final pipe mass rate from generated report

Configuration Sheets
Configuration sheets are recommended for most report templates. They must be named <#Config>, and
they will be removed after the report is generated. Complete rules for setting up a configuration sheet can
be found in the TMS Software FlexCel documentation; this section discusses some simple examples of how
the configuration sheet in the example BioWin Report.xls template file is used. A screen shot of the
configuration sheet is shown below.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 741

Configuration sheet used in “BioWin Report.xls” template file

Global Formatting
Columns H and I are used to define format names and properties, respectively, that can be used throughout
a report template. For example, in the sample BioWin Report.xls template file, a format named “Header”
has been defined in cell H10, with a set of properties (e.g. bold Arial font, 16 point size, blue color, left
justified) defined in cell I10. Any text in the report template that has the tag <#format cell(Header)> in front
of it will have this formatting applied to it. For example, the following text input in the report template…

…will result in the following appearance in the generated report:

742 • Data Output (charts, tables, reports) Biowin 6 Help Manual

This is a powerful formatting approach, since it is possible to set up a number of formatting definitions, and
have those applied throughout the report. Any changes to the formatting made on the configuration sheet
can be cascaded throughout the final report.
Table Naming
Named ranges can only be defined once in Excel; each named range must refer to a unique group of cells.
Because of this, if we want to create multiple tables in a report that presents duplicate information, we need
to (a) give each table / named range a unique name, and (b) indicate to the BioWin report tool the internal
BioWin table that is being queried for information.
One example of this application are the different tables presented in the sample BioWin Report.xls
template file that illustrate the various combinations for presenting concentrations and/or mass rates for
pipes (e.g. mass rates only, with streams listed by column as discussed above). Each of these “pipe tables” is
given a unique name in the “Table Name” column of the configuration sheet which corresponds to their
range names (e.g. ConcPipes, MRPipes, ColMRPipes). The “Source Name” column is then used to tell the
report tool that each of these “pipe tables” will be getting their data from an internal BioWin table named
“Pipes”. Note that if we only had a single table for pipe information in the report template, this Name-
Source mapping would not be necessary; we could simply call our single table “Pipes”.
A reference list of BioWin’s internal data tables will be provided at the end of this section.
Filtering Data
For the sake of efficiency, BioWin does not generate unique internal tables for every type of element.
Rather, it groups similar elements in common internal tables. For example, certain elements that separate
solids from liquid streams are grouped in a BioWin internal table named “MiscSeparators”. Therefore, if we
want to create a table for only some of the elements from this common table, we may need to do similar
Name-Source mapping as discussed above – but additionally, a filter must be applied so that only
information for the desired element type is used to fill the table.
For example, in the sample BioWin Report.xls template file there is a sheet named Other Elements (e.g.
splitters). In row 58 of this tab, there is a table/range named “DewatElements” that will tabulate
information about any dewatering units elements in a BioWin flowsheet. In row 21 of the configuration tab,
we can see that the “DewatElements” table is obtaining its data from BioWin’s internal table named
“MiscSeparators”; however, in the Filter column (Column C), the filter “ElementType=TPtDewaterElement”
has been specified. This means that only information for this type of element (i.e. dewatering element) will
be collected from the “MiscSeparators” table and used to populate the “DewatElements” table in the
generated report.
A reference list of BioWin’s internal element type names will be provided at the end of this section.
Sorting Data
A table can be sorted on any of its data, by defining the name of the property the sorting is based on and the
sorting order in Column D of the configuration sheet. The sorting order can be defined as ascending from
smallest to largest using the ASC sort code, or as descending from largest to smallest using the DESC sort
code.
For example, the entry in cell D18 “Name ASC” means that columns in the “pipe mass rates by column” table
discussed previously will be sorted by the pipe names in ascending order (i.e. alphabetically starting from A).
In the sample BioWin Report.xls template file, all of the sorting examples are based on the Name property,
but it is important to note that sorting can be on any table property, e.g. Flow, Volume, Area, TSS_C,
TSS_MR, etc.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 743

Excel Report Chart Templates
BioWin’s Excel reporting tool includes the option to include the contents of a BioWin file’s Album (e.g.
charts, tables, etc.). [This is done by selecting the Tools|Customize menu command, clicking the Report
options tab, and placing a check in the Album charts and/or Album tabular information boxes.]
When a current value or time series chart is exported from the BioWin Album to an Excel report, it is not
simply copied as a static picture (as is the case for BioWin’s Word reporting feature). Rather, each chart and
its source data will be placed on separate sheets at the end of the generated Excel report. The charts in the
report are “active” Excel charts; that is, they can be formatted, data may be added or removed, etc.
Two chart template files are shipped with BioWin to allow users to set default formatting options. These
template files only affect the Album Charts once they are exported to Excel. To modify Album Charts within
BioWin, refer to (General Operation > Customizing BioWin > Chart Template Options). The templates are as
follows:
“CVChart.xls” – this file contains default formatting that will be applied to current value-type series in
BioWin, e.g. bar charts, pie charts.
“DVChart.xls” – this file contains default formatting that will be applied to “dynamic value” time series-type
charts in BioWin, e.g. time series charts, state point analysis charts.
Examples of the Bar chart from the CVChart template and Time Series chart from the DVChart template are
shown below:

Example Bar chart template

744 • Data Output (charts, tables, reports) Biowin 6 Help Manual

Example Time Series chart template

Users can modify basic chart formatting options by editing the template charts using standard Excel
techniques. For example, the font type / size for the chart title can be modified by editing the “Title place
holder” text; the position/size of the legend can be modified, etc.
Changes made to the template chart formatting will be reflected in the charts added to the generated Excel
reports. The screen shots below show example current value and time series from a generated report.

Bar chart and its data from a generated Excel report

Biowin 6 Help Manual Data Output (charts, tables, reports) • 745

Time Series chart and its data from a generated Excel report

Due to compatibility issues across Excel versions, the chart templates that ship with BioWin are saved in
XLS format. This may result in slight differences in appearance if the generated report is viewed in
different versions of Excel.

Tag & Table Reference for Examples Shipped With BioWin

BioWin ships with a few report templates that users are free to modify as they wish. These include the
following templates:
BioWin Report.xls: This template has a wide variety of sheets, example tables, and is meant to serve as a
learning example or the basis for a user-customized report template. For example, it has several sheets
which essentially present the same information in different ways; a user can simply delete the sheets they
feel are superfluous to create their own template.
BioWin Report – SV Influents Only.xls: This template is similar to the BioWin Report.xls template; however,
it has been modified to accommodate BioWin flowsheets that use only state variable influents as their
inputs (i.e. flowsheets that have neither COD- or BOD-based influent elements).
Names.xls: This template is not a “BioWin report” template per se; it will not provide any meaningful
summary of a BioWin file. However, generating an Excel report by using this template will create an Excel
file that contains the most up to date information on element type filters and tag properties that are
documented later in this section.
The following sections summarize the internal BioWin tables that can be queried for generating Excel
reports, BioWin’s internal element names that can be used to filter table queries, and element parameters
that can be obtained from tables.

746 • Data Output (charts, tables, reports) Biowin 6 Help Manual

Internal BioWin Information Tables
The following list summarizes the internal BioWin tables that can be queried when generating an Excel
report:

BioWin Internal Table Name Contains information on…

Elements All elements
Influents COD- and BOD-based influent elements
SVInfluents State variable (stream) influent elements
MetalInfluents Metal (e.g. Fe, Al) elements
Methanol Influents Methanol elements
Effluents Effluent elements
Sludge Sludge elements
PSTs Primary settling tank elements
SecondaryClarifiers Other settling tank elements (i.e. model, ideal, point)
DiffusedAirReactors All elements that could be aerated with diffused air (including
trickling filters and aerobic digesters).
SurfaceAeratedReactors All elements that could be aerated with mechanical Surface
aerators.
AnaerobicDigesters Anaerobic digesters
AerobicDigesters Aerobic digesters
Splitters Splitters
MiscSeparators Elements that separate solids and liquid streams (e.g. grit tanks,
dewatering units, microscreens, ISS cyclones, cyclones)

Internal BioWin Element Names for Table Filtering

The following list summarizes the internal names used by BioWin for all the elements:

Element Internal BioWin Name

Settler - Ideal primary TActivatedPSTElement

Digester - Aerobic TAerobicDigesterElement
Digester - Aerobic TAerobicDigestorElement

Biowin 6 Help Manual Data Output (charts, tables, reports) • 747

 Digester - Anaerobic TAnaerobicDigElement
Pipe TBasicPipe
Bioreactor - Variable volume TBatchBioElement
Bioreactor TBioreactorElement
Bioreactor - Membrane TMBRElement
Influent - BOD TBODInfluentElement
Input - Methanol TCH3OHInfluentElement
Input - SSO TSSOInfluentElement
Clarifier - Model TClarifierElement
Effluent TEffluentElement
Bioreactor - Model Builder TGreyBoxElement
Separator - Grit tank TGritTankElement
Clarifier - Ideal TIdealClarifierElement
Influent - COD TInfluentElement
Influent - Industrial COD TIndCODInfElement
Bioreactor - Media TMediaBioreactorElement
Granular sludge sequencing tank (GSST) TGranularSludgeSBRElement
Bioreactor - Sidestream (Media) TSideStrmMediaBioRElement
Input - Metal addition TMetalInfluentElement
Input - Iron (ferric) TFerricInfluentElement
Input - Aluminum TAlInfluentElement
Input - Iron (ferrous) TFerrousInfluentElement
Mixer - Sidestream TMix2Element
Mixer - General TMixNElement
Pump TPumpElement
Settler - Ideal primary (old) TPrimarySettlingTankElement
Separator - Dewatering unit TPtDewaterElement
Separator - Microscreen TPtMicroScreen
Separator - Cyclone (ISS) TPtISSCyclone
Separator - Cyclone (dewatering) TPtSolidsCyclone
Clarifier - Point (volumeless) TPtIdealSettlerElement
SBR TSBRElement

748 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 SBR - 1 always-mixed prezone TSBRP1Element
SBR - 2 always-mixed prezones TSBRP2Element
SBR - 1 mix/settle prezone TSBRSP1Element
SBR - 2 mix/settle prezones TSBRSP2Element
Bioreactor - Sidestream TSideStreamReactorElement
Sludge TSludgeEffluentElement
Splitter TSplit2Element
Influent - State variable TStrmInfluentElement
Bioreactor - Surface aeration (brush) TSurfAer1BRElement
Bioreactor - Surface aeration TSurfAer2BRElement
Equalization Tank TTankElement
Trickling filter TMediaFilterReactorElement
Bioreactor - Submerged aerated filter TSubmergedMedaFilterElem
Bioreactor - Submerged aerated filter (shallow) TShortSAF
Thermal hydrolysis unit TThermHydElement
Plug flow channel TBasePFRElement

Excel Reporting Tags Reference

There is a large number of parameters that could be included in Excel reports for the various element types
in BioWin. Parameters may include physical information (e.g. area, depth, volume), operational (e.g. flow,
airflow), generic process information (e.g. VSS concentration), state variables (e.g. ammonia, nitrate), or
element-specific information (e.g. %TSS Removal for clarifiers, biogas production per unit VSS destroyed for
anaerobic digesters).
A comprehensive list of all the parameters available for each element type and their tag naming convention
can be found in the spreadsheet named TagParametersList.xls in the Manuals directory of the BioWin
installation folder.
The following general naming convention applies for many parameters:
“Parameter_C” returns the concentration for that parameter. For example, a tag such as
<Influents.BODt_C> will return the total BOD concentration for all elements listed in the table named
Influents.
“Parameter_MR” returns the mass rate for that parameter. For example, a tag such as
<Effluents.BODt_MR> will return the total BOD mass rate for all elements listed in the table named
Effluents.
For elements with multiple outputs (e.g. settling tanks, splitters), adding “_U” will return the parameter in
the element underflow (or sidestream for splitters). For example, a tag such as <#PSTs.TSS_C_U> will return
the TSS concentration in the underflow for all elements listed in the table named PSTs.

Biowin 6 Help Manual Data Output (charts, tables, reports) • 749

Some elements also allow state variable influent concentrations to be reported. For example, a tag such as
<#AnaerobicDigesters.NH3N_C_I> will return the ammonia concentration in the influent to each anaerobic
digester element listed in the table named AnaerobicDigesters.
The following tables list other “project” tags and tags for displaying units in BioWin projects using SI or US
units.

Tag Name BioWin Equivalent

<#PlantName;Not Available> Project Info > Plant name

<#ProjectName;Not Available> Project Info > Project name
<#ProjectNumber;Not Available> Project Info > Project ref.
<#UserName;Not Available> Project Info > User name
<#FileCreationDate;Not Available> Project Info > Creation date
<#LastSavedDate;Not Available> Project Info > Last saved
<#SimStartDate;Not Available> Project Info > Simulation start date
<#SimStartTime;Not Available> Project Info > Simulation start time
<#LiquidTemp;Not Available> Project | Plant | Liquid temperature - Reports current value
<#AmbientAirTemp;Not Available> Project | Plant | Inlet air conditions |Inlet air temperature -
Reports current value
<#AmbientAirHumidity;Not Project | Plant | Inlet air conditions |Inlet air humidity - Reports
Available> current value
<#SurfacePressure;Not Available> Project | Parameters | Aeratio/Mass transfer ... | Aeration |
Surface pressure - Reports global value only
<#TotalSRT;Not Available> SRT named "SRT Total" or "active" SRT – Reports value for steady-
state solution
<#AerobicSRT;Not Available> SRT named "Aerobic SRT" or nothing
<#TotalHRT;Not Available> SRT named "Total HRT" or nothing
<#AnoxicHRT;Not Available> SRT named "Anoxic HRT" or nothing
<#AtSteadyState;Not Available> If true report was generated when system was at S.S

Unit Tag SI US
<#ConcUnits> mg/L mg/L
<#LiquidFlowUnits> m3/d [m3/h, L/d, ML/d] mgd [gal/d]
3
<#VolumeUnits> m [L, ML] Mil. Gal [gallons]
<#AreaUnits> m2 ft2
<#LengthUnits> m ft

750 • Data Output (charts, tables, reports) Biowin 6 Help Manual

 <#RecipLengthUnits> /m /ft
<#SpecificVelocityUnits> m3/(m2 d) gal/(ft2 d)
<#RecipSpecVelUnits> m2 d/m3 ft2 d/gal
<#MassUnits> kg lb
<#MassRateUnits> kg/d lb/d
<#StdAirFlowUnits> m3/hr (20C, 101.325 kPa) ft3/min (20C, 1 atm)
<#SolidsLoadingUnits> kg/(m2 d) lb/(ft2 d)
<#PressureUnits> kPa psi
<#TemperatureUnits> C C
<#FieldGasFlowUnits> m3/hr [field] ft3/min (field)
<#PowerUnits> kW hp
<#EnergyUnits> kJ BTU
<#SettlingVelocityUnits> m/d ft/min
<#PowerPerVolUnits> W/ m3 hp/mgal
<#PowerPerFlowUnits> W/( m3.d-1) hp/mgd
2
<#VolumeFluxUnits> L/m /hr gal/(ft2 d)
<#BioGasProdUnits> m3/kg VSS ft3/lb VSS
<#MethaneProdUnits> m3/kg CODt ft3/lb CODt
<#MassRatePHrUnits> kg/hr lb/hr

Biowin 6 Help Manual Data Output (charts, tables, reports) • 751

Model Reference

Biological/Chemical Models
BioWin uses a general Activated Sludge/Anaerobic Digestion (ASDM) model which is referred to as the
BioWin ASDM. The BioWin ASDM has more than fifty state variables and over eighty process expressions.
These expressions are used to describe the biological processes typically occurring in wastewater treatment
plants. This complete model approach frees the user from having to map one model’s output to another
model’s input which significantly reduces the complexity of building full plant models, particularly those
incorporating many different process units.
The following sections describe different parts of the overall model:
• Activated Sludge Processes
• Anaerobic Digestion Processes
• Modeling of Sulfur
• Chemical Precipitation Reactions
• Modeling of pH and Alkalinity
• Modeling of Industrial Components
• General Parameters
This chapter provides an overview of the ASDM and the parameters included in the model. In some cases, a
section called “Further Reading” describes the model in greater detail. In this section the model parameters
(kinetic, stoichiometric, settling and chemical constants) are listed in full with a brief description of the
model process. Parameters that are of special importance (those having a direct impact on a measurable
wastewater, effluent or plant characteristics) are highlighted in the tables.
The default BioWin ASDM can be augmented with additional processes or entirely replaced by other models
which have been defined in the Model Builder. BioWin includes a library of Model Builder models. Details
on the Model Builder are in the Model Builder section of the “General Operation” chapter.

Activated Sludge Processes

BioWin contains the following processes typically occurring in activated sludge systems.

Biowin 6 Help Manual Model Reference • 753

 • Growth and Decay of Ordinary Heterotrophic Biomass
• Growth and Decay of Methylotrophic Biomass
• Hydrolysis, Adsorption, Ammonification and Assimilative denitrification
• Growth and Decay of Ammonia Oxidizing Biomass
• Growth and Decay of Nitrite Oxidizing Biomass
• Growth and Decay of Anaerobic Ammonia Oxidizing Biomass (AAOs)
• Growth and Decay of Phosphorus Accumulating Biomass
• Growth and Decay of Sulfur Oxidizing Biomass
• Growth and Decay of Sulfur Reducing Biomass
These modules are described in detail below.

Growth and Decay of Ordinary Heterotrophic Biomass

Number of Processes: 44
Engineering Objective: organics removal, denitrification
Implementation: permanent, always active in the BioWin model
Module Description:
This group of processes describes the growth and decay of ordinary heterotrophic organisms under all
conditions. The activated sludge model allows for direct ordinary heterotrophic aerobic growth on acetate,
propionate, readily biodegradable complex substrate, methanol and four “industrial” COD components. The
character and behavior of the “industrial” components are partially user definable. The organisms will tend
to use the more readily degradable substrates preferentially. That is, preferring substrates like acetate,
propionate and readily biodegradable complex substrate over the industrial substrates (that are equally the
least preferred substrates). Under anoxic conditions, the ordinary heterotrophic organisms (OHOs) cannot
use methanol as a substrate. In the BioWin model, anoxic use of methanol is restricted to a specialized
group of organisms (see anoxic methylotrophs).
The base rate expression for each of the growth processes is the product of a maximum specific growth rate,
the heterotrophic biomass concentration and a Monod expression for the substrates. This base rate is
modified to account for environmental conditions (dissolved oxygen, nitrate and nitrite), nutrient limitations
(ammonia, phosphate, calcium, magnesium as well as other cations and anions) and pH inhibition and
substrate preference weighting. BioWin uses ammonia as a nitrogen source for cell synthesis with all of the
substrates under aerobic, anoxic and anaerobic conditions. At low ammonia concentrations BioWin allows
for assimilative ammonia production from either nitrate or nitrite in order to satisfy synthesis demands. For
some of the “industrial” substrates it is also possible to have substrate inhibition which is controlled by the
substrate inhibition coefficient.
Although the maximum specific growth rate under aerobic and anoxic conditions is the same, under anoxic
conditions the base rate is also multiplied by an anoxic growth factor. This allows for anoxic growth at a
different rate or for only a fraction of the OHOs being able to perform any kind of denitrification (or both of
these). Of the OHOs that can perform denitrification, a fraction can use either nitrate or nitrite (with
nitrogen gas as an end product), and the remainder of the denitrifying OHOs can only use nitrate (with
nitrite as an end product). If the nitrous oxide model is enabled, additional pathways (2) are available which
result in the generation of nitrous oxide on anoxic growth at elevated free nitrous acid concentrations.

754 • Model Reference Biowin 6 Help Manual

There are two pathways for ordinary heterotrophic growth through fermentation of readily biodegradable
(complex) substrate to acetate, propionate, carbon dioxide and hydrogen. The dominant pathway is
governed by the dissolved hydrogen concentration. The “industrial” components are fermented to acetate,
carbon dioxide and hydrogen. The “industrial” components have an anaerobic growth factor applied to the
fermentation rate which allows the user to independently control the rate of fermentation for each
“industrial” substrate. In activated sludge vessels there is also an anaerobic growth factor applied to all
growth through fermentation. That is, the “industrial” substrates have two anaerobic growth factors
applied.
There are decay processes appropriate for each environment (aerobic, anoxic and anaerobic).
Model parameters affecting the performance of this module are listed below:

Kinetic Parameters

Menu Location: Project|Parameters|Kinetic|Ordinary heterotrophic

All default kinetic parameters are referenced to 20C.

Name Default Unit Explanation

Max. spec. growth rate 3.2 d-1 Determines the maximum specific growth
rate of ordinary heterotrophs. Substrate
and nutrient limitations will decrease the
growth rate. This parameter is sensitive
only in very high loaded plants (short SRT),
and determines maximum BOD removal
capacity.
Substrate half sat. 5.0 mgCOD/L This parameter impacts the residual
soluble substrate concentration in the
effluent. The value is usually low in normal
municipal plants.
Anoxic growth factor 0.5 - This parameter represents the fraction of
organisms that are able to grow under
anoxic conditions and/or a reduction in
the growth rate under anoxic conditions.
Substrate and nutrient limitations may
further reduce the growth rate.
Denite N2 producers (NO3 0.5 - This parameter represents the fraction of
or NO2) organisms which are able to reduce either
nitrate or nitrite to nitrogen gas. [The
remaining organisms being those only
capable of reducing nitrate to nitrite.]
Aerobic decay rate 0.62 d-1 Decay rate constant under aerobic
conditions. This parameter impacts the

Biowin 6 Help Manual Model Reference • 755

 endogenous respiration rate and VSS
destruction during aerobic stabilization.
Anoxic decay rate 0.233 d-1 Decay rate constant when there is no
oxygen, but either nitrate or nitrite is
available.
Anaerobic decay rate 0.131 d-1 Decay rate constant when there is no
oxygen, nitrate or nitrite available.
Fermentation rate 1.6 d-1 Maximum specific growth rate of ordinary
heterotrophs under anaerobic conditions.
Fermentation half sat. 5.0 mgCOD/L Half saturation of complex substrate
under anaerobic conditions
Fermentation growth factor 0. 25 - Growth rate reduction under anaerobic
(AS) conditions in activated sludge
Free Nitrous acid inhibition 1.00e-07 mol N /L Inhibitory concentration of free nitrous
acid resulting in incomplete
denitrification and the production of
some nitrous oxide. Note: This
parameter is only used if the Nitrous
oxide model option is turned on.

Menu Location: Project|Parameters|Kinetic|Heterotrophic on industrial COD

Name Default Unit Explanation

Maximum specific growth 4.3 d-1 Determines the maximum specific growth
rate on Ind #1 COD rate of Ordinary heterotrophic biomass
on the substrate “Ind# 1”.
Substrate (Ind #1) half sat. 1.0 mgCOD/L This parameter impacts the residual
substrate concentration in the effluent.
Inhibition coefficient for Ind 60.0 mgCOD/L This parameter is used in the Haldane
#1 equation for substrate inhibition.
Anaerobic growth factor for 0.05 - Reduces the growth rate through
Ind #1 fermentation of Ind# 1.
Maximum specific growth 1.5 d-1 Determines the maximum specific growth
rate on Ind #2 COD rate of Ordinary heterotrophic biomass
on the substrate “Ind# 2”.
Substrate (Ind #2) half sat. 30.0 mgCOD/L This parameter impacts the residual
substrate concentration in the effluent.
Inhibition coefficient for Ind 3000.0 mgCOD/L This parameter is used in the Haldane
#2 equation for substrate inhibition.

756 • Model Reference Biowin 6 Help Manual

 Anaerobic growth factor for 0.05 - Reduces the growth rate through
Ind #2 fermentation of Ind# 2.
Maximum specific growth 4.3 d-1 Determines the maximum specific growth
rate on Ind #3 COD rate of Ordinary heterotrophic biomass
on the substrate “Ind# 3”.
Substrate (Ind #3) half sat. 1.0 mgCOD/L This parameter impacts the residual
substrate concentration in the effluent.
Inhibition coefficient for Ind 60.0 mgCOD/L This parameter is used in the Haldane
#3 equation for substrate inhibition.
Anaerobic growth factor for 0.05 - Reduces the growth rate through
Ind #3 fermentation of Ind# 3.
Maximum specific growth 2.0 d-1 Determines the maximum specific growth
rate on adsorbed rate of Ordinary heterotrophic biomass
hydrocarbon COD on adsorbed hydrocarbon COD.
Substrate (adsorbed 0.15 mgCOD/L This parameter impacts the residual
hydrocarbon ) half sat. substrate concentration in the effluent.
Anaerobic growth factor for 0.01 - Reduces the growth rate through
adsorbed hydrocarbons fermentation of adsorbed hydrocarbon
COD.
Adsorption rate of soluble 0.2 L/mgCOD d-1 Adsorption rate of soluble hydrocarbons.
hydrocarbons

Stoichiometric Parameters
Menu Location: Project|Parameters|Stoichiometric|Ordinary heterotrophic

Name Default Unit Explanation

Yield (Aerobic) 0.666 mgCOD/mgCOD Amount of biomass COD

produced using one unit of
readily biodegradable complex
substrate COD. The remaining
COD is oxidized. This parameter
is very stable in municipal plants
and seldom needs adjustment.
In case there is a mismatch
between measured and
simulated sludge production
and OUR, try adjusting the
influent fup (unbiodegradable
particulate COD fraction)

Biowin 6 Help Manual Model Reference • 757

 parameter or check wastage
and SRT.
Yield (fermentation 0.1 mgCOD/mgCOD Amount of biomass produced
low H2) on one unit of complex
substrate fermented, under
low H2 concentration.
Yield (fermentation 0.1 mgCOD/mgCOD Amount of biomass produced
high H2) on one unit of complex
substrate fermented, under
high H2 concentration.
H2 yield (fermentation 0.35 mgCOD/mgCOD Amount of hydrogen produced
low H2) on one unit of complex
substrate fermented, under
low H2 concentration.
H2 yield (fermentation 0.0 mgCOD/mgCOD Amount of hydrogen produced
high H2) on one unit of complex
substrate fermented, under
high H2 concentration.
Propionate yield 0.0 mgCOD/mgCOD Amount of propionate
(fermentation low H2) produced on one unit of
complex substrate fermented,
under low H2 concentration.
Propionate yield 0.7 mgCOD/mgCOD Amount of propionate
(fermentation high H2) produced on one unit of
complex substrate fermented,
under high H2 concentration.
CO2 yield 0.7 mmolCO2/mmolHAC Moles of CO2 produced per
(fermentation low H2) mole of acetate formed at low
dissolved H2 concentrations.
CO2 yield 0.0 mmolCO2/mmolHAC Moles of CO2 produced per
(fermentation high H2) mole of acetate formed at
high dissolved H2
concentrations.
N in Biomass 0.07 mgN/mgCOD N content of heterotrophs. This
parameter impacts the nitrogen
available for nitrification and
therefore oxygen demand.
P in Biomass 0.022 mgP/mgCOD P content of heterotrophs. This
parameter influences the P
removal in non bio-P systems,
and the P content of the sludge.
Endogenous fraction - 0.08 - Fraction of biomass that
aerobic becomes inert upon aerobic
decay.

758 • Model Reference Biowin 6 Help Manual

 Endogenous fraction - 0.103 - Fraction of biomass that
anoxic becomes inert upon anoxic
decay.
Endogenous fraction - 0.184 - Fraction of biomass that
anaerobic becomes inert upon anaerobic
decay.
COD:VSS Ratio 1.42 mgCOD/mgVSS Conversion factor between
biomass as measured in COD
and its VSS content. This value is
relatively stable for biomass.
Yield (anoxic) 0.54 mgCOD/mgCOD Biomass yield on readily
biodegradable complex
substrate COD under anoxic
conditions.
Yield propionic (aerobic) 0.64 mgCOD/mgCOD Biomass yield on propionic acid
COD under aerobic conditions.
Yield propionic (anoxic) 0.46 mgCOD/mgCOD Biomass yield on propionic acid
COD under anoxic conditions.
Yield acetic (aerobic) 0.6 mgCOD/mgCOD Biomass yield on acetic acid
COD under aerobic conditions.
Yield acetic (anoxic) 0.43 mgCOD/mgCOD Biomass yield on acetic acid
COD under anoxic conditions.
Yield methanol 0.5 mgCOD/mgCOD Biomass yield on methanol COD
(Aerobic) under anoxic conditions.
Max fraction to N2O at 0.05 mgN/mgN Maximum amount of nitrate N
high FNA over nitrate that can end up as nitrous
oxide under inhibitory free
nitrous acid conditions. Note:
This parameter is only used if
the Nitrous oxide model
option is turned on.
Max fraction to N2O at 0.10 mgN/mgN Maximum amount of nitrite N
high FNA over nitrite that can end up as nitrous
oxide under inhibitory free
nitrous acid conditions. Note:
This parameter is only used if
the Nitrous oxide model
option is turned on.

Menu Location: Project|Parameters|Stoichiometric|Ordinary heterotrophic on industrial COD

Biowin 6 Help Manual Model Reference • 759

 Name Default Unit Explanation

Yield Ind #1 COD (Aerobic) 0.5 mgCOD/mgCOD Amount of biomass COD produced
using one unit of Ind#1 substrate
COD. The remaining COD is
oxidized.
Yield Ind #1 COD (Anoxic) 0.4 mgCOD/mgCOD Biomass yield on Ind#1 substrate
COD under anoxic conditions.
Yield Ind #1 COD 0.04 mgCOD/mgCOD Biomass yield on Ind#1 substrate
(Anaerobic) COD under anaerobic conditions.
COD:Mole ratio - Ind #1 224 gCOD/Mol gCOD to gMole ratio for Ind#1.
COD [The default is based on the
value for phenol C6H6O.]
Yield Ind #2 COD (Aerobic) 0.5 mgCOD/mgCOD Amount of biomass COD produced
using one unit of Ind#2 substrate
COD. The remaining COD is
oxidized.
Yield Ind #2 COD (Anoxic) 0.4 mgCOD/mgCOD Biomass yield on Ind#2 substrate
COD under anoxic conditions.
Yield Ind #2 COD 0.05 mgCOD/mgCOD Biomass yield on Ind#2 substrate
(Anaerobic) COD under anaerobic conditions.
COD:Mole ratio - Ind #2 240 gCOD/Mol gCOD to gMole ratio for Ind#2.
COD [The default is based on the
value for benzene C6H6.]
Yield Ind #3 COD (Aerobic) 0.5 mgCOD/mgCOD Amount of biomass COD produced
using one unit of Ind#3 substrate
COD. The remaining COD is
oxidized.
Yield Ind #3 COD (Anoxic) 0.4 mgCOD/mgCOD Biomass yield on Ind#3 substrate
COD under anoxic conditions.
Yield Ind #3 COD 0.04 mgCOD/mgCOD Biomass yield on Ind#3 substrate
(Anaerobic) COD under anaerobic conditions.
COD:Mole ratio - Ind#3 288 gCOD/Mol gCOD to gMole ratio for Ind#3.
COD [The default is based on the
value for toluene C7H8.]
Yield enmeshed 0.5 mgCOD/mgCOD Amount of biomass COD produced
hydrocarbons (Aerobic) using one unit of Ind#3 substrate
COD. The remaining COD is
oxidized..
Yield enmeshed 0.4 mgCOD/mgCOD Biomass yield on enmeshed
hydrocarbons (Anoxic) hydrocarbons COD under anoxic
conditions.

760 • Model Reference Biowin 6 Help Manual

 Yield enmeshed 0.04 mgCOD/mgCOD Biomass yield on enmeshed
hydrocarbons (Anaerobic) hydrocarbons COD under
anaerobic conditions.
COD:Mole ratio - 336 gCOD/Mol gCOD to gMole ratio for
Hydrocarbon COD Hydrocarbon COD. [The default
is based on the value for C8H10.
(Ethylbenzene, xylene, etc.)]
Hydrocarbon COD:VSS 3.2 mgCOD/mgVSS gCOD to gVSS ratio for
ratio Hydrocarbon COD. [The default
is approximately based on the
value for C8H10.]
Max. hydrocarbon adsorp. 1.0 - Target maximum ratio of adsorbed
ratio hydrocarbon to ordinary
heterotrophic organism COD.
Yield of Ind #1 on Ind #3 0.0 mgCOD/mgCOD Yield of Ind#1 on aerobic growth
COD (Aerobic) using Ind#3.
Yield of Ind #1 on Ind #3 0.0 mgCOD/mgCOD Yield of Ind#1 on anoxic growth
COD (Anoxic) using Ind#3 as a substrate.
Hydrocarbon Yield on Ind 0.0 mgCOD/mgCOD Yield of soluble hydrocarbon on
#3 COD (Aerobic) aerobic growth using Ind#3 as a
substrate.
Hydrocarbon Yield on Ind 0.0 mgCOD/mgCOD Yield of soluble hydrocarbon on
#3 COD (Anoxic) anoxic growth using Ind#3 as a
substrate.

Menu Location: Project|Parameters|Stoichiometric|Common

Name Default Unit Explanation

Biomass/Endog Ca 3.912x10-3 gCa/gCOD Calcium content of active

content biomass and endogenous
residue. Part of cellular ISS
generated by biomass growth.
Biomass/Endog Mg 3.912x10-3 gMg/gCOD Magnesium content of active
content biomass and endogenous
residue. Part of cellular ISS
generated by biomass growth.
Biomass/Endog other 5.115x10-4 mol/gCOD The amount of “Other cations”
cations content in active biomass and
endogenous residue. Part of
cellular ISS generated by
biomass growth.

Biowin 6 Help Manual Model Reference • 761

 Biomass/Endog other 1.41x10-4 mol/gCOD The amount of “Other anions”
anions content in active biomass and
endogenous residue. Part of
cellular ISS generated by
biomass growth.
N in endogenous residue 0.07 mgN/ mgCOD N content of endogenous
residue from organism decay.
P in endogenous residue 0.022 mgP/ mgCOD P content of endogenous
residue from organism decay.
Endogenous residue 1.42 mgCOD/mgVSS Conversion factor between
COD:VSS Ratio endogenous residue measured
as COD and its VSS content.
Particulate substrate 1.6 mgCOD/mgVSS Conversion factor between
COD:VSS Ratio particulate substrate measured
as COD and its VSS content.
Particulate inert COD:VSS 1.6 mgCOD/mgVSS Conversion factor between
Ratio particulate inert measured as
COD and its VSS content.
Cellulose COD:VSS Ratio 1.1852 mgCOD/mgVSS Conversion factor between
cellulose portion of particulate
inert measured as COD and its
VSS content.
Solid organic COD:VSS 1.62 mgCOD/mgVSS Conversion factor between
Ratio solid organics from external
input (i.e. “SSO”) measured as
COD and its VSS content.

pH Inhibition
Menu Location: Project|Parameters|Kinetic|pH

Name Default Unit Explanation

Ordinary heterotrophic 4.0 pH units At a pH equal to this value the growth rate of
low pH limit ordinary heterotrophic biomass will be reduced by
50%. Heterotrophs exhibit tolerance for pH changes
– hence the wide pH range.
Ordinary heterotrophic 10.0 pH units At a pH equal to this value the growth rate of
high pH limit ordinary heterotrophic biomass will be reduced by
50%.

762 • Model Reference Biowin 6 Help Manual

 Ordinary heterotrophic 5.5 pH units At a pH equal to this value the growth rate of
low pH limit (anaerobic) ordinary heterotrophic biomass under anaerobic
conditions will be reduced by 50%.
Ordinary heterotrophic 8.5 pH units At a pH equal to this value the growth rate of
high pH limit ordinary heterotrophic biomass under anaerobic
(anaerobic) conditions will be reduced by 50%.

Switching Functions
Menu Location: Project|Parameters|Kinetic|Switches

Name Default Unit Explanation

Ordinary heterotrophic DO 0.15 mgO2/L This constant is used to switch off aerobic
half sat. Ordinary heterotrophic biomass activity
under low DO conditions (that is in anaerobic
and anoxic reactors). Anoxic or anaerobic
processes will become active as
environmentally appropriate.
Anoxic/anaerobic NOx 0.15 mgN/L This constant is used to turn off anoxic
half sat. growth, decay and hydrolysis processes on
under conditions of low nitrate and nitrite.
Anoxic NO3 (→NO2) half 0.1 mgN/L This constant is used to switch off anoxic
sat. growth processes producing nitrite under
low nitrate conditions.
Anoxic NO3 (→N2) half 0.05 mgN/L This constant is used to switch off anoxic
sat. growth processes using nitrate under low
nitrate conditions.
Anoxic NO2 (→N2) half 0.01 mgN/L This constant is used to switch off anoxic
sat. growth processes using nitrite under low
nitrite conditions.
NH3 nutrient half sat. 0.005 mgN/L This constant is used to slow all biomass
growth processes at low ammonia-N
concentrations (N nutrient limiting
conditions – see assimilative denitrification).
P nutrient half sat. 0.001 mgP/L This constant is used to slow the growth of
biomass when there is no phosphorus
available as nutrient.
H2 low/high half sat. 1.0 mgCOD/L This constant switches between two
fermentation pathways, generating acetate
and propionate in various ratios, depending
on available H2 concentration.

Biowin 6 Help Manual Model Reference • 763

 Synthesis anion/cation half 0.01 meq/L Half saturation concentration for anions and
sat. cations.

Growth and Decay of Methylotrophic Biomass

Number of Processes: 6
Engineering Objective: denitrification using methanol
Implementation: permanent, always active in the BioWin model
Module Description:
These processes describe the growth and decay of specialized heterotrophs using methanol under anoxic
conditions. In the BioWin model anoxic methylotrophs can only grow under anoxic conditions using
methanol as substrate and either nitrate or nitrite as an electron acceptor. They require a minimum “anoxic
SRT” to maintain themselves in the activated sludge system without washing out. Nitrogen source for cell
synthesis of these microorganisms is ammonia. The base rate expression for this growth process is the
product of the maximum specific growth rate, the anoxic methylotrophs concentration and a Monod
expression for methanol. This base rate is modified to account for environmental conditions (dissolved
oxygen, nitrate and nitrite), nutrient limitations (ammonia, phosphate, calcium, magnesium as well as other
cations and anions), pH inhibition and electron acceptor preference weighting. If the nitrous oxide model is
enabled, additional pathways (2) are available which result in the generation of nitrous oxide on anoxic
growth at elevated free nitrous acid concentrations.
The single decay rate varies between an aerobic value and an anoxic/anaerobic value depending on the
oxygen concentration.
Model parameters are listed in:

Kinetic Parameters
Menu Location: Project|Parameters|Kinetic|Methylotrophic
All default kinetic parameters are referenced to 20C.

Name Default Unit Explanation

Max. spec. growth rate 1.3 d-1 Determines the maximum specific growth
rate of methylotrophic biomass. Substrate
and nutrient limitations will decrease the
growth rate. This parameter will determine
the necessary anoxic SRT to maintain a
viable denitrifying population on methanol.
Methanol half sat. 0.5 mgCOD/L This parameter impacts the residual
methanol concentration
bleeding out of the anoxic tank. The value is
usually very low in normal municipal plants
(once the suitable population has been
established).

764 • Model Reference Biowin 6 Help Manual

 Denite N2 producers (NO3 0.5 - This parameter represents the fraction of
or NO2) organisms which are able to reduce either
nitrate or nitrite to nitrogen gas. [The
remaining organisms being those only
capable of reducing nitrate to nitrite.]
Aerobic decay rate 0.04 d-1 Decay rate constant under aerobic
conditions. This parameter impacts the
minimum anoxic SRT.
Anoxic/anaerobic decay 0.03 d-1 Decay rate constant in the absence of
rate oxygen. This parameter impacts the
minimum anoxic SRT.
Free Nitrous acid inhibition 1.00e-07 mol N /L Inhibitory concentration of free nitrous
acid resulting in incomplete denitrification
and the production of some nitrous oxide.
Note: This parameter is only used if the
Nitrous oxide model option is turned on.

Stoichiometric Parameters
Menu Location: Project|Parameters|Stoichiometric|Methylotrophic

Name Default Unit Explanation

Yield (anoxic) 0.4 mgCOD/mgCOD Anoxic methylotrophic biomass yield

on readily methanol COD under anoxic
conditions. This parameter has
significant impact on the methanol
dosage required to denitrify 1 mgN
nitrate (3.2mg methanol/mgNO3-N by
default)
N in Biomass 0.07 mgN/ mgCOD N content of anoxic methylotrophic
biomass.
P in Biomass 0.022 mgP/ mgCOD P content of anoxic methylotrophic
biomass.
Fraction going to 0.08 - Fraction of biomass that becomes inert
endogenous residue upon decay.
COD:VSS Ratio 1.42 mgCOD/mgVSS Conversion factor between biomass as
measured in COD and its VSS content.
This value is relatively stable for
biomass.

Biowin 6 Help Manual Model Reference • 765

 Max fraction to N2O 0.10 mgN/mgN Maximum amount of nitrate N that can
at high FNA over end up as nitrous oxide under
nitrate inhibitory free nitrous acid conditions.
Note: This parameter is only used if the
Nitrous oxide model option is turned
on.
Max fraction to N2O 0.15 mgN/mgN Maximum amount of nitrite N that can
at high FNA over end up as nitrous oxide under
nitrite inhibitory free nitrous acid conditions.
Note: This parameter is only used if the
Nitrous oxide model option is turned
on.

Menu Location: Project|Parameters|Stoichiometric|Common

Name Default Unit Explanation

Biomass/Endog Ca 3.912x10-3 gCa/gCOD Calcium content of active

content biomass and endogenous
residue. Part of cellular ISS
generated by biomass growth.
Biomass/Endog Mg 3.912x10-3 gMg/gCOD Magnesium content of active
content biomass and endogenous
residue. Part of cellular ISS
generated by biomass growth.
Biomass/Endog other 5.115x10-4 mol/gCOD The amount of “Other cations”
cations content in active biomass and
endogenous residue. Part of
cellular ISS generated by
biomass growth.
Biomass/Endog other 1.41x10-4 mol/gCOD The amount of “Other anions”
anions content in active biomass and
endogenous residue. Part of
cellular ISS generated by
biomass growth.
N in endogenous residue 0.07 mgN/ mgCOD N content of endogenous
residue from organism decay.
P in endogenous residue 0.022 mgP/ mgCOD P content of endogenous
residue from organism decay.
Endogenous residue 1.42 mgCOD/mgVSS Conversion factor between
COD:VSS Ratio endogenous residue measured
as COD and its VSS content.

766 • Model Reference Biowin 6 Help Manual

pH Inhibition
Menu Location: Project|Parameters|Kinetic|pH

Name Default Unit Explanation

Methylotrophic low 4.0 pH units At a pH equal to this value the growth rate of
pH limit methylotrophs will be reduced by 50%.
Methylotrophic high 10.0 pH units At a pH equal to this value the growth rate of
pH limit methylotrophs will be reduced by 50%.

Switching Functions
Menu Location: Project|Parameters|Kinetic|Switches

Name Default Unit Explanation

Name Default Unit Explanation

Ordinary 0.15 mgO2/L This constant is used to switch off aerobic activity
heterotrophic DO half under low DO conditions (that is in anaerobic and
sat. anoxic reactors).
Anoxic/anaerobic 0.15 mgN/L This constant is used to turn off anoxic growth,
NOx half sat. decay and hydrolysis processes under conditions of
low nitrate and nitrite.
Anoxic NO3 (→NO2) 0.1 mgN/L This constant is used to switch off anoxic growth
half sat. processes producing nitrite under low nitrate
conditions.
Anoxic NO3 (→N2) 0.05 mgN/L This constant is used to switch off anoxic growth
half sat. processes using nitrate under low nitrate
conditions.
Anoxic NO2 (→N2) 0.01 mgN/L This constant is used to switch off anoxic growth
half sat. processes using nitrite under low nitrite conditions.
NH3 nutrient half 0.005 mgN/L This constant is used to slow all biomass growth
sat. processes at low ammonia-N concentrations (N
nutrient limiting conditions – see assimilative
denitrification).
P nutrient half sat. 0.001 mgP/L This constant is used to slow the growth of biomass
when there is no phosphorus available as nutrient.
Synthesis anion/cation 0.01 meq/L Half saturation concentration for anions and
half sat. cations.

Biowin 6 Help Manual Model Reference • 767

Hydrolysis, Biological adsorption, Ammonification and Assimilative denitrification
Number of Processes: 14
Engineering Objective: Conversion of organic, nitrogen and phosphorus fractions
Implementation: permanent, always active in the BioWin model
Module Description:
These processes are discussed here separately from the organism groupings because they involve more than
one organism type (in general both the ordinary heterotrophic organisms and the phosphate accumulating
organisms).
Hydrolysis of biodegradable particulate organic substrate to readily biodegradable complex substrate: The
base rate is the product of the hydrolysis rate constant, the sum of the ordinary heterotrophs and the
phosphate accumulating organisms, and a Monod expression for the ratio of particulate substrate to
organism COD. There is an efficiency factor applied for anoxic conditions and another for anaerobic
conditions.
Hydrolysis of biodegradable particulate organic nitrogen and phosphorus: The hydrolysis of biodegradable
particulate nitrogen (phosphorus) is assumed to proceed at the same rate as the biodegradable particulate
organics but is adjusted by the ratio of biodegradable particulate organic nitrogen (phosphorus) to
biodegradable particulate organic.
Adsorption or flocculation of colloidal organic material to particulate organic material (occurring
spontaneously as opposed to chemically facilitated flocculation with metal (ferric or alum) addition: The
rate is the product of the adsorption rate constant, the colloidal substrate concentration and the sum of the
ordinary heterotrophs and the phosphate accumulating organism concentrations. The rate is decreased as
the ratio of particulate substrate to organism COD approaches the maximum adsorption ratio constant.
Adsorption soluble hydrocarbon material to particulate adsorbed hydrocarbons: The rate is the product of
the adsorption rate constant, the soluble hydrocarbon concentration and the ordinary heterotrophic
organism concentration. The rate is decreased as the ratio of adsorbed hydrocarbons to organism COD
approaches the maximum adsorption ratio constant.
Ammonification of soluble organic nitrogen to ammonia: The rate is the product of the ammonification
rate constant, the soluble organic nitrogen concentration and the sum of the ordinary heterotrophic and the
phosphate accumulating organisms concentrations.
Assimilative denitrification of nitrate or nitrite to ammonia for synthesis: BioWin allows for the production
of ammonia for synthesis by OHOs, PAOs and methylotrophs under low ammonia conditions (as ammonia
becomes limiting for growth). The assimilative process will use nitrite if it is available otherwise it will use
nitrate. The base rate is the product of the assimilation rate constant and the organism COD. This base rate
is modified to account for environmental conditions (off with ammonia, and selecting between nitrate and
nitrite).
Slow decay of endogenous products to particulate substrate: BioWin allows for the conversion of
endogenous decay products to particulate substrate. The rate is the product of the specified rate constant
and the endogenous products concentration.
Model parameters are listed in:

768 • Model Reference Biowin 6 Help Manual

Kinetic Parameters
Menu Location: Project|Parameters|Kinetic|Common
All default kinetic parameters are referenced to 20C.

Name Default Unit Explanation

Hydrolysis rate 2.1 d-1 Rate constant for hydrolysis of slowly

degradable organics (influent and external (i.e.
“SSO”) into readily degradable substrate.
Hydrolysis half sat. 0.06 - Monod half saturation constant for the
regulation of hydrolysis rate, expressed in terms
of particulate substrate to heterotrophic biomass
ratio.
Anoxic hydrolysis factor 0.28 - Rate reduction factor for hydrolysis under anoxic
conditions.
Anaerobic hydrolysis factor 0.04 - Rate reduction factor for hydrolysis under
(AS) anaerobic conditions in activated sludge.
Anaerobic hydrolysis factor 0.5 - Rate reduction factor for hydrolysis under
(AD) anaerobic conditions in anaerobic digestion.
Adsorption rate of colloids 0.15 d-1 Conversion rate of colloidal material to
particulate.
Ammonification rate 0.08 d-1 Conversion rate of soluble organic nitrogen
compounds to ammonia
Assimilative nitrate/nitrite 0.5 d-1 Conversion rate of nitrite and/or nitrate to
reduction rate ammonia under ammonia limited conditions
Endogenous products decay 0 d-1 Conversion rate of endogenous products to
rate particulate substrate.

Menu Location: Project|Parameters|Kinetic|Ordinary Heterotrophic on industrial COD

Name Default Unit Explanation

Adsorption rate of soluble 0.2 L/mgCOD d-1 Conversion rate of soluble hydrocarbons
hydrocarbons to material to adsorbed hydrocarbons.

Stoichiometric Parameters
Menu Location: Project|Parameters|Stoichiometric|Ordinary heterotrophic

Biowin 6 Help Manual Model Reference • 769

 Name Default Unit Explanation

Adsorp. Max. 1.0 mgCOD/mgCOD Threshold ratio of adsorbed slowly

biodegradable substrate to
heterotrophic organisms. Above this
threshold ratio colloidal adsorption
ceases.

Menu Location: Project|Parameters|Stoichiometric| Ordinary Heterotrophic on industrial COD

Name Default Unit Explanation

Max. hydrocarbon adsorp. 1.0 - Target maximum ratio of adsorbed

ratio hydrocarbon to ordinary
heterotrophic biomass COD.

Switching Functions
Menu Location: Project|Parameters|Kinetic|Switches

Name Default Unit Explanation

Name Default Unit Explanation

Ordinary heterotrophic 0.15 mgO2/L This constant is used to switch off aerobic activity
DO half sat. under low DO conditions (that is in anaerobic and
anoxic reactors).
Anoxic/anaerobic NOx 0.15 mgN/L This constant is used to turn off anoxic growth,
half sat. decay and hydrolysis processes under conditions
of low nitrate and nitrite.
NH3 nutrient half sat. 0.005 mgN/L This constant is used to slow all biomass growth
processes at low ammonia-N concentrations (N
nutrient limiting conditions – see assimilative
denitrification).

Growth and Decay of Ammonia Oxidizing Biomass

Number of Processes: 4
Engineering Objective: Nitrification
Implementation: permanent, always active in the BioWin model
Module Description:

770 • Model Reference Biowin 6 Help Manual

This biomass grows by oxidizing ammonia to nitrite or possibly nitrous oxide and using the energy to
synthesize organic material from inorganic carbon (fixing CO2). Nitrogen source for cell synthesis is
ammonia.
The base rate expression for the growth process is the product of the maximum specific growth rate, the
ammonia oxidizing biomass concentration and a Monod expression for ammonia. This base rate is modified
to account for environmental conditions (off at low dissolved oxygen), nutrient limitations (phosphate,
inorganic carbon, calcium, magnesium as well as other cations and anions) and pH inhibition. If the nitrous
oxide model is on then nitrous oxide can be produced as a byproduct of nitrification (when ammonia is
present in excess) and the presence of free nitrous acid is also the trigger for a shift towards the production
of additional nitrous oxide through an autotrophic denitrification process. The level of production and onset
of nitrous oxide production are controlled by the parameters described below.
The decay rate varies between an aerobic value and an anoxic/anaerobic value depending on the dissolved
oxygen concentration.
Model parameters are listed in:

Kinetic Parameters
Menu Location: Project|Parameters|Kinetic|Ammonia oxidizing
All default kinetic parameters are referenced to 20C.

Name Default Unit Explanation

Max. spec. 0.9 d-1 Determines the maximum specific growth rate of ammonia
growth rate oxidizing biomass. Substrate and nutrient limitations will
decrease the growth rate. This parameter has a direct impact
on the nitrification capacity.
Substrate (NH4) 0.7 mgN/L This parameter impacts the residual ammonia concentration
half sat. in the effluent. The value is usually low in normal municipal
plants.
Byproduct NH4 50.0 - Controls the transition period between N2O byproduct and
logistic slope no by product. Note: This parameter is only used if the
Nitrous oxide model option is turned on.
Byproduct NH4 1.4 mgN/L Ammonia level resulting which will result in half of the
inflection point maximum N2O production as a byproduct of nitrification.
Note: This parameter is only used if the Nitrous oxide
model option is turned on.
Denite DO half 0.10 mg/L- DO half saturation concentration for ammonia oxidizing
sat. biomass denitrification. Note: This parameter is only used if
the Nitrous oxide model option is turned on.
Denite HNO2 half 5.00e-6 mgN/L- Free nitrous acid half saturation concentration for
sat. ammonia oxidizing biomass denitrification. Note: This
parameter is only used if the Nitrous oxide model option is
turned on.

Biowin 6 Help Manual Model Reference • 771

 Aerobic decay 0.17 d-1 Decay rate constant under aerobic conditions for ammonia
rate oxidizing biomass.
Anoxic/anaerobic 0.08 d-1 Decay rate constant under non-aerobic conditions for
decay rate ammonia oxidizing biomass.
KiHNO2 0.005 mmol/L Nitrous acid inhibition concentration.

Stoichiometric Parameters
Menu Location: Project|Parameters|Stoichiometric|Ammonia oxidizing

Name Default Unit Explanation

Yield 0.15 mgCOD/mgN Ammonia oxidizing biomass COD

produced by oxidizing 1 mg of ammonia
to nitrite.
Denite NO2 fraction as 0. 50 mgN/mgN Fraction of nitrite used as a terminal
TEA electron acceptor (low dissolved
oxygen). Note: This parameter is only
used if the Nitrous oxide model option
is turned on.
Byproduct NH4 0. 0025 mgN/mgN Fraction of ammonia nitrified to nitrous
fraction to N2O oxide (excess ammonia). Note: This
parameter is only used if the Nitrous
oxide model option is turned on.
N in biomass 0.07 mgN/ mgCOD N content of Ammonia oxidizing biomass.
P in biomass 0.022 mgP/ mgCOD P content of Ammonia oxidizing biomass.
Fraction going to 0.08 - Fraction of biomass that becomes inert
endogenous residue upon decay.
COD:VSS ratio 1.42 mgCOD/mgVSS Conversion factor between biomass as
measured in COD and its VSS content.
This value is relatively stable for biomass.

Menu Location: Project|Parameters|Stoichiometric|Common

Name Default Unit Explanation

Biomass/Endog Ca 3.912x10-3 gCa/gCOD Calcium content of active

content biomass and endogenous
residue. Part of cellular ISS
generated by biomass growth.
Biomass/Endog Mg 3.912x10-3 gMg/gCOD Magnesium content of active
content biomass and endogenous

772 • Model Reference Biowin 6 Help Manual

 residue. Part of cellular ISS
generated by biomass growth.
Biomass/Endog other 5.115x10-4 mol/gCOD The amount of “Other cations”
cations content in active biomass and
endogenous residue. Part of
cellular ISS generated by
biomass growth.
Biomass/Endog other 1.41x10-4 mol/gCOD The amount of “Other anions”
anions content in active biomass and
endogenous residue. Part of
cellular ISS generated by
biomass growth.
N in endogenous residue 0.07 mgN/ mgCOD N content of endogenous
residue from organism decay.
P in endogenous residue 0.022 mgP/ mgCOD P content of endogenous
residue from organism decay.
Endogenous residue 1.42 mgCOD/mgVSS Conversion factor between
COD:VSS Ratio endogenous residue measured
as COD and its VSS content.

pH Inhibition
Menu Location: Project|Parameters|Kinetic|pH

Name Default Unit Explanation

Autotrophs low pH 5.5 pH units At a pH equal to this value the growth rate of
limit Ammonia oxidizing, Nitrite oxidizing, Anaerobic
ammonia oxidizing, sulfur reducing, and sulfur
oxidizing organisms will be reduced by 50%.
Autotrophs high pH 9.5 pH units At a pH equal to this value the growth rate of
limit Ammonia oxidizing, Nitrite oxidizing, Anaerobic
ammonia oxidizing, sulfur reducing, and sulfur
oxidizing organisms will be reduced by 50%.

Switching Functions
Menu Location: Project|Parameters|Kinetic|Switches

Name Default Unit Explanation

Ammonia oxidizing DO 0.25 mgO2/L This parameter is used to switch off ammonia
half sat. oxidation by Ammonia oxidizing organisms under
low DO conditions.

Biowin 6 Help Manual Model Reference • 773

 P nutrient half sat. 0.001 mgP/L This parameter is used to switch off the growth
of biomass when there is no phosphorus
available as nutrient.
Autotroph CO2 half 0.1 mmol/L This parameter is used to switch off the growth
sat. of Ammonia oxidizing, Nitrite oxidizing,
Anaerobic ammonia oxidizing, and sulfur
oxidizing organisms.
Synthesis anion/cation 0.01 meq/L Half saturation concentration for anions and
half sat. cations.

Growth and Decay of Nitrite Oxidizing Biomass

Number of Processes: 2
Engineering Objective: Nitrification
Implementation: permanent, always active in the BioWin model
Module Description:
This biomass grows by oxidizing nitrite to nitrate and using the energy to synthesize organic material from
inorganic carbon (fixing CO2). Nitrogen source for cell synthesis is ammonia.
The base rate expression for the growth process is the product of the maximum specific growth rate, the
nitrite oxidizing biomass concentration and a Monod expression for nitrite. This base rate is modified to
account for environmental conditions (off at low dissolved oxygen and inhibited by ammonia), nutrient
limitations (ammonia, phosphate, inorganic carbon, calcium, magnesium as well as other cations and
anions) and pH inhibition.
The decay rate varies between an aerobic value and an anoxic/anaerobic value depending on the dissolved
oxygen concentration.
Model parameters are listed in:

Kinetic Parameters
Menu Location: Project|Parameters|Kinetic|Nitrite oxidizing
All default kinetic parameters are referenced to 20C.
Name Default Unit Explanation

Max. spec. growth rate 0.7 d-1 Determines the maximum specific growth rate of
nitrite oxidizing biomass. Substrate, nutrient
limitations and environmental conditions will
decrease the growth rate. This parameter has a
direct impact on the nitrification capacity.
Substrate (NO2) half 0.1 mgN/L This parameter impacts the residual nitrite
sat. concentration in the effluent. The value is usually
very low in normal municipal plants.
Aerobic decay rate 0.17 d-1 Decay rate constant under aerobic conditions for
nitrite oxidizing biomass.

774 • Model Reference Biowin 6 Help Manual

 Anoxic/anaerobic 0.08 d-1 Decay rate constant under non-aerobic conditions
decay rate for nitrite oxidizing biomass.
KiHNH3 0.075 mmol/L Ammonia inhibition concentration.

Stoichiometric Parameters
Menu Location: Project|Parameters|Stoichiometric|Nitrite oxidizing

Name Default Unit Explanation

Yield 0.09 mgCOD/mgN Nitrite oxidizing biomass COD

produced by oxidizing 1 mg of
nitrite N.
N in biomass 0.07 mgN/ mgCOD N content of nitrite oxidizing
biomass.
P in biomass 0.022 mgP/ mgCOD P content of nitrite oxidizing
biomass.
Fraction going to 0.08 - Fraction of biomass that becomes
endogenous residue inert upon decay.
COD:VSS ratio 1.42 mgCOD/mgVSS Conversion factor between biomass
as measured in COD and its VSS
content. This value is relatively
stable for biomass.

Menu Location: Project|Parameters|Stoichiometric|Common

Name Default Unit Explanation

Biomass/Endog Ca 3.912x10-3 gCa/gCOD Calcium content of active

content biomass and endogenous
residue. Part of cellular ISS
generated by biomass growth.
Biomass/Endog Mg 3.912x10-3 gMg/gCOD Magnesium content of active
content biomass and endogenous
residue. Part of cellular ISS
generated by biomass growth.
Biomass/Endog other 5.115x10-4 mol/gCOD The amount of “Other cations”
cations content in active biomass and
endogenous residue. Part of
cellular ISS generated by
biomass growth.

Biowin 6 Help Manual Model Reference • 775

 Biomass/Endog other 1.41x10-4 mol/gCOD The amount of “Other anions”
anions content in active biomass and
endogenous residue. Part of
cellular ISS generated by
biomass growth.
N in endogenous residue 0.07 mgN/ mgCOD N content of endogenous
residue from organism decay.
P in endogenous residue 0.022 mgP/ mgCOD P content of endogenous
residue from organism decay.
Endogenous residue 1.42 mgCOD/mgVSS Conversion factor between
COD:VSS Ratio endogenous residue measured
as COD and its VSS content.

pH Inhibition
Menu Location: Project|Parameters|Kinetic|pH

Name Default Unit Explanation

Autotrophs low pH limit 5.5 pH units At a pH equal to this value the growth rate of
Ammonia oxidizing, Nitrite oxidizing,
Anaerobic ammonia oxidizing, sulfur
reducing, and sulfur oxidizing organisms will
be reduced by 50%.
Autotrophs high pH limit 9.5 pH units At a pH equal to this value the growth rate of
Ammonia oxidizing, Nitrite oxidizing,
Anaerobic ammonia oxidizing, sulfur
reducing, and sulfur oxidizing organisms will
be reduced by 50%.

Switching Functions
Menu Location: Project|Parameters|Kinetic|Switches

Name Default Unit Explanation

Nitrite oxidizing biomass 0.5 mgO2/L This parameter is used to switch off nitrite
DO half sat. oxidation by nitrite oxidizing biomass under
low DO conditions.
NH3 nutrient half sat. 0.005 mgN/L This constant is used to slow all biomass
growth processes at low ammonia-N
concentrations (N nutrient limiting conditions –
see assimilative denitrification).

776 • Model Reference Biowin 6 Help Manual

 P nutrient half sat. 0.001 mgP/L This parameter is used to switch off the growth
of biomass when there is no phosphorus
available as nutrient.
Autotroph CO2 half sat. 0.1 mmol/L This parameter is used to switch off the growth
of Ammonia oxidizing, Nitrite oxidizing,
Anaerobic ammonia oxidizing, and sulfur
oxidizing organisms.
Synthesis anion/cation 0.01 meq/L Half saturation concentration for anions and
half sat. cations.

Growth and Decay of Anaerobic Ammonia Oxidizing Biomass

Number of Processes: 2
Engineering Objective: Nitrification
Implementation: permanent, always active in the BioWin model
Module Description:
This biomass grows by converting ammonia and nitrite to nitrogen gas and nitrate. The energy from this
process is used to synthesize organic material from inorganic carbon (fixing CO2). Nitrogen source for cell
synthesis is ammonia.
The base rate expression for the growth process is the product of the maximum specific growth rate, the
anaerobic ammonia oxidizing biomass concentration, a Monod expression for ammonia and a Monod
expression for nitrite. This base rate is modified to account for environmental conditions (switched off
under aerobic conditions and inhibited by nitrite), nutrient limitations (phosphate, inorganic carbon,
calcium, magnesium as well as other cations and anions) and pH inhibition.
The decay rate varies between an aerobic and anoxic/anaerobic value depending on the dissolved oxygen
concentration. Nitrite toxicity is modeled by increasing the decay rate by the product of the nitrite
sensitivity constant and the nitrite concentration.
Model parameters are listed in:

Kinetic Parameters
Menu Location: Project|Parameters|Kinetic|Anaerobic ammonia oxidizing
All default kinetic parameters are referenced to 20C.

Name Default Unit Explanation

Max. spec. growth rate 0.2 d-1 Determines the maximum specific growth rate
of anaerobic ammonia oxidizing biomass.
Substrate, nutrient limitations and
environmental conditions will decrease the
growth rate. This parameter has a direct impact
on the nitrification capacity.

Biowin 6 Help Manual Model Reference • 777

 Substrate (NH4) half 2.0 mgN/L Ammonia half saturation concentration for
sat. anaerobic ammonia oxidizing biomass.
Substrate (NO2) half 1.0 mgN/L Nitrite half saturation concentration for
sat. anaerobic ammonia oxidizing biomass.
Aerobic decay rate 0.019 d-1 Decay rate constant under aerobic conditions
for anaerobic ammonia oxidizing biomass.
Anoxic/anaerobic decay 0.0095 d-1 Decay rate constant under non-aerobic
rate conditions for anaerobic ammonia oxidizing
biomass.
Ki Nitrite 1000.0 mgN/L Nitrite inhibition concentration.
Nitrite sensitivity 0.016 L/ (d mgN) Nitrite toxicity constant.
constant

Stoichiometric Parameters
Menu Location: Project|Parameters|Stoichiometric|Anaerobic ammonia oxidizing

Name Default Unit Explanation

Yield 0.114 mgCOD/mgN Anaerobic ammonia oxidizing biomass

produced by oxidizing 1 mg of ammonia.
Nitrate production 2.28 mgN/mgCOD Nitrate production yield
N in biomass 0.07 mgN/ mgCOD N content of anaerobic ammonia oxidizing
biomass.
P in biomass 0.022 mgP/ mgCOD P content of anaerobic ammonia oxidizing
biomass.
Fraction going to 0.08 - Fraction of biomass that becomes inert
endogenous residue upon decay.
COD:VSS ratio 1.42 mgCOD/mgVSS Conversion factor between biomass as
measured in COD and its VSS content. This
value is relatively stable for biomass.

Menu Location: Project|Parameters|Stoichiometric|Common

Name Default Unit Explanation

778 • Model Reference Biowin 6 Help Manual

 Biomass/Endog Ca 3.912x10-3 gCa/gCOD Calcium content of active
content biomass and endogenous
residue. Part of cellular ISS
generated by biomass growth.
Biomass/Endog Mg 3.912x10-3 gMg/gCOD Magnesium content of active
content biomass and endogenous
residue. Part of cellular ISS
generated by biomass growth.
Biomass/Endog other 5.115x10-4 mol/gCOD The amount of “Other cations”
cations content in active biomass and
endogenous residue. Part of
cellular ISS generated by
biomass growth.
Biomass/Endog other 1.41x10-4 mol/gCOD The amount of “Other anions”
anions content in active biomass and
endogenous residue. Part of
cellular ISS generated by
biomass growth.
N in endogenous residue 0.07 mgN/ mgCOD N content of endogenous
residue from organism decay.
P in endogenous residue 0.022 mgP/ mgCOD P content of endogenous
residue from organism decay.
Endogenous residue 1.42 mgCOD/mgVSS Conversion factor between
COD:VSS Ratio endogenous residue measured
as COD and its VSS content.

pH Inhibition
Menu Location: Project|Parameters|Kinetic|pH

Name Default Unit Explanation

Autotrophs low pH limit 5.5 pH units At a pH equal to this value the growth rate of
Ammonia oxidizing, Nitrite oxidizing,
Anaerobic ammonia oxidizing, sulfur reducing,
and sulfur oxidizing organisms will be reduced
by 50%.
Autotrophs high pH limit 9.5 pH units At a pH equal to this value the growth rate of
Ammonia oxidizing, Nitrite oxidizing,
Anaerobic ammonia oxidizing, sulfur reducing,
and sulfur oxidizing organisms will be reduced
by 50%.

Biowin 6 Help Manual Model Reference • 779

Switching Functions
Menu Location: Project|Parameters|Kinetic|Switches

Name Default Unit Explanation

Anaerobic ammonia 0.01 mgO2/L This parameter is used to switch on anaerobic

oxidizing biomass DO ammonia oxidation by anaerobic ammonia
half sat. oxidizing biomass under very low DO
conditions.
P nutrient half sat. 0.001 mgP/L This parameter is used to switch off the
growth of biomass when there is no
phosphorus available as nutrient.
Autotroph CO2 half sat. 0.1 mmol/L This parameter is used to switch off the
growth of Ammonia oxidizing, Nitrite oxidizing,
Anaerobic ammonia oxidizing, and sulfur
oxidizing organisms.
Synthesis anion/cation 0.01 meq/L Half saturation concentration for anions and
half sat. cations.

Growth and Decay of Phosphorus Accumulating Biomass

Number of Processes: 17
Engineering Objective: Biological phosphorus removal
Implementation: permanent, always active in the BioWin model
Module Description:
This group of processes describes the growth and decay of phosphorus accumulating biomass under all
conditions. This includes descriptions of aerobic and anoxic growth, volatile fatty acid (VFA) sequestration
(The sequestered VFAs are stored internally as polyhydroxy alkanoates [PHA]) and polyphosphate lysis.
There are two maximum specific growth rates for phosphorus accumulating biomass under aerobic
conditions. The lower growth rate constant is used under P limited conditions and has a different
stoichiometry (no polyphosphate storage). There are also two anoxic growth processes, one uses nitrate and
the other nitrite. Growth processes under phosphate rich conditions result in uptake of phosphate, as well
as balancing calcium ions magnesium ions and other cations. A lack of these ions will stop the growth
processes by appropriate Monod switches. For all of these growth processes, the base growth rate is the
product of the maximum specific rate constant, the phosphorus accumulating biomass concentration and a
Monod switch on the ratio PHA to phosphorus accumulating biomass. This base rate is modified to account
for environmental conditions (dissolved oxygen, nitrate and nitrite), nutrient limitations (ammonia, anions,
cations, for polyphosphate storage magnesium, and calcium are also required) and pH inhibition. BioWin
uses ammonia as a nitrogen source for cell synthesis under aerobic, anoxic and anaerobic conditions. At low
ammonia concentrations BioWin allows for assimilative ammonia production from either nitrate or nitrite in
order to satisfy synthesis demands.

780 • Model Reference Biowin 6 Help Manual

Although the maximum specific growth rate under aerobic and anoxic conditions is the same, under anoxic
conditions the base rate is also multiplied by an anoxic growth factor. This allows for anoxic growth at a
different rate or for only a fraction of the phosphorus accumulating biomass being able to perform any kind
of denitrification (or both of these). Of the phosphorus accumulating biomass that can perform
denitrification, a fraction can use either nitrate or nitrite (with nitrogen gas as an end product), and the
remainder of the denitrifying phosphorus accumulating biomass can only use nitrate (with nitrite as an end
product).
The phosphorus accumulating biomass uses polyphosphate as an energy source to sequester VFAs under
anaerobic conditions. The sequestered VFAs are stored internally as polyhydroxy alkanoates (PHA). In the
BioWin model the phosphorus accumulating biomass can use both acetate and propionate for this process.
The base sequestration rate is the product of the sequestration rate constant, the phosphorus accumulating
biomass concentration and a Monod switch on the appropriate substrate (acetate or propionate). The rate is
also dependent on the availability of the stored polyphosphate (poly-P).
There are two decay processes (aerobic/anoxic and anaerobic). Associated with each decay process is a lysis
process for PHA, low and high molecular weight polyphosphate. The lysis rates are directly proportional to
the decay rate itself.
There is a polyphosphate cleavage process for anaerobic maintenance that releases phosphate if no oxygen
is present [default off].
There is also an aerobic/anoxic maintenance process that releases organism COD as well as synthesis
nitrogen and phosphorus but no polyphosphate or PHA [default off]..
Model parameters are listed in:

Kinetic Parameters
Menu Location: Project|Parameters|Kinetic|Phosphorus accumulating
All default kinetic parameters are referenced to 20C.

Name Default Unit Explanation

-1
Max. spec. growth 0.95 d Determines the maximum attainable growth rate of
rate phosphorus accumulating heterotrophic organisms if
no substrate, DO or P limitation occurs.
Max. spec. growth 0.42 d-1 Determines the maximum attainable growth rate of
rate, P-limited phosphorus accumulating biomass organisms under
phosphorus limiting conditions.
Substrate half sat. 0.1 mg CODPHB / Half saturation constant for PHA, used as substrate
mg CODPAO by phosphorus accumulating biomass.
Substrate half sat., 0.05 mg CODPHB / Half saturation constant for PHA, under phosphorus
P-limited mg CODPAO limiting conditions.
Magnesium half 0.1 mgMg / L Half saturation constant for Magnesium storage
sat. during poly-P synthesis.

Biowin 6 Help Manual Model Reference • 781

 Cation half sat. 0.1 meq / L Half saturation constant for cation (primarily
potassium) storage during poly-P synthesis.
Calcium half sat. 0.1 mgCa / L Half saturation constant for Calcium storage during
poly-P synthesis.
Aerobic/anoxic 0.1 d-1 Decay rate constant under aerobic or anoxic
decay rate conditions.
Aerobic/anoxic 0 d-1 Maintenance rate constant under aerobic or anoxic
maintenance rate conditions. [Default off]
Anaerobic decay 0.04 d-1 Decay rate constant under anaerobic conditions.
rate
Anaerobic 0 d-1 Maintenance/polyphosphate cleavage rate constant
maintenance rate under anaerobic conditions. [Default off]
Sequestration rate 4.5 d-1 Rate constant for VFA sequestration to form PHA
(stored substrate).
Anoxic growth 0.33 - This parameter represents the fraction of organisms
factor that are able to grow under anoxic conditions and/or
a reduction in the growth rate under anoxic
conditions. Substrate and nutrient limitations may
further reduce the growth rate.

Stoichiometric Parameters
Menu Location: Project|Parameters|Stoichiometric|Phosphorus accumulating

Name Default Unit Explanation

Yield (aerobic) 0.639 mgCOD/mgCOD Amount of biomass produced using one unit
of substrate under aerobic conditions. The
rest of the substrate will be oxidized.
Yield (anoxic) 0.52 mgCOD/mgCOD Amount of biomass produced using one unit
of substrate under anoxic conditions.
Aerobic P/PHA 0.93 mgP/mgCOD Amount of P stored per unit of PHA oxidized
uptake in aerobic conditions
Anoxic P/PHA 0.35 mgP/mgCOD Amount of P stored per unit of PHA in
uptake anoxic conditions.
Yield of PHA on 0.889 mgCOD/mgCOD Amount of PHA stored when 1 mg of
sequestration acetate or propionate is sequestered.
N in biomass 0.07 mgN/ mgCOD N content of phosphorus accumulating
biomass. Has a significant effect on nitrogen
availability for nitrification and therefore
oxygen demand.

782 • Model Reference Biowin 6 Help Manual

 N in sol. inert 0.07 mgN/ mgCOD N content of soluble inert organics
originating from phosphorus accumulating
biomass decay.
P in biomass 0.022 mgP/ mgCOD P content of phosphorus accumulating
biomass, not including P stored in the form
of Poly-P
Fraction to 0.25 - Fraction of biomass that becomes
endogenous part. particulate inert upon decay.
Inert fraction of 0.2 - Fraction of biomass that becomes soluble
endogenous sol. inert upon decay.
P/Ac release ratio 0.51 mgP/mgCOD Amount of P released for one mg of acetate
sequestered in the form of PHA
COD:VSS Ratio 1.42 mgCOD/mgVSS Conversion factor between biomass as
measured in COD and its VSS content. This
value is relatively stable for biomass.
Yield of low PP 0.94 mgP/mgP Fraction of P stored in releasable poly-P
form (rest of P is stored in high molecular
weight, non-releasable poly-P)
Mg to P mole ratio 0.3 molMg/molP Mole ratio of magnesium to phosphorus in
in polyphosphate stored polyphosphate. This magnesium is
released when polyphosphate is used
(together with the phosphate release).
Cation to P mole 0.15 meq/mmolP Mole ratio of other cations (primarily
ratio in potassium) to phosphorus in stored
polyphosphate polyphosphate. These cations are released
when polyphosphate is used (together with
the phosphate release).
Ca to P mole ratio in 0.05 molCa/molP Mole ratio of calcium to phosphorus in
polyphosphate stored polyphosphate. This calcium is
released when polyphosphate is used
(together with the phosphate release).

Menu Location: Project|Parameters|Stoichiometric|Common

Name Default Unit Explanation

Biomass/Endog Ca 3.912x10-3 gCa/gCOD Calcium content of active

content biomass and endogenous
residue. Part of cellular ISS
generated by biomass growth.

Biowin 6 Help Manual Model Reference • 783

 Biomass/Endog Mg 3.912x10-3 gMg/gCOD Magnesium content of active
content biomass and endogenous
residue. Part of cellular ISS
generated by biomass growth.
Biomass/Endog other 5.115x10-4 mol/gCOD The amount of “Other cations”
cations content in active biomass and
endogenous residue. Part of
cellular ISS generated by
biomass growth.
Biomass/Endog other 1.41x10-4 mol/gCOD The amount of “Other anions”
anions content in active biomass and
endogenous residue. Part of
cellular ISS generated by
biomass growth.
N in endogenous residue 0.07 mgN/ mgCOD N content of endogenous
residue from organism decay.
P in endogenous residue 0.022 mgP/ mgCOD P content of endogenous
residue from organism decay.
Endogenous residue 1.42 mgCOD/mgVSS Conversion factor between
COD:VSS Ratio endogenous residue measured
as COD and its VSS content.

pH Inhibition
Menu Location: Project|Parameters|Kinetic|pH

Name Default Unit Explanation

Phosphorus 4.0 pH units At a pH equal to this value the growth rate of

accumulating biomass polyphosphate accumulating biomass will be
low pH limit reduced by 50%.
Phosphorus 10.0 pH units At a pH equal to this value the growth rate of
accumulating biomass polyphosphate accumulating biomass will be
high pH limit reduced by 50%.

Switching Functions
Menu Location: Project|Parameters|Kinetic|Switches

Name Default Unit Explanation

Phosphorus accumulating 0.05 mgO2/L This constant is used to switch off aerobic
DO half sat. phosphorus accumulating biomass activity

784 • Model Reference Biowin 6 Help Manual

 under low DO conditions (that is in
anaerobic and anoxic reactors).
Anoxic/anaerobic NOx 0.15 mgN/L This constant is used to turn off anoxic
half sat. growth, decay and hydrolysis processes
under conditions of low nitrate and nitrite.
Anoxic NO3 (→NO2) half 0.1 mgN/L This constant is used to switch off anoxic
sat. growth processes producing nitrite under
low nitrate conditions.
Anoxic NO3 (→N2) half 0.05 mgN/L This constant is used to switch off anoxic
sat. growth processes using nitrate under low
nitrate conditions.
Anoxic NO2 (→N2) half 0.01 mgN/L This constant is used to switch off anoxic
sat. growth processes using nitrite under low
nitrite conditions.
NH3 nutrient half sat. 0.005 mgN/L This constant is used to slow all biomass
growth processes at low ammonia-N
concentrations (N nutrient limiting
conditions – see assimilative
denitrification).
PolyP half sat. 0.01 mgP/mgCOD This constant stops sequestration of VFA
and P release as the ratio of low molecular
weight polyphosphate to PAO falls.
VFA sequestration half 5.0 mgCOD/L This is the half saturation concentration for
sat. the sequestration of acetate and
propionate.
P uptake half sat. 0.15 mgP/L This constant stops growth with
polyphosphate storage at low soluble
phosphate concentrations. This constant
will have an impact on the effluent soluble
P concentration in a bio-P system.
P nutrient half sat. 0.001 mgP/L This constant is used to slow the growth of
biomass when there is no phosphorus
available as nutrient.
Synthesis anion/cation 0.01 meq/L Half saturation concentration for anions
half sat. and cations.

Anaerobic Digestion Processes

The anaerobic digestion model in BioWin contains the following functional categories, modules
• Heterotrophic Growth through Fermentation
• Growth and Decay of Propionic Acetogens

Biowin 6 Help Manual Model Reference • 785

 • Growth and Decay of Methanogens

Anaerobic Processes
This section provides a general description of the modeling of anaerobic processes in BioWin particularly as
they would occur in anaerobic digestion processes. The following subsections are included in this
discussion.
• Background on Anaerobic Model Development: This sub-section provides a brief literature review
on anaerobic digestion modeling.
• Model Formulation: This sub-section provides an overview of the structure and interactions of the
model processes that predominate in an anaerobic digestion simulation.
• Activated Sludge vs. Anaerobic Digestion: In BioWin, one comprehensive model for the biochemical
and physical-chemical systems is used for the entire treatment plant. However, the behavior of a
specific unit process element and the dominant reactions in that element are dependent on the
process environmental conditions such as SRT, temperature, and pH. This sub-section describes
how certain processes behave differently in anaerobic digestion vs. activated sludge.

Background on Anaerobic Model Development

Early mechanistic mathematical models of anaerobic digestion considered only methanogenic reactions
based on the assumption that methane production is the rate-limiting step in the process (Andrews, 1969;
Andrews and Graef, 1971). An initial extension of this conceptual framework (Hill and Barth, 1977) included
the reactions of “acid-formers” which considered both particulate hydrolysis and production of volatile fatty
acids (VFAs). These early models represented the VFA concentration as one “bulk” component that was
considered to be the sole substrate for the methanogens.
The role of hydrogen in the regulation of product distribution and consumption was a key development that
formed the basis for many subsequent models of anaerobic digestion (Mosey, 1983). This advancement
allowed models to predict the formation of various fermentation products in addition to acetic acid, such as
the higher acids propionic and butyric. In addition, methane production from both acetic acid and
hydrogen could be included. A number of models were developed based on the “four population”
framework of Mosey, including Costello et al. (1991) and Jones et al. (1992).
Most new models for anaerobic digestion include hydrogen regulation functions and are being presented
using the Petersen matrix format. Examples include the work of Massé and Droste (2000), and Bagley and
Brodkorb (1999).
Important considerations in an anaerobic sludge digestion model, when included in a comprehensive
wastewater treatment plant simulator, include:
• Fate of influent biomass in the digester;
• Net release of ammonia and phosphate in the digester;
• Role of the anaerobic reactions in the activated sludge process.
The International Water Association recently has published the Anaerobic Digestion Model No. 1 (ADM1).
Although this is a detailed and comprehensive model for anaerobic digestion processes, it has a number of
limitations for application to plant-wide wastewater treatment plant simulation:

786 • Model Reference Biowin 6 Help Manual

 • ADM1 contains a set of state variables that is not consistent with standard activated sludge models
(i.e. the ASM-series, the BioWin model and others). An "Interface Model" is required between the
liquid and solids line if ADM1 is used to model the digester. Some of the activated sludge state
variables must be “combined” into ADM1 state variables, and important information is lost on the
fate of specific states.
• ADM1 does not include phosphorus as a state variable. The release of phosphorus in digesters is
particularly important in simulating performance of BNR treatment plants.
• ADM1 does not include nitrogen release on organism decay and does not maintain a nitrogen mass
balance. However, Ammonia release in the digester and return of the digester supernatant to the
liquid line is an important consideration in a plant-wide simulation.

Model Formulation (Anaerobic Processes)

A key objective in formulation of the anaerobic processes in the model was to maintain a consistent set of
state variables, stoichiometry, and process rate equations throughout the BioWin model. This allows
BioWin to use one comprehensive model for the biochemical systems in the treatment plant – the behavior
of a specific unit process element and the dominant reactions in that element being dependent on the
process environmental conditions such as SRT, temperature, and pH.
The anaerobic degradation processes in the model are based on the “four population” model concept. A
conceptual schematic of the model is shown in the figure below. The following points describe the key
stages:
• Influent biomass (which would be present in significant quantities in waste activated sludge)
undergoes anaerobic decay in the digester. The process rates and stoichiometry are the same as for
anaerobic decay in the activated sludge process. The products of decay include unbiodegradable
organics (ZE, SU), nitrogen (ZE,N, NUS), and phosphorus (ZE,P) components. If phosphate accumulating
organisms (ZPA) are present, the decay process also releases ammonia (NH3), phosphate (PO4),
Magnesium (Mg) and Calcium (Ca).
• Hydrolysis of particulate matter is mediated by the ordinary heterotrophic organisms (ZH).
Particulate matter may be present in the influent, or may consist of products from biomass decay.
The products of hydrolysis are phosphate (PO4) soluble organic nitrogen (NOS), and readily
biodegradable COD (Sc).
• Soluble organic nitrogen undergoes ammonification to produce ammonia (NH3). This process is
mediated by the heterotrophs (ZH and ZPA).
• Precipitation of struvite and calcium phosphates removes PO4 and NH3from solution. These are
kinetically controlled processes described in Spontaneous Chemical Precipitation section.
• Ordinary heterotrophic organisms (ZH) ferment the complex readily degradable COD (Sc) to acetic
acid (Sa), propionic acid (Sp) hydrogen (SbH2), and carbon dioxide (SCO2t). There are two model
processes for this reaction step. One is for low dissolved hydrogen concentrations while the other is
for high dissolved hydrogen concentrations. The stoichiometry of each of these processes can be
calibrated to achieve the appropriate product mix (see the Fermentation section).
• Dissolved hydrogen (SbH2) and carbon dioxide (SCO2t) are stripped from solution at a rate that is
proportional to the difference between the saturated dissolved component concentration and the
actual dissolved component concentration (see the Aeration and Gas Transfer Model section. It is
only the undissociated carbonic acid form (H2CO3) of the SCO2t component that is stripped from

Biowin 6 Help Manual Model Reference • 787

 solution, so carbon dioxide stripping is pH dependent (see the Modeling of pH and Alkalinity
section).
• Propionic acid (Sp) is converted to acetic acid by acetogenic bacteria. This process also produces
hydrogen and is switched off at high hydrogen concentrations.
• Methane production occurs as a result of the growth of two different groups of organisms.
Acetoclastic methanogens consume acetic acid. The substrate of hydrogenotrophic methanogens is
dissolved hydrogen and dissolved carbon dioxide.
• The growth of the heterotrophs, acetogens, and methanogens is switched off at high pH and at low
pH.

Note: The diagram below shows only nutrients, organics, and related potential precipitates. Sulfur and its
related processes are not shown on the diagram, but are outlined in elsewhere in this section (see the Sulfur
Modeling section).

788 • Model Reference Biowin 6 Help Manual

Conceptual schematic for the anaerobic degradation model.

Activated Sludge vs. Anaerobic Digestion

There are some differences in the model processes in activated sludge vs. anaerobic digestion. These are
noted here:
• The anaerobic digester hydrolysis process is the same for both the anaerobic digester and the
activated sludge elements. However, a different Anaerobic hydrolysis factor is specified for the
anaerobic digestion processes.
• The anaerobic fermentation process is the same for both the anaerobic digester and activated
sludge elements. However, the Fermentation rate is reduced in the activated sludge process
through the Fermentation growth factor (AS).
There are a number of processes in the model that, although calculated in all bioreactors, are not likely to be
significant under the typical conditions in activated sludge systems. These are described below:
• The growth rate of acetogens is very low at ambient temperatures, and these organisms only grow
under anaerobic conditions. In addition, the acetogen substrate concentration, Sp, is typically quite
low in an activated sludge process. For these reasons, propionate acetogens will usually washout in
the activated sludge process.
• Methanogen growth rates are very low at ambient temperatures, and methanogens are obligate
anaerobes. As a result, methanogens will usually washout in the activated sludge process.
• In an anaerobic digester, hydrogen COD (SbH2) is converted to methane. In an activated sludge
system, there is an insignificant concentration of hydrogenotrophic methanogens, so that SbH2
formed is largely stripped through aeration.
• The struvite precipitation model process exists in both the activated sludge and the anaerobic
digester elements. However, struvite precipitation only occurs at the high NH3, PO4 and alkalinity
concentrations usually found in the anaerobic digester. This model is optional so the user can
choose to include struvite precipitation modeling or to exclude it. The selection that the user makes
is applied both for activated sludge conditions and anaerobic digestion conditions.

References
Andrews, J. F. (1969). Dynamic model of the anaerobic digestion process. J. Sanit. Eng. Div. Proc. ASCE, 95
(SA1), pp. 95-116.
Andrews, J. F. and Graef, S. P. (1971). Dynamic modeling and simulation of the anaerobic digestion process.
Anaerobic Biological Treatment Processes. Advances in Chemistry Series, R.F. Gould (Ed.), 105, American
Chemical Society, New York, pp. 126-162.
Bagley, D. M. and Brodkorb, T. S. (1999). Modeling microbial kinetics in an anaerobic sequencing batch
reactor – Model development and experimental validation. Water Environment Research, 71(7), pp. 1320-
1332.
Costello, D. J., Greenfield, P.F., Lee, P.L. (1991). Dynamic modeling of a single stage high rate anaerobic
reactor – I. Model derivation. Wat. Res., 25, pp. 847-858.

Biowin 6 Help Manual Model Reference • 789

De Souza Araújo, L., Catunda, P.F.C., van Haandel, A.C. (1998). Biological sludge stablisation Part 2: Influence
of the compostition of waste activated sludge on anaerobic stabilization. Water SA, 24, pp. 231-236.
Hill, D.T. and Barth, C.L. (1977). A dynamic model for simulation of animal waste digestion. J. Wat. Pollut.
Control Fed., 10, pp. 2129-2143.
Jones, R.M., MacGregor, J.F., Murphy, K.L., and Hall, E.R. (1992). Towards a useful dynamic model of the
anaerobic digestion process. Wat. Sci. Technol., 25 (7), pp. 61-72.
Massé, D.I., and Droste, R.L. (2000). Comprehensive model of anaerobic digestion of swine manure slurry in
a sequencing batch reactor. Wat. Res., 34, pp. 3087-3106.
Mosey, F.E. (1983). Mathematical modeling of the anaerobic digestion process: regulatory mechanisms for
the formation of short chain volatile acids from glucose. Wat. Sci. Technol., 21, pp. 187-196.

Heterotrophic Growth through Fermentation

Number of Processes: 6
Engineering Objective: VFA generation (fermenters, digesters)
Implementation: permanent, always active in the BioWin model
Module Description:
There are two pathways for ordinary heterotrophic growth through fermentation of readily biodegradable
(complex) substrate to acetate, propionate, carbon dioxide and hydrogen. The dominant pathway is
governed by the dissolved hydrogen concentration. The industrial COD components are fermented to
acetate, carbon dioxide and hydrogen. The relative yields of acetate, carbon dioxide and hydrogen are
determined by the specified COD to mole ratio and organism yield for each substrate. The “industrial”
components have an anaerobic growth factor applied to the fermentation rate which allows the user to
independently control the rate of fermentation for each “industrial” substrate. In activated sludge vessels
there is an anaerobic growth factor applied to all growth through fermentation. That is, the “industrial”
substrates have two anaerobic growth factors applied.
The base rate expression for the fermentation growth process is the product of the maximum specific
growth rate constant, the heterotrophic biomass concentration and a Monod expression for the substrate.
This base rate is modified to account for environmental conditions, nutrient limitations (ammonia,
phosphate, calcium, magnesium as well as other cations and anions) and pH inhibition. BioWin uses
ammonia as a nitrogen source for cell synthesis.
The decay process has a rate that varies according to the electron acceptor environment.
Model parameters affecting the performance of this module are listed below.

Kinetic Parameters
Menu Location: Project|Parameters|Kinetic|Ordinary heterotrophic
All default kinetic parameters are referenced to 20C.

Name Default Unit Explanation

-1
Anaerobic decay 0.131 d Ordinary heterotrophic biomass decay rate
under anaerobic conditions.

790 • Model Reference Biowin 6 Help Manual

 Fermentation rate 1.6 d-1 Maximum specific growth rate of OHO under
anaerobic conditions.
Fermentation half sat. 5.0 mgCOD/L Half saturation of complex substrate under
anaerobic conditions
Fermentation growth 0.25 - Growth rate reduction under anaerobic
factor (AS) conditions in activated sludge

Menu Location: Project|Parameters|Kinetic|Ordinary heterotrophic on industrial COD

Name Default Unit Explanation

Anaerobic growth factor for 0.05 - Reduces the growth rate through
Ind #1 fermentation of Ind# 1.
Anaerobic growth factor for 0.05 - Reduces the growth rate through
Ind #2 fermentation of Ind# 2.
Anaerobic growth factor for 0.05 - Reduces the growth rate through
Ind #3 fermentation of Ind# 3.
Anaerobic growth factor for 0.01 - Reduces the growth rate through
adsorbed hydrocarbons fermentation of adsorbed hydrocarbon
COD.

Stoichiometric Parameters
Menu Location: Project|Parameters|Stoichiometric|Ordinary heterotrophic

Name Default Unit Explanation

Yield 0.1 mgCOD/mgCOD Amount of ordinary heterotrophic
(fermentation, biomass produced on one unit of complex
low H2) substrate fermented, under low H2
concentration.
Yield 0.1 mgCOD/mgCOD Amount of ordinary heterotrophic
(fermentation, biomass produced on one unit of complex
high H2) substrate fermented, under high H2
concentration.
H2 yield 0.35 mgCOD/mgCOD Amount of hydrogen produced on one
(fermentation unit of complex substrate fermented,
low H2) under low H2 concentration.

Biowin 6 Help Manual Model Reference • 791

 H2 yield 0.0 mgCOD/mgCOD Amount of hydrogen produced on one
(fermentation unit of complex substrate fermented,
high H2) under high H2 concentration.
Propionate 0.0 mgCOD/mgCOD Amount of propionate produced on one
yield unit of complex substrate fermented,
(fermentation, under low H2 concentration.
low H2)
Propionate 0.7 mgCOD/mgCOD Amount of propionate produced on one
yield unit of complex substrate fermented,
(fermentation, under high H2 concentration.
high H2)
CO2 yield 0.7 mmolCO2/mmolHAC Moles of CO2 produced per mole of
(fermentation, acetate formed at low dissolved H2
low H2) concentrations.
CO2 yield 0.0 mmolCO2/mmolHAC Moles of CO2 produced per mole of
(fermentation, acetate formed at high dissolved H2
high H2) concentrations.
N in Biomass 0.07 mgN/ mgCOD N content of ordinary heterotrophic
biomass.
P in Biomass 0.022 mgP/ mgCOD P content of ordinary heterotrophic
biomass. This parameter influences the P
removal in non bio-P systems, and the P
content of the sludge.
Endogenous 0.184 - Fraction of ordinary heterotrophic biomass
fraction - that becomes inert upon anaerobic decay.
anaerobic
COD:VSS Ratio 1.42 mgCOD/mgVSS Conversion factor between biomass as
measured in COD and its VSS content. This
value is relatively stable for biomass.

Menu Location: Project|Parameters|Stoichiometric|Ordinary heterotrophic on industrial COD

Name Default Unit Explanation

Yield Ind #1 COD 0.04 mgCOD/mgCOD Ordinary heterotrophic biomass

(Anaerobic) yield on Ind#1 substrate COD
under anaerobic conditions.
COD:Mole ratio - Ind #1 224 gCOD/Mol gCOD to gMole ratio for Ind#1.
COD [The default is based on the
value for phenol C6H6O.]

792 • Model Reference Biowin 6 Help Manual

 Yield Ind #2 COD 0.05 mgCOD/mgCOD Ordinary heterotrophic biomass
(Anaerobic) yield on Ind#2 substrate COD
under anaerobic conditions.
COD:Mole ratio - Ind #2 240 gCOD/Mol gCOD to gMole ratio for Ind#2.
COD [The default is based on the
value for benzene C6H6.]
Yield Ind #3 COD 0.04 mgCOD/mgCOD Ordinary heterotrophic biomass
(Anaerobic) yield on Ind#3 substrate COD
under anaerobic conditions.
COD:Mole ratio - Ind#3 288 gCOD/Mol gCOD to gMole ratio for Ind#3.
COD [The default is based on the
value for toluene C7H8.]
Yield enmeshed 0.04 mgCOD/mgCOD Ordinary heterotrophic biomass
hydrocarbons (Anaerobic) yield on enmeshed hydrocarbons
COD under anaerobic conditions.
COD:Mole ratio - 336 gCOD/Mol gCOD to gMole ratio for
Hydrocarbon COD Hydrocarbon COD. [The default
is based on the value for C8H10.
(Ethylbenzene, xylene, etc.)]
Hydrocarbon COD:VSS 3.2 mgCOD/mgVSS gCOD to gVSS ratio for
ratio Hydrocarbon COD. [The default
is approximately based on the
value for C8H10.]
Max. hydrocarbon adsorp. 1.0 - Target maximum ratio of adsorbed
ratio hydrocarbon to ordinary
heterotrophic organism COD.

Menu Location: Project|Parameters|Stoichiometric|Common

Name Default Unit Explanation

Biomass/Endog Ca 3.912x10-3 gCa/gCOD Calcium content of active

content biomass and endogenous
residue. Part of cellular ISS
generated by biomass growth.
Biomass/Endog Mg 3.912x10-3 gMg/gCOD Magnesium content of active
content biomass and endogenous
residue. Part of cellular ISS
generated by biomass growth.
Biomass/Endog other 5.115x10-4 mol/gCOD The amount of “Other cations”
cations content in active biomass and
endogenous residue. Part of

Biowin 6 Help Manual Model Reference • 793

 cellular ISS generated by
biomass growth.
Biomass/Endog other 1.41x10-4 mol/gCOD The amount of “Other anions”
anions content in active biomass and
endogenous residue. Part of
cellular ISS generated by
biomass growth.
N in endogenous residue 0.07 mgN/ mgCOD N content of endogenous
residue from organism decay.
P in endogenous residue 0.022 mgP/ mgCOD P content of endogenous
residue from organism decay.
Endogenous residue 1.42 mgCOD/mgVSS Conversion factor between
COD:VSS Ratio endogenous residue measured
as COD and its VSS content.

pH Inhibition
Menu Location: Project|Parameters|Kinetic|pH

Name Default Unit Explanation

Ordinary heterotrophic 5.5 pH units At a pH equal to this value the growth rate of
low pH limit ordinary heterotrophic biomass under anaerobic
(anaerobic) conditions will be reduced by 50%.
Ordinary heterotrophic 8.5 pH units At a pH equal to this value the growth rate of
high pH limit ordinary heterotrophic biomass under anaerobic
(anaerobic) conditions will be reduced by 50%.

Switching Functions
Menu Location: Project|Parameters|Kinetic|Switches

Name Default Unit Explanation

Ordinary heterotrophic 0.15 mgO2/L This constant is used to switch off aerobic
DO half sat. ordinary heterotrophic biomass activity under
low DO conditions (that is in anaerobic and
anoxic reactors).
Anoxic/anaerobic NOx 0.15 mgN/L This constant is used to turn off anoxic growth,
half sat. decay and hydrolysis processes on under
conditions of low nitrate and nitrite.

794 • Model Reference Biowin 6 Help Manual

 NH3 nutrient half sat. 0.005 mgN/L This constant is used to slow all biomass growth
processes at low ammonia-N concentrations (N
nutrient limiting conditions – see assimilative
denitrification).
P nutrient half sat. 0.001 mgP/L This constant is used to slow the growth of
biomass when there is no phosphorus available
as nutrient.
H2 low/high half sat. 1.0 mgCOD/L This constant switches between two
fermentation pathways, generating acetate
and propionate in various ratios, depending
on available H2 concentration.
Synthesis anion/cation 0.01 meq/L Half saturation concentration for anions and
half sat. cations.

Growth and Decay of Propionic Acetogenic Biomass

Number of Processes: 2
Engineering Objective: anaerobic digestion
Implementation: permanent, always active in the BioWin model
Module Description:
These two processes describe the growth and decay of propionic acetogens, converting propionate to
acetate, CO2 and hydrogen. The nitrogen source for cell synthesis is ammonia. The base rate expression for
the growth process is the product of the maximum specific growth rate, the propionic acetogens
concentration and a Monod expression for propionate. This base rate is modified to account for
environmental conditions (off unless anaerobic, inhibited by hydrogen and acetate), nutrient limitations
(nitrogen, phosphate, calcium, magnesium as well as other cations and anions) and pH inhibition.
The decay process has a rate that varies according to the electron acceptor environment.
Model parameters are listed in:

Kinetic Parameters
Menu Location: Project|Parameters|Kinetic|Propionic acetogenic
All default kinetic parameters are referenced to 20C.

Name Default Unit Explanation

-1
Max. spec. growth 0.25 d Maximum specific growth rate in the absence of
rate substrate limitations.
Substrate half sat. 10.0 mgCOD/L Half saturation for regulation of growth rate, based
on availability of propionate as substrate
Acetate inhibition 10000 mgCOD/L Acetate inhibition constant: high acetate
concentrations inhibit propionic acetogen growth.

Biowin 6 Help Manual Model Reference • 795

 Anaerobic decay 0.05 d-1 Decay rate under anaerobic conditions.
rate
Aerobic/anoxic 0.52 d-1 Decay rate under aerobic or anoxic conditions.
decay rate

Stoichiometric
Menu Location: Project|Parameters|Stoichiometric|Propionic acetogenic

Name Default Unit Explanation

Yield 0.1 mgCOD/mgCOD Amount of biomass produced on one unit of

propionate converted.
H2 yield 0.4 mgCOD/mgCOD Amount of H2 produced on one unit of
propionate converted.
CO2 yield 1.0 mmolCO2/mmol Moles of CO2 produced per mole of acetate

N in biomass 0.07 mgN/ mgCOD N content of propionic acetogenic biomass.

P in biomass 0.022 mgP/ mgCOD P content of propionic acetogenic biomass.
Fraction to 0.08 - Fraction of propionic acetogenic biomass
endogenous that becomes inert upon decay.
residue
COD:VSS ratio 1.42 mgVSS/mgCOD Conversion factor between propionic
acetogenic biomass as measured in COD and
its VSS content. This value is relatively stable
for biomass.

Menu Location: Project|Parameters|Stoichiometric|Common

Name Default Unit Explanation

Biomass/Endog Ca 3.912x10-3 gCa/gCOD Calcium content of active

content biomass and endogenous
residue. Part of cellular ISS
generated by biomass growth.
Biomass/Endog Mg 3.912x10-3 gMg/gCOD Magnesium content of active
content biomass and endogenous
residue. Part of cellular ISS
generated by biomass growth.
Biomass/Endog other 5.115x10-4 mol/gCOD The amount of “Other cations”
cations content in active biomass and
endogenous residue. Part of

796 • Model Reference Biowin 6 Help Manual

 cellular ISS generated by
biomass growth.
Biomass/Endog other 1.41x10-4 mol/gCOD The amount of “Other anions”
anions content in active biomass and
endogenous residue. Part of
cellular ISS generated by
biomass growth.
N in endogenous residue 0.07 mgN/ mgCOD N content of endogenous
residue from organism decay.
P in endogenous residue 0.022 mgP/ mgCOD P content of endogenous
residue from organism decay.
Endogenous residue 1.42 mgCOD/mgVSS Conversion factor between
COD:VSS Ratio endogenous residue measured
as COD and its VSS content.

pH Inhibition
Menu Location: Project|Parameters|Kinetic|pH

Name Default Unit Explanation

Propionic acetogenic 4.0 pH units At a pH equal to this value the growth rate of
low pH limit propionic acetogenic biomass will be reduced by
50%.
Propionic acetogenic 10.0 pH units At a pH equal to this value the growth rate of
high pH limit propionic acetogenic biomass will be reduced by
50%.

Switching Functions
Menu Location: Project|Parameters|Kinetic|Switches

Name Default Unit Explanation

Ordinary heterotrophic 0.15 mgO2/L This constant is used to switch off aerobic
DO half sat. activity under low DO conditions (that is in
anaerobic and anoxic reactors).
Anoxic/anaerobic NOx 0.15 mgN/L This constant is used to turn off anoxic growth,
half sat. decay and hydrolysis processes on under
conditions of low nitrate and nitrite.
NH3 nutrient half sat. 0.005 mgN/L This constant is used to slow all biomass growth
processes at low ammonia-N concentrations (N

Biowin 6 Help Manual Model Reference • 797

 nutrient limiting conditions – see assimilative
denitrification).
P nutrient half sat. 0.001 mgP/L This constant is used to slow the growth of
biomass when there is no phosphorus available
as nutrient.
Propionic acetogens H2 5.0 mgCOD/L This constant is used to inhibit the growth of
inhibition biomass when high levels of H2 are present.
Synthesis anion/cation 0.01 meq/L Half saturation concentration for anions and
half sat. cations.

Growth and Decay of Methanogenic Biomass

Number of Processes: 6
Engineering Objective: anaerobic digestion
Implementation: permanent, always active in the BioWin model
Module Description:
These six processes describe the growth and decay of two of the principal groups of obligate anaerobic
microorganisms: acetoclastic methanogenic biomass converting acetate (or methanol) to methane and CO2;
and hydrogenotrophic methanogenic biomass, converting CO2 (or methanol) and hydrogen to methane and
water.
The base rate expression for each of the four growth processes is the product of the maximum specific
growth rate constant, the appropriate biomass concentration and a Monod expression for each of the
substrates. This base rate is modified to account for nutrient limitations (ammonia, phosphate, calcium,
magnesium as well as other cations and anions) and pH inhibition. BioWin uses ammonia as a nitrogen
source for cell synthesis
For both populations, the decay rate varies according to the electron acceptor environment.
Model parameters are listed in:

Kinetic Parameters
Menu Location: Project|Parameters|Kinetic|Methanogenic
All default kinetic parameters are referenced to 20C.

Name Default Unit Explanation

Acetoclastic max. 0.3 d-1 Maximum specific growth rate for the
spec growth rate acetoclastic methanogenic biomass if no
substrate limitation or inhibition occurs.
H2-utilizing max. 1.4 d-1 Maximum specific growth rate for the H2-
spec growth rate utilizing methanogenic biomass if no
substrate limitation or inhibition occurs.

798 • Model Reference Biowin 6 Help Manual

 Acetoclastic 100 mgCOD/L Half saturation for regulation of acetoclastic
substrate half sat. methanogenic biomass growth rate, based on
availability of acetate as substrate.
Acetoclastic 0.5 mgCOD/L Half saturation concentration of methanol for
methanol half sat. acetoclastic methanogenic biomass.
H2-utilizing CO2 half 0.1 mmolCO2/L Half saturation for regulation of H2-utilizing
sat. methanogenic biomass growth rate, based on
availability of CO2 for synthesis.
H2-utilizing 0.1 mgCOD/L Half saturation for regulation of H2-utilizing
substrate half sat. methanogenic biomass growth rate, based on
availability of hydrogen as substrate.
H2-utilizing 0.5 mgCOD/L Half saturation concentration of methanol for
methanol half sat. H2-utilizing methanogenic biomass.
Acetoclastic 10000 mgCOD/L Propionate inhibition constant: high levels of
propionic inhibition propionate inhibit acetoclastic methanogenic
biomass growth.
Acetoclastic 0.13 d-1 Decay rate under anaerobic conditions.
anaerobic decay rate
Acetoclastic 0.6 d-1 Decay rate under aerobic or anoxic conditions.
aerobic/anoxic decay
rate
H2-utilizing 0.13 d-1 Decay rate under anaerobic conditions.
anaerobic decay
rate
H2-utilizing 2.8 d-1 Decay rate under aerobic or anoxic conditions.
aerobic/anoxic
decay rate

Stoichiometric
Menu Location: Project|Parameters|Stoichiometric|Methanogenic

Name Default Unit Explanation

Acetoclastic yield 0.1 mgCOD/mgCOD Amount of acetoclastic methanogenic

biomass produced using one unit of
substrate (acetate). The rest of the
substrate will be converted to CO2.
Methanol 0.1 mgCOD/mgCOD Acetoclastic methanogenic biomass yield
acetoclastic yield on one unit of methanol COD.
H2-utilizing yield 0.1 mgCOD/mgCOD Amount of H2-utilizing methanogenic
biomass produced using one unit of
substrate (hydrogen). The rest of the

Biowin 6 Help Manual Model Reference • 799

 substrate will be converted to methane
and water.
Methanol H2- 0.1 mgCOD/mgCOD H2-utilizing methanogenic biomass yield
utilizing yield on one unit of methanol COD
N in acetoclastic 0.07 mgN/mgCOD N content of acetoclastic methanogenic
biomass biomass.
N in H2-utilizing 0.07 mgN/mgCOD N content of H2-utilizing methanogenic
biomass biomass.
P in acetoclastic 0.022 mgP/mgCOD P content of acetoclastic methanogenic
biomass biomass.
P in H2-utilizing 0.022 mgP/mgCOD P content of H2-utilizing methanogenic
biomass biomass.
Acetoclastic fraction 0.08 - Fraction of acetoclastic methanogenic
to endog. residue biomass that becomes inert upon decay.
H2-utilizing 0.08 - Fraction of H2-utilizing methanogenic
fraction to endog. biomass that becomes inert upon decay.
residue
Acetoclastic 1.42 mgCOD/mgVSS Conversion factor between methanogenic
COD:VSS ratio biomass as measured in COD and its VSS
content. This value is relatively stable for
biomass.
H2-utilizing 1.42 mgCOD/mgVSS Conversion factor between methanogenic
COD:VSS ratio biomass as measured in COD and its VSS
content. This value is relatively stable for
biomass.

Menu Location: Project|Parameters|Stoichiometric|Common

Name Default Unit Explanation

Biomass/Endog Ca 3.912x10-3 gCa/gCOD Calcium content of active

content biomass and endogenous
residue. Part of cellular ISS
generated by biomass growth.
Biomass/Endog Mg 3.912x10-3 gMg/gCOD Magnesium content of active
content biomass and endogenous
residue. Part of cellular ISS
generated by biomass growth.
Biomass/Endog other 5.115x10-4 mol/gCOD The amount of “Other cations”
cations content in active biomass and
endogenous residue. Part of

800 • Model Reference Biowin 6 Help Manual

 cellular ISS generated by
biomass growth.
Biomass/Endog other 1.41x10-4 mol/gCOD The amount of “Other anions”
anions content in active biomass and
endogenous residue. Part of
cellular ISS generated by
biomass growth.
N in endogenous residue 0.07 mgN/ mgCOD N content of endogenous
residue from organism decay.
P in endogenous residue 0.022 mgP/ mgCOD P content of endogenous
residue from organism decay.
Endogenous residue 1.42 mgCOD/mgVSS Conversion factor between
COD:VSS Ratio endogenous residue measured
as COD and its VSS content.

pH Inhibition
Menu Location: Project|Parameters|Kinetic|pH

Name Default Unit Explanation

Acetoclastic 5 pH units At a pH equal to this value the growth rate of

methanogenic low pH the methanogenic biomass will be reduced by
limit 50%. Methanogenic biomass is sensitive to low
pH, the digester can easily turn acid.
Acetoclastic 9 pH units At a pH equal to this value the growth rate of
methanogenic high pH the methanogenic biomass will be reduced by
limit 50%
H2-utilizing 5 pH units At a pH equal to this value the growth rate of
methanogenic low pH the methanogenic biomass will be reduced by
limit 50%. Methanogenic biomass is sensitive to low
pH, the digester can easily turn acid.
H2-utilizing 9 pH units At a pH equal to this value the growth rate of
methanogenic high pH the methanogenic biomass will be reduced by
limit 50%

Switching Functions
Menu Location: Project|Parameters|Kinetic|Switches

Name Default Unit Explanation

Biowin 6 Help Manual Model Reference • 801

 Ordinary heterotrophic 0.15 mgO2/L This constant is used to switch off aerobic
DO half sat. activity under low DO conditions (that is in
anaerobic and anoxic reactors).
Anoxic/anaerobic NOx 0.15 mgN/L This constant is used to turn off anoxic growth,
half sat. decay and hydrolysis processes under
conditions of low nitrate and nitrite.
NH3 nutrient half sat. 0.005 mgN/L This constant is used to slow all biomass growth
processes at low ammonia-N concentrations (N
nutrient limiting conditions – see assimilative
denitrification).
P nutrient half sat. 0.001 mgP/L This constant is used to slow the growth of
biomass when there is no phosphorus available
as nutrient.
Synthesis anion/cation 0.01 meq/L Half saturation concentration for anions and
half sat. cations.

802 • Model Reference Biowin 6 Help Manual

Sulfur Modeling
Sulfur modeling in BioWin is involved in both Activated Sludge and Anaerobic Digestion processes. There are
also interactions with the Ferric / Ferrous portion of the chemical precipitation model. The diagram below
illustrates potential pathways involving sulfur in BioWin.

Potential sulfur pathways in BioWin

The following points with respect to the diagram are worth noting:
• The top portion of the diagram mainly shows potential sulfur oxidation pathways.
• The bottom portion of the diagram shows potential sulfur reduction pathways.
• Additional related precipitation reactions are also shown at the very bottom of the diagram.
• Under low dissolved oxygen (DO) conditions (0.05 mg/L < DO < 0.25 mg/L), reduced sulfur will be
oxidized to particulate elemental sulfur. In the presence of DO > 0.25 mg/L, particulate elemental
sulfur is oxidized. In a reducing environment, it is reduced to sulfide.

Biowin 6 Help Manual Model Reference • 803

 • In more fully aerobic conditions (DO > 0.25 mg/L), the elemental sulfur pathway is bypassed and
reduced sulfur will be oxidized to sulfate.
• Under anoxic conditions, reduced sulfur is oxidized to sulfate with nitrate serving as the terminal
electron acceptor (autotrophic denitrification).
• Reduced sulfur in the form of hydrogen sulfide is modelled as a strippable dissolved gas.
• Under anaerobic conditions, different sulfur reducing biomasses can reduce sulfate to hydrogen
sulfide using dissolved hydrogen, propionic acid or acetic acid.
• Dissolved hydrogen sulfide can react with soluble iron as ferrous (Fe2+) to form ferrous sulfide
precipitate.
• Dissolved hydrogen sulfide also can be oxidized to particulate elemental sulfur with soluble iron as
ferric (Fe3+) serving as the electron acceptor, therby forming soluble iron as ferrous (Fe2+).

Growth and Decay of Sulfur Oxidizing Biomass

Number of Processes: 5
Engineering Objective: Sulfur oxidation
Implementation: permanent, always active in the BioWin model
Module Description:
This biomass grows by oxidizing hydrogen sulfide (H2S) to elemental sulfur under low dissolved oxygen (DO)
conditions (0.05 mg/L < DO < 0.25 mg/L), and sulfuric acid (H2SO4) under more fully aerobic conditions (DO >
0.25 mg/L) and using the energy to synthesize organic material from inorganic carbon (fixing CO2). Nitrogen
source for cell synthesis is ammonia.
The base rate expression for the growth process is the product of the maximum specific growth rate, the
sulfur oxidizing biomass concentration and a Monod expression for hydrogen sulfide (Sulfide inhibition is
NOT considered). This base rate is modified to account for environmental conditions (off at low dissolved
oxygen), nutrient limitations (ammonia, phosphate, inorganic carbon, calcium, magnesium as well as other
cations and anions) and pH inhibition.
Although the maximum specific growth rate under aerobic and anoxic conditions is the same, under anoxic
conditions the base rate is also multiplied by the anoxic growth factor. This allows for anoxic growth at a
different rate or for only a fraction of the sulfur oxidizing biomass being able to perform any kind of
denitrification (or both of these). For these organisms it is assumes that only nitrate (not nitrite) can be
used and nitrogen gas is the end product.
Model parameters are listed in:

Kinetic Parameters
Menu Location: Project|Parameters|Kinetic|Sulfur oxidizing

Name Default Unit Explanation

Maximum specific 0.75 d-1 Determines the maximum specific growth rate of sulfur
growth rate oxidizing biomass using hydrogen sulfide as substrate.
(sulfide)

804 • Model Reference Biowin 6 Help Manual

 Substrate and nutrient limitations will decrease the
growth rate.
Maximum specific 0.10 d-1 Determines the maximum specific growth rate of sulfur
growth rate (sulfur) oxidizing biomass using elemental sulfur as substrate.
Substrate and nutrient limitations will decrease the
growth rate.
Substrate (H2S) 1.0 mgS/L Growth kinetics substrate half-saturation constant. This
half sat. parameter impacts the residual hydrogen sulfide
concentration.
Substrate (sulfur) 1.0 mgS/L Growth kinetics substrate half-saturation constant. This
half sat. parameter impacts the residual elemental sulfur
concentration.
Anoxic growth 0.5 - This parameter decreases the maximum specific growth
factor rate under anoxic conditions. Substrate and nutrient
limitations may further reduce the growth rate.
Decay rate 0.04 d-1 Decay rate constant under aerobic conditions for sulfur
oxidizing biomass.

Stoichiometric Parameters
Menu Location: Project|Parameters|Stoichiometric|Sulfur oxidizing

Name Default Unit Explanation

Yield (aerobic) 0.50 mgCOD/mgS Sulfur oxidizing biomass COD produced

by oxidizing 1 mg of hydrogen sulfide (as
S) or elemental sulfur.
Yield (anoxic) 0.35 mgCOD/mgS Sulfur oxidizing biomass COD produced
by oxidizing 1 mg of hydrogen sulfide (as
S) under anoxic conditions.
N in biomass 0.07 mgN/ mgCOD N content of sulfur oxidizing biomass.
P in biomass 0.022 mgP/ mgCOD P content of sulfur oxidizing biomass.
Fraction going to 0.08 - Fraction of biomass that becomes inert
endogenous residue upon decay.
COD:VSS ratio 1.42 mgCOD/mgVSS Conversion factor between biomass as
measured in COD and its VSS content.
This value is relatively stable for biomass.

Menu Location: Project|Parameters|Stoichiometric|Common

Biowin 6 Help Manual Model Reference • 805

 Name Default Unit Explanation

Biomass/Endog Ca 3.912x10-3 gCa/gCOD Calcium content of active

content biomass and endogenous
residue. Part of cellular ISS
generated by biomass growth.
Biomass/Endog Mg 3.912x10-3 gMg/gCOD Magnesium content of active
content biomass and endogenous
residue. Part of cellular ISS
generated by biomass growth.
Biomass/Endog other 5.115x10-4 mol/gCOD The amount of “Other cations”
cations content in active biomass and
endogenous residue. Part of
cellular ISS generated by
biomass growth.
Biomass/Endog other 1.41x10-4 mol/gCOD The amount of “Other anions”
anions content in active biomass and
endogenous residue. Part of
cellular ISS generated by
biomass growth.
N in endogenous residue 0.07 mgN/ mgCOD N content of endogenous
residue from organism decay.
P in endogenous residue 0.022 mgP/ mgCOD P content of endogenous
residue from organism decay.
Endogenous residue 1.42 mgCOD/mgVSS Conversion factor between
COD:VSS Ratio endogenous residue measured
as COD and its VSS content.

pH Inhibition
Menu Location: Project|Parameters|Kinetic|pH

Name Default Unit Explanation

Autotrophs low pH 5.5 pH units At a pH equal to this value the growth rate of
limit AOB, NOB, AAO, sulfur reducing autotrophs, and
sulfur oxidizing organisms will be reduced by 50%.
Autotrophs high pH 9.5 pH units At a pH equal to this value the growth rate of
limit AOB, NOB, AAO, sulfur reducing autotrophs, and
sulfur oxidizing organisms will be reduced by 50%.

806 • Model Reference Biowin 6 Help Manual

Switching Functions
Menu Location: Project|Parameters|Kinetic|Switches

Name Default Unit Explanation

Sulfur oxidizing sulfate 0.25 mgO2/L This parameter determines the dissolved oxygen
pathway DO half sat. concentration at which oxidation of hydrogen
sulfide to sulfuric acid becomes significant.
Sulfur oxidizing sulfur 0.05 mgO2/L This parameter detwermines the dissolved
pathway DO half sat. oxygen concentration at which oxidation of
hydrogen sulfide to elemental sulfur begins to
switch off.
NH3 nutrient half sat. 0.005 mgN/L This constant is used to slow all biomass growth
processes at low ammonia-N concentrations (N
nutrient limiting conditions – see assimilative
denitrification).
P nutrient half sat. 0.001 mgP/L This parameter is used to switch off the growth
of biomass when there is no phosphorus
available as nutrient.
Autotroph CO2 half 0.1 mmol/L This parameter is used to switch off the growth
sat. of AOB, NOB, AAO, sulfur reducing autotrophs,
and sulfur oxidizing organisms when there is little
inorganic carbon available.
Synthesis anion/cation 0.01 meq/L Half saturation concentration for anions and
half sat. cations.

Growth and Decay of Sulfur Reducing Biomass

Number of Processes: 7
Engineering Objective: anaerobic digestion
Implementation: permanent, always active in the BioWin model
Module Description:
This section describes the growth and decay processes for sulfur reducing biomass converting sulfuric acid
to hydrogen sulfide using propionate, acetate and hydrogen as substrates and producing acetate, CO2 and
hydrogen. Hydrogenotrophic sulfur reducing biomass also reduces elemental sulfur to hydrogen sulfide. The
nitrogen source for cell synthesis is ammonia. The base rate expression for the growth process is the
product of the maximum specific growth rate, the appropriate sulfur reducing biomass concentration and
Monod expressions for the substrate and sulfate concentrations. This base rate is modified to account for
environmental conditions (off unless anaerobic, inhibited by undissociated hydrogen sulfide), nutrient
limitations (nitrogen, phosphate, calcium, magnesium as well as other cations and anions) and pH inhibition.
The growth rate of the hydrogen utilizing sulfur reducing autotrophic organisms is also limited by the

Biowin 6 Help Manual Model Reference • 807

availability of inorganic carbon. The yields of the various products are determined by the specified organism
yield (and elemental balancing considerations).
Model parameters are listed in:

Kinetic Parameters
Menu Location: Project|Parameters|Kinetic|Sulfur reducing

Name Default Unit Explanation

-1
Propionic max. spec. growth 0.583 d Maximum specific growth rate in the absence
rate of substrate limitations.
mgCOD/L
Propionic acid half sat. 295 Half saturation for regulation of growth rate,
based on availability of propionic acid as
substrate.
mgS/L
Hydrogen sulfide inhibition 185 Hydrogen sulfide inhibition constant.
coefficient
Sulfate (SO4=) half sat. 2.47
mgS/L Half saturation for regulation of growth
rate, based on availability of sulfate (SO4=)
as an electron acceptor.
Decay rate 0.0185 d-1 Decay rate of propionic sulfur reducing
biomass.
Acetotrophic max. spec. 0.612 d-1 Maximum specific growth rate in the absence
growth rate of substrate limitations.
mgCOD/L
Acetic acid half sat. 24 Half saturation for regulation of growth rate,
based on availability of acetic acid as
substrate
mgS/L
Hydrogen sulfide inhibition 164 Hydrogen sulfide inhibition constant.
coefficient
Sulfate (SO4=) half sat. 6.41
mgS/L Half saturation for regulation of growth
rate, based on availability of sulfate (SO4=)
as an electron acceptor.
Decay rate 0.0275 d-1 Decay rate of acetotrophic sulfur reducing
biomass.
Hydrogenotrophic max. 2.8 d-1 Maximum specific growth rate in the absence
spec. growth rate with of substrate limitations.
SO4=
Hydrogenotrophic max. 0.1 d-1 Maximum specific growth rate in the absence
spec. growth rate with S of substrate limitations.
mgCOD/L
Hydrogen half sat. 0.07 Half saturation for regulation of growth rate,
based on availability of hydrogen as substrate

808 • Model Reference Biowin 6 Help Manual

 mgS/L
Hydrogen sulfide inhibition 550 Hydrogen sulfide inhibition constant.
coefficient
Sulfate (SO4=) half sat. 6.41
mgS/L Half saturation for regulation of growth
rate, based on availability of sulfate (SO4=)
as an electron acceptor.
mgS/L
Sulfur (S) half sat. 6.41 Half saturation for regulation of growth rate,
based on availability of elemental sulfur as an
electron acceptor.
Decay rate 0.06 d-1 Decay rate.

Stoichiometric
Menu Location: Project|Parameters|Stoichiometric|Sulfur reducing

Name Default Unit Explanation

Yield 0.0712 mgCOD/mgH2 COD Amount of biomass produced per unit of

hydrogen COD.
Yield 0.0470 mgCOD/mgAc COD Amount of biomass produced per unit of
acetic acid COD.
Yield 0.0384 mgCOD/mgPr COD Amount of biomass produced per unit of
propionic acid COD.
N in biomass 0.07 mgN/ mgCOD N content of propionic acetogens.
P in biomass 0.022 mgP/ mgCOD P content of propionic acetogens.
Fraction going to 0.08 - Fraction of biomass that becomes inert
endogenous upon decay.
residue
COD:VSS ratio 1.42 mgVSS/mgCOD Conversion factor between biomass as
measured in COD and its VSS content. This
value is relatively stable for biomass.

Menu Location: Project|Parameters|Stoichiometric|Common

Name Default Unit Explanation

Biomass/Endog Ca 3.912x10-3 gCa/gCOD Calcium content of active

content biomass and endogenous
residue. Part of cellular ISS
generated by biomass growth.
Biomass/Endog Mg 3.912x10-3 gMg/gCOD Magnesium content of active
content biomass and endogenous

Biowin 6 Help Manual Model Reference • 809

 residue. Part of cellular ISS
generated by biomass growth.
Biomass/Endog other 5.115x10-4 mol/gCOD The amount of “Other cations”
cations content in active biomass and
endogenous residue. Part of
cellular ISS generated by
biomass growth.
Biomass/Endog other 1.41x10-4 mol/gCOD The amount of “Other anions”
anions content in active biomass and
endogenous residue. Part of
cellular ISS generated by
biomass growth.
N in endogenous residue 0.07 mgN/ mgCOD N content of endogenous
residue from organism decay.
P in endogenous residue 0.022 mgP/ mgCOD P content of endogenous
residue from organism decay.
Endogenous residue 1.42 mgCOD/mgVSS Conversion factor between
COD:VSS Ratio endogenous residue measured
as COD and its VSS content.

pH Inhibition
Menu Location: Project|Parameters|Kinetic|pH

Name Default Unit Explanation

Autotrophs low pH limit 5.5 pH units At a pH equal to this value the growth rate of
AOB, NOB, AAO, sulfur reducing autotrophs,
and sulfur oxidizing organisms will be reduced
by 50%.
Autotrophs high pH limit 9.5 pH units At a pH equal to this value the growth rate of
AOB, NOB, AAO, sulfur reducing autotrophs,
and sulfur oxidizing organisms will be reduced
by 50%.
Heterotrophs low pH 4.0 pH units At a pH equal to this value the growth rate of
limit heterotrophic sulfur reducing biomass will be
reduced by 50%.
Heterotrophs high pH 10.0 pH units At a pH equal to this value the growth rate of
limit heterotrophic sulfur reducing biomass will be
reduced by 50%.

810 • Model Reference Biowin 6 Help Manual

Switching Functions
Menu Location: Project|Parameters|Kinetic|Switches

Name Default Unit Explanation

OHO DO half sat. 0.05 mgO2/L This constant is used to switch off aerobic
activity under low DO conditions (that is in
anaerobic and anoxic reactors).
Anoxic/anaerobic NOx 0.15 mgN/L This constant is used to turn off anoxic growth,
half sat. decay and hydrolysis processes on under
conditions of low nitrate and nitrite.
NH3 nutrient half sat. 0.005 mgN/L This constant is used to slow all biomass growth
processes at low ammonia-N concentrations (N
nutrient limiting.
P nutrient half sat. 0.001 mgP/L This constant is used to slow the growth of
biomass when there is no phosphorus available
as nutrient.
Autotroph CO2 half sat. 0.1 mmol/L This parameter is used to switch off the growth
of AOB, NOB, AAO, sulfur reducing autotrophs,
and sulfur oxidizing organisms when there is
little inorganic carbon available.
Synthesis anion/cation 0.01 meq/L Half saturation concentration for anions and
half sat. cations.

Chemical Precipitation Reactions

Chemical Phosphorus Removal with Iron Salts

Important note about the updated chemical phosphorus removal model in BioWin 6.0: This model
requires that metal streams must be added to elements that have volume. It is no longer applicable to add
a metal input stream to a mixing node element. If you want to simulate adding a metal stream to a channel
at your plant, you should use the new Plug Flow Channel element. The Plug Flow Channel element should be
sized appropriately; e.g. it should have a linear flow velocity of between 0.3 and 0.5 m/s, and likely an HRT
on the order of a few minutes. It also may be necessary to increase the velocity gradient in the first zone of
the plug flow channel to reflect turbulent mixing conditions. You can also add a metal input stream directly
to a bioreactor; BioWin will use the velocity gradient it calculates based on factors such as flow through the
reactor, air flow rates, and specified mixing intensity in the chemical phosphorus model calculations.
The following figure illustrates the processes involved in chemical phosphorus removal with iron salts.

Biowin 6 Help Manual Model Reference • 811

Schematic representation of the ferric precipitation model in BioWin

When the model option Include ferric – phosphate adsorption/precipitation reactions is selected addition
of ferric to water results in the rapid precipitation of hydrous ferric oxides (HFO) with a high number of
active surface sites for interaction, HFO - High surface. When the model options Include ferric – phosphate
adsorption/precipitation reactions AND Include iron reduction/oxidation reactions are selected, addition
of ferrous to an oxidizing environment can result in the oxidation of ferrous to HFO – High surface. Unbound
HFO - High surface will either age to unbound HFO - Low surface (which has a low number of active surface
sites for interaction compared to the high surface) or adsorb/co-precipitate with H2PO4-, H+, or colloidal COD
(Xsc).
Depending on the pH, H2PO4- can co-precipitate with HMO - High surface to form HFO - High surface with
H2P04-. When the pH is low, H+ adsorbs onto HFO - High surface to form HFO - High surface with H+. The
level of interaction between HFO – High surface and H2P04-, H+, or colloidal material depends on mixing, the
pH, and the equilibrium concentration of P. The number of high surface sites available for interaction is a
function of mixing and the Ferric active site factor(high) (See Factors Impacting HFO Interactions).
HFO – High surface with H2P04- and HFO – High surface with H+ will also age to the respective low surface
forms of these compounds i.e. HFO – Low surface with H2P04- and HFO-Low surface with H+ depending on
their respective aging factors. Note: When HFO – High surface with H2P04- ages to HFO – High surface with
H2P04- the surplus P remains bound and is tracked as P bound to Aged HMO.
Unbound HFO - Low surface can either age to HFO - Aged (which has no available surface sites for
interactions), or interact with H2P04-, H+, or colloidal material. Depending on the pH, H2PO4- will adsorb onto
HFO - Low surface to form HFO - Low surface with H2P04-. When the pH is low, H+ adsorbs onto HFO - Low
surface to form HFO - Low surface with H+. The level of interaction between HFO – Low surface and H2P04-,
H+, or colloidal material depends on mixing, the pH, and the equilibrium concentration of P. The number of
low surface sites available for interaction is a function of mixing and the Ferric active site factor(low) (See
Factors Impacting HFO Interactions).

812 • Model Reference Biowin 6 Help Manual

HFO – Low surface with H2P04- and HFO – Low surface with H+ will also age to HFO – Aged. Note: The P
associated with the low surface P-bound species will be tracked as P bound to Aged HMO.

Factors Impacting HFO Interactions

Mixing intensity – mixing dictates the total number of active sites available for interaction. Aging of bound
and unbound metal oxides is inversely proportional to the mixing provided in bioreactors and channels. If
mixing is high then aging will be low, and if mixing is low then aging will be high. Low aging implies more
time for the unbound active sites to interact. While fast aging takes away the number of unbound active
sites faster thus lowering the efficiency of removal.
Within channels or bioreactors mixing is provided by either: flow (linear velocity through a unit), aeration, or
by specifying a mixing power requirement in bioreactors or a velocity gradient in channels. See Setting up
Channels. Aging of HFO – High surface to HFO – Low surface and HFO – High surface with H+ to HFO - Aged
is a function of the aging rate. When HFO – Low surface is aged to HFO – Aged and HFO – High Low surface
with H+ to HFO - Aged the HFO(L) aging rate factor gets applied to the aging rate. When HFO – High surface
with H2PO4- is aged to HFO – Low surface with H2PO4-HFO - Aged the HFO(H) with H2PO4- bound aging
factor gets applied to the aging rate. When HFO – Low surface with H2PO4- is aged to HFO - Aged both the
HFO(L) aging rate factor, and the HFO(L) with H2PO4- bound aging factor get applied to the aging rate.
pH – the pH dictates the species of phosphorus (i.e. HPO42- versus H2P04-) available for interactions. Only
H2PO4- gets removed in the model via chemical P removal. In addition, if the pH is low then H+ will compete
with H2PO4- for active surface sites on the iron oxide lowering the efficiency of P removal. If the pH increases,
the adsorbed H+ will desorb off from the HFO.
Equilibrium P Concentration/Minimum residual P level – the rate of co-precipitation or adsorption of H2PO4-
is dependent on the equilibrium P concentration. The higher the concentration of P the faster the rates of
interaction. This helps to bring in the influence of the dose location on P removal. For example, more
efficient removal is expected if metal is added to an influent channel where the P concentration is high
compared to addition of metal in an effluent channel where the P concentration is lower due to dilution and
synthesis uptake. In addition, if the soluble P concentration falls below the minimum residual P
concentration for Fe then H2PO4- will desorb off of the HFO. The rate of P released will depend on the
HFO(H) with H2PO4-P release factor and the HFO(L) with H2PO4-P release factor.
Metal – colloidal coagulation – if the model option Include metal salt – colloidal material coagulation
reactions is turned on then colloidal COD will compete with H2P04- for active surface sites on the metal oxide
thus lowering the efficiency of P removal. When the Metal-colloidal coagulation option is on some of the
HFO – High surface and HFO – Low surface will be converted to HFO – Aged, making less available for P
removal. In addition, CODp - slowly biodegradable colloidal is converted to CODp - slowly biodegradable
particulate. CODp – slowly biodegradable particulate can then settle out of solution in a primary clarifier.
The level of interaction between colloidal COD and metal depends on the mixing at the point of addition and
within the activated sludge process, the residence time provided, and the level of competition between
colloidal COD and soluble P for precipitation/adsorption. See Modeling Metal-Colloidal Coagulation
Reactions.

Biowin 6 Help Manual Model Reference • 813

Kinetic Parameters

Menu Location: Project|Parameters|Physical/Chemical…|Fe Rates

Name Unit Default Explanation

Value

A in aging rate = A*exp(- 1/d 16.115 Controls the aging of all HFO species.
G/B)
B in aging rate = A*exp(- 1/s 57.3 Controls the dependency of HFO aging
G/B)
on mixing. Increasing this value decreases
the dependency of aging on mixing.
HFO(L) aging rate factor [] 2.5E-4 Reduces the rate of aging of bound and unbound
HFO(L)
HFO(H) with H2PO4- [] 1E-5 Reduces the rate of aging of HFO(H) with H2PO4-
bound aging factor bound
HFO(L) with H2PO4- [] 0.4 Reducing the rate of aging of HFO(L) with H2PO4-
bound aging factor bound
H2PO4- coprecipitation mol/(L.d) 1.5E-9 The rate at which H2PO4- co-precipitates with
rate HFO(H)
H2PO4- adsorption rate mol/(L.d) 2E-11 The rate at which H2PO4- adsorbs onto HFO(L)
H+ competition for L/(mmol.d) 1000 The rate at which H+ adsorbs onto HFO(H)
HFO(H) protonation sites
H+ competition for L/(mmol.d) 100 The rate at which H+ adsorbs onto HFO(L)
HFO(L) protonation sites

Menu Location: Project|Parameters|Physical/Chemical…|Fe constants

Name Unit Default Explanation

Value

Ferric active site factor mol sites/mol HFO(H) 2 Controls the quantity of high active
(high) sites available for interaction
Ferric active site factor mol sites/mol HFO(L) 1.2 Controls the quantity of low active
(low) sites available for interaction

814 • Model Reference Biowin 6 Help Manual

 H+ competition level of mol/L 7E-7 The pH at which H+ will start
Fe(OH)3 competing for sites on HFO
Equilibrium constant for mf 2E-9
FeOH3- H2PO4- HFO(H).H2PO4/(mol
H2PO4-)(mf HFO(H)^2)
Colloidal COD removed gCOD/Fe active site 130 Controls the amount of colloidal COD
with Ferric that can interact with active sites
Minimum residual P 0.015 The minimum soluble P concentration
level with iron addition that can be achieved with chemical P
removal
HFO(H) with H2PO4- P [] 10,000 Controls the release of P from HFO(H)
release factor with H2PO4- when the P concentration
falls below the minimum residual level.
HFO(L) with H2PO4- P [] 10,000 Controls the release of P from HFO(L)
release factor with H2PO4- when the P concentration
falls below the minimum residual level.

Chemical Phosphorus Removal with Aluminum Salts

The following figure illustrates the processes involved in chemical phosphorus removal with aluminum salts.

Schematic representation of the aluminum precipitation model in BioWin

When the model option Include aluminum – phosphate adsorption/precipitation reactions is selected
addition of aluminum to water results in the rapid precipitation of hydrous aluminum oxides (HAO) with a
high number of active surface sites for interaction, HAO - High surface. Unbound HAO - High surface will

Biowin 6 Help Manual Model Reference • 815

either age to unbound HAO - Low surface (which has a low number of active surface sites for interaction
compared to the high surface) or adsorb with H2PO4- or colloidal COD (Xsc).
Depending on the pH, H2PO4- can co-precipitate with HAO - High surface to form HAO - High surface with
H2P04-. The level of interaction between HAO – High surface and H2P04- or colloidal material depends on
mixing, the pH, and the equilibrium concentration of P. The number of high surface sites available for
interaction is a function of the mixing and the Al active site factor(high) (see Factors Impacting HAO
Interactions)).
HAO – High surface with H2P04- will also age to HAO – Low surface with H2P04- depending on the respective
aging factor. Note: When HAO – High surface with H2P04- ages to HAO – High surface with H2P04- the
surplus P remains bound and is tracked as P bound to Aged HMO.
Unbound HAO - Low surface can either age to HAO - Aged (which has no available surface sites for
interaction), or interact with H2P04- or colloidal material. Depending on the pH, H2PO4- will adsorb onto HAO
- Low surface to form HAO - Low surface with H2P04-. The level of interaction between HAO – Low surface
and H2P04- or colloidal material depends on mixing, the pH, and the equilibrium concentration of P. The
number of low surface sites available for interaction is a function of the mixing and the Al active site
factor(low) (see Factors Impacting HAO Interactions)).
HAO – Low surface with H2P04- will also age to HFO – Aged. Note: The P associated with the low surface P-
bound species will be tracked as P bound to Aged HMO.

Factors Impacting HAO Interactions

Mixing intensity – mixing dictates the total number of active sites available for interaction. Aging of bound
and unbound metal oxides is inversely proportional to the mixing provided in bioreactors and channels. If
mixing is high then aging will be low, and if mixing is low then aging will be high. Low aging implies more
time for the unbound active sites to interact. While fast aging takes away the number of unbound active
sites faster thus lowering the efficiency of removal. Within channels or bioreactors mixing is provided by
either: flow (linear velocity through a unit), aeration, or by specifying a mixing power requirement in
bioreactors or a velocity gradient in channels (see Setting up Channels)).
Aging of HAO – High surface to HAO – Low surface is a function of the aging rate. When HAO – Low surface
is aged to HAO – Aged the HAO(L) aging rate factor gets applied to the aging rate. When HAO – High
surface with H2PO4- is aged to HAO – Low surface with H2PO4-HAO - Aged the HAO(H) with H2PO4- bound
aging factor gets applied to the aging rate. When HAO – Low surface with H2PO4- is aged to HAO - Aged
both the HAO(L) aging rate factor, and the HAO(L) with H2PO4- bound aging factor get applied to the aging
rate.
pH – the pH dictates the species of phosphorus (i.e. HPO42- versus H2P04-) available for interactions. Only
H2PO4- gets removed in the model via chemical P removal.
Equilibrium P Concentration/ Minimum residual P level – The rate of co-precipitation or adsorption of
H2PO4- is dependent on the equilibrium P concentration. The higher the concentration of P the faster the
rates of interaction. This helps to bring in the influence of the dose location on P removal. For example,
more efficient removal is expected if metal is added to an influent channel where the P concentration is high
compared to addition of metal in an effluent channel where the P concentration is lower due to dilution and
synthesis uptake. In addition, if the soluble P concentration falls below the equilibrium minimum residual P
concentration then H2PO4- will desorb off of HAO. The rate of P released will depend on the HAO(H) with
H2PO4-P release factor and the HAO(L) with H2PO4-P release factor.

816 • Model Reference Biowin 6 Help Manual

Metal – colloidal coagulation – if the model option Include metal salt – colloidal material coagulation
reactions is turned on then colloidal COD will compete with H2P04- for active surface sites on the metal oxide
thus lowering the efficiency of P removal. When the Metal-colloidal coagulation option is on, some of the
HAO – High surface and HAO – Low surface will be converted to HAO – Aged, making less available for P
removal. In addition, CODp - slowly biodegradable colloidal is converted to CODp - slowly biodegradable
particulate. CODp – slowly biodegradable particulate can then settle out of solution in a primary clarifier.
The level of interaction between colloidal COD and metal depends on the mixing at the point of addition and
within the activated sludge process, the residence time provided, and the level of competition between
colloidal COD and soluble P for precipitation/adsorption (see Modeling Metal-Colloidal Coagulation
Reactions)).

Kinetic Parameters

Menu Location: Project|Parameters|Physical/Chemical…|Al rates

Name Unit Default Explanation

Value

A in aging rate = A*exp(- 1/d 16.115 Controls the aging of all HAO species.
G/B)
B in aging rate = A*exp(- 1/s 57.3 Controls the dependency of HAO aging
G/B)
on mixing. Increasing this value decreases
the dependency of aging on mixing.
HAO(L) aging rate factor [] 2.5E-4 Reduces the rate of aging of bound and unbound
HAO(L)
HAO(H) with H2PO4- [] 1E-5 Reduces the rate of aging of HAO(H) with H2PO4-
bound aging factor bound
HAO(L) with H2PO4- [] 0.4 Reducing the rate of aging of HAO(L) with H2PO4-
bound aging factor bound
H2PO4- coprecipitation mol/(L.d) 1.5E-9 The rate at which H2PO4- co-precipitates with
rate HAO(H)
H2PO4- adsorption rate mol/(L.d) 1E-9 The rate at which H2PO4- adsorbs onto HAO(L)

Menu Location: Project|Parameters|Physical/Chemical…|Al constants

Name Unit Default Explanation

Value

Biowin 6 Help Manual Model Reference • 817

 Al active site factor mol sites/mol HAO(H) 3 Controls the quantity of high active sites
(high) available for interaction
Al active site factor (low) mol sites/mol HAO(L) 1.5 Controls the quantity of low active sites
available for interaction
Equilibrium constant for mf HAO(H).H2PO4/(mol 8E-10
AlOH3- H2PO4- H2PO4-)(mf HAO(H)^2)
Colloidal COD removed gCOD/Al active site 30 Controls the amount of colloidal COD
with Al that can interact with active sites
Minimum residual P 0.015 The minimum soluble P concentration
level with Al addition that can be achieved with chemical P
removal
HAO(H) with H2PO4-P [] 10,000 Controls the release of P from HAO(H)
release factor with H2PO4- when the P concentration
falls below the minimum residual level.
HAO(L) with H2PO4- P [] 10,000 Controls the release of P from HAO(L)
release factor with H2PO4- when the P concentration
falls below the minimum residual level.

Setting up Channels

For metal interactions to be active and most efficient, metal must be added into an element containing both
volume AND reactions. It is recommended that metal be added into a channel element or a bioreactor
element. For example, for simulating the addition of metal into an ideal clarifier, it is best to add the
chemical into a channel element ahead of the clarifier to ensure that mixing and reactions at the point of
metal addition are accounted for (see Modeling Metal-Colloidal Coagulation Reactions)).
The channel element is essentially 4 bioreactor elements in series. When a metal addition element is
connected to a channel element, the metal gets added into the first zone of the channel. On the Operation
tab of the channel’s property dialog box, the velocity gradient at the point of metal addition (i.e. within the
first zone) can be specified. The velocity gradient that gets applied to the first zone will be the maximum of
the value specified or the velocity gradient associated with power dissipated by the flow of the liquid
through the channel. The mixing in the remaining 3 zones is the velocity gradient associated with liquid flow.
The liquid depth and width of the channel should be specified on the Dimensions tab of the channel’s
property dialog box. The liquid depth, width, and the flow through the channel are used to calculate the
linear velocity. BioWin does not account for the hydraulic gradient in a channel. Typically, a linear velocity
above 0.3 m/s is required to avoid settlement. In addition, the velocity in an influent channel containing raw
wastewater should be higher when compared to the velocity in a downstream channel containing mixed
liquor or effluent.
The length of the channel together with the depth, width, and flow through the channel will set the
residence time of the channel. The residence time along with the mixing through the channel will determine
the level of aging that occurs within the channel and hence the degree of interaction between HMO and
H2P04-, H+ (ferric only), or colloidal material depending on the pH and what model options are active.

818 • Model Reference Biowin 6 Help Manual

Note: When condensing multiple channels into one combined channel it is important to ensure that the
width specified in the one combined channel is equal to the total width of all of the channels together. This
will ensure that the linear velocity is representative of what is actually observed at the plant.

Chemical Phosphorus Removal Example

The example MLE configuration shown below is found in the cabinet files under Chemical P Removal >
Ferric to Influent Channel. The example plant has an influent flow of 24,000 m3/d with an influent TP
concentration of 6.5 mg/L, and an SRT of 11 days. A ferric addition element is used to dose 15 mg Fe/L
influent (~360 kg Fe/d) into an influent channel. The Fe dose:influent TP molar ratio is approximately 1.28
mol/mol. The influent channel is set up to provide a linear velocity of approximately 0.56 m/s and a
residence time of approximately 1.2 minutes. Within the Operation tab of the channel’s property dialog box,
the mixing at the point of metal addition is specified with a velocity gradient of 150/s. The mixing in the
remaining zones is the velocity gradient associated with the power dissipated by the liquid flow (~115/s).
The higher the mixing is in an element, the slower the aging of HFO will be; slow aging implies more active
sites can be available for interactions with P. Reactions have been turned on in the secondary clarifier to
track the dynamic response of the system to turning the influent ferric addition off.

BioWin flowsheet with a ferric addition channel

The resulting steady state TSS, VSS and ISS precipitate concentration profiles are shown in the figures below.
The influent VSS/TSS ratio is approximately 0.8. The addition of metal salts into the Fe Addition Channel (Fe
Addn Chnl) results in the formation of ISS precipitate which accumulates in the activated sludge system (i.e.
Anoxic, Aerobic 1, Aerobic 2) as a function of the SRT. The increased concentration of ISS precipitate lowers
the VSS/TSS ratio of the mixed liquor. In the attached example the mixed liquor VSS/TSS ratio is
approximately 60%. Note in practice VSS concentrations of mixed liquor containing metal hydroxides are
typically overestimated. This is because metal hydroxides are oxidized during VSS analysis in the muffle
furnace1. The effluent solids concentration depends on the efficiency of the secondary clarifier. Since the P
content of the solids is higher in chemical phosphorus removal systems, ensuring good final solid/liquid
separation is important when trying to achieve low residual P concentrations.
1
Jeyanayagam, S and Husband, J. (2009) “Chain reaction: How chemical phosphorus removal really works.”
Water Environ. and Tech. 21 (4).

Biowin 6 Help Manual Model Reference • 819

The resulting TP and soluble P profiles are illustrated below. Approximately 5.8 mg P/L of TP (2.9 mg P/L of
soluble P) are removed. The majority of the removal occurs at the point of metal addition i.e. within the
influent channel as a result of co-precipitation with HFO-High surface, while a much smaller amount is
removed downstream as a result of adsorption onto HFO-Low surface. The distribution of unbound and
bound HFO is also illustrated below. In the influent channel a small amount of residual unbound HFO-High
surface remains but is used up downstream. HFO-Low surface and HFO-Aged make up the majority of the
unbound species found in the mixed liquor. In the event that iron is not added to the system, this residual
unbound HFO-Low surface will provide addition adsorption capacity until it is used up and the effluent
soluble P concentration beings to increase to a concentration similar to what is coming into the process via
the influent. The amount of residual unbound HFO-Low surface depends on the HRT and SRT. The majority
of the bound P is associated with HFO-High surface since the majority of removal occurs via co-precipitation.
Since the pH in this process is close to neutral, interactions between HFO and H+ are not observed.

820 • Model Reference Biowin 6 Help Manual

Biowin 6 Help Manual Model Reference • 821
The figure below demonstrates the case where iron addition to the processes is stopped. To generate this
dynamic response, the following steps were taken:
1. A steady state simulation was run with ferric dosing on.

822 • Model Reference Biowin 6 Help Manual

 2. A dynamic simulation was run for 5 days with ferric dosing on. In the chart below, the dynamic
simulation starts on 06/07/18.
3. Ferric dosing was turned off, and the simulation was then continued. In the chart below, the ferric
dose is stopped on 06/12/18.
The effluent soluble P concentration is shown below. The soluble P concentration remains low for a few
days after metal addition stops on 06/12/18, and then beings increasing on 06/14/18 as the unbound metal
hydroxide that persists in the system after dosing stops gets used up.

The amount of P removal observed or the time that it takes for P breakthrough to occur after metal addition
is stopped can be calibrated by adjusting the high and low active site factors (i.e. ferric active site
factor(high) and ferric active site factor(low)).

Modeling Metal-Colloidal Coagulation Reactions

When Fe and/or Al salts are added for P removal and the model option Include metal salt – colloidal
material coagulation reactions is turned on then colloidal COD will compete with H2P04- for active surface
sites on the hydrated metal oxide (HMO) where ‘M’ can be ‘F’ if iron is added or ‘Al’ if Al is added. See
Modeling Chemical Phosphorus Removal with Iron Salts or Modeling Chemical Phosphorus Removal with
Aluminum Salts.
Metal-colloidal interactions lower the efficiency of P removal. This is modeled by aging some of the HMO –
High surface and/or HMO – Low surface to HMO – Aged, making less available for P removal. In addition,
CODp - slowly biodegradable colloidal is converted to COD - slowly biodegradable particulate. The CODp –
slowly biodegradable particulate can then be settled out of solution in a primary clarifier if the objective of

Biowin 6 Help Manual Model Reference • 823

metal-colloidal coagulation reactions is chemically enhanced primary treatment (CEPT). The figures below
summarize the Metal-colloidal coagulation processes for Fe or Al.

Ferric – Colloidal interactions in BioWin

Aluminum – Colloidal interactions in BioWin

The level of interaction between colloidal COD and metal depends on the mixing at the point of addition and
within the activated sludge process, the residence time provided, and the level of competition between
colloidal COD and soluble P for co-precipitation/adsorption.
Mixing within bioreactors and channels controls the availability of active sites for interaction. Aging of
bound and unbound metal oxides is inversely proportional to the mixing provided in bioreactors and
channels. If mixing is high then aging will be low, and if mixing is low then aging will be high. Within channels
or bioreactors mixing is provided by either: flow (linear velocity through a unit), aeration, or by specifying a
mixing power requirement in bioreactors or a velocity gradient in channels (see the Setting up Channels
section of the “Model Reference” chapter).

Kinetic Parameters

Menu Location: Project|Parameters|Physical/Chemical…|Fe constants

824 • Model Reference Biowin 6 Help Manual

 Name Unit Default Explanation
Value

Ferric active site factor mol sites/mol HFO(H) 2 Controls the quantity of high active sites
(high) available for interaction
Ferric active site factor mol sites/mol HFO(L) 1.2 Controls the quantity of low active sites
(low) available for interaction
Colloidal COD removed gCOD/Fe active site 130 Controls the amount of colloidal COD
with Ferric that can interact with active sites

Menu Location: Project|Parameters|Physical/Chemical…|Al constants

Name Unit Default Explanation

Value

Al active site factor mol sites/mol HAO(H) 3 Controls the quantity of high active sites
(high) available for interaction
Al active site factor (low) mol sites/mol HAO(L) 1.5 Controls the quantity of low active sites
available for interaction
Colloidal COD removed gCOD/Al active site 30 Controls the amount of colloidal COD
with Al that can interact with active sites

Menu Location: Project|Parameters|Physical/Chemical…|CEPT rates

Name Unit Default Explanation

Value

HFO colloidal 1 Controls the rate of colloidal adsorption

adsorption rate onto HFO active sites
Residual Xsc for 5 The minimum colloidal COD
adsorption to HFO concentration that can be achieved with
Fe-colloidal coagulation reactions
Slope for Xsc residual 1
HAO colloidal 1 Controls the rate of colloidal adsorption
adsorption rate onto HAO active sites
Residual Xsc for 5 The minimum colloidal COD
adsorption to HAO concentration that can be achieved with
Al-colloidal coagulation reactions
Slope for Xsc residual 1

Biowin 6 Help Manual Model Reference • 825

Setting up Chemically Enhanced Primary Treatment

Metal Addition with an Ideal Primary Clarifier Element

Metal-colloidal coagulation reactions are dependent on mixing. However, mixing is not tracked in an ideal
clarifier element. Therefore, when using an ideal clarifier element for CEPT, it is recommended that a
bioreactor or channel be placed upstream of the clarifier to mimic the mixing zone within the clarifier. The
choice of using a channel versus a bioreactor or both a channel and a bioreactor depends on the
configuration most representative of the location where metal is added at the plant.

In the cabinet file found under Chemically Enhanced Primary Treatment > Ferric addition – ideal primary,
metal is added into a channel upstream of the ideal primary clarifier. A velocity gradient of 250/s is specified
within the channel to ensure good mixing at the point of metal addition. As described in Modeling Chemical
Phosphorus Removal with Iron Salts or Modeling Chemical Phosphorus Removal with Aluminum Salts, the
higher the mixing power the slower the aging of HMO thus increasing the efficiency of colloidal and P
interactions with HMO. However, the residence time in the channel is fairly short (0.2 minutes) so the extent
of the interactions in the channel will be time limited.
Following the channel, is a bioreactor called PC Inf Mixing Zone containing 10% of the volume of the
primary clarifier. Within the Power tab of this bioreactor a fairly low mixing power of 0.5 W/m3 is specified
corresponding to a velocity gradient of approximately 22/s. This low mixing power implies that HMO species
will be aging fast in this reactor and thus the efficiency of interactions with HMO will be low.
On the Operation tab of the ideal primary clarifier element the percent removal of solids is specified as 55%.
A modified removal of 1.5 is specified for CODp-slowly degradable particulate which increases the removal
of CODp-slowly degradable particulate to 82.5%. The right summary pane indicates the resulting percent TSS
removal of 71%.

826 • Model Reference Biowin 6 Help Manual

Reactions are on in the Ideal clarifier element (specified on the Model tab), however having reactions on or
off does not have much impact on the results in this example since the majority of the reactions occur
within the plug flow channel where there is higher efficiency for HMO interactions.

Metal Addition with a Model Clarifier Element

Metal for P removal or metal-colloidal coagulation can be added directly into a model clarifier element when
reactions are specified to be on in the Model tab of the clarifier’s property dialog box. The clarifier depth is
divided into a number of layers and the 1-D flux model is used to quantify the movement of solids between
layers via bulk movement, gravity settling flux, and boundary conditions. The model clarifier element and
the default settling parameters are typically used to describe secondary settling. Therefore, when using a
model clarifier to describe primary settling, changes to the default settling parameters are required. For
example, in the cabinet found under Chemically Enhanced Primary Treatment > Ferric addition – model
primary local settling parameters are applied within the model clarifier as follows:

A lower Vo acts to slow down settling at lower concentrations. A slightly higher K value acts to slightly
increase the “velocity penalty” at higher concentrations thus slowing down settling at higher concentrations.
An increased clarification switching function is used to turn down settling at low concentrations in order to
“leave behind” some solids in the effluent; a higher value means more turbid effluent.
Adding a channel upstream of the model clarifier may improve the efficiency of HMO interactions. In the
cabinet file found under Chemically Enhanced Primary Treatment > Ferric addition – model primary, metal
is added into a channel upstream of the model clarifier. A velocity gradient of 250/s is specified within the
channel to ensure good mixing at the point of metal addition. As described in Modeling Chemical
Phosphorus Removal with Iron Salts or Modeling Chemical Phosphorus Removal with Aluminum Salts, the
higher the mixing power the slower the aging of HMO thus increasing the efficiency of colloidal and P
interactions with HMO. However, the residence time in the channel is fairly short (0.2 minutes) so the extent
of the interactions in the channel will be time limited.

Biowin 6 Help Manual Model Reference • 827

Iron RedOx Reactions and Precipitation of Vivianite and FeS
In reducing environments, the various forms of HFO i.e. bound, unbound and aged species (note that aged
species are reduced at 1/5th of the rate of other species) can be reduced to Fe2+ if the option to Include iron
reduction/oxidation reactions is selected in addition to Include ferric – phosphate
adsorption/precipitation reactions (see Modeling Chemical Phosphorus Removal with Iron Salts.) Reduction
can occur biotically and/or abiotically utilizing either acetate, propionate, dissolved hydrogen gas, or
hydrogen sulfide as electron donor. The extent of reduction that occurs is dependent on the respective rates
for each process. In addition to forming Fe2+, the following end products are formed: CO2 (from acetate and
propionate), acetate (from propionate), S (from H2S). Phosphorus is also released from the various HFO
species containing P. See figure below. Fe2+ can precipitate with S and P in reducing environments to form
FeS and vivianite (Fe3(PO4)2) if the option to Include vivianite and FeS precipitation/dissolution reactions is
also selected. The amount of FeS and vivianite that can form will depend on the amounts of Fe2+, S and P
available, and the precipitation and redissolution rates of the mineral. For more information on processes
involving sulfur see Sulfur Modeling.
In oxidizing environments, Fe2+ can be oxidized to HFO-High surface if the option to Include iron
reduction/oxidation reactions is selected in addition to Include ferric – phosphate
adsorption/precipitation reactions (see Modeling Chemical Phosphorus Removal with Iron Salts. See figure
below. Oxidation can occur biotically and/or abiotically utilizing oxygen as terminal electron acceptor. The
extent of oxidation that occurs is dependent on the respective rates for each process.

Kinetic Parameters

Menu Location: Project|Parameters|Physical/Chemical…|Fe RedOx rates

Name Unit Default Explanation

Value

Iron reduction using acetic acid 1E-7 The rate at which all HFO species will be
reduced biotically using acetic acid as
the electron donor.
Half Sat. acetic acid 0.5 Half saturation for regulation of HFO
reduction, based on availability of acetic
acid as electron donor.

828 • Model Reference Biowin 6 Help Manual

 Iron reduction using propionic acid 1E-7 The rate at which all HFO species will be
reduced biotically using propionic acid
as the electron donor.
Half Sat. propionic acid 0.5 Half saturation for regulation of HFO
reduction, based on availability of
propionic acid as electron donor.
Iron reduction using dissolved 1E-7 The rate at which all HFO species will be
hydrogen gas reduced biotically using dissolved
hydrogen gas as the electron donor.
Half Sat. dissolved hydrogen gas 0.5 Half saturation for regulation of HFO
reduction, based on availability of
dissolved hydrogen gas as electron
donor.
Iron reduction using hydrogen 5E-5 The rate at which all HFO species will be
sulfide reduced biotically using hydrogen
sulfide as the electron donor.
Half Sat. hydrogen sulfide 0.5 Half saturation for regulation of HFO
reduction, based on availability of
hydrogen sulfide as electron donor.

Iron oxidation rate (aerobic) 1E-3 The rate at which Fe2+ is oxidized
biotically using oxygen as terminal
electron acceptor.
Abiotic iron reduction using acetic 2E-5 The rate at which all HFO species will be
acid reduced abiotically using acetic acid as
the electron donor.
Abiotic iron reduction using 2E-5 The rate at which all HFO species will be
propionic acid reduced abiotically using propionic acid
as the electron donor.
Abiotic iron reduction using 2E-5 The rate at which all HFO species will be
dissolved hydrogen gas reduced abiotically using dissolved
hydrogen gas as the electron donor.
Abiotic iron reduction using 2E-5 The rate at which all HFO species will be
hydrogen sulfide reduced abiotically using hydrogen
sulfide as the electron donor.
Abiotic iron oxidation rate (aerobic) 1.0 The rate at which Fe2+ is oxidized
abiotically using oxygen as terminal
electron acceptor.

Menu Location: Project|Parameters|Physical/Chemical…|Mineral precipitation rates

Biowin 6 Help Manual Model Reference • 829

 Name Unit Default Explanation
Value

Vivianite precipitation rate L/(mol d) 1E+5 The value of this rate constant controls
the rate of vivianite formation when
supersaturated. This will affect how
close to the equilibrium the Fe3(PO4)2
concentration will be under the given
hydraulic residence times.
Vivianite redissolution rate L/(mol d) 1E+5 The value of this rate constant controls
the rate of vivianite dissolution. This
will affect how close to equilibrium the
residual Fe3(PO4)2 concentration will be
under the given hydraulic residence
times.
Vivianite half sat. mg TSS/L 0.01 This is an empirical constant designed to
provide continuity to the mathematical
solution by reducing the dissolution rate
at low vivianite concentrations by
maintaining low levels of Fe3(PO4)2 even
under lower pH conditions. Its value
should not be changed.
FeS precipitation rate L/(mol d) 1,000 The value of this rate constant controls
the rate of FeS formation when
supersaturated. This will affect how
close to the equilibrium the FeS
concentration will be under the given
hydraulic residence times.
FeS redissolution rate L/(mol d) 10 The value of this rate constant controls
the rate of FeS dissolution. This will
affect how close to equilibrium the
residual FeS concentration will be under
the given hydraulic residence times. If it
is necessary to change it, it should be
changed together with the precipitation
rate constant.
FeS half sat. mg TSS/L 0.1 This is an empirical constant designed to
provide continuity to the mathematical
solution by maintaining low levels of
FeS even under lower pH conditions by
reducing the FeS dissolution rate at low
FeS concentrations. Its value should not
be changed.

Menu Location: Project|Parameters|Physical/Chemical…|Mineral precipitation constants

830 • Model Reference Biowin 6 Help Manual

 Name Unit Default Explanation
Value

Vivianite solubility product mol/L^5 1.71E-36 This solubility constant should not be
changed
FeS solubility product mol/L^2 4.258E-4 This solubility constant should not be
changed

Precipitation of Brushite, Hydroxy-Apatite and Struvite

Calcium and Magnesium is present in most wastewater and can spontaneously form precipitates. From the
large number of phosphate and carbonate precipitates that can be formed, the most important ones
affecting soluble phosphorus levels are struvite (magnesium-ammonium-phosphate, MgNH4PO46H2O) and
brushite (CaHPO4). The concentration of soluble calcium and magnesium is specified in COD & BOD influent
elements. Both Ca and Mg are incorporated into the biomass for growth which allows Ca and Mg to
accumulate with the solids in addition to being present in the liquid phase. The amount of these nutrients
that gets incorporated into the biomass is specified in Project > Parameters > Stoichiometric on the
Common tab. This Calcium and Magnesium incorporated into the biomass is released back into solution
upon biomass lysis and decay. Ca and Mg release is especially evident in an anaerobic digester.
Calcium can interact with P to form Ca-P precipitates including Brushite (DCDP) and Hydroxyapatite (HAP) if
the option to Include precipitation reactions for struvite (MAP), brushite (DCDP) and apatite(HAP) is
selected. The amount of brushite and HAP that can form will depend on the amount of Ca and P available,
the pH, and the precipitation/redissolution rates of brushite and the precipitation rate of HAP. Hydroxy-
apatite (HAP) is considered a sink for calcium that does not redissolve.
Magnesium can interact with P and ammonia to form Struvite (MAP) if the option to Include precipitation
reactions for struvite (MAP), brushite (DCDP) and apatite(HAP) is selected. The amount of struvite that can
form will depend on the amount of Mg, P and ammonia available, the pH, and the
precipitation/redissolution rates for struvite. Struvite typically forms under higher than neutral pH. The
resulting struvite precipitation can occur particularly in pipes and overflow weirs, where degassing of CO2
raises the pH. The model is described in detail in Musvoto et al. (2000).
These precipitation processes are formulated with kinetic equations, according to the referenced papers.
Musvoto, E.V.; Ekama, G.A.; Wentzel, M.C.; Loewenthal, R.E. (2000). Extension and application of the three-
phase weak acid/base kinetic model to the aeration treatment of anaerobic digester liquors. Water SA,
26(4):417-438.

Kinetic Parameters

Menu Location: Project|Parameters|Physical/Chemical…| Mineral precipitation rates

Name Unit Default Value Explanation

Struvite precipitation rate L2/(mol2 d) 3.0E+10 The published precipitation rate

(Musvoto et al. expressed in molar

Biowin 6 Help Manual Model Reference • 831

 terms) is 3*1015. Mixing effects likely
have an influence on rate constants.
The default selected is a compromise
and can be changed in the range of 109
to 3*1015.
Struvite redissolution rate L2/(mol2 d) 3.0E+11 This constant has a lower importance as
struvite redissolution is not typically
encountered in wastewater processes.
Struvite half sat. mg TSS/L 1.0 This is an empirical constant designed to
provide continuity to the mathematical
solution by reducing the struvite
dissolution rate at low struvite
concentrations maintaining low levels of
struvite even under lower pH
conditions. Its value should not be
changed.
Brushite precipitation rate L/(mol d) 1E+6 The value of this rate constant controls
the rate of brushite formation when
supersaturated. This will affect how
close to the equilibrium the CaHPO4
concentration will be under the given
hydraulic residence times. If it is
necessary to change it, it should be
changed together with the redissolution
rate constant.
Brushite redissolution rate L/(mol d) 10,000 The value of this rate constant controls
the rate of brushite dissolution. This
will affect how close to equilibrium the
residual CaHPO4 concentration will be
under the given hydraulic residence
times. If it is necessary to change it, it
should be changed together with the
precipitation rate constant.
Brushite half sat. mg TSS/L 1.0 This is an empirical constant designed to
provide continuity to the mathematical
solution by reducing the brushite
dissolution rate at low brushite
concentrations by maintaining low
levels of brushite even under lower pH
conditions. Its value should not be
changed.
HAP precipitation rate g/d 5E-4 This constant rate will generate
insoluble HAP that cannot be
redissolved.

832 • Model Reference Biowin 6 Help Manual

Menu Location: Project|Parameters|Physical/Chemical…|Mineral precipitation constants

Name Unit Default Explanation

Value

Struvite solubility product mol/L^3 6.918E-14 This solubility constant should not
be changed
Brushite solubility product mol/L^2 2.49E-7 This solubility constant should not
be changed

Modeling of pH and Alkalinity

Importance of pH Modeling
It has been recognized from the early stages of wastewater process modeling that pH is an important factor
in simulating the performance of biological wastewater treatment processes, including activated sludge and
anaerobic digestion. The pH impacts the species distribution of the weak acid systems (carbonate,
ammonia, phosphate, acetate, propionate, etc.) present in the process. This in turn dictates the rate of
many of the biological and physico-chemical phenomena occurring in these systems. For example,
• biological activity, that can be severely limited outside an optimal pH range,
• chemical precipitation reactions when metal salts such as alum or ferric chloride are added for
chemical P removal,
• spontaneous precipitation of struvite, calcium and iron phosphates, and
• stripping of ammonia at high pH.
It is difficult to model pH because the underlying components and reactions are so fast and complex. The
approach to date in activated sludge models has been to track alkalinity changes instead, and use that as a
pseudo indicator of potential pH instability problems. This approach assumes that the pH remains
approximately constant and is in a region where it does not impact biological activity. Another disadvantage
of using alkalinity is that it offers no means for modeling physico-chemical phenomena such as precipitation.
In systems with significant volatile fatty acid concentrations, such as acid fermenters and digesters, or in
systems where significant gas transfer may occur, the predicted alkalinity may not be a good indicator of
steady pH conditions. Calculation of the pH must consider the concentrations of strong acids and bases, the
dissociation states of the weak acid/base, carbonate and phosphate systems, chemical precipitation
reactions, and potential stripping of components involved in the acid-base systems such as ammonia and
carbon dioxide. All of these processes can be described using a kinetic approach (Musvoto et al., 2000), but
the rates of many of the reactions involved typically are four to twenty orders of magnitude larger than
typical biological rates. As a result, calculation of the pH using a kinetic-based model will significantly reduce
simulation speed or use lower than realistic rates to ameliorate this problem. BioWin uses a mixed
kinetic/equilibrium based approach to minimize the negative impact on simulations speed. This approach is
applicable across a wide range of biological treatment process models (i.e. activated sludge and anaerobic
digestion, etc.).

Biowin 6 Help Manual Model Reference • 833

Model Description
The pH model is based on the following elements:
1. Equilibrium modeling of the phosphate, carbonate, ammonium, volatile fatty acid systems and
typical strong ions in wastewater (Mg2+, Ca2+, NO3-etc.).
2. Incorporation of activity coefficients based on the ionic strength of the solution.
3. Gas-liquid transfer of ammonia, carbon dioxide, nitrogen, hydrogen, methane, nitrous oxide and
oxygen. Ammonia and dissolved carbon dioxide have a direct bearing on pH but in some
circumstances it is important to track all major gas species to be able to accurately determine
saturation concentrations for ammonia and carbon dioxide.
4. Biological activity affecting compounds included in the model (e.g. CO2 and many others)
Equilibrium expressions for the acid-base systems included in the model are shown in the table below.
These equilibria represent the predominant acid-base systems occurring in wastewater treatment systems.
All equilibrium expressions in the table below are expressed in terms of active concentrations rather than
molar concentrations. The interaction of ions in solution causes a deviation from ideal behavior whereby
the activity of the ions in equilibrium reactions is less than expected from the molar concentrations. To
account for this behavior, the molar concentration of the ions is reduced by a factor known as the activity
coefficient. The reduced ionic concentration is called the active concentration, as determined in the
following expression:

(𝑋𝑖 ) = 𝑓𝑖 ⋅ [𝑋𝑖 ] (1)

where

(𝑋𝑖 ) = active concentration of Xi

[𝑋𝑖 ] = molar concentration of ion Xi

𝑓𝑖 = activity coefficient of ion Xi

Activity coefficients are estimated in the BioWin pH model using the Davies equation, which is a
simplification of the extended Debye-Hückel law. The activity coefficient (fi) for each ion i in solution is
determined as follows (Loewenthal and Marais, 1976):

√𝜇 (2)
𝑙𝑜𝑔 𝑓𝑖 = −0.5 ⋅ 𝑍𝑖2 ⋅ ( − 0.2𝜇)
1 + √𝜇

where
𝑍𝑖 = ionic charge of ion Xi
𝜇 = ionic strength of solution

834 • Model Reference Biowin 6 Help Manual

Note: Because the deviation from ideal solution behavior is caused by electrostatic attraction between ions,
the activity coefficient of a neutral species in solution (i.e. H2CO3* ) is 1.

The expression for ionic strength is as follows:

𝑛
(3)
𝜇 = 0.5 ∑[𝑋𝑖 ] ⋅ 𝑍𝑖2
𝑖=1

where
𝑛 = the number of ionic species in solution
Since the overall charge of the solution must be neutral, the sum of the concentrations of the positively
charged ions in solution must equal the sum of the negatively charged ion concentrations. This charge
balance relationship is expressed for the pH model as follows (note that for metals such as Al and Fe, the
terms in the equation below may represent totals from other forms):

[𝐻 + ] + [𝑁𝐻4+ ] + 2[𝑀𝑔2+ ] + 2[𝐶𝑎2+ ] + 3[𝐴𝑙 3+ ] + 3[𝐹𝑒 3+ ] + 2[𝐹𝑒 2+ ] + [𝐶𝑎𝑡𝑖𝑜𝑛𝑠 + ] (4)

= [𝑂𝐻 − ] + [𝐻2 𝑃𝑂4− ] + 2[𝐻𝑃𝑂42− ] + 3[𝑃𝑂43− ] + [𝐻𝐶𝑂3− ] + 2[𝐶𝑂32− ] + [𝐶𝐻3 𝐶𝑂𝑂 − ]
+ [𝐶𝐻3 𝐶𝐻2 𝐶𝑂𝑂− ] + [𝑁𝑂3− ] + [𝑁𝑂2− ] + [𝐻𝑆 − ] + [𝐻𝑆𝑂4− ] + 2[𝑆𝑂42− ][𝐴𝑛𝑖𝑜𝑛𝑠 − ]

Acid-base equilibrium expressions included in the general pH model

System Equilibrium Expression Equilibrium Constant

@20oC

Water (𝐻 + )(𝑂𝐻 − ) = 𝐾𝑊 6.867 × 10−15

Carbonic acid (𝐻 + )(𝐻𝐶𝑂3− ) 4.14 × 10−7

= 𝐾𝑖𝐶𝑂3 ,1
(𝐻2 𝐶𝑂3∗ )
Carbonic acid (𝐻 + )(𝐶𝑂32− ) 4.201 × 10−11
= 𝐾𝑖𝐶𝑂3 ,2
(𝐻𝐶𝑂3− )
Acetic acid (𝐻 + )(𝐶𝐻3 𝐶𝑂𝑂 − ) 1.754 × 10−5
= 𝐾𝑖𝐴𝑐
(𝐶𝐻3 𝐶𝑂𝑂𝐻)
Propionic acid (𝐻 + )(𝐶𝐻3 𝐶𝐻2 𝐶𝑂𝑂− ) 1.318 × 10−15
= 𝐾𝑖𝑃𝑟
(𝐶𝐻3 𝐶𝐻2 𝑂𝑂𝐻)
Phosphoric acid (𝐻 + )(𝐻2 𝑃𝑂4− ) 7.452 × 10−3
= 𝐾𝑖𝑃𝑂4 ,1
(𝐻3 𝑃𝑂4 )
Phosphoric acid (𝐻 + )(𝐻𝑃𝑂42− ) 6.103 × 10−8
= 𝐾𝑖𝑃𝑂4 ,2
(𝐻2 𝑃𝑂4− )
Phosphoric acid (𝐻 + )(𝑃𝑂43− ) 9.484 × 10−13
= 𝐾𝑖𝑃𝑂4 ,3
(𝐻𝑃𝑂42− )

Biowin 6 Help Manual Model Reference • 835

 Ammonium (𝐻 + )(𝑁𝐻3 ) 3.966 × 10−10
= 𝐾𝑖𝑁𝐻3
(𝑁𝐻4+ )
Nitrous acid (𝐻 + )(𝑁𝑂2 ) 4.5 × 10−4
= 𝐾𝑖𝐻𝑁𝑂2
(𝐻𝑁𝑂2 )
Hydrogen sulfide* (𝐻 + )(𝐻𝑆 − ) 7.943 × 10−8
= 𝐾𝑖𝐻2 𝑆
(𝐻2 𝑆)
Sulfuric acid** (𝐻 + )(𝑆𝑂42− ) 1.0233 × 10−2
= 𝐾𝑖𝐻𝑆𝑂4−
(𝐻𝑆𝑂4− )
* The second dissociation step hydrosulfide to sulfide (S=) is considered negligible in typical
wastewater applications because the values reported for pKi of the second dissociation step are
generally over 15. That is, it is assumed that S= is 0.0.
** The first dissociation step for sulfuric acid is considered to have gone to completion at pH values
typical of wastewater treatment systems. That is, the concentration of undissociated H2SO4 is
assumed to be zero. Reported pKi values are around 0.0.
In addition to the ionic species shown in the table above, there are a number of other ions likely to occur in
significant concentrations in wastewater treatment systems, and these have been included in the charge
balance. Calcium (Ca2+) and Magnesium (Mg2+) will be present in the natural source waters and general
variables have also been added for cations (Cations+) and anions (Anions-) which can be used to account for
additional species not included separately (for example, modeling addition of strong acids or bases - Na+, Cl-
, etc.). In addition to naturally occurring ions such as Mg and Ca the charge balance also includes a general
term for metal species which have been included to allow for modeling of chemical phosphorus removal.
(See the Ferric or Alum section of this chapter).
BioWin state variables track the total species concentrations for all the appropriate species thus the set of
equations described by equations (1) through (4), the dissociation expressions in the table above and
individual component material balances may be solved simultaneously to determine the individual ion
concentrations, pH and ionic strength. This allows material balances to be calculated for each of the total
species concentrations. For example, a material balance for total dissolved inorganic carbon in a reaction
vessel is written as follows:

𝑑𝑀𝐶𝑂2 (5)
= 𝑄𝐿,𝑖 ⋅ 𝑆𝐶𝑂2 ,𝑖 − 𝑄𝐿,𝑜 ⋅ 𝑆𝐶𝑂2 ,𝑜 − (𝐶𝑂2 𝑆𝑡𝑟𝑖𝑝𝑝𝑖𝑛𝑔) + (𝑁𝑒𝑡 𝑅𝑒𝑎𝑐𝑡𝑖𝑜𝑛)
𝑑𝑡

where

Subscript “𝑖 ” = influent
Subscript “𝑜” = effluent
𝑀𝐶𝑂2 = mass of dissolved total inorganic carbon
𝑆𝐶𝑂2 = total dissolved inorganic carbon concentration
𝑄𝐿 = liquid flow rate

836 • Model Reference Biowin 6 Help Manual

 𝑁𝑒𝑡 𝑅𝑒𝑎𝑐𝑡𝑖𝑜𝑛 = biological reaction rate

𝐶𝑂2 𝑆𝑡𝑟𝑖𝑝𝑝𝑖𝑛𝑔 = 𝑘𝐿,𝐶𝑂2 ⋅ 𝐴𝐺𝑇 ⋅ (𝑆𝐶𝑂2 ,𝑆𝐴𝑇 − [𝐻2 𝐶𝑂3∗ ]) ⋅ 𝑉𝐿 (6)

where

𝑘𝐿 = liquid phase mass transfer coefficient

𝐴𝐺𝑇 = specific interfacial area for gas transfer
𝑆𝐶𝑂2 ,𝑆𝐴𝑇 = saturation dissolved CO2 concentration
[𝐻2 𝐶𝑂3∗ ] = undissociated carbonic acid concentration

The Net Production by Reaction term accounts for biological generation (e.g. from oxidation of organics
by heterotrophs) and consumption (e.g. by autotrophs). The saturation concentration (𝑆𝐶𝑂2,𝑆𝐴𝑇 ) in the
“Gas Stripping” term is calculated from a Henry’s law relationship at the system temperature and
pressure. A simplification of the model assumes that the gas phase concentration of the component is
constant (i.e. atmospheric concentration for CO2, zero for ammonia), and therefore the saturation
concentration of the dissolved component is constant for a given temperature. However, for many
systems (e.g., anaerobic digesters), a material balance is also required for the gas phase. For the carbon
dioxide component, the gas phase material balance is written as follows:

𝑑𝑀𝐶𝑂2 ,𝐺 (6b)
= 𝑄𝐺,𝑖 ⋅ 𝐺𝐶𝑂2 ,𝑖 − 𝑄𝐺,𝑜 ⋅ 𝐺𝐶𝑂2 ,𝑜 + (𝐶𝑂2 𝑆𝑡𝑟𝑖𝑝𝑝𝑖𝑛𝑔)
𝑑𝑡

where

𝑀𝐶𝑂2 ,𝐺 = mass of CO2 in the gas phase

𝑄𝐺 = gas flow rate
𝐺𝐶𝑂2 = gas phase carbon dioxide concentration
Similar material balances (gas and liquid phase) are required for the total ammonia concentration. For the
other ionic species in solution (i.e. volatile acids, phosphate, etc.), there is no stripping and thus material
balances for these components are written only for the liquid phase.

Alkalinity determination
The chart below shows a logarithmic concentration versus pH diagram for the carbonate system. This
diagram was generated with the BioWin pH model by simulating a system with a total dissolved inorganic
carbon concentration of 10 mmol/L, and successively adding an increasing number of anions to the system
to change the pH. The model determines alkalinity by noting that at the H2CO3* equivalence point [H+] =
[HCO3-]. This additional equation can then be used to solve the carbonate equilibrium explicitly to

Biowin 6 Help Manual Model Reference • 837

determine the [HCO3-] concentration at the equivalence point (and consequently the pH). From this a
charge balance (at the equivalence point) can be used to calculate the amount of strong acid that would be
required to move the solution from its current state to the H2CO3* equivalence point. As a result, the
impact of all of the ionic species included in the general pH model is considered in the calculation of
alkalinity.

Note: The alkalinity is not explicitly related to the stoichiometry of the biological processes in the system
when estimated with the pH model. Instead, it is related to concentrations of ionic species at the current
system state.

Logarithmic concentration versus pH diagram for the carbonate system as generated by the general pH model

Specifying pH and Alkalinity

In certain influent elements BioWin allows the user to specify the pH and alkalinity. Since both of these
values are “calculated” from the current system state, it is necessary for BioWin to adjust certain state
variables to achieve the desired pH and alkalinity. In this case BioWin adjusts the total carbon dioxide, the
anions and the cations until it achieves the desired pH and alkalinity. Note that it is possible to specify
values that are not able to be achieved and BioWin will not warn you of the problem.

Biological inhibition due to pH

BioWin uses the calculated pH to determine the level of biological inhibition according to the following
equation:
(𝑝𝐻𝐿𝑜𝑤 𝐿𝑖𝑚𝑖𝑡 −𝑝𝐻𝐻𝑖𝑔ℎ 𝐿𝑖𝑚𝑖𝑡 ) (7)
1 + 2 (10 2 )
𝐼𝑛ℎ𝑖𝑏𝑖𝑡𝑖𝑜𝑛 =
1 + 10(𝑝𝐻−𝑝𝐻𝐻𝑖𝑔ℎ 𝐿𝑖𝑚𝑖𝑡) + 10(𝑝𝐻𝐿𝑜𝑤 𝐿𝑖𝑚𝑖𝑡−𝑝𝐻)

838 • Model Reference Biowin 6 Help Manual

where

𝑝𝐻 = Calculated pH
𝑝𝐻𝐿𝑜𝑤 𝐿𝑖𝑚𝑖𝑡 = Low pH limit for a particular organism
𝑝𝐻𝐻𝑖𝑔ℎ 𝐿𝑖𝑚𝑖𝑡 = High pH limit for a particular organism
The user may select to turn off pH inhibition (essentially setting inhibition to 1.0) in all elements except the
anaerobic digester element and the activated primary element. These units require a pH, but the user can
choose to specify the pH that will be used in that element (i.e. either the calculated value, or a user specified
value).

Note: Turning off pH inhibition (or specifying a pH in an element) does not stop BioWin from calculating the
pH.

Examples
The following section contains a number of examples that highlight model performance and behavior.

Titration of Acids and Bases

Validation of the pH model included the simulation of various titrations of acids and bases in clean water.
The simulation configuration shown below consisted of a variable volume reactor to represent a titration
vessel, and an influent stream with a constant flow to represent the standard solution. The initial volume of
the reactor was 50 L. The flow rate of the standard solution was 1 L/min. The table below summarizes
simulated experimental conditions that represent the following types of titrations:
• Strong acid titrated with a strong base standard solution;
• Weak acid titrated with a strong base standard;
• Weak base titrated with a strong acid standard;
• Weak acid titrated with a weak base standard.
The table shows the concentrations of the reagents, and the components and concentrations used in the
model to reflect those conditions. Note that in BioWin, the concentrations of reagents that are involved in
the biological processes of the model (i.e. acetic acid and ammonia) are expressed in mg/L units. The
concentrations of reagents that are primarily part of the acid base system (i.e. cations and anions), are
expressed in units of meq/L.
The figures below show the results of the titration simulations compared to data from a standard chemistry
text (Mortimer, 1975). These results verify that the acid-base equilibrium chemistry is correctly formulated
in the pH model. The slight discrepancies between the actual and observed titration curves (for example,
the equivalence point in the simulation of 0.10 N CH3COOH titrated with 0.10 N NaOH) are due to the
incorporation of activity coefficients and the use of slightly different equilibrium constants in the general pH
model.

Biowin 6 Help Manual Model Reference • 839

BioWin configuration for the simulation of various acid and base titration experiments

Summary of simulated titration experiments

Titration Vessel Standard Titration Vessel Initial Standard Solution

Reagent Reagent Concentrations Concentrations

0.10 N HCl 0.10 N NaOH [Anions-] = 100 meq/L [Cations] = 100 meq/L
0.10 N CH3COOH 0.10 N NaOH [CH3COOH] = 6000 mg/L [Cations] = 100 meq/L
0.10 N NH3 0.10 N HCl [NH3] = 1400 mg/L [Anions] = 100 meq/L
0.10 N CH3COOH 0.10 N NH3 [CH3COOH] = 6000 mg/L [NH3] = 1400 mg/L

840 • Model Reference Biowin 6 Help Manual

Results from simulation of 0.10 N HCL titrated with 0.10 N NaOH.

Results from simulation of 0.10 N CH3COOH titrated with 0.10 N NaOH.

Results from simulation of 0.10 N NH3 titrated with 0.10 N HCL.

Biowin 6 Help Manual Model Reference • 841

Results from simulation of 0.10 N CH3COOH titrated with 0.10 N NH3.

Considerations
A pH model is essential for reliable simulation of many important wastewater treatment operations,
including:
1. Gas phase modeling which is important for modeling anaerobic digestion and precipitation
processes. Calculation of gas transfer rates requires knowledge of the species ionization states and
consequently the pH of the system.
2. Inhibition of biological activity at low and high pH.
3. Equilibrium-based, pH dependent modeling of aluminum and ferric dosing for phosphorus
precipitation, including hydroxide sludge formation.
4. Kinetic-based, pH dependent modeling of the spontaneous precipitation of struvite and calcium
phosphates. Accurate prediction of struvite precipitation also requires modeling of magnesium
concentrations, both the soluble magnesium and that stored in organisms.

References
Batstone, D.J.; Keller, J.; Angelidaki, I.; Kalyuzhnyi, S.V.; Pavlostathis, S.G.; Rozzi, A.; Sanders, W.T.M.;
Siegrist, H.; Vavlin, V.A. (2002). Anaerobic Digestion Model No.1, IWA Scientific and Technical Report No.
13. IWA Publishing, London, UK.
Henze, M.; Grady, C.P.L.; Gujer, W.; Marais, G.v.R.; Matsuo, T. (1987a). Activated Sludge Model No. 1,
IAWPRC Scientific and Technical Report No. 1. London, UK: International Water Association.
Henze, M.; Grady, C.P.L.; Gujer, W.; Marais, G.v.R.; Matsuo, T. (1987b). A general model for single sludge
wastewater treatment systems. Water Res., 21(5):505-515.
Jones, R. M.; Bye, C. M.; Dold, P. L. (2003). Nitrification Parameter Measurement for Plant Design:
Experience with New Methods. Proceedings of the Water Environment Federation 76th Annual
Technical Exhibition and Conference, Los Angeles, California, USA, October 11-15, 2003.

842 • Model Reference Biowin 6 Help Manual

Loewenthal, R.E.; Marais, G.v.R. (1976). Carbonate Chemistry of Aquatic Systems: Theory and Application.
Ann Arbor Science, Ann Arbor Michigan.
Melcer, H., Dold, P.L., Jones, R.M., Bye, C.M., Takacs, I., Stensel, H.D., Wilson, A.W., Sun, P., Bury, S. (2004).
Methods for wastewater characterization in activated sludge modeling. 99-WWF-3, Water Environment
Research Foundation (WERF), Alexandria, VA, USA.
Mortimer, C.E. (1975). Chemistry a Conceptual Approach, 3rd Edition, D. Van Nostrand, 572-578.
Musvoto, E.V.; Ekama, G.A.; Wentzel, M.C.; Loewenthal, R.E. (2000). Extension and application of the three-
phase weak acid/base kinetic model to the aeration treatment of anaerobic digester liquors. Water SA,
26(4):417-438.
Musvoto, E.V.; Wentzel, M.C.; Loewenthal, R.E.; Ekama, G.A. (1997). Kinetic-based model for mixed weak
acid/base systems. Water SA, 23(4):311-322.
Perry, R.; Green, D. (1985). Perry’s Chemical Engineer’s Handbook, Sixth Edition. McGraw-Hill Inc.

General Parameters
The following miscellaneous model parameters can be found under:
Project|Parameters|Stoichiometric|Common

Name Default Unit Explanation

Value

Molecular weight of 35.50 mg/mmol Assumed molecular weight of “other

other anions anions” state variable.
Molecular weight of 39.10 mg/mmol Assumed molecular weight of “other
other cations cations” state variable.

Project|Parameters|Stoichiometric|PAO

Name Default Unit Explanation

Value

Mg to P mole ratio in 0.30 mmol Mg/mmol P Mole ratio of magnesium to

polyphosphate phosphorus in polyphosphate.
Cation to P mole ratio in 0.15 meq/mmol P Mole ratio of other cations to
polyphosphate phosphorus in polyphosphate.
Ca to P mole ratio in 0.05 mmol Ca/mmol P Mole ratio of calcium to phosphorus in
polyphosphate polyphosphate.

Project|Parameters|Aeration/Mass transfer|Anaerobic Digester

Biowin 6 Help Manual Model Reference • 843

 Name Default Unit Explanation
Value

Bubble rise velocity 23.9 cm/s The bubble rise velocity is used to
(anaerobic digester) calculate the gas holdup in anaerobic
digesters. Increasing the rise velocity
will decrease the gas holdup.
Bubble Sauter mean 0.35 Cm The Sauter mean diameter is the
diameter (anaerobic diameter of a sphere with the same
digester) volume to surface ratio as the volume
to surface ratio of the total dispersion.
Anaerobic digester gas 1 This parameter can be used to adjust
hold-up factor the digester mass transfer.

Project|Parameters|Other

Name Default Unit Explanation

Value

Tank head loss per metre 2.5E-3 m/m Used in calculation of G values for tank
of length and channel elements.
BOD calculation rate 0.5 d-1 Time constant used to calculate BOD
constant for Xsc versus time change due to colloidal
degradation material.

BOD calculation rate 0.5 d-1 Time constant used to calculate BOD
constant for Xsp and versus time change due to
hydrocarbon particulate degradable material.
degradation
BOD calculation rate 0.5 d-1 Time constant used to calculate BOD
constant for Xso versus time change due to externally
added particulate degradable
material (e.g. SSO).

Modeling of Industrial Components

Introduction
This section provides a general description of the modeling of industrial COD in BioWin. Over and above the
four user-defined state variables, five industrial COD state variables are included in BioWin that allow
considerable flexibility in modeling different industrial COD fractions. Unlike the ordinary user defined state
variables, these state variables are involved in several processes of the BioWin Industrial Activated
Sludge/Anaerobic Digestion Model (ASDMi). This document describes the kinetic and stoichiometric
behavior of the model processes involving the following industrial COD components:

844 • Model Reference Biowin 6 Help Manual

 • Ind. #1 - Sol. bio. vol. COD
• Ind. #2 - Sol. bio. vol. COD
• Ind. #3 - Sol. bio. vol. COD
• Soluble hydrocarbon COD
• Adsorbed hydrocarbon COD
The approach used for modeling biological degradation of the industrial COD components is similar to that
described by Baker and Dold (1992). The approach to modeling the gas liquid mass transfer of these
components is described in detail in “BioWin Model for Mass Transfer”..

Ind. #1 - Soluble biodegradable volatile COD

The first industrial component in BioWin, Ind. #1, is a soluble and, potentially, both biodegradable and
volatile. The Ind. #1 COD (also called SInd1 or S_Ind1 depending on your settings) component has an
associated gas phase state variable, “Off gas Ind #1” (also called “Ind1 (g)”). By default, this state variable
has several properties consistent with the compound Phenol. There are ten processes in the model that can
impact on this state variable; nine are related to biological utilization and the tenth process is the gas liquid
mass transfer process.

Biological Processes
Ind. #1 may be utilized biologically by OHOs under aerobic and anoxic conditions as shown in the diagrams
below. The nitrogen and phosphorus requirements for ordinary heterotrophic organism growth (from
ammonia and phosphorus respectively) are controlled by the appropriate stoichiometric parameters (see
Project|Parameters|Stoichiometric…|OHOs).

Aerobic growth on Ind. #1 COD.

The yields for growth on industrial COD components are listed on the
Project|Parameters|Stoichiometric…|OHOs on other COD tab.

Biowin 6 Help Manual Model Reference • 845

Anoxic growth on Ind. #1 COD.

The aerobic and anoxic growth processes on Ind. #1 were assumed to follow Haldane substrate kinetics and
to be inhibited outside of the optimal pH range. The basic growth rate expression used is shown in the
following equation:

846 • Model Reference Biowin 6 Help Manual

 (8)
[𝐼𝑛𝑑. #1]
𝜇 = 𝜇𝑚𝑎𝑥 ⋅ [ ] ⋅ 𝐼𝑝𝐻
[𝐼𝑛𝑑. #1]2
𝐾𝑆 + [𝐼𝑛𝑑. #1] +
𝐾𝐼

where

𝜇𝑚𝑎𝑥 - Maximum specific growth rate of OHOs on Ind. #1 (d-1)

[𝐼𝑛𝑑. #1] - Ind. #1concentration (gCOD/m3)
𝐾𝑆 - Half saturation constant for Ind. #1(gCOD/m3)
𝐾𝐼 - Inhibition constant for Ind. #1 (gCOD/m3)
𝐼𝑝𝐻 - pH inhibition function.

The aerobic and anoxic growth rates also can be limited by the level of required nutrients, substrate
preferences (traditional COD over industrial COD) and the environmental conditions (including application of
anoxic growth factor and a preference for nitrite over nitrate). For these processes to occur the following
components are required (in addition to oxygen or either nitrate or nitrite): ammonia, phosphorus, and
synthesis anions and cations.
Ind. #1 may be utilized biologically under anaerobic conditions. For this process Phenol is used as a
surrogate component for Ind. #1. BioWin models anaerobic growth on Ind. #1 as the result of two
processes. Firstly, the anabolic requirements for cell formation according to the following general equation:

𝑎𝐶6 𝐻6 𝑂 + 𝑏𝑁𝐻3 + 𝐻3 𝑃𝑂4 + 𝑐𝐻2 𝑂 ⟶ 𝐶𝑤 𝐻𝑥 𝑂𝑦 𝑁𝑧 𝑃 + 𝑑𝐻2 (9)

Secondly, the catabolic (energy) requirement for the growth of biomass through the fermentation of Ind. #1
is obtained from the catabolic reaction in the equation below.

𝑓𝐶6 𝐻6 𝑂 + 7𝑓𝐻2 𝑂 ⟶ 2𝑓𝐶2 𝐻4 𝑂2 + 2𝑓𝐶𝑂2 + 6𝑓𝐻2 (10)

Combining equations above results in the overall stoichiometry for biomass growth through phenol
fermentation shown below.

Biowin 6 Help Manual Model Reference • 847

 (𝑓 + 𝑎) 𝐶6 𝐻6 𝑂 + 𝑏𝑁𝐻3 + 𝐻3 𝑃𝑂4 + (7𝑓 + 𝑐) 𝐻2 𝑂 (11)
⟶ 𝐶𝑤 𝐻𝑥 𝑂𝑦 𝑁𝑧 𝑃 + (6𝑓 + 𝑑) 𝐻2 + 2𝑓𝐶2 𝐻4 𝑂2 + 2𝑓𝐶𝑂2

The yield of OHOs on Ind. #1 can be directly related to the selected sludge formula 𝐶𝑤 𝐻𝑥 𝑂𝑦 𝑁𝑧 𝑃 , 𝑓 and
COD to mole ratio for the substrate. This relationship is used to determine the stoichiometry of acetic
acid, hydrogen and carbon dioxide as shown in the diagram below. However, the user can
independently define the N and P content of the organism (although this would defy the stoichiometry
developed above).

Anaerobic growth on Ind. #1 COD.

The fermentation of Ind. #1 by OHOs was assumed to have the same kinetic behavior as for other substrates
with the exception that an “Anaerobic growth factor for Ind. #1” (Project|Parameters|Kinetic…|OHOs on
other COD) is applied. This allows the fermentation rate of Ind. #1 to be adjusted independently.
Ind. #1 COD may be formed by the degradation of Ind. #3, as described in Ind. #3 - Soluble biodegradable
volatile COD. However, by default the yield of Ind#1 on degradation of Ind. #3 is 0.

Gas-Liquid Mass Transfer

Ind. #1 COD can occur in gas phase and dissolved (or dispersed) in the liquid phase. The distribution of Ind.
#1 between these is primarily controlled by the saturation concentration of Ind. #1, the mass transfer
coefficient and the area for gas liquid transfer. The liquid phase mass transfer coefficient, 𝑘𝐿 , can be
entered on the Project|Parameters|Other…|Mass transfer tab, by default the 𝑘𝐿 for Ind. #1 is zero which
∗
means that no gas liquid mass transfer will occur. In BioWin the saturation concentration for Ind. #1, 𝐶𝐼𝑛𝑑1 ,
is determined by the following Henry’s law expression.

848 • Model Reference Biowin 6 Help Manual

 ∗ 𝜃 −𝛥𝑠𝑜𝑙𝑛 𝐻 1 1 (12)
𝐶𝐼𝑛𝑑1 = 𝑝𝐼𝑛𝑑1 ⋅ 𝑘𝐻,𝐼𝑛𝑑1 = 𝑝𝐼𝑛𝑑1 ⋅ 𝑘𝐻,𝐼𝑛𝑑1 × 𝑒𝑥𝑝 [ 𝑅
(𝑇 − 𝑇 𝜃 )]

where

𝑝𝐼𝑛𝑑1 = Partial pressure of Ind. #1 in the gas phase

𝑘𝐻,𝐼𝑛𝑑1 = Henry’s law constant at field temperature
𝜃
𝑘𝐻,𝐼𝑛𝑑1 = Henry’s law constant at reference temperature
−𝛥𝑠𝑜𝑙𝑛 𝐻 = Henry’s Law temperature dependency constant
𝑅
𝑇 = Field temperature
𝑇𝜃 = Reference temperature

The parameters Henry’s law constant and temperature dependency constant are user defined and may be
entered on the Project|Parameters|Other…|Henry’s law constants tab. The default Henry’s law constants
∗
for Ind. #1 are appropriate for phenol (which is very soluble). Note that the expression for 𝐶𝐼𝑛𝑑1 provides
the concentration with units [Mole L-1] but the state variable Ind. #1 has units [mgCOD L-1] consequently an
additional parameter - the COD per mole of Ind. #1 is required. The default value for this parameter is 224
gCOD mole-1 calculated from the following reaction.

𝐶6 𝐻6 𝑂 + 7𝑂2 ⟶ 6𝐶𝑂2 + 3𝐻2 𝑂 (13)

The COD to mole ratio is specified on the Project|Parameters|Stoichiometric…|OHOs on other COD tab.

Ind. #2 - Soluble biodegradable volatile COD

The industrial component Ind. #2, is a soluble and, potentially, both biodegradable and volatile. The Ind. #2
COD component has an associated gas phase state variable, “Off gas Ind #2”. By default, this state variable
has several properties consistent with the compound Benzene. There are six processes in the model that can
impact on this state variable; five are related to biological utilization and the sixth process is the gas-liquid
mass transfer process.

Biological Processes
Ind. #2 may be utilized biologically by OHOs under aerobic and anoxic conditions. These processes are very
similar to the aerobic and anoxic processes described in Ind. #1 - Soluble biodegradable volatile COD and
shown in the diagrams below.

Biowin 6 Help Manual Model Reference • 849

Ind. #2 may be utilized biologically under anaerobic conditions. For this process Benzene is used as a
surrogate component for Ind. #2. BioWin models anaerobic growth on Ind. #2 as the result of two processes
namely; anabolic and catabolic. The following equation describes the anabolic requirements for cell
formation:

𝑎𝐶6 𝐻6 + 𝑏𝑁𝐻3 + 𝐻3 𝑃𝑂4 + 𝑐𝐻2 𝑂 ⟶ 𝐶𝑤 𝐻𝑥 𝑂𝑦 𝑁𝑧 𝑃 + 𝑑𝐻2 (14)

Secondly, the catabolic (energy) requirement for the growth of biomass through the fermentation of Ind. #2
is obtained from the catabolic reaction in the equation below.

𝑓𝐶6 𝐻6 + 8𝑓𝐻2 𝑂 ⟶ 2𝑓𝐶2 𝐻4 𝑂2 + 2𝑓𝐶𝑂2 + 7𝑓𝐻2 (15)

Combining equations above results in the overall stoichiometry for biomass growth through benzene
fermentation shown below.
(𝑓 + 𝑎) 𝐶6 𝐻6 + 𝑏𝑁𝐻3 + 𝐻3 𝑃𝑂4 + (8𝑓 + 𝑐) 𝐻2 𝑂 ⟶ (16)
𝐶𝑤 𝐻𝑥 𝑂𝑦 𝑁𝑧 𝑃 + (7𝑓 + 𝑑) 𝐻2 + 2𝑓𝐶2 𝐻4 𝑂2 + 2𝑓𝐶𝑂2

The yield of OHOs on Ind. #2 can be directly related to the selected sludge formula 𝐶𝑤 𝐻𝑥 𝑂𝑦 𝑁𝑧 𝑃 , 𝑓 and
COD to mole ratio for the substrate. This relationship is used to determine the stoichiometry of acetic acid,
hydrogen and carbon dioxide as shown in the diagram below. The user can independently define the N and
P content of the organism although this would defy the stoichiometry developed above.

850 • Model Reference Biowin 6 Help Manual

Anaerobic growth on Ind. #2 COD.

The fermentation of Ind. #2 by OHOs was assumed to have the same kinetic behavior as for other substrates
with the exception that an “Anaerobic growth factor for Ind. #2” (Project|Parameters|Kinetic…|OHOs on
other COD) is applied. This allows the fermentation rate of Ind. #2 to be adjusted independently.

Gas-Liquid Mass Transfer

Ind. #2 COD can occur in gas phase and dissolved (or dispersed) in the liquid phase. The distribution of Ind.
#2 between these is primarily controlled by the saturation concentration of Ind. #2, the mass transfer
coefficient and the area for gas liquid transfer. The liquid phase mass transfer coefficient, 𝑘𝐿 , can be
entered on the Project|Parameters|Other…|Mass transfer tab, by default the 𝑘𝐿 for Ind. #2 is 0.5 which is
∗
a relatively low value (larger molecule). In BioWin the saturation concentration for Ind. #2, 𝐶𝐼𝑛𝑑2 , is
determined using a Henry’s law expression (see Henry’s Law constants temperature dependencies).
The parameters used in the Henry’s law expression are user defined and may be entered on the
Project|Parameters|Other…|Henry’s law constants tab. The default Henry’s law constants for Ind. #2 are
∗
appropriate for Benzene. Note that the expression for 𝐶𝐼𝑛𝑑2 provides the concentration with units [Mole L-
1] but the state variable Ind. #2 has units [mgCOD L-1] consequently an additional parameter - the COD per
mole of Ind. #2 - is required. The default value for this parameter is 240 gCOD mole-1 calculated from the
following reaction.

1
𝐶6 𝐻6 + 72𝑂2 ⟶ 6𝐶𝑂2 + 3𝐻2 𝑂 (17)

The COD to mole ratio is specified on the Project|Parameters|Stoichiometric…|OHOs on other COD tab.

Biowin 6 Help Manual Model Reference • 851

Ind. #3 - Soluble biodegradable volatile COD
The industrial component Ind. #3, is a soluble and, potentially, both biodegradable and volatile. The Ind. #3
COD component has an associated gas phase state variable, “Off gas Ind #3”. By default, this state variable
has several properties consistent with the compound Toluene. There are six processes in the model that
can impact on this state variable; five are related to biological utilization and the sixth process is the gas-
liquid mass transfer process.

Biological Processes
Ind. #3 may be utilized biologically by OHOs under aerobic and anoxic conditions as shown in the diagrams
below. By default the yields of “Soluble hydrocarbons” and “Ind. #1” are both zero, but the stoichiometry is
designed to be flexible. The yields for growth on industrial COD components are listed on the
Project|Parameters|Stoichiometric…|OHOs on other COD tab.

Aerobic growth on Ind. #3 COD.

852 • Model Reference Biowin 6 Help Manual

Anoxic growth (nitrate to nitrite) on Ind. #3 COD.

Biowin 6 Help Manual Model Reference • 853

 OHO
Yield (Anoxic)

Soluble Hydrocarbon COD

YieldHC

Ind. #3
Ind. #1 COD
YieldInd #1
(OHO)

Yield-YieldHC -YieldInd #1
1- ( )
32
Carbon dioxide

Yield-YieldHC -YieldInd #1 Yield-YieldHC -YieldInd #1

1- ( ) 1- ( )
1.71 1.71
Nitrite Nitrogen (N2 )

Anoxic growth (nitrite to nitrogen gas) on Ind. #3 COD.

854 • Model Reference Biowin 6 Help Manual

 OHO
Yield (Anoxic)

Soluble Hydrocarbon COD

YieldHC

Ind. #3
Ind. #1 COD
YieldInd #1
(OHO)

Yield-YieldHC -YieldInd #1
1- ( )
32
Carbon dioxide

Yield-YieldHC -YieldInd #1 Yield-YieldHC -YieldInd #1

1- ( ) 1- ( )
2.86 2.86
Nitrate Nitrogen (N2)

Anoxic growth (nitrate to nitrogen gas) on Ind. #3 COD.

The aerobic and anoxic growth processes on Ind. #3 were assumed to follow Haldane substrate kinetics and
to be inhibited outside of the optimal pH range.. The basic growth rate expression used is shown in the
following equation:

(18)
[𝐼𝑛𝑑. #3]
𝜇 = 𝜇𝑚𝑎𝑥 ⋅ [ ] ⋅ 𝐼𝑝𝐻
[𝐼𝑛𝑑. #3]2
𝐾𝑆 + [𝐼𝑛𝑑. #3] +
𝐾𝐼

where

𝜇𝑚𝑎𝑥 - Maximum specific growth rate of OHOs on Ind. #3 (d-1)

[𝐼𝑛𝑑. #3] - Ind. #3concentration (gCOD/m3)

𝐾𝑆 - Half saturation constant for Ind. #3 (gCOD/m3)

𝐾𝐼 - Inhibition constant for Ind. #3 (gCOD/m3)
𝐼𝑝𝐻 - pH inhibition function.

Biowin 6 Help Manual Model Reference • 855

The aerobic and anoxic growth rates also can be limited by the level of required nutrients, substrate
preference (traditional COD over “industrial” COD) and the environmental conditions (including application
of an anoxic growth factor and a preference for nitrite over nitrate). For these processes to occur the
following components are required (in addition to oxygen or either nitrate or nitrite): ammonia,
phosphorus, and synthesis anions and cations.
Ind. #3 may be utilized biologically under anaerobic conditions. For this process Toluene is used as a
surrogate component for Ind. #3. Growth on Ind. #3 is modeled as the result of an anabolic and a catabolic
reaction. The anabolic reaction fulfils the requirements for cell formation according to the following general
equation:

𝑎𝐶7 𝐻8 + 𝑏𝑁𝐻3 + 𝐻3 𝑃𝑂4 + 𝑐𝐻2 𝑂 ⟶ 𝐶𝑤 𝐻𝑥 𝑂𝑦 𝑁𝑧 𝑃 + 𝑑𝐻2 (19)

The catabolic reaction provides the energy requirement for the growth of biomass through the fermentation
of Ind. #3 according to the equation below.

𝑓𝐶7 𝐻8 + 8𝑓𝐻2 𝑂 ⟶ 3𝑓𝐶2 𝐻4 𝑂2 + 𝑓𝐶𝑂2 + 6𝑓𝐻2 (20)

Combining equations above results in the overall stoichiometry for biomass growth through toluene
fermentation shown below.

(𝑓 + 𝑎) 𝐶7 𝐻8 + 𝑏𝑁𝐻3 + 𝐻3 𝑃𝑂4 + (8𝑓 + 𝑐) 𝐻2 𝑂 ⟶ (21)

𝐶𝑤 𝐻𝑥 𝑂𝑦 𝑁𝑧 𝑃 + (6𝑓 + 𝑑) 𝐻2 + 3𝑓𝐶2 𝐻4 𝑂2 + 𝑓𝐶𝑂2

The yield of OHOs on Ind. #3 can be directly related to the selected sludge formula 𝐶𝑤 𝐻𝑥 𝑂𝑦 𝑁𝑧 𝑃, 𝑓 and COD
to mole ratio for the substrate. This relationship is used to determine the stoichiometry of acetic acid,
hydrogen and carbon dioxide as shown in the diagram below. The user can independently define the N and
P content of the organism although this would defy the nitrogen and phosphorus stoichiometry developed
above.

856 • Model Reference Biowin 6 Help Manual

Anaerobic growth on Ind. #3 COD.

The fermentation of Ind. #3 by OHOs was assumed to have the same kinetic behavior as for other substrates
with the exception that an “Anaerobic growth factor for Ind. #3” (Project|Parameters|Kinetic|OHOs on
other COD) is applied. This allows the fermentation rate of Ind. #3 to be adjusted independently.

Gas-Liquid Mass Transfer

Ind. #3 COD can occur in gas phase and dissolved (or dispersed) in the liquid phase. The distribution of Ind.
#3 between these is primarily controlled by the saturation concentration of Ind. #3, the mass transfer
coefficient and the area for gas liquid transfer. The liquid phase mass transfer coefficient, 𝑘𝐿 , can be
entered on the Project|Parameters|Other…|Mass transfer tab, by default the 𝑘𝐿 for Ind. #3 is zero which
∗
means that no gas liquid mass transfer will occur. In BioWin the saturation concentration for Ind. #3, 𝐶𝐼𝑛𝑑3 ,
is determined using a Henry’s law expression (see Henry’s Law constants temperature dependencies). The
parameters used in the Henry’s law expression are user defined and may be entered on the
Project|Parameters|Other…|Henry’s law constants tab. The default Henry’s law constants for Ind. #3 are
∗
appropriate for Toluene. Note that the expression for 𝐶𝐼𝑛𝑑3 provides the concentration with units [Mole L-
1] but the state variable Ind. #3 has units [mgCOD L-1] consequently an additional parameter - the COD per
mole of Ind. #3 - is required. The default value for this parameter is 288 gCOD mole-1 calculated from the
following reaction.

Biowin 6 Help Manual Model Reference • 857

 𝐶7 𝐻8 + 9𝑂2 ⟶ 7𝐶𝑂2 + 4𝐻2 𝑂 (22)

The COD to mole ratio is specified on the Project|Parameters|Stoichiometric…|OHOs on other COD tab.

Soluble hydrocarbon COD

Hydrocarbon compounds are a common constituent of industrial, or mixed domestic and industrial
wastewaters. In BioWin one of the state variables that can be used to model this diverse group of
compounds is the Soluble hydrocarbon COD state variable (also called “Shc”, and “S_HC” depending on your
settings). This state is assumed to be non-volatile, soluble (or at least dispersed), and not directly
biodegradable. That is, it needs to be adsorbed onto the sludge before it can be utilized. This process is
very simple, Soluble hydrocarbon COD is adsorbed to become Adsorbed hydrocarbon COD. The rate of
adsorption was assumed to follow first order kinetics with respect to the Soluble hydrocarbon COD and the
ordinary heterotrophic organism concentration. The adsorption rate expression used is shown in the
following equation:

[𝑋𝐻𝐶 ] (23)
𝑟 = 𝐾𝑎 ⋅ [𝑍𝐵𝐻 ] ⋅ [𝑆𝐻𝐶 ] ⋅ 𝑚𝑎𝑥 (0, 𝐾𝑚 − ( ))
[𝑍𝐵𝐻 ]

where

𝐾𝑎 - Adsorption rate of soluble hydrocarbons (m3 gCOD-1 d-1)

[𝑍𝐵𝐻 ] - Ordinary heterotrophic organisms (gCOD/m3)
[𝑆𝐻𝐶 ] - Soluble hydrocarbon concentration (gCOD/m3)
[𝑋𝐻𝐶 ] - Adsorbed hydrocarbon concentration (gCOD/m3)
𝐾𝑚 - Maximum hydrocarbon adsorption ratio.
In BioWin this state variable can also be produced during the breakdown of the state variable “Ind #3”.

Adsorbed hydrocarbon COD

Adsorbed hydrocarbon COD, the only particulate industrial COD component in BioWin, is considered
biodegradable. By default, this state variable has several properties consistent with the compound
Ethylbenzene (or Xylene). There are six processes in the model that can impact on this state variable; five
growth processes and the adsorption of soluble COD described above.

858 • Model Reference Biowin 6 Help Manual

Growth Processes
Adsorbed hydrocarbon COD (XHC) may be utilized biologically under aerobic and anoxic conditions as shown
in the diagrams below. The nitrogen and phosphorus requirements for ordinary heterotrophic organism
growth (from ammonia and phosphorus respectively) are controlled by the appropriate stoichiometric
parameters (see Project|Parameters|Stoichiometric…|OHOs). The yields for growth on industrial COD
components are listed on the Project|Parameters|Stoichiometric…|OHOs on other COD tab.

Aerobic growth on Adsorbed hydrocarbon COD.

Biowin 6 Help Manual Model Reference • 859

Anoxic growth on Adsorbed hydrocarbon COD.

The rates of aerobic and anoxic growth processes on XHC were represented using a modified Monod
expression. Instead of growth being a function of the bulk concentration of the hydrocarbon COD, the
Monod equation was expressed as a function of the surface concentration of the Adsorbed hydrocarbon
COD on the ordinary heterotrophic organisms. This concentration is estimated by the ratio of Adsorbed
hydrocarbon COD to ordinary heterotrophic organism COD. The basic growth rate expression used is shown
in the following equation:

860 • Model Reference Biowin 6 Help Manual

 [𝑋𝐻𝐶 ] (24)
( ⁄[𝑍 ])
𝐵𝐻
𝜇 = 𝜇𝑚𝑎𝑥 ⋅ { } ⋅ 𝐼𝑝𝐻
[𝑋𝐻𝐶 ]
𝐾𝑆 + ( ⁄[𝑍 ])
𝐵𝐻

where

𝜇𝑚𝑎𝑥 - Maximum specific growth rate of OHOs on XHC (d-1)

[𝑍𝐵𝐻 ] - Ordinary heterotrophic organisms (gCOD/m3)
[𝑋𝐻𝐶 ] - Adsorbed hydrocarbon concentration (gCOD/m3)
𝐾𝑆 [𝑋𝐻𝐶 ]
- Half saturation constant for ( ⁄[𝑍 ])
𝐵𝐻
𝐼𝑝𝐻 - pH inhibition function.
The aerobic and anoxic growth rates also can be limited by the level of required nutrients, substrate
preferences (traditional COD over industrial COD) and the environmental conditions (including application of
an anoxic growth factor and a preference for nitrite over nitrate). For these processes to occur the following
components are required (in addition to oxygen or either nitrate or nitrite): ammonia, phosphorus, and
synthesis anions and cations.
Adsorbed hydrocarbon COD may be utilized biologically under anaerobic conditions. For this process
Ethylbenzene (or Xylene) is used as a surrogate component for Adsorbed hydrocarbon COD. Growth on
Adsorbed hydrocarbon COD is modeled as the result of an anabolic and a catabolic reaction. The anabolic
reaction fulfils the requirements for cell formation according to the following general equation:

𝑎𝐶8 𝐻10 + 𝑏𝑁𝐻3 + 𝐻3 𝑃𝑂4 + 𝑐𝐻2 𝑂 ⟶ 𝐶𝑤 𝐻𝑥 𝑂𝑦 𝑁𝑧 𝑃 + 𝑑𝐻2 (25)

The catabolic reaction provides the energy requirement for the growth of biomass through the fermentation
of Adsorbed hydrocarbon COD according to the equation below.

𝑓𝐶8 𝐻10 + 10𝑓𝐻2 𝑂 ⟶ 3𝑓𝐶2 𝐻4 𝑂2 + 2𝑓𝐶𝑂2 + 9𝑓𝐻2 (26)

Combining equations above results in the overall stoichiometry for biomass growth through Ethylbenzene
fermentation shown below.

Biowin 6 Help Manual Model Reference • 861

 (𝑓 + 𝑎) 𝐶8 𝐻10 + 𝑏𝑁𝐻3 + 𝐻3 𝑃𝑂4 + (10𝑓 + 𝑐) 𝐻2 𝑂 ⟶ (27)
𝐶𝑤 𝐻𝑥 𝑂𝑦 𝑁𝑧 𝑃 + (9𝑓 + 𝑑) 𝐻2 + 3𝑓𝐶2 𝐻4 𝑂2 + 2𝑓𝐶𝑂2

The yield can be directly related to the selected sludge formula 𝐶𝑤 𝐻𝑥 𝑂𝑦 𝑁𝑧 𝑃, 𝑓 and COD to mole ratio for
the substrate. This relationship is used to determine the stoichiometry of acetic acid, hydrogen and carbon
dioxide as shown in the diagram below. The user can independently define the N and P content of the
organism although this would defy the nitrogen and phosphorus stoichiometry developed above.

Anaerobic growth on Adsorbed hydrocarbon COD.

The fermentation of Adsorbed hydrocarbon COD by OHOs was assumed to have the same kinetic behavior as
for other substrates with the exception that a specific anaerobic growth factor for the Adsorbed
hydrocarbon COD is also applied. This allows the fermentation rate of the Adsorbed hydrocarbon COD to be
adjusted independently.

Note: XHC is modeled as a particulate component so the user needs to specify the COD:VSS ratio. The
default value of 3.2 is close the theoretical value for ethylbenzene of 3.165.

References
Baker, A., Dold, P. (1992) Activated Sludge Treatment of Petroleum Refinery wastewater: Part 1 –
Experimental behaviour. Water Science and Technology, 26(1-2):333-343.
Baker, A., Dold, P. (1992) Activated Sludge Treatment of Petroleum Refinery wastewater: Part 2 – Model
development. Unpublished.
Baker, A., Dold, P. (1992) Activated Sludge Treatment of Petroleum Refinery wastewater: Part 3 – Model
Calibration and Verification. Unpublished.

862 • Model Reference Biowin 6 Help Manual

General Parameters
The following miscellaneous model parameters can be found under:
Project|Parameters|Stoichiometric|Common

Name Default Unit Explanation

Value

Molecular weight of 35.50 mg/mmol Assume molecular weight of “other

other anions anions” state variable.
Molecular weight of 39.10 mg/mmol Assume molecular weight of “other
other cations cations” state variable.

Project|Parameters|Stoichiometric|PAO

Name Default Unit Explanation

Value

Mg to P mole ratio in 0.30 mmol Mg/mmol P Mole ratio of magnesium to

polyphosphate phosphorus in polyphosphate.
Cation to P mole ratio in 0.15 meq/mmol P Mole ratio of other cations to
polyphosphate phosphorus in polyphosphate.
Ca to P mole ratio in 0.05 mmol Ca/mmol P Mole ratio of calcium to phosphorus in
polyphosphate polyphosphate.
Cation to P mole ratio in 0.01 meq/mmol P Mole ratio of cations to phosphorus in
organic phosphate organic phosphate.

Project|Parameters|Aeration/Mass transfer|Anaerobic Digester

Name Default Unit Explanation

Value

Bubble rise velocity 23.9 cm/s The bubble rise velocity is used to
(anaerobic digester) calculate the gas holdup in anaerobic
digesters. Increasing the rise velocity
will decrease the gas holdup.
Bubble Sauter mean 0.35 Cm The Sauter mean diameter is the
diameter (anaerobic diameter of a sphere with the same
digester) volume to surface ratio as the volume
to surface ratio of the total dispersion.

Biowin 6 Help Manual Model Reference • 863

 Anaerobic digester gas 1 This parameter can be used to adjust
hold-up factor the digester mass transfer.

Aeration and Gas Transfer Model

Parameters used in BioWin's aeration and gas transfer model are accessed via a number of different tabs.
These are listed in the following sections.
Number of Processes: 11
Engineering Objective: Gas-liquid mass transfer
Implementation: permanent, always active in the BioWin model
Module Description:
There are eleven gas-liquid mass transfer processes to allow interphase transfer of oxygen, carbon-dioxide,
methane, nitrogen, ammonia, hydrogen and nitrous oxide. More details about the mass transfer model may
be found in the "Further Reading" section at the end of this chapter.
The Mass transfer model is impacted by the values of the following model parameters.

Mass transfer Parameters

Menu Location: Project|Parameters|Aeration/Mass transfer|Mass transfer
All default mass transfer parameters are referenced to 20C.
Name Default Unit Explanation
KL for H2 17.0 m/d Liquid phase mass transfer coefficient for H2
KL for CO2 10.0 m/d Liquid phase mass transfer coefficient for CO2
KL for NH3 1.0 m/d Liquid phase mass transfer coefficient for NH3
KL for CH4 8.0 m/d Liquid phase mass transfer coefficient for CH4
KL for N2 15.0 m/d Liquid phase mass transfer coefficient for N2
KL for N2O 8.0 m/d Liquid phase mass transfer coefficient for N2O
KL for H2S 1.0 m/d Liquid phase mass transfer coefficient for H2S
KL for Ind#1 COD 0.0 m/d Liquid phase mass transfer coefficient for Ind#1 COD
KL for Ind#2 COD 0.5 m/d Liquid phase mass transfer coefficient for Ind#2 COD
KL for Ind#3 COD 0.0 m/d Liquid phase mass transfer coefficient for Ind#3 COD
KL for O2 13.0 m/d Liquid phase mass transfer coefficient for O2

Menu Location: Project|Parameters|Aeration/Mass transfer|Henry's law constants

864 • Model Reference Biowin 6 Help Manual

 Name Value Unit -Hsoln / R Explanation

CO2 3.4000 E-2 M/Atm 2400 Henry’s law coefficient for CO2

O2 1.3000 E-3 M/Atm 1500 Henry’s law coefficient for O2

N2 6.5000 E-4 M/Atm 1300 Henry’s law coefficient for N2

N2O 2.5000 E-2 M/Atm 2600 Henry’s law coefficient for N2O

NH3 5.8000 E+1 M/Atm 4100 Henry’s law coefficient for NH3

CH4 1.4000 E-3 M/Atm 1600 Henry’s law coefficient for CH4

H2 7.8000 E-4 M/Atm 500 Henry’s law coefficient for H2

H2S 1.0000 E-1 M/Atm 2200 Henry’s law coefficient for H2S

Ind#1 COD 1.9000 E+3 M/Atm 7300 Henry’s law coefficient for Ind#1
COD

Ind#2 COD 1.8000 E-1 M/Atm 2200 Henry’s law coefficient for Ind#2
COD

Ind#3 COD 1.5000 E-1 M/Atm 1900 Henry’s law coefficient for Ind#3
COD

M/Atm = Mole L-1 Atm-1.

Note: The column “-Hsoln / R” is used to determine the temperature sensitivity of the Henry’s law
coefficients. See “Henry’s Law constants temperature dependencies in the "Aeration and Gas Transfer
Model" section for more details.

Aeration Parameters
Menu Location: Project|Parameters|Aeration/Mass transfer|Aeration

Name Default Value Unit Explanation

Surface pressure 101.325 kPa Atmospheric pressure at field conditions.

Biowin 6 Help Manual Model Reference • 865

 Fractional effective 0.325 - The effective saturation depth is the depth at
saturation depth which the total pressure (hydrostatic and
(Fed) atmospheric) would produce a saturation
concentration equal to the steady state
saturation concentration for the system.
Supply gas CO2 0.035 vol. % The volume percentage of carbon dioxide in
the supply gas to a diffused air system. This
parameter is also used to determine the
dissolved carbon dioxide saturation
concentration for surface aerator systems.
Supply gas O2 20.95 vol. % The volume percentage of oxygen in the supply
gas to a diffused air system. This parameter is
also used to determine the dissolved oxygen
saturation concentration for surface aerator
systems.
Off-gas CO2 2.0 vol. % The volume percentage of carbon dioxide in
the gas leaving a diffused air system. [This
parameter is not used if the gas phase is
modeled.]
Off-gas O2 18.8 vol. % The volume percentage of oxygen in the gas
leaving a diffused air system. [This parameter is
not used if the gas phase is modeled.]
Off-gas H2 0.00 vol. % The volume percentage of hydrogen in the gas
leaving a diffused air system. [This parameter is
not used if the gas phase is modeled.]
Off-gas NH3 0.00 vol. % The volume percentage of ammonia in the gas
leaving a diffused air system. [This parameter is
not used if the gas phase is modeled.]
Off-gas CH4 0.00 vol. % The volume percentage of methane in the gas
leaving a diffused air system. [This parameter is
not used if the gas phase is modeled.]
Surface turbulence 2 Unitless This parameter indicates the intensity of mixing
factor on the surface conditions (it has little impact in
aerated systems).
Set point controller 1.0 Unitless This parameter may be used to increase the
gain gain of the dissolved oxygen controller.
Typically the user would increase this value if
the controller was slow in achieving the
dissolved oxygen set point.

Menu Location: Element “Model” tab

866 • Model Reference Biowin 6 Help Manual

 Name Default Value Unit Explanation

Alpha (surf) OR 0.50 -  is the ratio of the overall mass transfer

Alpha F (diff) coefficient in process water to the overall mass
transfer coefficient in clean water. F (diffuser
fouling factor) is the ratio of the overall mass
transfer coefficient for a particular diffuser after
a given time in service to that of a new diffuser
in the same process water.
Beta 0.95 -  is the ratio of the dissolved oxygen saturation
concentration in process water to the saturation
concentration in clean water
By default Alpha and Beta can only be specified locally.

Diffuser Parameters
Menu Location: Project|Parameters|Aeration/Mass transfer|Diffuser|Set example fine bubble
diffusers

Name Default Unit Explanation

Value
k1 in C = k1(PC)0.25 + k2 1.2400 Correlation parameter
0.25
k2 in C = k1(PC) + k2 0.8960 Correlation parameter
Y
Y in KLa = C Usg 0.8880 Correlation parameter
2
Area of one diffuser 0.04100 m Area of a single diffuser is required to
determine the number of diffusers.
Diffuser mounting height 0.25 m Height of diffuser discharge above tank
floor
Min. air flow rate per diffuser 0.500 m3 hr-1 Minimum of X axis in SOTE plot.
Max. air flow rate per diffuser 10.00 m3 hr-1 Maximum of X axis in SOTE plot.

Menu Location: Project|Parameters|Aeration/Mass transfer|Diffuser|Set example coarse bubble

diffusers

Name Default Unit Explanation

Value
k1 in C = k1(PC)0.25 + k2 0.0500 Correlation parameter
0.25
k2 in C = k1(PC) + k2 0.3800 Correlation parameter
Y
Y in KLa = C Usg 1.0000 Correlation parameter

Biowin 6 Help Manual Model Reference • 867

 Area of one diffuser 0.0500 m2 Area of a single diffuser is required to
determine the number of diffusers.
Diffuser mounting height 0.2500 m Height of diffuser discharge above tank
floor
Min. air flow rate per diffuser 2.0000 m3 hr-1 Minimum of X axis in SOTE plot.
3 -1
Max. air flow rate per diffuser 50.000 m hr Maximum of X axis in SOTE plot.
By default, diffuser parameters are global but can be overridden locally on the Element’s “Model” tab.

Location: ‘Diffusers’ on Element “Operation” tab

Name Default Unit Explanation

Value

Density (%) 10.00000 % Ratio of the total active diffuser area to

the tank area as a percentage.
Diffuser information may also be specified by an ATAD or by the Number of Diffusers on the Element’s
“Operation” tab.

Surface aerator Parameters

Menu Location: Project|Parameters|Aeration/Mass transfer|Surface aerators

Name Default Value Unit Explanation

-1 -1
Surface aerator Std. 1.50000 kg O kW hr Standard oxygen transfer rate for
oxygen transfer rate rotary surface aerators

Further Reading: Gas-Liquid Mass Transfer Model

Introduction to Gas-Liquid Mass Transfer
Supply of oxygen constitutes a major operating cost for biological wastewater treatment systems. Emphasis
on energy conservation has highlighted the need to develop effective methods for design and operation of
aeration systems. Oxygen demand in activated sludge reactors varies with time, necessitating a varying
oxygen supply rate to maintain the desired dissolved oxygen (DO) concentration.
In diffused air systems bubbles are distributed from diffusers at the base of the reactor. Mass transfer
occurs between the rising bubbles and the mixed liquor. The transfer of oxygen from the gas to the liquid is
required to supply the oxygen requirements for the biological process. A number of equipment and
operational parameters interact to influence the efficiency and rate of transfer of oxygen; inter alia, diffuser
pore size and density, and air flow rate. These parameters determine factors such as bubble size, the rate of
bubble rise, the bubble residence time in the reactor, the fractional gas hold-up, the interfacial surface area
available for mass transfer, the change in oxygen partial pressure in the rising bubbles and the degree of
turbulence. Conditions in the mixed liquor also impact on the transfer; for example, temperature, ionic

868 • Model Reference Biowin 6 Help Manual

strength, presence of surface-active compounds, and solids concentration. Quantifying the impact of all
these factors on the overall mass transfer behavior is very difficult.
This section explains briefly the gas-liquid mass transfer model used in BioWin. The discussion is structured
in five parts:
1. Mass Transfer Theory: Several theoretical approaches for quantifying mass transfer have been
proposed. Researchers have used these theories as the basis for suggesting correlations for the
design of aeration systems. These theories are reviewed to highlight the assumptions required by
each approach.
2. BioWin Model for Mass Transfer:This section will provide details on the modeling approach used in
BioWin.
3. Modeling Fine Pore Diffuser Performance:This section describes parameters available in BioWin to
match fine pore diffuser performance.
4. Modeling Coarse Bubble Diffuser Performance:This section describes the parameters available in
BioWin to match coarse bubble aeration performance.
5. Basic Parameters and Relationships:This section defines a number of commonly used terms and
their formulation. The emphasis in this section is on oxygen mass transfer.
6. Conclusion:This section provides an example illustrating the differences between the methods used
in BioWin and more traditional approaches.

Mass Transfer Theory

A number of theories have been proposed to explain the phenomenon of mass transfer in gas-liquid
systems. These theories divide into two groups, describing the behavior under either laminar or turbulent
flow conditions. Under laminar flow conditions, the mass transfer coefficient may be calculated directly
since molecular diffusion prevails and the mathematics describing laminar flow and molecular diffusion are
well defined. However, most practical applications of mass transfer involve turbulent flow where the flow
regime is not well defined, and turbulent and molecular diffusion interact to determine mass transfer
behavior. In bubble aeration systems such as those encountered in wastewater treatment applications
turbulent flow conditions generally prevail.

Mass Transfer Theories under Turbulent Flow Conditions

A number of theories have been proposed to describe mass transfer behavior under turbulent flow
conditions. The principles of the more commonly used theories are discussed briefly below. Although there
is some degree of overlap the theories generally fall into two major categories: those based on a rigid
interface and those based on some form of surface renewal at the gas-liquid interface.

Rigid Interface Theories

Theories based on a rigid interface were the first to be proposed for modeling mass transfer behavior.
These are conceptually similar to theories describing conductive heat transfer, and are based on the film
theory of Lewis & Whitman (1924). In this approach it is proposed that the transfer process may be
represented by molecular diffusion across a thin, static liquid film at the interfacial surface. The driving
force for mass transfer is the concentration gradient between the interface and the outer edge of the thin
liquid film (see diagram below). Using this representation, the liquid phase mass transfer coefficient, kL, may

Biowin 6 Help Manual Model Reference • 869

be found from molecular diffusion theory (knowing the diffusivity) provided the effective film thickness can
be determined. The effective film thickness is commonly considered to be a function of the flow conditions
only. These models consequently predict that kL depends directly on the molecular diffusivity of the solute
D. However experimental data has refuted this prediction. For example, Treybal (1981) reported that kL is
proportional to Db where the exponent b varies from close to zero to 0.9.
The primary reason for the inability of rigid interface models to provide acceptable estimates of mass
transfer coefficients is that there is movement of the liquid at the interface. Therefore the steady state
situation depicted in (see diagram below) is not realistic and an alternate means for estimating the mass
transfer coefficients is necessary. Nevertheless, mass transfer coefficients are still commonly called film
transfer coefficients due to their historical origins in film theory.

BOUNDARY
LAYER
GAS PHASE LIQUID PHASE
( Well mixed and (Well mixed)
without boundary
STAGNANT
layer )
LIQUID
FILM
Saturated
concentration

INTERFACE

STEADY STATE
CONCENTRATION
PROFILE

Schematic representation of film theory for mass transfer

Surface Renewal/Penetration Theories

The inability of rigid film theory to accurately predict mass transfer coefficients resulted in the proposal of a
number of theories which incorporate some degree of unsteady state transfer. The most common of these
theories are those which are based on the concept of surface renewal, where it is assumed that there is a
continual interchange of liquid elements in contact with the gas phase. Theories based on the surface
renewal concept, or theories combining rigid interface theory with surface renewal theory, have been
widely accepted (Prasher & Wills, 1973). Perhaps the first surface renewal/penetration theory was
proposed by Higbie (1935). Higbie's penetration theory has been used by a number of authors; for example,
Calderbank (1959); Calderbank & Moo-Young (1961); Meijboom & Vogtlander (1973); Akita & Yoshida
(1974); Kiode et al. (1976); and Pöpel & Wagner (1991). Modified surface renewal/penetration models have

870 • Model Reference Biowin 6 Help Manual

subsequently been presented and used by a number of authors (including Danckwerts 1951; Dobbins 1956;
Marchello & Toor, 1963; Harriot, 1962; Sano et al. 1974; Hughmark, 1967; Treybal, 1981). Most currently
accepted correlations for mass transfer parameters make use of one or more of these theories.
The mass transfer theories presented above are useful in determining the relationship between the mass
transfer coefficient and other parameters involved in transfer. However they do not, in general, provide a
direct means of predicting the transfer coefficient because they require the evaluation, or estimation of one
or more of the hydrodynamic parameters in the model (exposure time, surface renewal rate, film thickness,
or eddy depth). Evaluation of the hydrodynamic parameters is most often achieved through analysis of
experimental mass transfer data (Prasher & Wills, 1973).

BioWin Model for Mass Transfer

The mass transfer theories proposed suggest several possible mechanisms controlling the phenomenon of
mass transfer in bubble aerated aqueous systems. Determination of which mechanism most closely
represents the actual transfer process must be based on experimental observations. Since direct
measurement of the liquid phase mass transfer coefficient is not usually possible, an average liquid phase
mass transfer coefficient is generally inferred from experimental determinations of the overall mass transfer
coefficient.
The overall mass transfer coefficient, kLaL, may be determined from a mass balance on the experimental
data. Simultaneous mass balances for a component should be conducted on both the gas and liquid phases.
This is necessary to account for the depletion of oxygen in the bubbles and mass transfer of other solutes
between the liquid and gas phases (e.g. carbon dioxide). In general, to simplify the calculation procedure,
certain assumptions are made regarding factors such as those mentioned above, as well as other factors
such as the mixing conditions in both phases. Material balances can be written for each of the species
concentrations (with gas phase interactions) by assuming that:
1. The gas phase in the reactor is completely mixed – that is the concentration of the components in
the bubbles is the same for all bubbles and uniform within each bubble. [A similar, but more
complicated model could be developed assuming plug flow of the gas through the liquid in the
control volume.]
2. The liquid phase is completely mixed – that is the liquid phase concentrations are uniform
throughout the control volume.
3. The gas hold up is constant.
These material balances can be expressed as follows:
For the liquid phase:
𝑑𝑀𝑗 𝑇 (28)
= [𝑄𝑖𝑛 ⋅ 𝐶𝑗𝑖𝑛𝑇 − 𝑄 ⋅ 𝐶𝑗 𝑇 ] + [𝛼𝐹 ⋅ (𝑘𝐿 𝑎𝐿 )𝑗 ⋅ (𝐶∞,𝑗
∗
− 𝐶𝑈𝑁,𝑗 ) ⋅ 𝑉𝐿 ] + 𝑅𝑥𝑗
𝑑𝑡

For the gas phase:

Biowin 6 Help Manual Model Reference • 871

 𝑑𝑚𝑗 (29)
= [𝑞 𝑖𝑛 ⋅ 𝑐𝑗𝑖𝑛 − 𝑞 ⋅ 𝑐𝑗 ] − [𝛼𝐹 ⋅ (𝑘𝐿 𝑎𝐿 )𝑗 ⋅ (𝐶∞,𝑗
∗
− 𝐶𝑈𝑁,𝑗 ) ⋅ 𝑉𝐿 ]
𝑑𝑡

where

𝑀𝑗 𝑇 = Mass of component j (total of all ionization states) in the liquid phase

𝑄𝑖𝑛 = Liquid flow into the control volume
𝑄 = Liquid flow out of the control volume
𝐶𝑗𝑖𝑛𝑇 = Influent liquid concentration of component j (total of all ionization states)
𝐶𝑗 𝑇 = Effluent liquid concentration of component j (total of all ionization states)
(𝑘𝐿 𝑎𝐿 )𝑗 = Overall liquid phase mass transfer coefficient for component j
𝛼 = Ratio of process water to clean water both for a new, clean diffuser
(𝑘𝐿 𝑎𝐿 )𝑃𝑟𝑜𝑐𝑒𝑠𝑠 𝑤𝑎𝑡𝑒𝑟
=
(𝑘𝐿 𝑎𝐿 )𝐶𝑙𝑒𝑎𝑛 𝑤𝑎𝑡𝑒𝑟
𝐹 = Ratio of process water after a given time in service to process water for a new
(𝑘𝐿 𝑎𝐿 )𝑆𝑒𝑟𝑣𝑖𝑐𝑒 𝑡𝑖𝑚𝑒 clean diffuser
=
(𝑘𝐿 𝑎𝐿 )𝑁𝑒𝑤 𝑑𝑖𝑓𝑓𝑢𝑠𝑒𝑟
∗
𝐶∞,𝑗 = Saturated concentration of component j at the gas/liquid interface
𝐶𝑈𝑁,𝑗 = Bulk liquid concentration of unionized component j
𝑉𝐿 = Volume of the liquid phase
𝑅𝑥𝑗 = Net production of component j by reaction
𝑚𝑗 = Mass of component j in the gas phase
𝑞 𝑖𝑛 = Gas flow into the control volume
𝑞 = Gas flow out of the control volume
𝑐𝑗𝑖𝑛 = Influent gas concentration of component j
𝑐𝑗 = Effluent gas concentration of component j
The “Net Production by Reaction” term accounts for biological generation and consumption of the
component of interest.

Note: A simplification of the model assumes that the gas phase concentration of the component is constant,
and therefore the saturation concentration of the dissolved component is constant for a given temperature.
In this case a gas phase material balance is not required however, for many systems (e.g., anaerobic
digesters), a material balance is also required for the gas phase. In BioWin the user has the option to decide
whether or not to include a gas phase material balance for bioreactors (for digesters a gas phase material
balance is always required). If the user selects to omit the gas phase material balance then BioWin will use

872 • Model Reference Biowin 6 Help Manual

the “off-gas” concentrations specified by the user on the “Aeration” parameters tab. For Surface aerators,
BioWin uses the “Supply gas” concentrations to determine the saturation concentration.

Application of the model described above requires a method for determining the saturation concentration,
and the overall mass transfer coefficient, for each species subject to gas transfer.

Determination of the Steady State Saturation Concentration at Field Conditions

The required saturation concentration at field conditions may be estimated using a Henry’s law expression
of the form:

𝑝𝑗 (30)
𝐶𝑗∗ = = 𝑝𝑗 ⋅ 𝑘𝐻,𝑗
𝐾𝐻,𝑗

where

𝑝𝑗 = Partial pressure of component j

𝑘𝐻,𝑗 = Henry’s law constant
𝐾𝐻,𝑗 = Alternate formulation Henry’s law constant
The Henry’s law constant is a function of the temperature. In BioWin the partial pressure is calculated, at 1
atmosphere, from the dry mole fraction of the solute in the gas phase (corrected for humidity) and the
temperature.

Note: If the gas phase is not modeled then BioWin uses off-gas concentrations specified (or zero if an off gas
specification is not provided for the particular component) to calculate the saturated concentration, except
in surface aerated vessels in which BioWin uses the supply gas concentrations.

The impact of diffuser submergence on pressure is calculated from:

𝑣
𝑃𝑖𝑛 𝑠𝑖𝑡𝑢 𝑃𝐹𝑖𝑒𝑙𝑑 + (𝜌𝑤𝑎𝑡𝑒𝑟 ⋅ 𝑑𝑒 ⋅ 𝑔) − 𝑃𝑤𝑎𝑡𝑒𝑟 (31)
𝛺′ = = 𝑣
𝑃𝑆𝑡𝑑 𝑃𝑆𝑡𝑑 − 𝑃𝑤𝑎𝑡𝑒𝑟

where

𝑃𝑖𝑛 𝑠𝑖𝑡𝑢 = Average pressure in the liquid phase

𝑃𝑆𝑡𝑑 = Standard atmospheric pressure
𝑃𝐹𝑖𝑒𝑙𝑑 = Atmospheric pressure at the liquid surface at field conditions

Biowin 6 Help Manual Model Reference • 873

 𝑣
𝑃𝑤𝑎𝑡𝑒𝑟 = Saturated water vapor pressure at field liquid temperature
𝜌𝑤𝑎𝑡𝑒𝑟 = Density of water at field liquid temperature
𝑑𝑒 = Equivalent saturation depth
𝑔 = Gravitational acceleration constant
The saturated vapor pressure of water at temperature T °C is calculated using the Antoine equation:

𝐵
{𝐴−(
𝑇𝑎,𝑖𝑛𝑙𝑒𝑡 +𝐶
)} (32)
𝑃𝑣𝑎𝑝 = 10 × 100

Note: The equivalent saturation depth for diffused air systems is determine by multiplying the difference
between the tank depth and the diffuser mounting height by the specified “Fractional effective saturation
depth”.

Note: For reactors with surface aeration the diffuser submergence term, evaluates to zero and the
correction reduces to a field pressure correction only.

The steady state dissolved component concentration may now be determined from:

∗
𝐶∞,𝑗 = 𝛽 ⋅ 𝛺′ ⋅ 𝑝𝑗 ⋅ 𝑘𝐻,𝑗 (33)

where

∗
𝑃𝑟𝑜𝑐𝑒𝑠𝑠 𝑤𝑎𝑡𝑒𝑟 𝐶∞
𝛽= ∗
𝐶𝑙𝑒𝑎𝑛 𝑤𝑎𝑡𝑒𝑟 𝐶∞

Henry’s Law constants temperature dependencies

There are seven possible gas phase components in BioWin, each of these uses a Henry’s law expression. The
form temperature dependency correction that is applied to the constant equation varies based on the data
available for that particular gas component. For nitrous oxide the temperature dependency is user-
configurable, the temperature correction expression is:

874 • Model Reference Biowin 6 Help Manual

 −𝛥𝑠𝑜𝑙𝑛 𝐻 1 1
𝐶𝑗∗ = 𝑝𝑗 ⋅ 𝑘𝐻,𝑗 = 𝑝𝑗 ⋅ 𝑘𝐻,𝑗
𝜃
× 𝑒𝑥𝑝 [ ( − 𝜃 )]
𝑅 𝑇 𝑇
where

𝑝𝑗 = Partial pressure of component j

𝑘𝐻,𝑗 = Henry’s law constant at field temperature
𝜃
𝑘𝐻,𝑗 = Henry’s law constant at reference temperature

−𝛥𝑠𝑜𝑙𝑛 𝐻 = Enthalpy of solution

𝑅 = Universal gas constant
−𝛥𝑠𝑜𝑙𝑛 𝐻 = Parameter used in BioWin to change the temperature dependency
𝑅
𝑇 = Field temperature
𝑇𝜃 = Reference temperature (i.e. 25oC)
For more information see: R. Sander (2015) Compilation of Henry's Law Constants for Water as Solvent
(version 4.0)
http://www.atmos-chem-phys.net/15/4399/2015/acp-15-4399-2015.html

Determination of the Overall Mass Transfer Coefficient at Field Conditions

The most appropriate method for estimating the overall mass transfer coefficient depends on the aeration
method.

Determination of the Overall Transfer Coefficient for Oxygen in Surface Aerated Vessels

In systems aerated using a surface aeration device BioWin allows the user to enter the “Device Standard
oxygen transfer rate” (mass transfer rate per unit power input at standard conditions) (SOTR’), which has
units of kg O2/kW hr or lb 02/hp hr. So the actual oxygen transferred at standard conditions is: (where theta
represents a temperature correction coefficient)
𝑆𝑂𝑇𝑅𝑇 = 𝑆𝑂𝑇𝑅′ ∙ 𝜃 𝑇−20 ∙ 𝛹
∗
Since 𝑆𝑂𝑇𝑅 = 𝑘𝐿 𝑎𝐿 ∙ 𝐶∞,𝑆𝑡𝑑 , by inputting the device standard oxygen transfer rate SOTR’ the user is
essentially specifying the overall mass transfer coefficient kLaL for the device in clean water, which BioWin
calculates as:
𝑆𝑂𝑇𝑅′
(𝑘𝐿 𝑎𝐿 )𝑂𝑥𝑦𝑔𝑒𝑛 = 𝛹 ⋅ ∗
(34)
𝐶∞,𝑆𝑡𝑑

where

Biowin 6 Help Manual Model Reference • 875

 ∗
𝐶∞,𝑆𝑡𝑑 = Steady state dissolved oxygen concentration at 20 °C and 1 atmosphere and the supply gas
oxygen concentration (dry basis)
𝛹 = Power input

The oxygen transfer rate under field conditions is given by:

∗ −𝐶
𝛺∙𝛽∙𝐶∞,𝑠
𝑂𝑇𝑅 = 𝛹 ∙ 𝛼 ∙ 𝑆𝑂𝑇𝑅′ ∙ 𝜃 𝑇−20 ∙ ( 𝑠
) (35)
∗
𝐶∞,𝑆𝑡𝑑 −0

where

∗
𝐶∞,𝑠 = saturated concentration of dissolved oxygen at the gas/liquid interface
𝐶𝑠 = DO concentration

Determination of the Overall Transfer Coefficient for Oxygen in Diffused Aeration Systems
Research has shown that the oxygen mass transfer coefficient correlates well with the superficial gas
velocity in diffused air systems. In BioWin the oxygen value is estimated using a correlation of the form:
(𝑘𝐿 𝑎𝐿 )𝑂𝑥𝑦𝑔𝑒𝑛 = 𝐶 ⋅ (𝑈𝑆𝐺 )𝑌 (36)

where

𝑈𝑆𝐺
𝑞 𝑖𝑛
= = Superficial gas velocity
𝐶𝑟𝑜𝑠𝑠 𝑠𝑒𝑐𝑡𝑖𝑜𝑛𝑎𝑙 𝑎𝑟𝑒𝑎 𝑜𝑓 𝑡𝑎𝑛𝑘

𝐶, 𝑌 = Correlation parameters
Selection of the correlation parameters C and Y depends on the type and are discussed in more detail in the
Modeling Fine Diffuser Performance section of this chapter.

Note: Correlation parameters for the mass transfer coefficient, kLaL, in BioWin are included in the model
parameter editor on the Diffuser tab. This tab can be accessed globally in
Project|Parameters|Aeration/Mass transfer|Diffuser or locally by clicking the Edit local diffuser
parameters button on the Model tab of an aerated bioreactor element.

876 • Model Reference Biowin 6 Help Manual

Determination of the Overall Transfer Coefficient for Other Components

There is little information about the overall mass transfer coefficient for other components (NH3, CO2, etc.)
in wastewater treatment processes; consequently BioWin uses the overall mass transfer coefficient
determined for oxygen to calculate the overall mass transfer coefficient of the other components. By noting
that:

(𝑘𝐿 𝑎𝐿 )𝑗 (𝑘𝐿,𝑗 ⋅ 𝑎𝐿 ) 𝑘𝐿,𝑗 (37)

= =
(𝑘𝐿 𝑎𝐿 )𝑖 (𝑘𝐿,𝑖 ⋅ 𝑎𝐿 ) 𝑘𝐿,𝑖
or
(𝑘𝐿 𝑎𝐿 )𝑖
(𝑘𝐿 𝑎𝐿 )𝑗 = ⋅ 𝑘𝐿,𝑗
𝑘𝐿,𝑖
where

𝑘𝐿,𝑖 = Liquid phase mass transfer coefficient for component j

𝐴𝑟𝑒𝑎𝐺𝑎𝑠 𝑖𝑛𝑡𝑒𝑟𝑓𝑎𝑐𝑒 = Specific interfacial gas transfer area
𝑎𝐿 =
𝑉𝐿
BioWin allows the user to enter liquid phase mass transfer coefficients for all components except oxygen
(which is assumed to be 12.96 m d-1 for the purpose of this calculation).

Modeling Fine Pore Diffuser Performance

This section describes the use of the BioWin diffused air correlation to model the performance of different
fine bubble diffusers. In the section Determination of the Overall Transfer Coefficient for Oxygen in Diffused
Aeration Systems the following correlation was introduced:
(𝑘𝐿 𝑎𝐿 )𝑂𝑥𝑦𝑔𝑒𝑛 = 𝐶 ⋅ (𝑈𝑆𝐺 )𝑌
An example of a fit using this correlation, to full-scale experimental data for 9 inch ceramic domes is shown
below.

Biowin 6 Help Manual Model Reference • 877

Overall oxygen mass transfer coefficient as a function of superficial gas velocity at a diffuser density of 25%.

The figure demonstrates that the correlation can accurately predict the observed data. Manufacturers
generally provide diffuser performance data in the form of a set of curves for a range of diffuser densities
showing SOTE/depth (%/m or %/ft) versus air flow rate per diffuser. Typically, for fine bubble systems the
curves start in the region of 8%/m (2.5%/ft) for low air flow rates, decrease with increasing air flow rate, and
level off at higher air flows. An example is shown below.

Impact of air flow per diffuser on standard oxygen transfer efficiency

These data reflect the change in the mass transfer coefficient, with increasing air flow rate and diffuser
density since SOTE is a function of the mass transfer coefficient.

Impact of Diffuser Density

The overall oxygen mass transfer coefficient for a given air flow per diffuser obviously increases with
increasing diffuser density because there is a greater total air flow. However, the figure below shows that
the increase is not proportional to the increase in diffuser density.

878 • Model Reference Biowin 6 Help Manual

Oxygen mass transfer coefficient versus air flow per diffuser for a range of diffuser densities.

In effect, the parameter C in Eq. 15 increases with diffuser density while Y is fixed for a specific diffuser type.
Analysis of data for a number of different diffuser types and sizes showed that the parameter C in Eq. 15 can
be related to the diffuser density as follows (see chart: Example relationship of correlation parameter C to
diffuser density).

𝐶 = 𝑘1 ⋅ 𝐷𝐷%0.25 + 𝑘2 (38)

where

𝑘1 , 𝑘2 = Correlation parameters with the following default values in BioWin

𝑘1 = 1.240 𝑘2 = 0.8960
𝐷𝐷% = Percentage diffuser density see Formulation of diffuser density, 𝐷𝐷%

Note: Correlation parameters for the mass transfer coefficient, kLaL, in BioWin are included in the model
parameter editor on the Diffuser tab. This tab can be accessed globally in
Project|Parameters|Aeration/Mass transfer|Diffuser or locally by clicking the Edit local diffuser
parameters button on the Model tab of an aerated bioreactor element.

The exponent parameter value in equation was determined empirically. However, there may be some
underlying theoretical basis for the value of 0.25. A theoretical analysis of aerated systems with separate
mixing by Kawase and Moo-Young (1990) indicated that the C parameter value should be related to the
power dissipation rate raised to the 0.25 power. In fine bubble diffuser systems power dissipation rate
should be related to diffuser density for a given air flow per diffuser.

Biowin 6 Help Manual Model Reference • 879

Example relationship of correlation parameter C to diffuser density.

The chart below illustrates the result of using Eq. 17 to determine C in Eq. 15. The figure demonstrates that
a single parameter set can be used to predict SOTE (%/m) with changing air flow per diffuser and diffuser
density (4 and 25%].

Predictions of SOTE (% per unit depth) versus air flow rate per diffuser for two diffuser densities [ATAD = 100/DD%].

Note: An important consideration in the design of diffused air systems is that the overall mass transfer
coefficient changes with changing air flow rate; that is, kLaL is not “constant”. Under dynamic loading
conditions, over periods when the oxygen demand is high, and a higher air flow is required, there is a drop-
off in transfer efficiency. This is an important factor when determining peak blower air delivery
requirements.

880 • Model Reference Biowin 6 Help Manual

BioWin allows the user to set up plots for bioreactors showing SOTE/depth (%/m or %/ft) versus air flow rate
per diffuser [An example system including an SOTE plot can be downloaded from the EnviroSim Web site
(www.envirosim.com)]. The chart is shown below. SOTE data are plotted for the diffuser density of the
bioreactor in question, and for four other user-selected diffuser densities. The example includes
experimental data for a number of diffuser types]. The plot can be compared to manufacturer data, and
used as a basis for selecting appropriate parameters (K1 and K2) for a particular diffuser type.

SOTE data
12
Bioreactor SOTE (%) at coverage of 20.00%
Bioreactor SOTE (%) at coverage of 15.00%
11 Bioreactor SOTE (%) at coverage of 10.00%
Bioreactor SOTE (%)
10 Bioreactor SOTE (%) at coverage of 5.00%
4.6m - 240mm Ceramic discs 7.5% coverage
4.6m - 240mm Ceramic discs 11.8% coverage
9 4.6m - 240mm Ceramic discs 15% coverage
4.6m - 220mm Ceramic discs 6.1 to 6.4% coverage
4.6m - 220mm Ceramic discs 7.0 to 7.8% coverage
8
4.6m - 220mm Ceramic discs 8.8 to 10.3% coverage
4.6m - 220mm Ceramic discs 12.1 to 12.9% coverage
7 4.6m - 220mm Ceramic discs 16.5 to 21.7% coverage
4.6m - 180mm Ceramic domes 4.8% coverage
4.6m - 180mm Ceramic domes 6.1 to 6.4% coverage
6 4.6m - 180mm Ceramic domes 8.1 to 8.4% coverage
4.6m - 180mm Ceramic domes 10.7 to 12.1% coverage
5 4.6m - 180mm Ceramic domes 17.8% coverage
4.6m - Ceramic plates
4.6m - Ceramic discs
4 4.6m - Ceramic domes
4.6m - Porous plastic discs
4.6m - Perforated membrane discs
3 4.6m - Rigid porous plastic tubes (Grid)
4.6m - Rigid porous plastic tubes (Dual spiral)
2 4.6m - Rigid porous plastic tubes (Single spiral)
0 2 4 6 8 10 4.6m - Non-rigid porous plastic tubes (Grid)
Airflow rate / Diffuser 4.6m - Non-rigid porous plastic tubes (Single spiral)

BioWin SOTE plot to assist with correlation parameter calibration

Modeling Coarse Bubble Diffuser Performance

In general the performance of coarse bubble diffuser systems is very application specific and the concept of
diffuser density and superficial gas velocity are not as useful as in fine bubble systems. Nevertheless, the
BioWin correlation Eq. 15 can usually be used to adequately predict performance. For coarse bubble
systems the impact of increasing superficial gas velocity is usually much less and consequently the
correlation between superficial gas velocity and overall mass transfer coefficient is almost linear (the Y
parameter approaches 1.0). The parameters K1 and K2 can be used to adjust the slope of the curve
appropriately (generally K1 is a small number reflecting the reduced impact of diffuser density).

Basic Parameters and Relationships

There are a number of parameters used to assist in describing and analyzing the mass transfer behavior of a
system that warrant definition or further discussion.

Biowin 6 Help Manual Model Reference • 881

Formulation for SOTR
Standard Oxygen Transfer Rate (SOTR) is defined as the mass rate at which oxygen is transferred to clean
water at 20°C and 1 atm surface pressure. In BioWin this is calculated as:

20
𝑆𝑂𝑇𝑅 = (𝑘𝐿 𝑎𝐿 )20 ′ ∗
𝑂𝑥𝑦𝑔𝑒𝑛 ⋅ 𝛺 1 𝑎𝑡𝑚 ⋅ 𝐶∞,𝑆𝑡𝑑 ⋅ 𝑉𝐿 (39)

where

∗
𝐶∞,𝑆𝑡𝑑 = Steady state dissolved oxygen concentration at 20°C and 1 atmosphere and an oxygen mole
fraction of 0.209 (dry basis).

Formulation of SOTE
The efficiency of aeration equipment usually is quantified in terms of the mass of oxygen transferred per
mass of oxygen input in clean water tests (Standard Oxygen Transfer Efficiency, SOTE). Diffuser
performance is often presented as a series of curves (for different diffuser densities and one diffuser
submergence) showing SOTE (% per unit depth) versus air flow per diffuser.

𝑆𝑂𝑇𝑅 (40)
𝑆𝑂𝑇𝐸 = ⋅ 100 %
𝑀𝑂2

where

𝑀𝑂2 = Mass rate of oxygen supply

Formulation for OTR

The oxygen transfer rate (OTR) is the rate at which oxygen is actually transferred under field conditions.

∗
𝑂𝑇𝑅 = 𝛼𝐹 ⋅ (𝑘𝐿 𝑎𝐿 )𝑗 ⋅ (𝐶∞,𝑗 − 𝐶𝑈𝑁,𝑗 ) ⋅ 𝑉𝐿 (41)

882 • Model Reference Biowin 6 Help Manual

Formulation for OTE
The oxygen transfer efficiency (OTE) is the field efficiency of oxygen transfer.

𝑂𝑇𝑅
𝑂𝑇𝐸 = ⋅ 100 % (42)
𝑀𝑂2

Formulation of Diffuser Density, DD%

Diffuser density is defined in terms of the coverage:

# 𝑑𝑖𝑓𝑓𝑢𝑠𝑒𝑟𝑠 × 𝐴𝑟𝑒𝑎 𝑝𝑒𝑟 𝑑𝑖𝑓𝑓𝑢𝑠𝑒𝑟 1 (43)

𝐷𝐷% = × 100 = × 100
𝑅𝑒𝑎𝑐𝑡𝑜𝑟 𝑎𝑟𝑒𝑎 𝐴𝑇𝐴𝐷

so:

𝐴𝑇 100 (44)
𝐴𝑇𝐴𝐷 = =
𝐴𝐷 𝐷𝐷%

where
𝐴𝑇 = Area of aeration tank.
𝐴𝐷 = Total area of diffusers in aeration tank.

Bubble Size
Bubble size and gas/liquid interfacial area are important parameters in the analysis of mass transfer
behavior. In a typical fine bubble diffused air system, the size of individual bubbles is not uniform; rather
the bubbles range in size.

Gas Hold-Up
The gas hold-up is an important parameter in mass transfer studies and is frequently used in correlations for
bubble diameter or Sauter diameter and interfacial area. Gas hold-up is generally reported as the fractional
gas hold-up; that is, the gas volume per unit dispersed phase volume. In BioWin when a gas hold up is
specified it is specified as a percentage of the liquid volume. The fractional gas hold-up can be determined
as follows:

Biowin 6 Help Manual Model Reference • 883

 𝜙⁄ (45)
𝑉𝐺 100
𝜀= =
𝑉𝐷 𝜙⁄
100 + 1

where

𝜀 = Fractional gas hold-up

𝑉𝐺 = Volume of gas phase
𝑉𝐷 = Volume of dispersed phase
𝜙 = BioWin gas hold-up percentage

Liquid Phase Mass Transfer Coefficient

The liquid phase resistance to mass transfer is the rate controlling process in most gas-liquid contacting
operations (Treybal, 1981). The liquid phase mass transfer coefficient kL is the parameter used to describe
this resistance and consequently is a fundamental parameter in oxygen transfer. Unfortunately, direct
measurement of the transfer coefficient in bubble aeration systems is not possible and it is generally
inferred from measurements of the overall mass transfer coefficient. This method results in an average
value for kL, since it is conceivable that kL varies even on the surface of a single bubble and probably from
bubble to bubble. It should also be noted that calculation of kL from the overall transfer coefficient assumes
that the specific interfacial area can be represented adequately by a single value for the whole reactor
(unless the overall transfer coefficient is found as a function of position in the reactor which is uncommon in
experimental work).

Units for Air Flow

BioWin presents air flow rates in:
• m3/hr
• ft3/min (SCFM)
In each case the basis is 20C, 1 atm (14.7 psi, 101.325 kPa)
The units for the off-gas are m3/hr (in SI units) and ft3/min (CFM) at field conditions.

Conclusion
The current approach for the design of aeration systems typically involves using a spreadsheet program to
estimate peak, average and minimum air demand in each aerated zone of a system, based on the estimated
oxygen demand. The peaks and minimums in different zones usually will not be coincident, so it is difficult
to accurately estimate total air requirements, as well as time-varying requirements. The modeling approach
in BioWin overcomes these problems through quantifying (1) the change in oxygen mass transfer coefficient
(kLaL) with changing air flow in each zone, and (2) accounting for different diffuser densities. BioWin
quantifies time-and-space variations in oxygen demand, providing accurate estimates of time-varying air
supply in different zones and hence more realistic estimates of total air supply needs. It also allows a

884 • Model Reference Biowin 6 Help Manual

comprehensive analysis of the interaction between diffuser density and oxygen transfer efficiency for the
optimal design of aeration systems.

References and Additional Reading

EPA Design Manual for Fine Pore Aeration Systems (EPA/625/1-89/023)
Fairlamb, P.M. (1991). Bubble size and oxygen transfer in diffused air activated sludge systems. M.Eng.
thesis, McMaster University, Department of Civil Engineering, Hamilton, Ontario.
Dold, P.L. and Fairlamb, P.M. (1990). Bubble size, size distribution and oxygen transfer in diffused air
systems. Proc. CSCE Conference, Hamilton, Ontario (May), pp.576-594.
Johnson, T.L. and McKinney, R.E. (1994). Modeling full-scale diffused aeration systems. Proc. ASCE
Environmental Engineering Conference.
Kawase, Y., and Moo-Young, M. (1990). Mathematical models for design of bioreactors: applications of
Kolmogoroff’s theory of isotropic turbulence. The Chemical Engineering Journal, 43, pp. B19-B41.
Randall, E.W., Goodall, C.M., Fairlamb, P.M., Dold, P.L. and O'Connor C.T. (1989). Method for measuring the
sizes of bubbles in two- and three-phase systems. J. Phys. E: Sci. Instrum., 22, pp. 827-833.

Solid-Liquid Separation / Clarifier Models

This chapter outlines the theory behind the different model types and gives examples of BioWin elements
that they are used in.

Types of Models
In BioWin there are three basic types of models used in solid / liquid separation elements:
1. Point Separation Models (i.e. dimensionless)
2. Ideal Separation Models (similar to point models, but with volume)
3. Flux based Models:
• Modified Vesilind
• Double Exponential
Each model has its own set of parameters; these are described at the end of each section.

Point Separation Models

Engineering Objective: Percentage removal of solids from a stream without volumes
Module Description:
Point separation models perform a simple mass balance calculation to split the incoming solids into two
streams. The percentage removal specified by the user is based on a mass basis. These models are
dimensionless (i.e. no volume) and therefore cannot be used to simulate biological/chemical processes.

Biowin 6 Help Manual Model Reference • 885

For example, if a user specifies that a point separator has a 95% solids capture, the point separator reports
95% of the incoming total suspended solids mass to the “thickened” stream (e.g. the underflow of a point
settling tank), and the remaining 5% reports to the “clarified” stream (e.g. the overflow of a point settling
tank).
Examples of BioWin elements that use point separation models include Dewatering Unit, Point Clarifier,
Microscreen and Cyclones.

Ideal Separation Models

Engineering Objective: Simple percentage solids removal model that accounts the impact of the separator
volume.
Module Description:
Ideal solid / liquid separation models are very similar to point separation models except for the fact that
they have volume. The total volume of BioWin elements employing ideal solid / liquid separation models is
divided into two sub-volumes:
• a “thickened” or “sludge” volume and
• a “clarified” or “liquid” volume
The relative volume proportions are specified by the user.
At steady state conditions, the mass coming out of the sludge volume zone will be the same as the mass
entering it, and specifying the flow split (e.g. the underflow rate for an ideal secondary settler) and the
percent solids removal will completely define the mass balance around the unit.
Under dynamic loading, the mass coming out of the sludge volume may not be the same as that coming in;
however it may not fluctuate as much as that coming in because the sludge zone volume has an attenuating
effect. Consider the following mass balance equation on TSS for the sludge zone, assuming a 95% solids
removal:
𝐴𝑐𝑐𝑢𝑚𝑢𝑙𝑎𝑡𝑖𝑜𝑛 = 𝑀𝑎𝑠𝑠 𝐼𝑛 − 𝑀𝑎𝑠𝑠 𝑜𝑢𝑡 (46)
𝜕𝐶
⋅ 𝑉 = 0.95 ⋅ 𝑄𝐼𝑁 ⋅ 𝐶𝐼𝑁 − 𝑄𝑂𝑈𝑇 ⋅ 𝐶𝑂𝑈𝑇
𝜕𝑡

where
𝐶 = TSS concentration (kg/m3), 𝑉 = sludge zone volume (m3), 𝑄 = Flow rate (m3/d).
For the steady state case, the change in concentration with respect to time is zero, so the left hand side of
the above equation goes to zero. Then the concentration out the bottom (COUT) may be obtained
algebraically. However, for the dynamic case, this term may not necessarily be zero - it could be positive or
negative depending on what is happening in the sludge zone, and in this case, the term involving the volume
of the thickened sludge zone does not drop out to zero. Therefore in a dynamic loading case, the volume of
the sludge zone will affect the concentration coming out the bottom. How much of an impact it has
depends on the volume, the variability of the incoming load, etc.
Ideal Separation Models can be used with the full ASDM switched on or off (default).
Examples of BioWin elements that use ideal separation models include Clarifier (Ideal), Primary Tank (Ideal)
and Activated Primary Tank (Ideal) and Grit Tank.

886 • Model Reference Biowin 6 Help Manual

Note: Grit removal elements are special cases that act only on inorganic suspended solids (ISS).

Flux Based Models

Engineering Objective: Gravitational solid / liquid separation
Implementation: Flux-based solids / liquid separation models (used in one-dimensional model clarifier
elements)
Module Description:
The general flux theory approach models solids settling in one dimension. In the one-dimensional approach
solids and liquid movement in the vertical direction are assumed to be dominant and horizontal movement
is ignored. The settling tank is divided into a number of layers in the vertical direction and a numerical
technique is used to solve the mass balance equations in the vertical direction. The solution to the mass
balance equations provides the solids concentration profile in the settling tank, and the solids concentration
in the effluent and underflow.
When considering a one-dimensional model of a secondary settling tank, one must consider the behavior in
three separate zones:
1. The zone above the feed layer.
2. The feed layer.
3. The zone below the feed layer.
This is necessary because the mass balance equations that describe a given layer change from zone to zone.
Above the feed layer, the bulk fluid movement (i.e. surface overflow rate) is upwards; therefore any solids
transport associated with the bulk fluid movement is upwards as well. Below the feed layer, the bulk fluid
movement (i.e. underflow rate) is downwards, so solids transport associated with the bulk fluid movement
also is downwards. At the feed layer, the solids mass loading of the feed must be considered, and there is
both upwards and downwards bulk fluid movement. [It is assumed that the feed flow is the sum of the
overflow and the underflow, and the "flow split" occurs in this layer]. Also, the top layer in the first zone
(i.e. overflow) and the bottom layer in the third zone (i.e. underflow) require special consideration. The top
layer in the first zone is unique as there is no solids flux into it. The bottom layer in the third zone is unique
as there only is bulk flux out of it. Another requirement of one-dimensional secondary settling tank models
is a quantitative relationship between solids concentration and settling velocity.
BioWin offers two types of flux theory-based models:
1. Modified Vesilind Settling Model
2. Double Exponential Settling Model

Note: To switch from the Modified Vesilind to the Double Exponential model click on the Model Options
button at the left of the Status bar. The settling parameters can be found under
Project|Parameters|Settling….

Modified Vesilind Settling Model

The approach used in this model is to divide the settling tank into a number of layers (minimum of 5), with a
solids concentration in each layer, resulting in an essentially one-dimensional model for sludge settling.

Biowin 6 Help Manual Model Reference • 887

The model is based essentially on standard solids flux analysis. That is, the mass flux of solids out of each
layer is assumed to be the sum of the gravity settling flux and the flux due to bulk movement (refer to the
diagram below).

Note: Fewer layers may overestimate the mass of solids on the base (i.e. bottom layer) of the settling tank.
The underflow TSS concentration essentially is determined by the thickening factor [(QI + QR) / QR], and this
will be the concentration in the bottom layer. The height of the bottom layer (settler depth divided by the
number of layers) largely determines the mass of sludge within an underloaded settling tank, so the layer
depth should correspond to the depth of sludge on the base of the settling tank. For example, to simulate
the case of say a 1 foot deep sludge layer in a 15 foot deep settling tank, set the number of layers to 15.

For steady state calculations, BioWin uses a non-linear equation solver to determine the solids
concentration in each layer of the settler. A set of equations is obtained by generating mass balance
expressions for the solids in each settler layer. Solids entering the settling tank are assumed to be
distributed instantaneously across the feed layer.
Solving the set of equations is not a trivial mathematical problem due to the exponential nature of the
sludge settling velocity expression (described in more detail below). Simulation problems can arise in
situations where the solids loading rate to the settler is high (and the settler would probably fail in practice).
These problems are due to the fact that, under certain circumstances, the set of mass balance equations
(one for each layer) can have multiple solutions. If this is encountered during the iterative solution
procedure BioWin may not be successful in moving away from a non-feasible solution to the correct
solution.
BULK MOVEMENT GRAVITY SETTLING

TOP LAYER

LAYERS ABOVE
FEED LAYER

FEED LAYER

LAYERS BELOW
FEED LAYER

BOTTOM LAYER

Representation of layered approach used in the Modified Vesilind settler model.

Bulk flux terms are given by the product of the up or downflow velocity and layer concentration, i.e.:

888 • Model Reference Biowin 6 Help Manual

 𝑄𝐼 (47)
𝐽𝐵𝑈𝐿𝐾 = ⋅ 𝑋𝑖 (𝑎𝑏𝑜𝑣𝑒 𝑡ℎ𝑒 𝑓𝑒𝑒𝑑 𝑙𝑎𝑦𝑒𝑟)
𝐴
𝑄𝑅
𝐽𝐵𝑈𝐿𝐾 = ⋅ 𝑋𝑖 (𝑏𝑒𝑙𝑜𝑤 𝑡ℎ𝑒 𝑓𝑒𝑒𝑑 𝑙𝑎𝑦𝑒𝑟)
𝐴

where
𝑄𝐼 = plant influent flow, 𝑄𝑅 = settling tank underflow rate, 𝐴 = settling tank cross-sectional area, and
𝑋𝑖 = suspended solids concentration in layer i.
Gravity flux terms are given by the product of settling velocity and layer concentration, i.e.:
𝐽𝑆,𝑖 = 𝑉𝑆,𝑖 ⋅ 𝑋𝑖 (48)

where
𝑉𝑆,𝑖 = settling velocity in layer i and 𝑋𝑖 = suspended solids concentration in layer i.

Sludge Settling Velocity

The development of a model for the settling tank requires an expression for the settling velocity of the
sludge. In order to obtain this expression it is necessary to make a number of assumptions. Firstly, zone
settling (or “hindered” settling) is assumed to be the main type of settling occurring in the settling tank.
That is, there is a distinct interface between settling particles and clarified liquid (i.e. the inter-particle forces
are sufficient for all particles in a given cross section to settle at the same rate regardless of particle size).
This means that the solids flux through the settling tank, which is given by the product of the solids
concentration and the settling velocity, varies with depth in the settling tank.
Sludge settling velocity is modeled according to the Vesilind equation for hindered settling. The settling
velocity in a given layer is given by:
𝑉𝑆,𝑖 = 𝑉0 𝑒 −𝐾𝑋𝑖 (49)

where
𝑉0 = maximum settling velocity (m/d), 𝐾 = settling parameter (m3/kg TSS), and 𝑋𝑖 = total suspended
solids (TSS) concentration (kgTSS/m3) in layer i.
The above equation can be fit to experimental data by regression to yield values for the settling
parameters 𝑉0 and K. A number of batch settling tests should be conducted to determine the zone
settling velocity (𝑉𝑆 ) over a range of suspended solids (X) concentrations. Referring to the diagram
below, the zone settling velocity for a given solids concentration is determined from the slope of the
first straight line portion of the interface height versus time plot as shown. By taking the natural
logarithm of both sides of the above equation, the following “linearized” expression is obtained:

Biowin 6 Help Manual Model Reference • 889

 𝑙𝑛 𝑉𝑆 = 𝑙𝑛 𝑉0 − 𝐾𝑋 (50)

A semi-log plot of 𝑙𝑛 𝑉0 versus 𝑋 can then be used to estimate 𝑉0 and 𝐾. The parameter 𝐾 is given by the
slope and 𝑉0 by the intercept of the line of best fit through the experimental data.
A flux curve can then be generated as a continuous function using the Vesilind expression for settling
velocity and the parameters derived from the experimental data (as shown). The expression for the mass
flux of solids can then be used in the mass balance expressions for each settler layer (the total flux being the
sum of the gravity settling flux, as described by the Vesilind equation, and the flux due to the bulk
movement of the liquid).
Due to the extensive amount of experimental testing required to determine Vesilind model parameters, a
number of correlations have been developed in order to estimate Vesilind model parameters from
settleability measures such as SVI, DSVI, etc. Extreme care should be taken in using these correlations, as
their applicability may be limited [Bye & Dold (1998), Bye & Dold (1999)].
EXPERIMENTAL CURVE FIT X / Vs

X Vs
INTERFACE HEIGHT

INCREASING X Vs (X) = f (X)

X1 Vs1
ln (Vs)

X2 Vs2
X3 Vs3

TIME X

FLUX = X * Vs (X)
FLUX

FLUX

X X

Procedure used to obtain Vesilind settling velocity model parameters.

Settling Velocity Switching Functions

A criticism of the Vesilind equation is that it over-predicts settling velocities at low concentrations.
Furthermore, the standard Vesilind equation does not account for compression settling. BioWin employs
switching functions to switch off the sludge settling velocity expression at very low solids concentrations,
and also as the solids concentration approaches the maximum solids compactability in the lower layers of
the settling tank. This provides a simplified method of modeling the poorly flocculating solids in the upper
layers of the settling tank, and compression setting in the lower layers. As the solids concentration in the
upper layers approaches the settling velocity TSS switch the settling velocity approaches zero, and solids are
carried upwards by the overflow stream (resulting in solids in the settling tank effluent). As the solids

890 • Model Reference Biowin 6 Help Manual

concentration in the lower layers approaches the maximum compactability, the settling velocity is quickly
and smoothly reduced to zero.
The settling velocity equation used by BioWin is:
𝑋𝑖 1 (51)
𝑉𝑆,𝑖 = 𝑉0 𝑒 −𝐾𝑋𝑖 ⋅ ( )⋅( )
𝐾𝑆 + 𝑋𝑖 1 + 𝑒 −𝐶𝑜𝑚𝑝𝑟𝑒𝑠𝑠𝑖𝑜𝑛 𝑆𝑒𝑡𝑡𝑙𝑖𝑛𝑔 𝑇𝑟𝑎𝑛𝑠𝑖𝑡𝑖𝑜𝑛 𝐹𝑎𝑐𝑡𝑜𝑟⋅(𝑋𝑀𝐴𝑋 −𝑋𝑖)

where
𝐾𝑆 is the upper layer settling velocity switch, 𝑋𝑀𝐴𝑋 is the maximum compactability, and other variables are
the same as in the base Vesilind equation.
The switching function effect at low concentrations for a given combination of settling velocity parameters is
shown in the figure below:

Traditional Vesilind
7

Modified Vesilind
SETTLING VELOCITY (m/h)

0
0 2 4 6

SOLIDS CONCENTRATION (kg/m3)

Settling velocity switch reduction of settling velocity at low concentration levels

You can increase the suspended solids concentration at which settling velocity is decreased by increasing the
KS parameter. Varying the KS parameter is a possible way to vary the predicted effluent suspended solids.
The switching function effect at high concentrations in the lower layers of the settling tank for a given
combination of settling velocity parameters is shown in the figure below:

Biowin 6 Help Manual Model Reference • 891

 0.25

Traditional Vesilind

0.20 Modified Vesilind

SETTLING VELOCITY (m/h)

0.15

0.10

0.05

0.00
8 10 12 14 16

SOLIDS CONCENTRATION (kg/m3)

Settling velocity switch reduction of settling velocity at high concentration levels

Lowering the XMAX parameter is a way to simulate poorly compressible bulking sludge.

Modified Vesilind Parameters

Menu Location: Project|Parameters|Settling|Modified Vesilind

Name Default Value Unit Explanation

Maximum Vesilind 170 m/d The maximum attainable settling velocity at
settling velocity (V0) theoretically infinite dilution in the
unmodified Vesilind relationship. Primarily
affects clarification function. Higher values
are associated with well-settling sludge.
Note that there is no upper limit on this
parameter so that sludge with very high
settling velocity (e.g. ballasted sludge) may
be simulated.
Vesilind hindered zone 0.37 L/g The term which describes the exponential
settling parameter (K) decrease in settling velocity with increasing
concentration in the Vesilind relationship.
Primarily affects the thickening function.
Higher values associated with poor settling
sludge.

892 • Model Reference Biowin 6 Help Manual

 Clarification switching 100 mg/L Switch applied in a Monod-type switching
function function to the Vesilind relationship.
Addresses unrealistically high settling
velocities predicted at low solids
concentrations by strict application of the
Vesilind model as originally published.
Increasing the value for this switch will result
in higher effluent suspended solids
predictions.
Specified TSS conc. for 2500 mg/L BioWin will locate and plot the height of the
height calc. specified suspended solids concentration
within the settler profile.
Maximum 15,000 mg/L The specified value is used to limit the
compactability constant maximum suspended solids concentration
that can be achieved in a model settler layer.
Also, as the solids concentration in a layer
approaches this concentration, resuspension
of solid particles occurs.

Avoiding Modified Vesilind Settler Model Problems

BioWin’s steady state solution algorithm has been improved significantly, and the Modified Vesilind settling
tank model is more robust as a result. Occasionally users may encounter situations where the solver
requires many iterations to move to a solution. Often these problems can be addressed by increasing the
maximum solids compactability.
Other hints for handling settler problems are given below:
1. It may be desirable to leave the settler profile window open during a simulation; this will allow the
user to observe the movement of the sludge blanket throughout the simulation, and indicates when
the settler is becoming overloaded.
2. If the steady state solver cannot find a solution, then subsequent dynamic simulations should allow
time for the settler to approach a solution (i.e. run the simulation over several sludge ages).
3. In order to obtain an accurate solution under dynamic conditions it may be necessary to run the
simulation over several sludge ages, until the starting point for the simulation reflects the actual
conditions of the system at the start of the time period being simulated (i.e. solids concentration in
the bioreactor, position of sludge blanket, etc. are reasonably close to initial conditions of system).

Double Exponential Settling Model

The Double Exponential settling model overcomes many of the difficulties that may be encountered with
unrestricted solids flux models (e.g. the Modified Vesilind) under certain conditions.

Note: If you want to use the Double Exponential model, you should change the dynamic integration routine
to the BWHeun method under Project > Current Porject Options > Numerical tab. Also note that use of the
Double Exponential model may result in steady state solution difficulties.

Biowin 6 Help Manual Model Reference • 893

BULK MOVEMENT GRAVITY SETTLING

TOP LAYER

LAYERS ABOVE
FEED LAYER

FEED LAYER

LAYERS BELOW
FEED LAYER

BOTTOM LAYER

Representation of layered approach used in the Double Exponential settler model.

Bulk flux terms are given by the product of the up or downflow velocity and layer concentration, i.e.:

𝑄𝐼 (52)
𝐽𝐵𝑈𝐿𝐾 = 𝐴
⋅ 𝑋𝑖 (𝑎𝑏𝑜𝑣𝑒 𝑡ℎ𝑒 𝑓𝑒𝑒𝑑 𝑙𝑎𝑦𝑒𝑟)
𝑄𝑅
𝐽𝐵𝑈𝐿𝐾 = ⋅ 𝑋𝑖 (𝑏𝑒𝑙𝑜𝑤 𝑡ℎ𝑒 𝑓𝑒𝑒𝑑 𝑙𝑎𝑦𝑒𝑟)
𝐴

where
𝑄𝐼 = plant influent flow, 𝑄𝑅 = settling tank underflow rate, 𝐴 = settling tank cross-sectional area, and 𝑋𝑖 =
suspended solids concentration in layer i.
An important aspect of this model is that the gravity flux out of a layer is not allowed to be greater than the
gravity flux that can be transmitted out of the next layer. This overcomes difficulties with “solids trapping”
that can occur under certain loading conditions in unrestricted flux models like the Modified Vesilind model.
Once again, gravity flux terms are given by the product of settling velocity and layer concentration but
incorporating the flux limit, i.e.:

𝐽𝑆,𝑖 = 𝑚𝑖𝑛(𝑉𝑆,𝑖 ⋅ 𝑋𝑖 , 𝑉𝑆,𝑖+1 ⋅ 𝑋𝑖+1 (53)

894 • Model Reference Biowin 6 Help Manual

𝑉𝑆,𝑖 = settling velocity in layer i and 𝑋𝑖 = suspended solids concentration in layer i.

Sludge Settling Velocity

The Double Exponential settling tank model uses the settling velocity function proposed by Takács et al.
(1991). The settling velocity function is applicable in regions of flocculent and hindered settling, and is given
by:

∗ ∗
𝑉𝑆,𝑖 = 𝑉0 𝑒 −𝐾ℎ 𝑋𝑖 − 𝑉0 𝑒 −𝐾𝑓𝑋𝐼 (54)

where

𝑉0 = maximum Vesilind settling velocity, 𝐾ℎ = hindered zone settling parameter, 𝐾𝑓 = flocculent zone
settling parameter, and 𝑋𝑖∗ = 𝑋𝑖 − 𝑋𝑚𝑖𝑛 where 𝑋𝑖 is the total suspended solids concentration in layer i and
𝑋𝑚𝑖𝑛 is the minimum attainable suspended solids concentration.
The minimum attainable suspended solids concentration in a layer (𝑋𝑚𝑖𝑛 ) is calculated as a fraction of the
settling tank influent solids concentration:

𝑋𝑚𝑖𝑛 = 𝑓𝑛𝑠 ⋅ 𝑋𝐹𝐸𝐸𝐷 (55)

Users may specify a maximum value for the 𝑋𝑚𝑖𝑛 parameter (the BioWin default for this parameter is 20
mg/L). Another important user-specified parameter for the Double Exponential settling tank model is the
maximum practical settling velocity, 𝑉0 ′ . This parameter sets the maximum gravitational settling velocity
that is attainable by the solids. A graphical representation of the Double Exponential settling velocity
function is shown in the figure below [note that this figure is meant to be conceptual – it is not necessarily
to scale (e.g. region I is disproportionately large in the figure)].

Biowin 6 Help Manual Model Reference • 895

 V0

SETTLING
VELOCITY

V0′

I II III IV

Xmin

TSS

The Double Exponential settling velocity function.

The Double Exponential settling velocity function consists of four regions:

1. In region I, the settling velocity is zero since the suspended solids concentration reaches the
minimum attainable suspended solids concentration.
2. In region II, the settling velocity increases with suspended solids concentration since it is strongly
influenced by the flocculent nature of the solids – the behavior of this zone is strongly influenced by
the value selected for 𝐾𝑓 .
3. In region III, settling velocity is independent of suspended solids concentration since it is
hypothesized that solids particles have reached a maximum attainable size. The settling velocity in
this region is set by the maximum practical settling velocity, 𝑉0 ′.
4. In region IV, hindered settling becomes the dominant process and the settling velocity function
reduces to the Vesilind function. The behavior of this zone is strongly influenced by the parameter
𝐾ℎ .

Double Exponential Parameters

Menu Location: Project|Parameters|Settling|Double Exponential

Name Default Value Unit Explanation

Maximum Vesilind 410 m/d The maximum attainable settling velocity at
settling velocity (V0) theoretically infinite dilution in the
unmodified Vesilind relationship.
Maximum (practical) 270 m/d The maximum settling velocity attainable in
settling velocity (V0') the Double Exponential model. This

896 • Model Reference Biowin 6 Help Manual

 constraint addresses the unrealistically high
settling velocities predicted at low solids
concentrations by strict application of the
Vesilind model. Higher values are associated
with well-settling sludge.
Hindered zone settling 0.40 L/g The term which describes the exponential
parameter (Kh) decrease in settling velocity with increasing
concentration in Zone 4 of the Double
Exponential model where hindered settling
dominates. Higher values associated with
poor settling sludge.
Flocculent zone settling 2.5 L/g The exponential term which describes settling
parameter (Kf) behavior in Zone 2 of the Double Exponential
model where flocculent settling is dominant.
Higher values associated with poor settling
sludge.
Maximum non- 20 mg/L The minimum attainable suspended solids
settleable TSS concentration in a layer is calculated as a
fraction of the settling tank influent solids
concentration, but it may not be less than this
user-specified value.
Non-settleable fraction 0.001 - The minimum attainable suspended solids
concentration in a layer is calculated as a
fraction of the settling tank influent solids
concentration.
Specified TSS conc. for 2500 mg/L BioWin will locate and plot the height of the
height calc. specified suspended solids concentration
within the settler profile.

References
Bye, C. M. and Dold, P. L. (1999) Evaluation of correlations for zone settling velocity parameters based
on sludge volume index-type measures and consequences in settling tank design, Water Environment
Research, 71, 1333-1344.
Bye, C.M. and Dold, P.L. (1998) Sludge volume index settleability measures: effect of solids characteristics
and test parameters. Water Environment Research, 70, (1), 87-93.
Takacs, I., Patry, G.G., and Nolasco, D. (1991) A dynamic model of the clarification-thickening process. Wat.
Res. 25(10), 1263-1271.
Vitasovic, Z. (1989) Continuous settler operation: a dynamic model. In: Dynamic Modeling and Expert
Systems in Wastewater Engineering. (G G Patry and D Chapman: eds.), Lewis Publishers, Inc., Chelsea,
Michigan.

Biowin 6 Help Manual Model Reference • 897

Modeling Fixed Film Processes
The objective of this chapter is to describe the biofilm model provided in BioWin. The model is implemented
in the Media Bioreactor element and is calibrated to simulate MBBR and IFAS systems.

• Model Formulation : this section describes the model structure, including the underlying
assumptions. The model belongs in the 1D dynamic layered biofilm model category, with
modifications that allow it to be used with one parameter set for a large range of process situations.
The biofilm model is integrated with BioWin’s ASDM model, which combines an Activated
Sludge/Anaerobic Digestion model with a chemical equilibrium, precipitation and pH module. This
allows the model to simulate the complex interactions that occur in the aerobic, anoxic and
anaerobic layers of the biofilm.
• Model Calibration : this section describes the basic process performance of the model with the
default parameter set.

Note: BioWin comes with several simulation examples. The model is shown to match a variety of design
guidelines, as well as experimental results from batch testing and full-scale plant operation. Both Moving
Bed BioReactors (MBBR) and Integrated Fixed Film Activated Sludge (IFAS) systems were simulated using the
same model and parameter set. Several examples are provided for the user in the Pre-Configured File
Cabinet (found on the BioWin main window toolbar). Pre-Configured File Cabinet : Click the arrow next
to this button (at the top of the main window) to select and load pre-configured BioWin process files.

Introduction
Several biofilm models have been published over the past 20 years. These vary in complexity from simple
analytical models to full 3-D dynamic models. An extensive summary is provided by Wanner et al. (2006).
The simpler models are easy to solve, but usually do not capture enough details of the important
engineering considerations. Their parameters are highly variable from situation to situation, and design
engineers often cannot allocate the time and effort required to calibrate them for different processes and
process conditions. On the other hand, the complex models, despite their sound fundamentals, are still not
used widely in engineering practice, unlike the activated sludge process models. The reason seems to be
that complex, detailed models require too much computer time to solve, and are impractical for everyday
engineering use. Their major purpose is for research.
For the specific purpose of engineering design and analysis, a balance is required between the simplified and
the complex mechanistic approach. This model should be based on biofilm and diffusion theories but
include certain empirical features that ensure solution stability and reasonable computational times. The
biofilm model must be integrated with a biological process model which includes all relevant reactions

898 • Model Reference Biowin 6 Help Manual

occurring in current wastewater treatment systems. Such a model should see widespread application in
engineering practice. This in turn will provide better designs and a basis for improving the model itself. The
engineering objective is to have a model that requires minimal calibration, and works for a wide range of
loadings and configurations, such as IFAS, MBBR, trickling filter (TF), rotating biological contactor (RBC),
biological aerated filter (BAF) with the same parameter set. In BioWin, the physical setup for IFAS and MBBR
systems is provided. However, other fixed film processes may be approximated using the existing model.

Model usage
The BioWin user working with wastewater treatment plants employing fixed film technology will be able to
obtain answers for the following questions:
• How much carrier material (i.e. area for biofilm growth) is required to achieve a specific process
objective?
• How much active biomass will the biofilm contain?
• How thick will the biofilm grow (in mm and in gTSS/m2) depending on loading and turbulence
conditions?
• How will soluble and particulate components be distributed inside the biofilm?
• What part of the biofilm will be penetrated by DO, substrate, what will be anoxic, and what part will
be anaerobic?
• How will the reaction rates for the biological processes (growth and decay of heterotrophic and
autotrophic biomass, fermentation, etc.) be distributed within the biofilm?
• How much will release of gases (N2, CH4, CO2) in the deeper layers of the biofilm contribute to
solids detachment?
• Will pH effects and precipitation reactions within the biofilm significantly change porosity, density
and conversion rates?
The typical use of models in BioWin is design, optimization, training and operations. This requires simplicity,
stability, quick solution times and proper process performance predictions on a wide range of systems. The
BioWin biofilm model achieves these objectives through the use of:
• a well calibrated, advanced biological/chemical model, including aerobic, anoxic, anaerobic,
fermentation, pH, chemical equilibrium, precipitation and gas transfer processes;
• a one dimensional (1D) fully dynamic biofilm model configuration;
• modified attachment/detachment and density calculation methods;
• one validated parameter set for a wide range of systems;
• calibration of the model to various design guidelines, batch test experiments and pilot and full-scale
performance indicators on several systems;
• a fast numerical method that provides solutions within a few minutes (note: the BioWin biofilm
model is a complex model and runs slower than a bioreactor model. However every effort was made
to provide a reasonable convergence and dynamic runtime).

Biowin 6 Help Manual Model Reference • 899

Model Formulation (Fixed Film Processes)
The dynamic mixed-culture biofilm model implemented in BioWin belongs to the class of 1D models as
described by Wanner and Reichert (1996) and Reichert and Wanner (1997). 1D models describe soluble and
particulate component profiles perpendicular to the media. Fundamental equations are listed in the two
references. The model includes diffusion of soluble and particulate components, a boundary layer between
the biofilm surface as a diffusion resistance for solutes, exchange of particulates due to detachment
(erosion) and attachment (impingement) of solids between the film surface and the bulk liquid
concentration. Film thickness can change dynamically due to substrate loading and solids exchange between
the film and the bulk liquid.
There are several differences and additions to the Wanner/Reichert model to improve its ability to predict
typical process conditions using one parameter set in the majority of cases.

The Biofilm Model Uses the Full ASDM Process Model

Due to the complexity of the numerical solution, 1D biofilm models have typically been integrated with
simple biological models. For example, models with 5-10 components [one or two biomasses (XH, XA) and
two or three limiting substrates (DO, SS, NH3), etc.]. The process model integrated with the biofilm model in
BioWin is the full Activated Sludge/Anaerobic Digestion Model (ASDM). This model is described in detail in
the Biological/Chemical models section. The model includes reactions for activated sludge and anaerobic
digestion environments, as well as pH, gas transfer and chemical precipitation within the same model
matrix.
This complex model has been applied extensively for modeling the large number of processes occurring in
suspended growth biological systems, and hence calibration requirements are significantly reduced.

Diffusion
Soluble component diffusion is described by Fick’s Second Law, with a diffusion resistance added due to the
laminar layer at the biofilm surface. Diffusion coefficients are taken at 80% (Diffusion neta) of the specified
effective diffusivities. The model provides a simple “streamer” function to increase diffusion (through
increasing available area) to the top layers of the biofilm in the case of porous films or films with streamers
in high turbulence situations (e.g. an aerated IFAS tank).

Attachment/Detachment
Particulate attachment and detachment rates have a major role in establishing biofilm thickness, dynamics,
and system activity, similar to SRT in activated sludge. Particulate attachment in this model is related to bulk
particulate concentration. Detachment is a combined function reflecting the most important variables
affecting film detachment, such as film thickness, EPS strength coefficient and the effect of N2 or CH4 gas
generation inside deeper film layers. Turbulence (G-value) is not included explicitly in the attachment and
detachment expressions above. An environment with a higher G-value will usually result in a denser, more
resistant biofilm, not necessarily a thinner film.

Biofilm Density
There are various mathematical descriptions in the literature to approximate density and porosity (Wanner
et al., 2006). In the BioWin model the long-term activity is linked to overall biofilm density through the
abundance of individual particulate state variables. Each particulate state variable has a characteristic
density or maximum concentration in the film. For example, heterotrophs and autotrophs grow to a
maximum concentration of 50 and 100 kgCOD.m-3, respectively, while inorganic solids have a maximum

900 • Model Reference Biowin 6 Help Manual

density of 1300 kg.m-3 in the film. Particulate substrate (XSP) and organic inerts (XI) are assigned a low density
(5 kgCOD.m-3). The total solids density, in each layer, is a weighted combination of the individual particulate
variable densities and is used to estimate biofilm volume, thickness and the density profile. Inorganic
suspended solids are less “sticky” (that is, have a lower EPS strength coefficient) and will detach more easily
than organic variables. This accounts for higher VSS/TSS ratios found in biofilms.

Biofilm parameters at a glance

Project|Parameters|Biofilm…
This menu item provides access to four groups of parameters through the following tabs:
• Biofilm general: General biofilm parameters (see table below)
• Maximum biofilm concentrations
• Effective diffusivities
• EPS strength coefficients
All default biofilm parameters are referenced to 20C.
Table with “Biofilm general” parameters

Name Default Value Typical use

Attachment rate [ g / (m2 d) ] 8
Attachment TSS half sat. [mg/L] 100
Detachment rate [1/d] 8.00E+03 Increase to reduce biofilm thickness
Solids movement factor [-] 10
Diffusion neta [-] 0.8 Effects all diffusivities (min 0.5)
Thin film limit [mm] 0.5
Thick film limit [mm] 3
Assumed film thickness for tank 0.75
volume correction [mm]
Film surface area to media area ratio - 1 Increase to form streamers (max 1.5)
Max.[ ]
Minimum biofilm conc. for streamer 4
formation [gTSS/m2]

Flyby panes

Flyby panes report the following values for the Media Bioreactor (example is using a typical IFAS reactor):
Physical parameters (bottom left):

Biowin 6 Help Manual Model Reference • 901

Performance parameters (bottom right):

Model Calibration
Calibration to Design and Engineering Criteria
Various design loading guidelines for IFAS and MBBR systems were checked against model performance for
each loading condition. A range of characteristics were monitored: DO and substrate penetration,
heterotrophic and autotrophic activity and location, the level of nitrification, substrate removal efficiency,
film thickness, biofilm mass per unit area, denitrification, fermentation, gas production in deep biofilm
layers, as well as pH. The model provides results according to engineering expectations. A few selected
examples are shown in the table below.

Calibration to design guidelines

System loading level Low Medium High

MBBR :
Design BOD loading gBOD.m-2.d-1 2.0 6.7 15.0
Model film thickness mm 0.1 0.5 1.0
Model mass gTSS.m-2 1.5 11.0 14.7
-3
Model effluent NO3 gN.m 14.5 0 0

902 • Model Reference Biowin 6 Help Manual

 IFAS :
Design BOD loading gBOD.m-2.d-1 3.3 10.0 16.7
Model film thickness mm 0.7 0.9 1.7
Model mass gTSS.m-2 8.3 14.2 22.1
-3
Model effluent NO3 gN.m 18.6 19.7 15.9

References
Grady, C.P.L., Daigger, G.T. and Lim, H.C. (1999). Biological Wastewater Treatment. Marcel Dekker, New
York.
Jones, R.M., Sen, D. and Lambert, R. (1998). Full scale evaluation of nitrification performance in an
integrated fixed film activated sludge process. Wat. Sci. Tech. 38(1), 71-78.
Jones, R., Lambert, R., Manoharan, R., Crane, R. and Campbell, H. (1999). Demonstration Of An Integrated
Fixed Film Activated Sludge (IFAS) System For Enhanced Nitrification Using A New Free Moving Media. Proc.
of 28th Annual Technical Symposium of the Water Environment Association of Ontario, Toronto, April.
Reichert, P. and Wanner, O. (1997). Movement of Solids in Biofilms: Significance of Liquid Phase Transport.
Wat. Sci. Tech. 36(1), 321-328.
Rusten, B., Siljudalen, J.G. and Nordeidet, B. (1994). Upgrading to nitrogen removal with the KMT moving
bed biofilm process. Wat. Sci. Tech. 29(12), 185-195.
Takács, I., Bye, C.M., Chapman, K., Dold, P.L., Fairlamb, P.M. and Jones R.M.(2007). A biofilm model for
engineering design. Wat. Sci. Tech. 55(8-9), 329-336.
Wanner, O. and Reichert, P. (1996) Mathematical Modeling of Mixed-Culture Biofilms. Biotechnology and
Bioengineering 49, 172-184.
Wanner, O., Eberl, H., Morgenroth, E., Noguera, D., Picioreanu, C., Rittman, B., and van Loosdrecht, M.
(2006). Mathematical Modeling of Biofilms. IWA Scientific and Technical Reports #18, IWA Publishing,
London, UK.
Yerrell K, Gobbie, M. Dold, P. Jones R. and Sickerdick, L. (2001). Full-scale demonstration of a free-moving
media IFAS process for enhancing nitrification performance. Proc. 74th Annual Conference of the Water
Environment Federation, Atlanta (October)

Modeling Sidestream Treatment Processes

The objective of this chapter is to describe how sidestream treatment processes are modeled in BioWin. A
sidestream reactor element is available to represent these processes in BioWin configurations.

Biowin 6 Help Manual Model Reference • 903

The Introduction provides general background information on modeling sidestream processes.
Model Formulation: this section describes the model structure. Sidestream modeling employs BioWin’s
ASDM model, which combines an Activated Sludge/Anaerobic Digestion model with a chemical equilibrium,
precipitation and pH module. This allows the model to simulate the complex interactions that occur in
sidestream processes.

Note: Examples: Several examples are provided for the user in the Pre-Configured File Cabinet : Click the
arrow next to this button (at the top of the main window) to select and load pre-configured BioWin process
files.

Introduction
Anaerobic digestion of waste activated sludge results in release of nitrogen as ammonia. Typically digested
sludge is dewatered before disposal, and the liquid stream from the dewatering step is returned to the
activated sludge process. The nutrient load of the reject water stream is considerable, and can increase the
influent nitrogen load by 15-25%. This additional load increases the cost and complexity of meeting
stringent effluent requirements for total nitrogen (TN). Also, the capacity of the liquid train to treat
additional ammonia load may be limited by factors such as influent alkalinity, insufficient aeration capacity,
or insufficient SRT.
A number of ‘named’ side-stream biological processes have been developed for treating the ammonia
component of the reject water before returning it to the liquid train (InNitri™, BABE™, SHARON™,
ANAMMOX™, CANON™, DEMON™, etc.). These systems involve one or more of the following biological
transformations, or a combination of these:
• Nitritation mediated by ammonia oxidizing autotrophic bacteria – AOB (i.e. conversion of ammonia
to NO2) or partial nitritation (i.e. converting a portion of the ammonia to NO2);
• Nitratation mediated by nitrite oxidizing autotrophic bacteria – NOB (i.e. conversion of nitrite to
nitrate –NO3);
• Denitritation mediated by ordinary heterotrophic organisms (OHOs) where nitrite serves as an
electron acceptor on the addition of organic substrate with production of nitrogen gas;
• Denitratation mediated by heterotrophic bacteria where nitrate serves as an electron acceptor on
the addition of organic substrate with production of nitrite;

904 • Model Reference Biowin 6 Help Manual

 • Nitrogen removal by autotrophic anaerobic ammonia oxidizing bacteria - AAO (Anaerobic Ammonia
Oxidizers). The process converts ammonia directly into nitrogen gas in unaerated conditions,
utilizing nitrite as an electron acceptor.
The following terminology is used to describe combinations of the basic biological transformations:
• Nitrification: nitritation followed by nitratation (i.e. conversion of ammonia to nitrite and then
nitrate);
• Denitrification: denitratation followed by denitritation (i.e. conversion of nitrate to nitrite and then
nitrogen gas);
• Deammonification: partial nitritation (i.e. converting a portion of the ammonia to nitrite) followed
by the anaerobic ammonia oxidation reaction (i.e. conversion of ammonia and nitrite to nitrogen
gas);
A range of benefits have been identified for the different side-stream treatment systems; for example:
• Seeding the activated sludge train with AOB and NOB grown in the side-stream stage, allowing
shorter SRTs (bioaugmentation).
• Less carbon substrate is required to denitrify nitrite rather than nitrate.
• Less aeration (and alkalinity) is required to convert ammonia to nitrite rather than nitrate.
• In the ANAMMOX™ process no organic carbon is added for denitrification, and so there is no
increased biosolids production or emission of CO2.
Side-stream systems focused on ammonia treatment have been implemented in a number of reactor
configurations; for example, single and series flow-through CSTRs, reactor-clarifiers with sludge recycle,
SBRs, attached growth systems. The operating conditions of side-stream biological processes are
considerably different from those in the main stream process. This leads to a number of unique
considerations for operation and control:
• Stopping nitrification at the nitrite stage and preventing nitrate formation relies on the difference in
growth rates between AOB and NOB, and the different temperature dependencies.
• High concentrations of substrate and product species such as ammonia and nitrous acid can lead to
inhibitory conditions for AOB and NOB. In some cases successful performance depends on inhibition
of certain reaction steps.
• Careful pH control often is required for successful operation.
• Anaerobic ammonia oxidizers have very low growth rates necessitating long SRTs, and long process
start-up times.

Model Formulation (Sidestream Treatment Processes)

The table below summarizes key process considerations that a model for side-stream processes should
include. Several models for a number of side-stream processes have been reported. For example, Volcke
(2006) developed a two-step nitrification and denitrification model to represent the SHARON process. Wett
and Rauch (2003) developed a two-step nitritation-denitritation model based on detailed data from two full-
scale reject water SBR treatment processes. Van Hulle (2005) incorporated anaerobic ammonia oxidation
reactions into a two-step nitrification/denitrification model.
Summary of key process aspects that a model for side-stream processes must include.

Biowin 6 Help Manual Model Reference • 905

 Process Aspect Model Process Important Considerations

Nitrification AOB growth and decay Different growth rates, temperature

dependencies and inhibition effects.
NOB growth and decay
Heterotrophic Growth on substrate through Differences in yield must be accounted
Denitrification denitritation (using nitrite as an for.
electron acceptor)
Growth on substrate through
denitratation (using nitrate as an
electron acceptor)
Deammonification Growth and decay of AAO Appropriate inhibitions (i.e. nitrite
(ANAMMOX™) toxicity) and limitations must be
included.
pH All significant equilibrium pH modeling is essential because, for
relationships (i.e. nitric and example, some inhibition effects are
nitrous acid, ammonia and caused by unionized species
carbonate system) concentrations.
Gas-liquid Stripping of certain model Gas-liquid interactions are essential to
interactions components such as ammonia and represent pH and in some cases, to
carbon dioxide properly represent growth-limiting
conditions.

Sidestream Modeling Uses the Full ASDM Process Model

The reported models for the biological transformations described in the Introduction as important in
sidestream processes were refined, and incorporated into BioWin’s full Activated Sludge/Anaerobic
Digestion Model (ASDM). This model is described in detail in the ASDM model (Biological/Chemical Models)
section. The model includes reactions for activated sludge, anaerobic digestion and sidestream reactor
environments, as well as pH, gas transfer and chemical precipitation within the same model matrix.
This complex model has been applied extensively for modeling the large number of processes occurring in
suspended growth biological systems, and hence calibration requirements are significantly reduced.
The key difference between a sidestream reactor element and a bioreactor element, is that the sidestream
reactor element has the Local temperature option selected by default as it is frequently used to model
digester effluents that may be elevated in temperature. The default setting is a constant temperature of 35
degrees Celsius. Also, the sidestream reactor element is seeded appropriately to improve solution speed.

References
Caffaz, S., C. Lubello, R. Canziani, and D. Santianni (2005). “Autotrophic nitrogen removal from supernatant
of Florence’s WWTP digesters”. Proceedings of the IWA Specialized Conference Nutrient Management in
Wastewater Treatment Processes and Recycle Streams, Krakow, Poland, 19-21 September, 2005.
Van Hulle, Stijn (2005). Modelling, simulation, and optimization of autotrophic nitrogen removal processes.
Ph.D. thesis, Ghent University, Belgium.

906 • Model Reference Biowin 6 Help Manual

Volcke, E.I.P. (2006). Modelling, analysis and control of partial nitritation in a SHARON reactor. Ph.D. thesis,
Ghent University, Belgium.
WERF (Water Environment Research Foundation) (2003) Methods for Wastewater Characterization in
Activated Sludge Modeling. Project 99-WWF-3, ISBN 1-893664-71-6. Alexandria, Virginia.
Wett, B. and W. Rauch (2003). The role of inorganic carbon limitation in biological nitrogen removal of
extremely ammonia concentrated wastewater. Water Research, 37, 1100-1110.

Modeling Granular Sludge Sequencing Tanks

This chapter describes how granular sludge sequencing tanks are modeled in BioWin. A Granular Sludge
Sequencing Tank (GSST) element is available to represent this process in BioWin configurations.

The Introduction provides general background information on modeling granular sludge sequencing tanks.
Model Description: This section describes the general approach and empirical assumptions therein. The
modeling approach uses BioWin’s one-dimensional dynamic biofilm model to mimic the granular sludge. A
one-dimesional layered solids flux model is applied for modeling settling of non-granular flocculant mixed
liquor solids. These are integrated with the general ASDM in a variable volume unit.
Model Calibration: This section illustrates the basic process performance of the model with the default
parameter set. The model is applied to the simulation of a full-scale GSST nutrient removal plant.

Note: An example GSST flowsheet is provided in the Pre-Configured File Cabinet (found on the BioWin main
window toolbar ). Click the arrow next to this button to select and load the example GSST flowsheet.

Introduction
This section presents BioWin’s approach to modeling GSSTs. The model has been developed to balance
pragmatic design elements with mechanistic modeling rigor, to provide quick solution times, and typical
process performance predictions.
Most GSST technology implementations employ a repeated batch-fed process. The microorganisms
responsible for the majority of the carbon, nitrogen and phosphorous removal grow in dense granules

Biowin 6 Help Manual Model Reference • 907

rather than conventional activated sludge flocs. These granules settle rapidly, eliminating the need for
separate settling tanks. The granules have a layered structure that may be more aerobic on the outside and
anoxic or anaerobic towards the centre. This structure allows the granular sludge to simultaneously remove
carbon, nitrogen and phosphorous from the wastewater in a single reactor/settler.

Model Description
The GSST modeling approach uses BioWin’s one-dimensional dynamic biofilm model (described in detail in
the Model Reference > Modeling Fixed Film Processes > Model usage section). The biofilm model is used to
represent the granules. This biofilm model is incorporated into BioWin’s full Activated Sludge/Anaerobic
Digestion Model (ASDM). The model is described in detail in the Model Reference > Biological/Chemical
Models section. The model includes reactions for activated sludge, anaerobic digestion and sidestream
reactor environments, as well as pH, gas transfer and chemical precipitation within the same model matrix.
A one-dimensional layered solids flux model simulates settling of non-granular mixed liquor solids during
unaerated/unmixed periods. This model is described in detail in the Model Reference > Solid-Liquid
Separation > Flux Based Models section. The standard implementation of the GSST element in BioWin uses
the Modified Vesilind settling model approach. The biofilm, ASDM and settling models are all implemented
in a variable volume unit that allows various phases of operation to be specified. The dynamic solver
generates fast solutions and allows interactive design and analysis with the complex model.
In the modeling approach, the granular sludge mass is represented by a biofilm with a calculated surface
area and film thickness. The biofilm thickness is assumed to be equivalent to the “average” granule radius.
The model does not predict new granule “formation” or consider a granule size distribution, but the
diameter of granules may change dynamically depending on loading. The dynamic mixed-culture biofilm
model used in the approach includes the following aspects:
A boundary layer at the biofilm surface as a diffusion resistance for mass transfer of solutes.
Diffusion of soluble, particulate and dissolved gaseous components within the biofilm.
Exchange of particulates between the film surface and the bulk liquid due to detachment (erosion) and
attachment (impingement).
Growth (and decay) of different biomass species within the biofilm.
In general, the GSST flowsheet element in which the models are implemented incorporates the following
features to capture typical operational aspects of GSSTs and the resulting process performance:
• Each cycle in the GSST has a mixing phase followed by a settling phase. Aeration may be switched on
and off during the mixing phase (based on DO setpoint or air flowrate).
• During the mixing phase, the granules are assumed to be completely mixed within the bulk liquid.
• When settling begins, the granules instantaneously settle to the bottom of the tank and occupy a
percentage of the reactor volume. The volume of the granules themselves is based on granular
biofilm volume. However, the volume occupied by the granules is larger because volume is reserved
for voidage between the granules.
• The GSST uses a variable volume one-dimensional solids flux model to simulate settling of mixed
liquor (non-granular) solids. The bulk liquid above the volume of settled granules is divided into “n”
equal-depth layers during settling (n = 10 in the default GSST implementation).
• The GSST typically is fed at or near the end of the settling phase. The feed enters the bottom of the
tank where the settled granules are located and flows through the voidage volume across the

908 • Model Reference Biowin 6 Help Manual

 surface of the settled granules. The voidage volume is considered to be completely mixed, rather
than plug or semi-plug flow. As the feed flows into the bottom of the unit, liquid is displaced
upward, through the layers above the granule volume. At the top of the GSST, liquid can overflow or
be decanted as treated effluent.
• Waste activated sludge (WAS) is removed from the bottom layer of the settled mixed liquor solids;
the granules are not removed in the waste flow. However, granular mass and composition is not
static because there is attachment to and detachment from the granule surface continuously during
the mixed phase.
• The user has the option to incorporate a small decant event prior to commencing a mix/react phase
to drop the liquid level in the GSST. This provides some freeboard to avoid spillage of mixed reactor
contents when aeration commences. The decant is removed from the top layer of the bulk liquid.

Flow schematic of the GSST in settle mode

The BioWin user working with wastewater treatment plants employing GSST technology will be able to
obtain answers for the following questions:
• How much granular sludge mass and granular sludge surface area is required to achieve a specific
process objective?
• How much active biomass will the granular sludge contain?

Biowin 6 Help Manual Model Reference • 909

 • What will the average diameter of the granules be (in mm) depending on substrate loading, solids
exchange between the granules and the bulk liquid, EPS strength coefficients and the effect of gas
(N2, CH4, CO2) generation inside the granules?
• How will soluble and particulate components be distributed inside the granules?
• Will different growth regimes (e.g. aerobic, anoxic, anaerobic) exist over the granual radius?
• How will the reaction rates for the biological processes (growth and decay of heterotrophic and
autotrophic biomass, fermentation, etc.) be distributed within the granules?
• Will pH effects and precipitation reactions within the granules significantly change porosity, density
and conversion rates?

GSST parameters

This section describes the rationale behind some of the “default” settings that exist within the GSST element
when it is first placed on the drawing board. It is important to note that these are not intended to serve as
strict design guidelines, but rather, reasonable starting points.
Dimensions tab
The GSST usually is 16 to 24 feet (4.9 to 7.3 m) deep. When the GSST element is placed onto the drawing
board, the default depth is 6 m.
Granules tab
The formation of the granules is not modelled; the GSST initially contains a user-input estimated volume of
granular sludge. The user also specifies estimates for the initial granule diameter (D) and a voidage factor ()
for settled granules, as follows:

910 • Model Reference Biowin 6 Help Manual

The granules tab of a GSST

• Estimated granule settled volume fraction (FG) of reactor volume (Vt). This sets the initial estimate
of the reactor volume occupied by both the granules and the intergranular voidage when granules
are settled on the bottom of the reactor at the beginning of a simulation from seed conditions.
• Estimated granule diameter (D) [mm]. This sets the initial diameter of the granules at the beginning
of a simulation from seed conditions.
• Voidage (of settled granules) (E). This sets the percentage of the granule settled volume occupied by
voidage.
These user-defined parameters are used to calculate the base granular surface area (A) [in metric units]:
[𝐹𝐺 × 𝑉𝑡 × (1 − 𝐸)]
𝐴 (𝑚2 ) =
𝐷
2000
The base granular surface area and the user-specified voidage fraction are held constant throughout a
dynamic simulation. The GSST model dynamically calculates the granular diameter depending on a number
of factors, such as substrate loading and solids exchange between the granules and the bulk liquid. The

Biowin 6 Help Manual Model Reference • 911

granular settled volume fraction of the reactor volume changes proportionally to the model-calculated
granular surface area, according to the rearranged base granular surface area equation:
[𝐴 × 𝐷]
𝐹𝐺 =
𝑉𝑡 × (1 − 𝐸) × 2000
When a GSST element is placed onto the drawing board, the default specifications are: Vt = 10,000 m3; D =
0.8 mm; FG = 16%; and E = 25%; this results in a base granular surface area of 3,000,000 m2, and the
granular surface area to tank volume ratio is 300 m2/m3.
Users are required to specify initial estimates of granule diameter (D), granular settled sludge volume
fraction (FG, as a %), and voidage fraction (E, as a %). Experience indicates that D may range from say 0.6 to
1.5 mm, and the voidage likely is in the range of 20 to 28%. In addition it appears that the granular surface
area to tank volume ratio [A/Vt] should be in the range of 300 to 500 m2/m3. If the user selects a target
diameter (D) and a voidage fraction (E), an initial estimate of the FG value can be obtained from:
(300 𝑡𝑜 500) × 𝐷
𝐹𝐺 =
(1 − 𝐸) × 2000
For a desired granule diameter of 0.8 mm and a surface area to tank volume of 300 m2/m3 at a voidage of
25%, the FG fraction would be 0.16 (16%).

Waste tab
Typically thickened mixed liquor is removed from the GSST partway into the settling period, before the GSST
is fed. Granules are never wasted from the GSST, only bulk mixed liquor. If wasting occurs at some point in
the settling period, it is removed from the bottom settling layer.
Model tab
When a GSST element is placed onto the drawing board, local biofilm, kinetic, diffuser and settling
parameters are applied. This is done to allow certain parameter values in the GSST to differ from BioWin’s
global defaults. The reasoning for adjusting these particular parameter values is described below. Again, it
should be noted that the user may adjust any of the model parameter values to a different value from those
specified when the GSST element is placed onto the drawing board. This should be done when calibrating
the GSST model to measured data from full-scale or pilot-scale GSST plants. The default settings are
provided as a means to achieve typical process performance, but are not intended to serve as strict design
guidelines.
Under the Granule model options section on the Model tab, the number of internal layers (through
granule) setting is specified as three. Increasing the number of layers may impact gradients of dissolved
oxygen, substrates and biomass species throughout the granules. However, the biofilm model is
computationally intensive, so increasing the number of layers increases simulation time. Assuming three
layers appears to provide a good balance of these factors in calibrating GSST models to full-scale and pilot-
scale systems.
The Boundary layer thickness is specified as 50 micrometers. This thickness appears suitable for calibrating
GSST models with respect to the observed removal of nitrogen and phosphorous.
Local biofilm parameters are used to specify thin and thick biofilm limits lower than the BioWin defaults,
and maximum biofilm concentrations of particulate organics greater than the BioWin defaults.
The granular sludge mass is represented by a biofilm with a calculated surface area and film thickness. The
biofilm thickness is assumed to be equivalent to the “average” granule radius. The granular diameter is

912 • Model Reference Biowin 6 Help Manual

therefore equivalent to two times the biofilm thickness. On the Biofilm general tab, the thin and thick film
limits are set at 0.30 mm and 0.75 mm, respectively. This favors the development of granular diameters
between 0.6 mm and 1.5 mm.
The concentration of organic particulate state variables may be higher in granules than in conventional
biofilms growing in IFAS and MBBR systems. (Model Reference > Modeling Fixed Film Processes > Model
Formation > Biofilm Density). The user may easily adjust the maximum biofilm concentrations of particulate
organics by right-clicking on the value column, selecting “Multiply column (Part. organics only)”, and then
specifying a factor. On the Maximum biofilm concentrations tab, the specified maximum biofilm
concentrations of particulate organics are 5 times the default values.
Local kinetic parameters are used to set the OHO dissolved oxygen half saturation parameter on the
Switches tab to 0.25 mgO2/L. This allows for more simultaneous nitrification/denitrification than is typically
observed in well-mixed well-aerated conventional activated sludge reactors. The user may adjust this
parameter to calibrate the GSST model to match measured effluent ammonia, nitrate and nitrite
concentrations.
Local diffuser parameters are used to modify the K1 parameter. The K1 parameter value has been
decreased to 1.0 to achieve reasonable SOTE performance at a GSST depth of 6 m.
Local settling parameters are set to adjust the maximum Vesilind settling velocity (Vo), Vesilind hindered
zone settling parameter (K) and Maximum compactability constant parameter values to reflect the rapid
settling observed in GSSTs. The Vo value is 340 m/d and the K value is 0.18 L/g. To avoid losing a significant
mass of bulk suspended solids, the settling velocity of the interface must be greater than the upflow velocity
when the influent flow is introduced in the bottom of the GSST, and these parameter values should achieve
that for most cases. However, they may require further adjustment if the simulated GSST effluent solids are
undesirably high. The maximum compactability constant is locally increased to 30,000 mg/L to reflect the
high compactability of solids observed in GSSTs. Note that all of the settling parameter adjustments are for
the Modified Vesilind approach of BioWin. As such, the Modified Vesilind settling model (Model Reference >
Solid-Liquid Separation / Clarifier Models > Flux Based Models > Modified Vesilind Settling Model) must be
used with the GSST element.

Flyby panes

Flyby panes report the following values for the GSST; note that the user is given an indication of what
parameters are set locally by red text.
Physical parameters (bottom left):

Biowin 6 Help Manual Model Reference • 913

Performance parameters (bottom right):

References
Pronk, M., de Kreuk, M.K., de Bruin, B., Kamminga, P., Kleerebezem, R. and M.C.M van Loosdrecht. (2015),
Full scale performance of the aerobic granular sludge process for sewage treatment. Wat. Res., 84, 207-217.
Reichert, P. and Wanner, O. (1997). Movement of Solids in Biofilms: Significance of Liquid Phase Transport.
Wat. Sci. Tech. 36(1), 321-328.
Takács, I., Bye, C.M., Chapman, K., Dold, P.L., Fairlamb, P.M. and Jones R.M.(2007). A biofilm model for
engineering design. Wat. Sci. Tech. 55(8-9), 329-336.
Wanner, O. and Reichert, P. (1996) Mathematical Modeling of Mixed-Culture Biofilms. Biotechnology and
Bioengineering 49, 172-184.
Wanner, O., Eberl, H., Morgenroth, E., Noguera, D., Picioreanu, C., Rittman, B., and van Loosdrecht, M.
(2006). Mathematical Modeling of Biofilms. IWA Scientific and Technical Reports #18, IWA Publishing,
London, UK.

Definition of Non-State Variables

To model the range of system types it is necessary to track the concentrations of a large number of
components (state variables) in each stream of a configuration. In certain cases tracking a number of the
variables may be superfluous. For example, if a system incorporates only an aerobic activated sludge unit
then all variables relating to biological phosphorus removal will have zero concentration values (PAO mass,
stored polyphosphate, etc.).
Each element in the configuration is modeled to provide a mass balance on the ASDM state variables shown
in the first table below.
BioWin calculates a number of combined variables and element-specific variables that may be displayed for
certain elements. The second table below defines these variables.

914 • Model Reference Biowin 6 Help Manual

BioWin ASDM state variables
Long name Short name Units

Biomass - Acetoclastic methanogenic B - Zam mgCOD/L

Biomass - Ammonia oxidizing B - Zao mgCOD/L
Biomass - Anaerobic ammonia oxidizing B - Zaao mgCOD/L
Biomass - Endogenous products B - Ze mgCOD/L
Biomass - Hydrogenotrophic methanogenic B - Zhm mgCOD/L
Biomass - Methylotrophic B - Zm mgCOD/L
Biomass - Nitrite oxidizing B - Zno mgCOD/L
Biomass - Ordinary heterotrophic B - Zh mgCOD/L
Biomass - Phosphorus accumulating B - Zpa mgCOD/L
Biomass - Propionic acetogenic B - Zppa mgCOD/L
Biomass - Sulfur oxidizing B - Zso mgCOD/L
Biomass - Sulfur reducing acetotrophic B - Zsra mgCOD/L
Biomass - Sulfur reducing hydrogenotrophic B - Zsrh mgCOD/L
Biomass - Sulfur reducing propionic acetogenic B - Zsrpa mgCOD/L
CODp - Adsorbed hydrocarbon CODp - Xhc mgCOD/L
CODp - Degradable external organics CODp - Xeo mgCOD/L
CODp - Slowly degradable colloidal CODp - Xsc mgCOD/L
CODp - Slowly degradable particulate CODp - Xsp mgCOD/L
CODp - Stored PHA CODp - Spha mgCOD/L
CODp - Undegradable cellulose CODp - Xuc mgCOD/L
CODp - Undegradable non-cellulose CODp - Xu mgCOD/L
CODs - Acetate CODs - Sa mgCOD/L
CODs - Complex readily degradable CODs - Sc mgCOD/L
CODs - Degradable volatile ind. #1 CODs - SInd1 mgCOD/L
CODs - Degradable volatile ind. #2 CODs - SInd2 mgCOD/L
CODs - Degradable volatile ind. #3 CODs - SInd3 mgCOD/L
CODs - Methanol CODs - Smeth mgCOD/L
CODs - Propionate CODs - Sp mgCOD/L
CODs - Soluble hydrocarbon CODs - Shc mgCOD/L
CODs - Undegradable CODs - Su mgCOD/L
Gas - Dissolved hydrogen G - H2 mgCOD/L

Biowin 6 Help Manual Model Reference • 915

 Gas - Dissolved methane G - CH4 mg/L
Gas - Dissolved nitrogen G - N2 mgN/L
Gas - Dissolved nitrous oxide G - N2O mgN/L
Gas - Dissolved oxygen G - DO mg/L
Gas - Dissolved total CO2 G - TCO2 mmol/L
Gas - Dissolved total sulfides G - H2S mgS/L
HAO - Aged HAO(A) mg/L
HAO - High surface HAO(H) mg/L
HAO - High with H2PO4- adsorbed HAO(H).P mg/L
HAO - Low surface HAO(L) mg/L
HAO - Low with H2PO4- adsorbed HAO(L).P mg/L
HFO - Aged HFO(A) mg/L
HFO - High surface HFO(H) mg/L
HFO - High with H+ adsorbed HFO(H).H mg/L
HFO - High with H2PO4- adsorbed HFO(H).P mg/L
HFO - Low surface HFO(L) mg/L
HFO - Low with H+ adsorbed HFO(L).H mg/L
HFO - Low with H2PO4- adsorbed HFO(L).P mg/L
Influent inorganic suspended solids ISSinf mgISS/L
Metal soluble - Aluminum M - Al mg/L
Metal soluble - Calcium M - Ca mg/L
Metal soluble - Ferric M - Fe3 mg/L
Metal soluble - Ferrous M - Fe2 mg/L
Metal soluble - Magnesium M - SMg mg/L
N - Ammonia N - NH3 mgN/L
N - Nitrate N - NO3 mgN/L
N - Nitrite N - NO2 mgN/L
N - Particulate degradable external organics N - Xeon mgN/L
N - Particulate degradable organic N - Xon mgN/L
N - Particulate undegradable N - Xun mgN/L
N - Soluble degradable organic N - Nos mgN/L
N - Soluble undegradable organic N - Nus mgN/L

916 • Model Reference Biowin 6 Help Manual

 Other Anions (strong acids) San meq/L
Other Cations (strong bases) Scat meq/L
P - Bound on aged HMO P - HMO(A) mgP/L
P - Particulate degradable external organics P - Xeop mgP/L
P - Particulate degradable organic P - Xop mgP/L
P - Particulate undegradable P - Xup mgP/L
P - Releasable stored polyP P - PP-lo mgP/L
P - Soluble phosphate P - PO4 mgP/L
P - Unreleasable stored polyP P - PP-hi mgP/L
Precipitate - Brushite Pr - XDCPD mgISS/L
Precipitate - Ferrous sulfide Pr - FeS mgISS/L
Precipitate - Hydroxy - apatite Pr - XHAP mgISS/L
Precipitate - Struvite Pr - MAP mgISS/L
Precipitate - Vivianite Pr - XHIP mgISS/L
S - Particulate elemental sulfur S - Sulf mgS/L
S - Soluble sulfate S - TSO4 mgS/L
User defined - UD1 UD1 mg/L
User defined - UD2 UD2 mg/L
User defined - UD3 UD3 mgVSS/L
User defined - UD4 UD4 mgISS/L
Flow Flow Unit system dependent
Liquid volume Liq.Vol. Unit system dependent
Temperature Temp. Degrees Celsius

BioWin Combined Variables

Long name Short name Description

Alkalinity Alk Alkalinity is calculated from weak acid/base chemistry – see the
Modeling of pH in BioWin section.

BOD – Filtered CBOD – S See BOD section below

Carbonaceous
BOD – Total CBOD – T See BOD section below
Carbonaceous

Biowin 6 Help Manual Model Reference • 917

 COD – Filtered COD – S Filtered COD is calculated as the sum of all soluble state variables
(including colloidal material) that contribute to COD as follows:

CODs-Sc + CODs-Sa + CODs-Sp + CODs-Smeth + CODs-Su + CODs-

Sind1 + CODs-Sind2 + CODs-Sind3 + CODs-Shc + CODp-Xsc + G-H2 +
(G-CH4)*4
COD – Volatile COD – VFA VFA contribution to COD is calculated as the sum of acetate and
fatty acids propionate:
CODs-Sa + CODs-Sp
COD – COD – P Particulate COD is calculated as the sum of all particulate state
Particulate variables that contribute to COD as follows:
B-Zam + B-Zao + B-Zaao + B-Zhm + B-Zm + B-Zno + B-Zh + B-Zpa + B-
Zppa + B-Zso + B-Zsra + B-Zsrh + B-Zsrpa + B-Ze + CODp-Xhc + CODp-
Xeo + CODp-Xsp + CODp-Spha + CODp-Xuc + CODp-Xu
COD – Total COD – T Total COD is the sum of filtered and particulate COD:
COD-S + COD-P
ISS cellular ISScell ISScell is the sum of inorganic solids from the poly-P content of
phosphorus accumulating biomass (Term A below), cations
associated with poly-P uptake (Term B below), synthesis P content of
biomass (Term C below), and biomass synthesis cations and anions
(Term D below):
Term A
(P-PP-lo + P-PP-hi)*MW P2O5 / MW P
where MW O is 15.9994; MW P is 30.97376
Term B
(P-PP-lo + P-PP-hi)*(“Mg to P mole ratio in polyphosphate”*MW Mg /
MW P + “Ca to P mole ratio in polyphosphate”*MW Ca / MW P +
“Cation to P mole ratio in polyphosphate”*MW Cations / MW P)
where MW Mg is 24.305; MW Ca is 40.08; MW Cations is 39.0983;
MW P is 30.97376; default Mg to P mole ratio in polyphosphate is 0.3
mmolMg/mmolP; default Ca to P mole ratio in polyphosphate is 0.05
mmolCa/mmolP; default Cation to P mole ratio in polyphosphate is
0.15 meq/mmolP
Term C
[(B-Zam + B-Zao + B-Zaao + B-Zhm + B-Zm + B-Zno + B-Zh + B-Zpa + B-
Zppa + B-Zso + B-Zsra + B-Zsrh + B-Zsrpa + B-Ze)*Stoichiometric P
Content]*MW P2O5 / MW P

918 • Model Reference Biowin 6 Help Manual

 where MW O is 15.9994; MW P is 30.97376; default Stoichiometric P
Content for biomass is 0.022 mgP/mgCOD (note each organism has
its own); default Stoichiometric P Content for endogenous material is
0.022 mgP/mgCOD
Term D
(B-Zam + B-Zao + B-Zaao + B-Zhm + B-Zm + B-Zno + B-Zh + B-Zpa + B-
Zppa + B-Zso + B-Zsra + B-Zsrh + B-Zsrpa + B-Ze)*(“Biomass/Endog Ca
content” + “Biomass/Endog Mg content” + “Biomass/Endog other
Cations content”*MW Cations + “Biomass/Endog other Anions
content”*MW Anions)
where MW Cations is 39.0983; MW Anions is 35.5; default
Biomass/Endog Ca content is 3.912x10-3 gCa/gCOD; default
Biomass/Endog Mg content is 3.912x10-3 gMg/gCOD; default
Biomass/Endog other Cations content is 5.115x10-4 mol/gCOD;
default Biomass/Endog other Anions content is 1.410x10-4 mol/gCOD
ISS precipitate ISSprec Precipitated solids are calculated as the sum of brushite, struvite,
hydroxy-apatite, ferrous sulfide, vivianite (Term A below), HFO state
variables (Term B below), HAO state variables (Term C below), and
“old” HMO with adsorbed P (Term D below):
Term A
Pr-XDCPD + Pr-MAP + Pr-XHAP + Pr-FeS + Pr-XHIP
Term B
[HFO(H) + HFO(H).P + HFO(L) + HFO(L).P + HFO(O)]*MW FeOH3 / MW
Fe
+ [HFO(H).P*“Ferric active site factor(high)” / (2*MW Fe)]*MW
H2PO4
+ [HFO(L).P*“Ferric active site factor(low)” / (2*MW Fe)]*MW H2PO4
+ HFO(L).H*(MW FeOH3 + MW H) / MW Fe
+ HFO(H).H*(MW FeOH3 + MW H) / MW Fe
where MW Fe is 55.847; MW O is 15.9994; MW H is 1.0079; MW P is
30.97376; default Ferric active site factor(high) is 2.0 mol Sites / mol
HFO(H); default Ferric active site factor(low) is 1.2 mol Sites / mol
HFO(L)
Term C
[HAO(H) + HAO(H).P + HAO(L) + HAO(L).P + HAO(O)]*MW AlOH3 /
MW Al
+ [HAO(H).P*“Al active site factor(high)” / (2*MW Al)]*MW H2PO4
+ [HAO(L).P*“Al active site factor(low)” / (2*MW Al)]*MW H2PO4

Biowin 6 Help Manual Model Reference • 919

 where MW Al is 26.98154; MW O is 15.9994; MW H is 1.0079; MW P
is 30.97376; default Al active site factor(high) is 3.0 mol Sites / mol
HAO(H); default Al active site factor(low) is 1.5 mol Sites / mol HFO(L)
Term D
P-HMO(A)*MW H2PO4/ MW P
where MW P is 30.97376; MW O is 15.9994; MW H is 1.0079
ISS Total ISStot The total ISS is the sum of inorganic solids from the influent (state
variable), cellular ISS, precipitated ISS, ISS associated with slowly
degradable particulate COD, and UD4:
ISSinf + ISScell + ISSprec + CODp-Xsp*(“Ca content of slowly
biodegradable COD” + “Mg content of slowly biodegradable COD”) +
UD4
where default Ca content of slowly biodegradable COD is 3.912x10-3
gCa/gCOD; default Mg content of slowly biodegradable COD is
3.700x10-4 gMg/gCOD
VSS Volatile VSS is calculated converting all particulate COD state variables
suspended (biomasses, substrates and inert organics) with their proper COD/VSS
solids ratios to VSS, adding User Defined Variable #3 and summing them.
Biomasses have their own Fcv (COD/VSS) conversion factors, while
for other components the ratios indicated in the
Project|Parameters|Stoichiometric|Common dialog are used. The
VSS is calculated as follows:
B-Zam/FCV,ZAM + B-Zao/FCV,ZAO + B-Zaao/FCV,ZAAO + B-Zhm/FCV,ZHM + B-
Zm/FCV,ZM + B-Zno/FCV,ZNO + B-Zh/FCV,ZH + B-Zpa/FCV,ZPA + B-Zppa/FCV,ZPPA
+ B-Zso/FCV,ZSO + B-Zsra/FCV,ZSRA + B-Zsrh/FCV,ZSRH + B-Zsrpa/FCV,ZSRPA + B-
Ze/FCV,ZE + CODp-Xhc/FCV,XHC + CODp-Xeo/FCV,XEO + CODp-Xsp/FCV,XSP +
CODp-Spha/FCV,XSP + CODp-Xuc/FCV,XUC + CODp-Xu/FCV,XU + UD3
TSS Total TSS is calculated as a sum of VSS and ISStot
suspended
solids
N – TKN – S N – Filtered Soluble TKN is the sum of ammonia, and soluble biodegradable and
TKN unbiodegradable organic nitrogen:
N-NH3 + N-Nos + N-Nus
N – TKN – P N– Particulate TKN is calculated as the sum of the N content of
Particulate biomasses, particulate inert and biodegradable organic N, and the N
TKN content of struvite:
[(B-Zam + B-Zao + B-Zaao + B-Zhm + B-Zm + B-Zno + B-Zh + B-Zpa + B-
Zppa + B-Zso + B-Zsra + B-Zsrh + B-Zsrpa + B-Ze)*Stoichiometric N
Content] + N-Xon + N-Xeon + N-Xun + Pr-MAP*MW N/MW MAP
where default Stoichiometric N Content for biomass is 0.07
mgN/mgCOD (note each organism has its own); default

920 • Model Reference Biowin 6 Help Manual

 Stoichiometric N Content for endogenous material is 0.07
mgN/mgCOD; MW N is 14.0067; MW MAP [NH4MgPO4*6H2O] is
245.27946

N – TKN – T N – Total Total Kjeldahl Nitrogen is the sum of filtered and particulate TKN:
Kjeldahl
N-TKN-S + N-TKN-P
Nitrogen
N – NOx N – Nitrite + N – NOx is calculated as the sum of nitrite and nitrate:
Nitrate
N-NO2 + N-NO3
N – TIN N – Total N-TIN is the sum of ammonia, nitrite, nitrate and struvite N:
inorganic N
N-NH3 + N-NO2 + N-NO3 + Pr-MAP*MW N/MW MAP
where MW N is 14.0067; MW MAP [NH4MgPO4*6H2O] is 245.27946
N – TN N – Total N N-TN is the sum of TKN, nitrite, and nitrate:
N-TKN-T + N-NO2 + N-NO3
P – HMO P– This variable tracks the total phosphorus that is bound to hydrated
Phosphorus metal oxides (i.e. HFO and HAO) as well as aged HMO with P:
in HMO
[HFO(H).P*“Ferric active site factor(high)” / (2*MW Fe)]*MW P
+ [HFO(L).P*“Ferric active site factor(low)” / (2*MW Fe)]*MW P
+ [HAO(H).P*“Al active site factor(high)” / (2*MW Al)]*MW P
+ [HAO(L).P*“Al active site factor(low)” / (2*MW Al)]*MW P
+ P-HMO(A)
where MW Fe is 55.847; MW Al is 26.98154; MW P is 30.97376;
default Ferric active site factor(high) is 2.0 mol Sites / mol HFO(H);
default Ferric active site factor(low) is 1.2 mol Sites / mol HFO(L);
default Al active site factor(high) is 3.0 mol Sites / mol HAO(H);
default Al active site factor(low) is 1.5 mol Sites / mol HFO(L)
P – PO4 P – Soluble In previous versions of BioWin, this was a combined variable that
PO4 represented the sum of all inorganic phosphate species, including
soluble metal phosphate complexes in case of metal dosage.
This is no longer the case with the new chemical phosphorus removal
model in BioWin 6, so there is no difference between the state
variable P-PO4 and this variable.
P – TP P – Total P Total P is calculated as the sum of soluble phosphate; particulate
organic inert and biodegradable P; P in polyphosphate (both
releasable and fixed); P content of biomasses and endogenous
residue; P bound in precipitates (brushite, struvite, hydroxy-apatite,
vivianite); and bound to hydrated metal oxides (i.e. HFO and HAO) as
well as aged HMO with P:
P-PO4 + P-Xup + P-Xop + P-Xeop + P-PP-hi + P-PP-lo

Biowin 6 Help Manual Model Reference • 921

 + (B-Zam + B-Zao + B-Zaao + B-Zhm + B-Zm + B-Zno + B-Zh + B-Zpa +
B-Zppa + B-Zso + B-Zsra + B-Zsrh + B-Zsrpa + B-Ze)*Stoichiometric P
Content
+ Pr-XDCPD*MW P / MW DCPD + Pr-MAP*MW P / MW MAP + Pr-
XHAP*3*MW P / MW HAP + Pr-XHIP*2*MW P / MW HIP + P-MHO
where default Stoichiometric P Content for biomass is 0.022
mgP/mgCOD (note each organism has its own); default
Stoichiometric P Content for endogenous material is 0.022
mgP/mgCOD; MW P is 30.97376; MW XDCPD [CaHPO4*2H2O] is
172.08966; MW MAP [NH4MgPO4*6H2O] is 245.27946; MW HAP
[Ca5(PO4)3OH] is 502.32138; MW HIP [Fe2(PO4)2*8H2O] is 501.60532
pH pH pH is calculated from weak acid/base chemistry – see the Modeling of
pH in BioWin section.

S – TS S – Total S Total S is calculated as the sum of sulfide, sulfate, elemental sulfur,

and sulfur content of ferrous sulfide precipitate:
G-H2S + S-TSO4 + S-Sulf + Pr-FeS*MW S / MW FeS
where MW S is 32.060; MW Fe is 55.847
M – Al – T Total The total aluminum variable sums all hydrated aluminm oxides (with
aluminum (all and without P) as well as any soluble aluminum:
forms)
HAO(H) + HAO(H).P + HAO(L) + HAO(L).P + HAO(O) + M-Al
M – Fe – T Total iron (all The total iron variable sums all hydrated ferric oxides (with and
forms) without P), all hydrated ferric oxides with hydrogen, soluble ferrous
iron, soluble ferric iron, and iron bound in vivianite and ferrous
sulfide:
HFO(H) + HFO(H).P + HFO(L) + HFO(L).P + HFO(O) + HFO(L).H +
HFO(H).H + M-Fe2 + M-Fe3 + Pr-XHIP*3*MW Fe / MW HIP + Pr-
FeS*MW Fe / MW FeS
where MW Fe is 55.847; MW HIP [Fe2(PO4)2*8H2O] is 501.60532; MW
FeS is 87.907

Note 1: Many state variable names in BioWin include the hyphen (-) character; for example, “CODp-Xsp”
denotes the name of the slowly biodegradable particulate COD state variable, not “particulate COD minus
Xsp”.

Note 2: “MW” is short for Molecular Weight

922 • Model Reference Biowin 6 Help Manual

COD and BOD in BioWin
In the BioWin simulator characterization of the carbonaceous material in wastewater is in terms of the
chemical oxygen demand (COD). This selection is based on a number of factors, but primarily because COD
provides a consistent basis for description of the activated sludge process, and for quantifying sludge
production, oxygen demand, etc. The rationale for preferring COD over other parameters such as
biochemical oxygen demand (BOD) or total organic carbon (TOC) is discussed in this section.
The simulator allows for calculation of soluble and total BOD for any input element, process unit, or stream.
The user may specify the time basis for the BOD calculation (5, 7, or 20 days).
In many instances data on treatment plant operation are recorded in terms of the BOD for both the influent
and effluent, usually reported as the 5-day value (BOD5). This section discusses a number of factors
regarding the application of BioWin where data are recorded on a BOD basis, or where there is a
requirement to quantify effluent BOD levels for regulatory purposes.
Notes
BioWin uses different aerobic yield coefficients for various substrates:
• Sewage RBCOD (SBSC) and SBCOD (XS) : YHET = 0.666 mgCOD/mgCOD;
• Acetate (SBSA): YSBSA = 0.600;
• Propionate (SBSP): YSBSP = 0.640; and
• Methanol (SMeOH): YMeOH = 0.50.
In BioWin 4.0 the influent introduced a possible COD fraction of endogenous residue, ZE. The fraction is fZE
of the total COD.
In BioWin 6.0 the calculation of soluble BOD for the colloidal influent COD is based on slow utilization at a
first order rate.

BOD Calculations in BioWin

Background
In the IWA-based models characterization of the carbonaceous material in municipal wastewater influent is
in terms of the chemical oxygen demand (COD). This selection is based on a number of factors, but primarily
because COD provides a consistent basis for description of the activated sludge process, and for quantifying
sludge production, oxygen demand, etc. The rationale for preferring COD over other parameters such as
biochemical oxygen demand (BOD) or total organic carbon (TOC) is discussed briefly later.
In many instances, data on treatment plant operation are recorded in terms of the carbonaceous
biochemical oxygen demand (BOD) for both the influent and effluent, usually reported as the 5-day value
(BOD5). [Certain European communities use the BOD7 parameter].
Observation on a large number of municipal wastewaters indicates that there is a near-constant ratio
between COD and BOD for a particular wastewater, viz.:
𝐶𝑂𝐷
=𝐹
𝐵𝑂𝐷5

Biowin 6 Help Manual Model Reference • 923

The factor or ratio, F, usually is in the range of 1.9 to 2.2 mg COD/mg BOD5. For a particular treatment plant
where there is an historical BOD database, and no COD data, a limited number of parallel measurements of
the two parameters likely will establish a reasonably consistent value for F. Thereafter, the F factor can be
used to estimate influent COD values for modeling, based on measurements of BOD5.
The following section presents a method for empirically calculating carbonaceous BOD of an influent
wastewater based on the total COD and the various wastewater characteristic fractions.

Additional Definition of Terms for this Section

Symbol Parameter

bHET Endogenous decay rate constant ( 0.24 d-1)

BODE Biochemical oxygen demand due to endogenous respiration

BODRBCOD Biochemical oxygen demand due to RBCOD component
BODXSC Biochemical oxygen demand due to colloidal slowly biodegradable component
BODXSP Biochemical oxygen demand due to particulate slowly biodegradable component
BODHET Biochemical oxygen demand due to active biomass component
BODT Total biochemical oxygen demand
f Fraction of active mass remaining as endogenous residue ( 0.20)
K First order rate constant for XSC degradation ( 0.40 d-1)

K First order rate constant for XSP degradation ( 0.40 d-1)

(MO2)G Mass of oxygen utilized for growth on RBCOD substrate

(MO2)E Mass of oxygen utilized for endogenous metabolism
OUR Oxygen utilization rate (mg/L/day)
OURE Oxygen utilization rate due to endogenous metabolism
OURG Oxygen utilization rate for substrate utilization (growth)
t Time (d)
XHET Active heterotrophic organism concentration at time zero (mg COD/L)
XSC,0 Slowly biodegradable colloidal COD concentration at time zero (mg COD/L)
XSP,0 Slowly biodegradable particulate COD concentration at time zero (mg COD/L)
YHET Yield of active organisms on SBSC and XS ( 0.666 mg cell COD mg COD-1)

YSBSA Yield of active organisms on SBSA ( 0.600 mg cell COD mg COD-1)

YSBSP Yield of active organisms on SBSP ( 0.640 mg cell COD mg COD-1)

YMeOH Yield of active organisms on SMeOH ( 0.500 mg cell COD mg COD-1)

924 • Model Reference Biowin 6 Help Manual

Basis for BOD Calculations

Note: Setting up the equations in a spreadsheet to calculate soluble and total BOD based on total COD and
the various wastewater characteristics provides a method for estimating fXI through comparing predicted
and observed COD/BOD ratios for different fXI estimates.

The objective here is to demonstrate a method for calculating filtered (GFC) and total carbonaceous BOD
concentrations based on wastewater characteristics in terms of COD, and show how the equations were
developed.
Assume that the sample for which the BOD is to be calculated contains the following biodegradable
component concentrations (all as mgCOD/L):

SBSC = complex RBCOD

SBSA = acetate
SBSP = propionate
SMeOH = methanol
XSC = colloidal SBCOD
XSP = particulate SBCOD
XHET,WW = heterotrophic biomass
Calculation of BOD is based on differing rates of degradation of the different components [e.g., influent
biodegradable material (readily and slowly biodegradable), active organism masses which exert an
endogenous oxygen demand and hence a BOD].
The approach for calculating BOD is to distinguish four components, and to calculate the BOD contribution
for each component independently. These components are as follows:
1. BOD associated with utilization of soluble COD (the various readily biodegradable components) and
the biomass generated from this utilization;
2. BOD associated with utilization of colloidal slowly biodegradable particulate COD and the biomass
generated from this utilization;
3. BOD associated with utilization of particulate slowly biodegradable particulate COD and the biomass
generated from this utilization; and
4. BOD exerted by active biomass present in the sample. That is, biomass initially present; not biomass
generated through utilization referred to in 1, 2 and 3.

BOD Associated with Readily Biodegradable COD Components:

For the purpose of BOD estimation, it is assumed that the oxidation of the different readily biodegradable
components occurs rapidly, and for the purpose of these calculations is assumed to occur instantaneously
(i.e., at t = 0).

𝑆𝑆 = 𝑆𝐵𝑆𝐶 + 𝑆𝐵𝑆𝐴 + 𝑆𝐵𝑆𝑃 + 𝑆𝑀𝑒𝑂𝐻 (1)

Biowin 6 Help Manual Model Reference • 925

The mass of oxygen consumed for utilization of the RBCOD substrate at t = 0 is:
(𝑀𝑂2 )𝐺 = (1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑆𝐵𝑆𝐶 + (1 − 𝑌𝑆𝐵𝑆𝐴 ) ∙ 𝑆𝐵𝑆𝐴 + (1 − 𝑌𝑆𝐵𝑆𝑃 ) ∙ 𝑆𝐵𝑆𝑃
+(1 − 𝑌𝑀𝑒𝑂𝐻 ) ∙ 𝑆𝑀𝑒𝑂𝐻 (2)

Assuming that the soluble biodegradable COD is oxidized instantly to form new cells at time t = 0, each with
its own yield coefficient:

𝑋𝐻𝐸𝑇,𝐺 = 𝑌𝐻𝐸𝑇 ∙ 𝑆𝐵𝑆𝐶 + 𝑌𝑆𝐵𝑆𝐴 ∙ 𝑆𝐵𝑆𝐴 + 𝑌𝑆𝐵𝑆𝑃 ∙ 𝑆𝐵𝑆𝑃 + 𝑌𝑀𝑒𝑂𝐻 ∙ 𝑆𝑀𝑒𝑂𝐻 (3)

The BOD due to endogenous metabolism by the organisms generated from growth on these RBCOD
components can then be calculated using either of the methods described below.

Method 1
Assuming that the rate of change in organism concentration due to endogenous decay is first order with
respect to the active organism concentration, an expression for active organism concentration remaining at
time t can be obtained, i.e.:
𝑑𝑋𝐻𝐸𝑇
= −𝑏𝐻𝐸𝑇 ∙ 𝑋𝐻𝐸𝑇 (4)
𝑑𝑡

hence:
𝑋𝐻𝐸𝑇 = 𝑋𝐻𝐸𝑇,𝐺 ∙ 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 (5)

From Eq. (3) and (5), the endogenous mass loss from time zero to time t can be calculated:
∆𝑋𝐻𝐸𝑇 = 𝑋𝐻𝐸𝑇,𝐺 − 𝑋𝐻𝐸𝑇 = 𝑋𝐻𝐸𝑇,𝐺 ∙ (1 − 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 ) (6)

and the mass of oxygen consumed for endogenous metabolism:

(𝑀𝑂2 )𝐸 = (1 − 𝑓) ∙ ∆𝑋𝐻𝐸𝑇 = (1 − 𝑓) ∙ 𝑋𝐻𝐸𝑇,𝐺 ∙ (1 − 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 )
(1 − 𝑓) ∙ [𝑌𝐻𝐸𝑇 ∙ 𝑆𝐵𝑆𝐶 + 𝑌𝑆𝐵𝑆𝐴 ∙ 𝑆𝐵𝑆𝐴 + 𝑌𝑆𝐵𝑆𝑃 ∙ 𝑆𝐵𝑆𝑃 + 𝑌𝑀𝑒𝑂𝐻 ∙ 𝑆𝑀𝑒𝑂𝐻 ]
= (7)
∙ (1 − 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 )

The BOD component for RBCOD can now be calculated by summing Eqs. (3) and (7), i.e.:
𝐵𝑂𝐷𝑅𝐵𝐶𝑂𝐷 = (𝑀𝑂2 )𝐺 + (𝑀𝑂2 )𝐸
= (1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑆𝐵𝑆𝐶 + (1 − 𝑌𝑆𝐵𝑆𝐴 ) ∙ 𝑆𝐵𝑆𝐴 + (1 − 𝑌𝑆𝐵𝑆𝑃 ) ∙ 𝑆𝐵𝑆𝑃
+(1 − 𝑌𝑀𝑒𝑂𝐻 ) ∙ 𝑆𝑀𝑒𝑂𝐻

926 • Model Reference Biowin 6 Help Manual

 +(1 − 𝑓) ∙ [𝑌𝐻𝐸𝑇 ∙ 𝑆𝐵𝑆𝐶 + 𝑌𝑆𝐵𝑆𝐴 ∙ 𝑆𝐵𝑆𝐴 + 𝑌𝑆𝐵𝑆𝑃 ∙ 𝑆𝐵𝑆𝑃 + 𝑌𝑀𝑒𝑂𝐻 ∙ 𝑆𝑀𝑒𝑂𝐻 ]
(8)
∙ (1 − 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 )

𝐵𝑂𝐷𝑅𝐵𝐶𝑂𝐷 = (1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑆𝐵𝑆𝐶 + (1 − 𝑌𝑆𝐵𝑆𝐴 ) ∙ 𝑆𝐵𝑆𝐴 + (1 − 𝑌𝑆𝐵𝑆𝑃 ) ∙ 𝑆𝐵𝑆𝑃 + (1 − 𝑌𝑀𝑒𝑂𝐻 ) ∙ 𝑆𝑀𝑒𝑂𝐻

+(1 − 𝑓) ∙ [𝑌𝐻𝐸𝑇 ∙ 𝑆𝐵𝑆𝐶 + 𝑌𝑆𝐵𝑆𝐴 ∙ 𝑆𝐵𝑆𝐴 + 𝑌𝑆𝐵𝑆𝑃 ∙ 𝑆𝐵𝑆𝑃 + 𝑌𝑀𝑒𝑂𝐻 ∙ 𝑆𝑀𝑒𝑂𝐻 ]
∙ (1 − 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 )

Method 2
The OUR due to endogenous metabolism can also be related to the rate of change in active organism
concentration (taking into account that a fraction of the active mass becomes endogenous residue), i.e.:
𝑑𝑋𝐻𝐸𝑇
𝑂𝑈𝑅𝐸 = −(1 − 𝑓) ∙
𝑑𝑡
= 𝑏𝐻𝐸𝑇 ∙ (1 − 𝑓) ∙ 𝑋𝐻𝐸𝑇,𝐺 ∙ 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 (9)

The BOD due to endogenous decay is then the cumulative mass of oxygen used over time, i.e.:
𝑡
𝐵𝑂𝐷𝐸 = ∫ 𝑂𝑈𝑅𝐸 ∙ 𝑑𝑡
0
𝑡
= 𝑏𝐻𝐸𝑇 ∙ (1 − 𝑓) ∙ 𝑋𝐻𝐸𝑇,𝐺 ∙ ∫ 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 ∙ 𝑑𝑡
0
1
= 𝑏𝐻𝐸𝑇 ∙ (1 − 𝑓) ∙ 𝑋𝐻𝐸𝑇,𝐺 ∙ (− ∙ 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 ) + 𝐶
𝑏𝐻𝐸𝑇
= −(1 − 𝑓) ∙ 𝑋𝐻𝐸𝑇,𝐺 ∙ 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 + 𝐶 (10)

and since at t = 0, BODE = 0,

𝐶 = (1 − 𝑓) ∙ 𝑋𝐻𝐸𝑇,𝐺

Substituting the expression obtained for XHET,G [Eq. (3)] into the above gives an expression for the BOD due
to endogenous decay:
𝐵𝑂𝐷𝐸 = −(1 − 𝑓) ∙ 𝑋𝐻𝐸𝑇,𝐺 ∙ 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 + (1 − 𝑓) ∙ 𝑋𝐻𝐸𝑇,𝐺
= (1 − 𝑓) ∙ 𝑋𝐻𝐸𝑇,𝐺 ∙ (1 − 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 )
(1 − 𝑓) ∙ [𝑌𝐻𝐸𝑇 ∙ 𝑆𝐵𝑆𝐶 + 𝑌𝑆𝐵𝑆𝐴 ∙ 𝑆𝐵𝑆𝐴 + 𝑌𝑆𝐵𝑆𝑃 ∙ 𝑆𝐵𝑆𝑃 + 𝑌𝑀𝑒𝑂𝐻 ∙ 𝑆𝑀𝑒𝑂𝐻 ]
= (11)
∙ (1 − 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 )
This is the same expression obtained using Method 1 [Eq. (7)]. The total RBCOD BOD portion is given by Eq.
(8).

Biowin 6 Help Manual Model Reference • 927

BOD Associated with Colloidal Slowly Biodegradable COD (XSC):
The biochemical oxygen demand related to the colloidal slowly biodegradable material can be calculated
from the cumulative oxygen consumption for growth on XSC and endogenous respiration exerted by
organisms from this growth. The OUR is the sum of two components:
𝑂𝑈𝑅 = 𝑂𝑈𝑅𝐺 + 𝑂𝑈𝑅𝐸
𝑑𝑋𝑆𝐶 𝑑𝑋𝐻𝐸𝑇
= (1 − 𝑌𝐻𝐸𝑇 ) ∙ (− ) + (1 − 𝑓) ∙ (− )
𝑑𝑡 𝑑𝑡 𝐸
𝑑𝑋𝑆𝐶
= (1 − 𝑌𝐻𝐸𝑇 ) ∙ (− ) + (1 − 𝑓) ∙ 𝑏𝐻𝐸𝑇 ∙ 𝑋𝐻𝐸𝑇 (12)
𝑑𝑡

The rate of change in colloidal slowly biodegradable substrate concentration is assumed to be first order
with respect to substrate concentration, i.e.:
𝑑𝑋𝑆𝐶
= −𝑘1 ∙ 𝑋𝑆𝐶
𝑑𝑡
Hence:
𝑋𝑆𝐶 = 𝑋𝑆𝐶,0 ∙ 𝑒 −𝑘1∙𝑡 (13)

The active organism concentration in Eq. (12) is obtained by integrating an expression for the rate of change
of XHET. This rate is a consequence of an increase due to growth on XSC, minus a decrease due to endogenous
metabolism, i.e.:

𝑑𝑋𝐻𝐸𝑇 𝑑𝑋𝑆𝐶
= 𝑌𝐻𝐸𝑇 ∙ (− ) − 𝑏𝐻𝐸𝑇 ∙ 𝑋𝐻𝐸𝑇 (14)
𝑑𝑡 𝑑𝑡

Substituting Eq. (13) into the above results in a linear differential equation for XHET as a function of time, i.e.:
𝑑𝑋𝐻𝐸𝑇 𝑑𝑋𝑆𝐶
= −𝑌𝐻𝐸𝑇 ∙ ( ) − 𝑏𝐻𝐸𝑇 ∙ 𝑋𝐻𝐸𝑇
𝑑𝑡 𝑑𝑡
= 𝑘1 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝐶,0 ∙ 𝑒 −𝑘1∙𝑡 − 𝑏𝐻𝐸𝑇 ∙ 𝑋𝐻𝐸𝑇 (15)

Or equivalently,

𝑑𝑋𝐻𝐸𝑇
𝑑𝑡
+ 𝑏𝐻𝐸𝑇 ∙ 𝑋𝐻𝐸𝑇 = 𝑘1 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝐶,0 ∙ 𝑒 −𝑘1∙𝑡 (16)

An integration factor of ebHET.t can be used to solve the differential equation. Multiplying both sides of the
equation by ebHET.t results in a simplified expression:

928 • Model Reference Biowin 6 Help Manual

 𝑋𝐻𝐸𝑇
𝑒 𝑏𝐻𝐸𝑇 𝑡 ∙ + 𝑏𝐻𝐸𝑇 ∙ 𝑒 𝑏𝐻𝐸𝑇 𝑡 ∙ 𝑋𝐻𝐸𝑇 = 𝑒 𝑏𝐻𝐸𝑇 𝑡 ∙ 𝑘1 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝐶,0 ∙ 𝑒 −𝑘1∙𝑡
𝑑𝑡
(17)
𝑑 𝑏 𝑡
(𝑒 𝐻𝐸𝑇 ∙ 𝑋𝐻𝐸𝑇 ) = 𝑘1 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝐶,0 ∙ 𝑒 (𝑏𝐻𝐸𝑇 −𝑘1)∙𝑡
𝑑𝑡

Integrating both sides of Eq. (17):

(𝑒 𝑏𝐻𝐸𝑇 𝑡 ∙ 𝑋𝐻𝐸𝑇 ) = ∫ 𝑘1 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝐶,0 ∙ 𝑒 (𝑏𝐻𝐸𝑇 −𝑘1)∙𝑡 𝑑𝑡 (18)

𝑘1∙𝑌𝐻𝐸𝑇 ∙𝑋𝑆𝐶,0
(𝑒 𝑏𝐻𝐸𝑇 𝑡 ∙ 𝑋𝐻𝐸𝑇 ) = 𝑏𝐻𝐸𝑇 −𝑘1
∙ 𝑒 (𝑏𝐻𝐸𝑇 −𝑘1)∙𝑡 + 𝐶

𝑘1∙𝑌𝐻𝐸𝑇 ∙𝑋𝑆𝐶,0
𝑋𝐻𝐸𝑇 = ( 𝑏𝐻𝐸𝑇 −𝑘1
) ∙ 𝑒 −𝑘1∙𝑡 + 𝐶 ∙ 𝑒 −𝑏𝐻𝐸𝑇∙𝑡

At t = 0, no heterotroph mass has been generated from growth on XSC; hence, XHET = 0, and:
𝑘1 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝐶,0
𝐶 = −( )
𝑏𝐻𝐸𝑇 − 𝑘1

𝑘1 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝐶,0 𝑘1 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝐶,0

𝑋𝐻𝐸𝑇 = ( ) ∙ 𝑒 −𝑘1∙𝑡 − ( ) ∙ 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡
𝑏𝐻𝐸𝑇 − 𝑘1 𝑏𝐻𝐸𝑇 − 𝑘1
𝑘1 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝐶,0
= ( ) ∙ (𝑒 −𝑘1∙𝑡 − 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 ) (19)
𝑏𝐻𝐸𝑇 − 𝑘1

Returning to Eq. (12) for the oxygen utilization rate and substituting for XHET:

𝑑𝑋𝑆𝐶
𝑂𝑈𝑅 = (1 − 𝑌𝐻𝐸𝑇 ) ∙ (− ) + (1 − 𝑓) ∙ 𝑏𝐻𝐸𝑇 ∙ 𝑋𝐻𝐸𝑇
𝑑𝑡
= (1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑘1 ∙ 𝑋𝑆𝐶 + (1 − 𝑓) ∙ 𝑏𝐻𝐸𝑇 ∙ 𝑋𝐻𝐸𝑇
= (1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑘1 ∙ 𝑋𝑆𝐶,0 ∙ 𝑒 −𝑘1∙𝑡 + (1 − 𝑓) ∙ 𝑏𝐻𝐸𝑇 ∙ 𝑋𝐻𝐸𝑇 (20)

Integrating Eq. (20) gives an expression for the BOD of the colloidal slowly biodegradable material as a
function of time, i.e.:
𝑡
𝐵𝑂𝐷𝑋𝑆𝐶 = ∫ 𝑂𝑈𝑅 ∙ 𝑑𝑡
0

Biowin 6 Help Manual Model Reference • 929

 𝑡
𝑘1 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝐶,0
∫ [(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑘1 ∙ 𝑋𝑆𝐶,0 ∙ 𝑒 −𝑘1∙𝑡 + (1 − 𝑓) ∙ 𝑏𝐻𝐸𝑇 ∙ ( )
= 0 𝑏𝐻𝐸𝑇 − 𝑘1
∙ (𝑒 −𝑘1∙𝑡 − 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 )] 𝑑𝑡

𝑘1 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝐶,0
−(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑋𝑆𝐶,0 ∙ 𝑒 −𝑘1∙𝑡 + (1 − 𝑓) ∙ 𝑏𝐻𝐸𝑇 ∙ ( )
𝑏𝐻𝐸𝑇 − 𝑘1
= 𝑒 −𝑘1∙𝑡 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡
∙( − )+𝐶
−𝑘1 −𝑏𝐻𝐸𝑇
𝑘1 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝐶,0
−(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑋𝑆𝐶,0 ∙ 𝑒 −𝑘1∙𝑡 + (1 − 𝑓) ∙ 𝑏𝐻𝐸𝑇 ∙ ( )
𝑏𝐻𝐸𝑇 − 𝑘1
= 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 𝑒 −𝑘1∙𝑡
(21)
∙( − )+𝐶
𝑏𝐻𝐸𝑇 𝑘1

At t = 0, no oxygen has been consumed through growth on XSC; hence, BODXSC,0 = 0, and:
𝑘1 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝐶,0 1 1
𝐶 = (1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑋𝑆𝐶,0 − (1 − 𝑓) ∙ 𝑏𝐻𝐸𝑇 ∙ ( )∙( − )
𝑏𝐻𝐸𝑇 − 𝑘1 𝑏𝐻𝐸𝑇 𝑘1

Substituting in Eq. (21):

𝑘1 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝐶,0
−(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑋𝑆𝐶,0 ∙ 𝑒 −𝑘1∙𝑡 + (1 − 𝑓) ∙ 𝑏𝐻𝐸𝑇 ∙ ( )
𝑏𝐻𝐸𝑇 − 𝑘1
𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 𝑒 −𝑘1∙𝑡
𝐵𝑂𝐷𝑋𝑆𝐶 = ∙( − ) + (1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑋𝑆𝐶,0 − (1 − 𝑓) ∙ 𝑏𝐻𝐸𝑇
𝑏𝐻𝐸𝑇 𝑘1
𝑘1 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝐶,0 1 1
∙( )∙( − )
𝑏𝐻𝐸𝑇 − 𝑘1 𝑏𝐻𝐸𝑇 𝑘1
𝑘1 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝐶,0
(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑋𝑆𝐶,0 ∙ (1 − 𝑒 −𝑘1∙𝑡 ) − (1 − 𝑓) ∙ ( ) ∙ (1 − 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 )
𝑏𝐻𝐸𝑇 − 𝑘1
= 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝐶,0 (22)
+ (1 − 𝑓) ∙ 𝑏𝐻𝐸𝑇 ∙ ( ) ∙ (1 − 𝑒 −𝑘1∙𝑡 )
𝑏𝐻𝐸𝑇 − 𝑘1

Re-arranging:

𝑘1 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝐶,0
−(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑋𝑆𝐶,0 ∙ 𝑒 −𝑘1∙𝑡 + (1 − 𝑓) ∙ 𝑏𝐻𝐸𝑇 ∙ ( )
𝑏𝐻𝐸𝑇 − 𝑘1
𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 𝑒 −𝑘1∙𝑡
𝐵𝑂𝐷𝑋𝑆𝐶 = ∙( − ) + (1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑋𝑆𝐶,0 − (1 − 𝑓) ∙ 𝑏𝐻𝐸𝑇
𝑏𝐻𝐸𝑇 𝑘1
𝑘1 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝐶,0 1 1
∙( )∙( − )
𝑏𝐻𝐸𝑇 − 𝑘1 𝑏𝐻𝐸𝑇 𝑘1

930 • Model Reference Biowin 6 Help Manual

 𝑌𝐻𝐸𝑇
𝑋𝑆𝐶,0 [(1 − 𝑌𝐻𝐸𝑇 ) ∙ (1 − 𝑒 −𝑘1∙𝑡 ) − (1 − 𝑓) ∙ ( )
= 𝑏𝐻𝐸𝑇 − 𝑘1 (23)
−𝑏𝐻𝐸𝑇 ∙𝑡 −𝑘1∙𝑡
∙ {𝑘1 ∙ (1 − 𝑒 ) − 𝑏𝐻𝐸𝑇 ∙ (1 − 𝑒 )}]

𝑌𝐻𝐸𝑇
𝑋𝑆𝐶,0 [(1 − 𝑌𝐻𝐸𝑇 ) ∙ (1 − 𝑒 −𝑘1∙𝑡 ) − (1 − 𝑓) ∙ ( )
𝐵𝑂𝐷𝑋𝑆𝐶 = 𝑏𝐻𝐸𝑇 − 𝑘1
∙ {𝑘1 ∙ (1 − 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 ) − 𝑏𝐻𝐸𝑇 ∙ (1 − 𝑒 −𝑘1∙𝑡 )}]

BOD Associated with Particulate Slowly Biodegradable COD (XSP):

Note: Degradable externally added solid organics (e.g. SSO) are handled the same as Xsp in the BOD
formulation; the equations in this section are not repeated for that variable for the sake of brevity.

The biochemical oxygen demand related to the particulate slowly biodegradable material can be calculated
from the cumulative oxygen consumption for growth on XSP and endogenous respiration exerted by
organisms from this growth. The OUR is the sum of two components:
𝑂𝑈𝑅 = 𝑂𝑈𝑅𝐺 + 𝑂𝑈𝑅𝐸
𝑑𝑋𝑆𝑃 𝑑𝑋𝐻𝐸𝑇
= (1 − 𝑌𝐻𝐸𝑇 ) ∙ (− ) + (1 − 𝑓) ∙ (− )
𝑑𝑡 𝑑𝑡 𝐸
𝑑𝑋𝑆𝑃
= (1 − 𝑌𝐻𝐸𝑇 ) ∙ (− ) + (1 − 𝑓) ∙ 𝑏𝐻𝐸𝑇 ∙ 𝑋𝐻𝐸𝑇 (24)
𝑑𝑡

The rate of change in particulate slowly biodegradable substrate concentration is assumed to be first order
with respect to substrate concentration, i.e.:
𝑑𝑋𝑆𝑃
= −𝑘2 ∙ 𝑋𝑆𝑃
𝑑𝑡

Hence:
𝑋𝑆𝑃 = 𝑋𝑆𝑃,0 ∙ 𝑒 −𝑘2∙𝑡 (25)

The active organism concentration in Eq. (12) is obtained by integrating an expression for the rate of change
of XHET. This rate is a consequence of an increase due to growth on XSP, minus a decrease due to endogenous
metabolism, i.e.:
𝑑𝑋𝐻𝐸𝑇 𝑑𝑋𝑆𝑃
= 𝑌𝐻𝐸𝑇 ∙ (− ) − 𝑏𝐻𝐸𝑇 ∙ 𝑋𝐻𝐸𝑇 (26)
𝑑𝑡 𝑑𝑡

Substituting Eq. (13) into the above results in a linear differential equation for XHET as a function of time, i.e.:

Biowin 6 Help Manual Model Reference • 931

 𝑑𝑋𝐻𝐸𝑇 𝑑𝑋𝑆𝑃
= −𝑌𝐻𝐸𝑇 ∙ ( ) − 𝑏𝐻𝐸𝑇 ∙ 𝑋𝐻𝐸𝑇
𝑑𝑡 𝑑𝑡
= 𝑘2 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝑃,0 ∙ 𝑒 −𝑘2∙𝑡 − 𝑏𝐻𝐸𝑇 ∙ 𝑋𝐻𝐸𝑇 (27)

Or equivalently,

𝑑𝑋𝐻𝐸𝑇
+ 𝑏𝐻𝐸𝑇 ∙ 𝑋𝐻𝐸𝑇 = 𝑘2 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝑃,0 ∙ 𝑒 −𝑘2∙𝑡 (28)
𝑑𝑡

An integration factor of ebHET.t can be used to solve the differential equation. Multiplying both sides of the
equation by ebHET.t results in a simplified expression:

𝑋𝐻𝐸𝑇
𝑒 𝑏𝐻𝐸𝑇 𝑡 ∙ + 𝑏𝐻𝐸𝑇 ∙ 𝑒 𝑏𝐻𝐸𝑇 𝑡 ∙ 𝑋𝐻𝐸𝑇 = 𝑒 𝑏𝐻𝐸𝑇 𝑡 ∙ 𝑘2 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝑃,0 ∙ 𝑒 −𝑘2∙𝑡
𝑑𝑡 (29)
𝑑 (𝑏𝐻𝐸𝑇 −𝑘2)∙𝑡
𝑑𝑡
(𝑒 𝑏𝐻𝐸𝑇 𝑡 ∙ 𝑋𝐻𝐸𝑇 ) = 𝑘2 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝑃,0 ∙ 𝑒

Integrating both sides of Eq. (17):

(𝑒 𝑏𝐻𝐸𝑇 𝑡 ∙ 𝑋𝐻𝐸𝑇 ) = ∫ 𝑘2 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝑃,0 ∙ 𝑒 (𝑏𝐻𝐸𝑇 −𝑘2)∙𝑡 𝑑𝑡

𝑘2∙𝑌𝐻𝐸𝑇 ∙𝑋𝑆𝑃,0
(𝑒 𝑏𝐻𝐸𝑇 𝑡 ∙ 𝑋𝐻𝐸𝑇 ) = 𝑏𝐻𝐸𝑇 −𝑘2
∙ 𝑒 (𝑏𝐻𝐸𝑇 −𝑘2)∙𝑡 + 𝐶 (30)
𝑘2∙𝑌𝐻𝐸𝑇 ∙𝑋𝑆𝑃,0
𝑋𝐻𝐸𝑇 = ( 𝑏𝐻𝐸𝑇 −𝑘2
) ∙ 𝑒 −𝑘2∙𝑡 + 𝐶 ∙ 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡

At t = 0, no heterotroph mass has been generated from growth on XSP; hence, XHET = 0, and:
𝑘2 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝑃,0
𝐶 = −( )
𝑏𝐻𝐸𝑇 − 𝑘2

𝑘2 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝑃,0 𝑘2 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝑃,0

𝑋𝐻𝐸𝑇 = ( ) ∙ 𝑒 −𝑘2∙𝑡 − ( ) ∙ 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡
𝑏𝐻𝐸𝑇 − 𝑘2 𝑏𝐻𝐸𝑇 − 𝑘2
𝑘2 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝑃,0
= ( ) ∙ (𝑒 −𝑘2∙𝑡 − 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 ) (31)
𝑏𝐻𝐸𝑇 − 𝑘2

Returning to Eq. (12) for the oxygen utilization rate and substituting for XHET:
𝑑𝑋𝑆𝑃
𝑂𝑈𝑅 = (1 − 𝑌𝐻𝐸𝑇 ) ∙ (− ) + (1 − 𝑓) ∙ 𝑏𝐻𝐸𝑇 ∙ 𝑋𝐻𝐸𝑇
𝑑𝑡

932 • Model Reference Biowin 6 Help Manual

 = (1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑘2 ∙ 𝑋𝑆𝑃 + (1 − 𝑓) ∙ 𝑏𝐻𝐸𝑇 ∙ 𝑋𝐻𝐸𝑇
= (1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑘2 ∙ 𝑋𝑆𝑃,0 ∙ 𝑒 −𝑘2∙𝑡 + (1 − 𝑓) ∙ 𝑏𝐻𝐸𝑇 ∙ 𝑋𝐻𝐸𝑇 (32)

Integrating Eq. (20) gives an expression for the BOD of the colloidal slowly biodegradable material as a
function of time, i.e.:
𝑡
𝐵𝑂𝐷𝑋𝑆𝑃 = ∫ 𝑂𝑈𝑅 ∙ 𝑑𝑡
0
𝑡
𝑘2 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝑃,0
∫ [(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑘2 ∙ 𝑋𝑆𝑃,0 ∙ 𝑒 −𝑘2∙𝑡 + (1 − 𝑓) ∙ 𝑏𝐻𝐸𝑇 ∙ ( )
= 0 𝑏𝐻𝐸𝑇 − 𝑘2
∙ (𝑒 −𝑘2∙𝑡 − 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 )] 𝑑𝑡

𝑘2 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝑃,0
−(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑋𝑆𝑃,0 ∙ 𝑒 −𝑘2∙𝑡 + (1 − 𝑓) ∙ 𝑏𝐻𝐸𝑇 ∙ ( )
𝑏𝐻𝐸𝑇 − 𝑘2
= 𝑒 −𝑘2∙𝑡 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡
∙( − )+𝐶
−𝑘2 −𝑏𝐻𝐸𝑇
𝑘2 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝑃,0
−(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑋𝑆𝑃,0 ∙ 𝑒 −𝑘2∙𝑡 + (1 − 𝑓) ∙ 𝑏𝐻𝐸𝑇 ∙ ( )
𝑏𝐻𝐸𝑇 − 𝑘2
= 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 𝑒 −𝑘2∙𝑡
(33)
∙( − )+𝐶
𝑏𝐻𝐸𝑇 𝑘2

At t = 0, no oxygen has been consumed through growth on XSC; hence, BODXSC,0 = 0, and:
𝑘2 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝑃,0 1 1
𝐶 = (1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑋𝑆𝑃,0 − (1 − 𝑓) ∙ 𝑏𝐻𝐸𝑇 ∙ ( )∙( − )
𝑏𝐻𝐸𝑇 − 𝑘2 𝑏𝐻𝐸𝑇 𝑘2

Substituting in Eq. (21):

𝑘2 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝑃,0
−(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑋𝑆𝑃,0 ∙ 𝑒 −𝑘2∙𝑡 + (1 − 𝑓) ∙ 𝑏𝐻𝐸𝑇 ∙ ( )
𝑏𝐻𝐸𝑇 − 𝑘2
𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 𝑒 −𝑘2∙𝑡
𝐵𝑂𝐷𝑋𝑆𝑃 = ∙( − ) + (1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑋𝑆𝑃,0 − (1 − 𝑓) ∙ 𝑏𝐻𝐸𝑇
𝑏𝐻𝐸𝑇 𝑘2
𝑘2 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝑃,0 1 1
∙( )∙( − )
𝑏𝐻𝐸𝑇 − 𝑘2 𝑏𝐻𝐸𝑇 𝑘2
𝑘2 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝑃,0
(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑋𝑆𝑃,0 ∙ (1 − 𝑒 −𝑘2∙𝑡 ) − (1 − 𝑓) ∙ ( ) ∙ (1 − 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 )
𝑏𝐻𝐸𝑇 − 𝑘2
= 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝑃,0 (34)
+ (1 − 𝑓) ∙ 𝑏𝐻𝐸𝑇 ∙ ( ) ∙ (1 − 𝑒 −𝑘2∙𝑡 )
𝑏𝐻𝐸𝑇 − 𝑘2

Re-arranging:

Biowin 6 Help Manual Model Reference • 933

 𝑘2 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝑃,0
−(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑋𝑆𝑃,0 ∙ 𝑒 −𝑘2∙𝑡 + (1 − 𝑓) ∙ 𝑏𝐻𝐸𝑇 ∙ ( )
𝑏𝐻𝐸𝑇 − 𝑘2
𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 𝑒 −𝑘2∙𝑡
𝐵𝑂𝐷𝑋𝑆𝑃 = ∙( − ) + (1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑋𝑆𝑃,0 − (1 − 𝑓) ∙ 𝑏𝐻𝐸𝑇
𝑏𝐻𝐸𝑇 𝑘2
𝑘2 ∙ 𝑌𝐻𝐸𝑇 ∙ 𝑋𝑆𝑃,0 1 1
∙( )∙( − )
𝑏𝐻𝐸𝑇 − 𝑘2 𝑏𝐻𝐸𝑇 𝑘2
𝑌𝐻𝐸𝑇
𝑋𝑆𝑃,0 [(1 − 𝑌𝐻𝐸𝑇 ) ∙ (1 − 𝑒 −𝑘2∙𝑡 ) − (1 − 𝑓) ∙ ( )
= 𝑏𝐻𝐸𝑇 − 𝑘2 (35)
∙ {𝑘2 ∙ (1 − 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 ) − 𝑏𝐻𝐸𝑇 ∙ (1 − 𝑒 −𝑘2∙𝑡 )}]

𝑌𝐻𝐸𝑇
𝑋𝑆𝑃,0 [(1 − 𝑌𝐻𝐸𝑇 ) ∙ (1 − 𝑒 −𝑘2∙𝑡 ) − (1 − 𝑓) ∙ ( )
𝐵𝑂𝐷𝑋𝑆𝑃 = 𝑏𝐻𝐸𝑇 − 𝑘2
∙ {𝑘2 ∙ (1 − 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 ) − 𝑏𝐻𝐸𝑇 ∙ (1 − 𝑒 −𝑘2∙𝑡 )}]

BOD Associated with Active Biomass

In cases where there are active organisms present in the sample at a concentration XHET,WW, the BOD exerted
by the organisms can be calculated from the rate of change in active organisms due to endogenous
metabolism, i.e.:

𝐵𝑂𝐷𝑋𝐻𝐸𝑇 = (1 − 𝑓) ∙ 𝑋𝐻𝐸𝑇,𝑊𝑊 ∙ (1 − 𝑒 −𝑏𝐻𝐸𝑇∙𝑡 ) (36)

Summary

The GFC filtrate BOD is given by summing Eq. (8) and Eq. (23):
𝐵𝑂𝐷𝐺𝐹𝐶 = 𝐵𝑂𝐷𝑅𝐵𝐶𝑂𝐷 + 𝐵𝑂𝐷𝑋𝑆𝐶

(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑆𝐵𝑆𝐶 + (1 − 𝑌𝑆𝐵𝑆𝐴 ) ∙ 𝑆𝐵𝑆𝐴 + (1 − 𝑌𝑆𝐵𝑆𝑃 ) ∙ 𝑆𝐵𝑆𝑃

+ (1 − 𝑌𝑀𝑒𝑂𝐻 ) ∙ 𝑆𝑀𝑒𝑂𝐻

= (37)
(1 − 𝑓) ∙ [𝑌𝐻𝐸𝑇 ∙ 𝑆𝐵𝑆𝐶 + 𝑌𝑆𝐵𝑆𝐴 ∙ 𝑆𝐵𝑆𝐴 + 𝑌𝑆𝐵𝑆𝑃 ∙ 𝑆𝐵𝑆𝑃 + 𝑌𝑀𝑒𝑂𝐻 ∙ 𝑆𝑀𝑒𝑂𝐻 ]
∙ (1 − 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 )

934 • Model Reference Biowin 6 Help Manual

 𝑌𝐻𝐸𝑇
+𝑋𝑆𝐶,0 [(1 − 𝑌𝐻𝐸𝑇 ) ∙ (1 − 𝑒 −𝑘1∙𝑡 ) − (1 − 𝑓) ∙ ( )
𝑏𝐻𝐸𝑇 − 𝑘1
∙ {𝑘1 ∙ (1 − 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 ) − 𝑏𝐻𝐸𝑇 ∙ (1 − 𝑒 −𝑘1∙𝑡 )}]

The BOD of the particulate influent COD (XSP and XHET,WW)is given by summing Eq. (35) and Eq. (36):

𝐵𝑂𝐷𝑃𝐴𝑅𝑇 = 𝐵𝑂𝐷𝑋𝑆𝑃 + 𝐵𝑂𝐷𝑋𝐻𝐸𝑇

𝑌𝐻𝐸𝑇
𝑋𝑆𝑃,0 [(1 − 𝑌𝐻𝐸𝑇 ) ∙ (1 − 𝑒 −𝑘2∙𝑡 ) − (1 − 𝑓) ∙ ( )
𝑏𝐻𝐸𝑇 − 𝑘2
∙ {𝑘2 ∙ (1 − 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 ) − 𝑏𝐻𝐸𝑇 ∙ (1 − 𝑒 −𝑘2∙𝑡 )}]
= (38)

+(1 − 𝑓) ∙ 𝑋𝐻𝐸𝑇,𝑊𝑊 ∙ (1 − 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 )

The total BOD is given by summing the two components:

𝐵𝑂𝐷𝑇 = 𝐵𝑂𝐷𝐺𝐹𝐶 + 𝐵𝑂𝐷𝑃𝐴𝑅𝑇

(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑆𝐵𝑆𝐶 + (1 − 𝑌𝑆𝐵𝑆𝐴 ) ∙ 𝑆𝐵𝑆𝐴 + (1 − 𝑌𝑆𝐵𝑆𝑃 ) ∙ 𝑆𝐵𝑆𝑃

+ (1 − 𝑌𝑀𝑒𝑂𝐻 ) ∙ 𝑆𝑀𝑒𝑂𝐻

+(1 − 𝑓) ∙ [𝑌𝐻𝐸𝑇 ∙ 𝑆𝐵𝑆𝐶 + 𝑌𝑆𝐵𝑆𝐴 ∙ 𝑆𝐵𝑆𝐴 + 𝑌𝑆𝐵𝑆𝑃 ∙ 𝑆𝐵𝑆𝑃 + 𝑌𝑀𝑒𝑂𝐻 ∙ 𝑆𝑀𝑒𝑂𝐻 ]

∙ (1 − 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 )

𝑌𝐻𝐸𝑇
+𝑋𝑆𝐶,0 [(1 − 𝑌𝐻𝐸𝑇 ) ∙ (1 − 𝑒 −𝑘1∙𝑡 ) − (1 − 𝑓) ∙ ( )
= 𝑏𝐻𝐸𝑇 − 𝑘1 (39)
−𝑏𝐻𝐸𝑇 ∙𝑡 −𝑘1∙𝑡
∙ {𝑘1 ∙ (1 − 𝑒 ) − 𝑏𝐻𝐸𝑇 ∙ (1 − 𝑒 )}]

𝑌𝐻𝐸𝑇
+𝑋𝑆𝑃,0 [(1 − 𝑌𝐻𝐸𝑇 ) ∙ (1 − 𝑒 −𝑘2∙𝑡 ) − (1 − 𝑓) ∙ ( )
𝑏𝐻𝐸𝑇 − 𝑘2
∙ {𝑘2 ∙ (1 − 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 ) − 𝑏𝐻𝐸𝑇 ∙ (1 − 𝑒 −𝑘2∙𝑡 )}]

+(1 − 𝑓) ∙ 𝑋𝐻𝐸𝑇,𝑊𝑊 ∙ (1 − 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 )

Biowin 6 Help Manual Model Reference • 935

Example
This example demonstrates the BOD5 calculation procedure for a municipal influent wastewater stream with
the following component concentrations (mgCOD/L):

CODT = 500
SUS = 25
SUP = 50
SBSC = 40
SBSA = 20
SBSP = 15
SMeOH = 5
SCOL = 85
XS = 240
XHET,WW = 10
XZE,WW = 10

NOTE:

• The unbiodegradable soluble fraction = 0.05;

• The unbiodegradable particulate fraction = 0.10;
• The readily biodegradable fraction = (40+20+15+5)/500 = 0.16;
• The heterotrophic biomass fraction = 0.02;
• The endogenous residue fraction = 0.02;
• The particulate fraction of the SBCOD = 240/(240+85) = 0.738.

Note: The parameter values for f and b are for endogenous respiration, and should not be confused with
the corresponding terms used in the death-regeneration approach for modeling biomass decay in the IWA-
type models.

The GFC filtrate BOD is given by Eq. (37):

𝐵𝑂𝐷𝐺𝐹𝐶 = 𝐵𝑂𝐷𝑅𝐵𝐶𝑂𝐷 + 𝐵𝑂𝐷𝑋𝑆𝐶

936 • Model Reference Biowin 6 Help Manual

 (1 − 0.666) ∙ 40 + (1 − 0.60) ∙ 20 + (1 − 0.64) ∙ 15 + (1 − 0.50) ∙ 5

+(1 − 0.2) ∙ [0.666 ∙ 40 + 0.60 ∙ 20 + 0.64 ∙ 15 + 0.50 ∙ 5] ∙ (1 − 𝑒 −0.24∙5 )

= (37)
0.666
+85 [(1 − 0.666) ∙ (1 − 𝑒 −𝑘1∙5 ) − (1 − 0.2) ∙ ( )
0.24 − 𝑘1
∙ {𝑘1 ∙ (1 − 𝑒 −0.24∙5 ) − 0.24 ∙ (1 − 𝑒 −𝑘1∙𝑡 )}]

= 29.260 + 28.366 + 48.547

= 57.626 + 48.547 = 106.173

The BOD of the particulate matter is given by Eq. (38):

𝐵𝑂𝐷𝑃𝐴𝑅𝑇 = 𝐵𝑂𝐷𝑋𝑆𝑃 + 𝐵𝑂𝐷𝑋𝐻𝐸𝑇

0.666
240 [(1 − 0.666) ∙ (1 − 𝑒 −𝑘2∙5 ) − (1 − 0.2) ∙ ( )
0.24 − 𝑘2
∙ {𝑘2 ∙ (1 − 𝑒 −0.24∙5 ) − 0.24 ∙ (1 − 𝑒 −𝑘2∙5 )}]
= (38)

+(1 − 0.2) ∙ 10 ∙ (1 − 𝑒 −0.24∙5 )

= 137.075 + 5.590 = 142.665

The total BOD is given by summing the two components:

𝐵𝑂𝐷𝑇 = 𝐵𝑂𝐷𝐺𝐹𝐶 + 𝐵𝑂𝐷𝑃𝐴𝑅𝑇 (39)
= 106.173 + 142.665 = 248.838

Calculating CODT in the BOD Influent Element

In the BOD Influent Element we need to calculate CODT based on the input BOD and VSS.

NOTE: For the municipal COD and BOD influent elements we do not have fractions for propionate or
methanol; that is, the concentrations of these are zero in both inputs. This simplifies the equations
somewhat.

In the following the equations are based on XHET as the biomass content (with one fCV value). When
implemented in BioWin, all the XHET terms below will actually be summations for the different biomass
fractions.

Biowin 6 Help Manual Model Reference • 937

Also note that:
𝑋𝑆𝑃 + 𝑋𝑆𝐶 = 𝐶𝑂𝐷𝑇 ∙ (1 − 𝑓𝑈𝑆 − 𝑓𝑈𝑃 − 𝑓𝐵𝑆 − 𝑓𝑋𝐻𝐸𝑇 − 𝑓𝑍𝐸 )

𝑋𝑆𝑃 = 𝐶𝑂𝐷𝑇 ∙ 𝑓𝑋𝑆𝑃 (1 − 𝑓𝑈𝑆 − 𝑓𝑈𝑃 − 𝑓𝐵𝑆 − 𝑓𝑋𝐻𝐸𝑇 − 𝑓𝑍𝐸 )

𝑋𝑆𝐶 = 𝐶𝑂𝐷𝑇 ∙ (1 − 𝑓𝑋𝑆𝑃 ) ∙ (1 − 𝑓𝑈𝑆 − 𝑓𝑈𝑃 − 𝑓𝐵𝑆 − 𝑓𝑋𝐻𝐸𝑇 − 𝑓𝑍𝐸 )

and that:
𝑆𝐵𝑆𝐶 = 𝐶𝑂𝐷𝑇 ∙ 𝑓𝐵𝑆 ∙ (1 − 𝑓𝐴𝐶 )
𝑆𝐵𝑆𝐴 = 𝐶𝑂𝐷𝑇 ∙ 𝑓𝐵𝑆 ∙ 𝑓𝐴𝐶

VSS is calculated as follows:

𝑋𝐻𝐸𝑇 𝑋𝑍𝐸 𝑋𝑈𝑃 𝑋𝑆𝑃
𝑉𝑆𝑆 = + + +
𝑓𝐶𝑉−𝑋𝐻𝐸𝑇 𝑓𝐶𝑉−𝑍𝐸 𝑓𝐶𝑉−𝑋𝐼 𝑓𝐶𝑉−𝑋𝑆𝑃

𝑓𝐻𝐸𝑇 ∙ 𝐶𝑂𝐷𝑇 𝑓𝑍𝐸 ∙ 𝐶𝑂𝐷𝑇 𝑓𝑈𝑃 ∙ 𝐶𝑂𝐷𝑇

+ +
𝑓𝐶𝑉−𝑋𝐻𝐸𝑇 𝑓𝐶𝑉−𝑍𝐸 𝑓𝐶𝑉−𝑋𝐼
= 𝑓𝑋𝑆𝑃 ∙ 𝐶𝑂𝐷𝑇 ∙ (1 − 𝑓𝑈𝑆 − 𝑓𝑈𝑃 − 𝑓𝐵𝑆 − 𝑓𝑋𝐻𝐸𝑇 − 𝑓𝑍𝐸 )
+
𝑓𝐶𝑉−𝑋𝑆𝑃

𝑓𝑋𝐻𝐸𝑇 𝑓𝑍𝐸 𝑓𝑈𝑃

𝐶𝑂𝐷𝑇 [ + +
𝑓𝐶𝑉−𝑋𝐻𝐸𝑇 𝑓𝐶𝑉−𝑍𝐸 𝑓𝐶𝑉−𝑋𝐼
= (40)
𝑓𝑋𝑆𝑃 ∙ (1 − 𝑓𝑈𝑆 − 𝑓𝑈𝑃 − 𝑓𝐵𝑆 − 𝑓𝑋𝐻𝐸𝑇 − 𝑓𝑍𝐸 )
+ ]
𝑓𝐶𝑉−𝑋𝑆𝑃

For the case of no propionate and methanol, the BOD equation becomes:
(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑆𝐵𝑆𝐶 + (1 − 𝑌𝑆𝐵𝑆𝐴 ) ∙ 𝑆𝐵𝑆𝐴

(1 − 𝑓) ∙ [𝑌𝐻𝐸𝑇 ∙ 𝑆𝐵𝑆𝐶 + 𝑌𝑆𝐵𝑆𝐴 ∙ 𝑆𝐵𝑆𝐴 ] ∙ (1 − 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 )

𝑌𝐻𝐸𝑇
+𝑋𝑆𝐶,0 [(1 − 𝑌𝐻𝐸𝑇 ) ∙ (1 − 𝑒 −𝑘1∙𝑡 ) − (1 − 𝑓) ∙ ( )
𝐵𝑂𝐷𝑇 = 𝑏𝐻𝐸𝑇 − 𝑘1 (41)
∙ {𝑘1 ∙ (1 − 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 ) − 𝑏𝐻𝐸𝑇 ∙ (1 − 𝑒 −𝑘1∙𝑡 )}]

𝑌𝐻𝐸𝑇
𝑋𝑆𝑃,0 [(1 − 𝑌𝐻𝐸𝑇 ) ∙ (1 − 𝑒 −𝑘2∙𝑡 ) − (1 − 𝑓) ∙ ( )
𝑏𝐻𝐸𝑇 − 𝑘2
∙ {𝑘2 ∙ (1 − 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 ) − 𝑏𝐻𝐸𝑇 ∙ (1 − 𝑒 −𝑘2∙𝑡 )}]

938 • Model Reference Biowin 6 Help Manual

 +(1 − 𝑓) ∙ 𝑋𝐻𝐸𝑇,𝑊𝑊 ∙ (1 − 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 )

To simplify the analysis, define the following constants:

𝐴 = (1 − 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 )
𝐵1 = (1 − 𝑒 −𝑘1∙𝑡 )
𝐵2 = (1 − 𝑒 −𝑘2∙𝑡 )
𝑌𝐻𝐸𝑇
𝐶1 = (1 − 𝑓) ∙ ( ) ∙ {𝑘1 ∙ (1 − 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 ) − 𝑏𝐻𝐸𝑇 ∙ (1 − 𝑒 −𝑘1∙𝑡 )}
𝑏𝐻𝐸𝑇 − 𝑘1
𝑌𝐻𝐸𝑇
𝐶2 = (1 − 𝑓) ∙ ( ) ∙ {𝑘2 ∙ (1 − 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 ) − 𝑏𝐻𝐸𝑇 ∙ (1 − 𝑒 −𝑘2∙𝑡 )}
𝑏𝐻𝐸𝑇 − 𝑘2
𝐷 = (1 − 𝑓𝑈𝑆 − 𝑓𝑈𝑃 − 𝑓𝐵𝑆 − 𝑓𝑋𝐻𝐸𝑇 − 𝑓𝑍𝐸 )

The BOD equation can now be written as:

(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑆𝐵𝑆𝐶 + (1 − 𝑌𝑆𝐵𝑆𝐴 ) ∙ 𝑆𝐵𝑆𝐴
+(1 − 𝑓) ∙ [𝑌𝐻𝐸𝑇 ∙ 𝑆𝐵𝑆𝐶 + 𝑌𝑆𝐵𝑆𝐴 ∙ 𝑆𝐵𝑆𝐴 ] ∙ 𝐴
𝐵𝑂𝐷𝑇 = +𝑋𝑆𝐶,0 [(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝐵1 − 𝐶1 ] (42)
+𝑋𝑆𝑃,0 [(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝐵2 − 𝐶2 ]
+(1 − 𝑓) ∙ 𝑋𝐻𝐸𝑇,𝑊𝑊 ∙ 𝐴

(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝐶𝑂𝐷𝑇 ∙ 𝑓𝐵𝑆 ∙ (1 − 𝑓𝐴𝐶 )

+(1 − 𝑌𝑆𝐵𝑆𝐴 ) ∙ 𝐶𝑂𝐷𝑇 ∙ 𝑓𝐵𝑆 ∙ 𝑓𝐴𝐶
+(1 − 𝑓) ∙ [𝑌𝐻𝐸𝑇 ∙ 𝐶𝑂𝐷𝑇 ∙ 𝑓𝐵𝑆 ∙ (1 − 𝑓𝐴𝐶 ) + 𝑌𝑆𝐵𝑆𝐴 ∙ 𝐶𝑂𝐷𝑇 ∙ 𝑓𝐵𝑆 ∙ 𝑓𝐴𝐶 ] ∙ 𝐴
=
+𝐶𝑂𝐷𝑇 ∙ (1 − 𝑓𝑋𝑆𝑃 ) ∙ 𝐷 ∙ [(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝐵1 − 𝐶1 ]
+𝐶𝑂𝐷𝑇 ∙ 𝑓𝑋𝑆𝑃 ∙ 𝐷 ∙ [(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝐵2 − 𝐶2 ]
+(1 − 𝑓) ∙ 𝐶𝑂𝐷𝑇 ∙ 𝑓𝑋𝐻𝐸𝑇 ∙ 𝐴

Removing CODT as a common factor:

𝐶𝑂𝐷𝑇 ∙ {(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑓𝐵𝑆 ∙ (1 − 𝑓𝐴𝐶 ) + (1 − 𝑌𝑆𝐵𝑆𝐴 ) ∙ 𝑓𝐵𝑆 ∙ 𝑓𝐴𝐶 + (1 − 𝑓)
∙ [𝑌𝐻𝐸𝑇 ∙ 𝑓𝐵𝑆 ∙ (1 − 𝑓𝐴𝐶 ) + 𝑌𝑆𝐵𝑆𝐴 ∙ 𝑓𝐵𝑆 ∙ 𝑓𝐴𝐶 ] ∙ 𝐴 + (1 − 𝑓𝑋𝑆𝑃 ) ∙ 𝐷
𝐵𝑂𝐷𝑇 = (43)
∙ [(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝐵1 − 𝐶1 ] + 𝑓𝑋𝑆𝑃 ∙ 𝐷 ∙ [(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝐵2 − 𝐶2 ]
+ (1 − 𝑓) ∙ 𝑓𝑋𝐻𝐸𝑇 ∙ 𝐴}

This equation must be solved simultaneously with Eq. (40). The objective is to determine CODT and we treat
fXSP as the other unknown. That is, in effect we want to adjust fXSP until we get a match of BOD and VSS. We

Biowin 6 Help Manual Model Reference • 939

use fXSP because that gives us the biggest degree of freedom; i.e. XSC + XSP is the largest concentration so we
have a lot of room for adjustment:
𝑓𝑋𝐻𝐸𝑇 𝑓𝑍𝐸 𝑓𝑈𝑃 𝑓𝑋𝑆𝑃 ∙ 𝐷
𝑉𝑆𝑆 = 𝐶𝑂𝐷𝑇 [ + + + ] (44)
𝑓𝐶𝑉−𝑋𝐻𝐸𝑇 𝑓𝐶𝑉−𝑍𝐸 𝑓𝐶𝑉−𝑋𝐼 𝑓𝐶𝑉−𝑋𝑆𝑃

If we rearrange Eq. (40) for CODT and substitute in Eq. (40) to eliminate CODT:

𝑉𝑆𝑆
𝐵𝑂𝐷𝑇 = 𝑓𝑋𝐻𝐸𝑇 𝑓𝑍𝐸 𝑓𝑈𝑃 𝑓 ∙𝐷 (45)
[𝑓 + + + 𝑋𝑆𝑃
𝐶𝑉−𝑋𝐻𝐸𝑇 𝑓𝐶𝑉−𝑍𝐸 𝑓𝐶𝑉−𝑋𝐼 𝑓𝐶𝑉−𝑋𝑆𝑃 ]
∙ {(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑓𝐵𝑆 ∙ (1 − 𝑓𝐴𝐶 ) + (1 − 𝑌𝑆𝐵𝑆𝐴 ) ∙ 𝑓𝐵𝑆 ∙ 𝑓𝐴𝐶 + (1 − 𝑓)
∙ [𝑌𝐻𝐸𝑇 ∙ 𝑓𝐵𝑆 ∙ (1 − 𝑓𝐴𝐶 ) + 𝑌𝑆𝐵𝑆𝐴 ∙ 𝑓𝐵𝑆 ∙ 𝑓𝐴𝐶 ] ∙ 𝐴 + (1 − 𝑓𝑋𝑆𝑃 ) ∙ 𝐷
∙ [(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝐵1 − 𝐶1 ] + 𝑓𝑋𝑆𝑃 ∙ 𝐷 ∙ [(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝐵2 − 𝐶2 ] + (1 − 𝑓)
∙ 𝑓𝑋𝐻𝐸𝑇 ∙ 𝐴}

Now we must solve Eq. (43) for fXSP. First expand the left-hand side to separate the fXSP terms:
𝑓𝑋𝑆𝑃 ∙ 𝐷 𝑓𝑋𝐻𝐸𝑇 𝑓𝑍𝐸 𝑓𝑈𝑃
𝐵𝑂𝐷𝑇 ∙ + 𝐵𝑂𝐷𝑇 [ + + ] (46)
𝑓𝐶𝑉−𝑋𝑆𝑃 𝑓𝐶𝑉−𝑋𝐻𝐸𝑇 𝑓𝐶𝑉−𝑍𝐸 𝑓𝐶𝑉−𝑋𝐼
= 𝑉𝑆𝑆 ∙ {(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑓𝐵𝑆 ∙ (1 − 𝑓𝐴𝐶 ) + (1 − 𝑌𝑆𝐵𝑆𝐴 ) ∙ 𝑓𝐵𝑆 ∙ 𝑓𝐴𝐶 + (1 − 𝑓)
∙ [𝑌𝐻𝐸𝑇 ∙ 𝑓𝐵𝑆 ∙ (1 − 𝑓𝐴𝐶 ) + 𝑌𝑆𝐵𝑆𝐴 ∙ 𝑓𝐵𝑆 ∙ 𝑓𝐴𝐶 ] ∙ 𝐴 + (1 − 𝑓𝑋𝑆𝑃 ) ∙ 𝐷
∙ [(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝐵1 − 𝐶1 ] + 𝑓𝑋𝑆𝑃 ∙ 𝐷 ∙ [(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝐵2 − 𝐶2 ] + (1 − 𝑓) ∙ 𝑓𝑋𝐻𝐸𝑇
∙ 𝐴}

Re-arranging further:

𝑓𝑋𝑆𝑃 ∙ 𝐷 𝑓𝑋𝐻𝐸𝑇 𝑓𝑍𝐸 𝑓𝑈𝑃

𝐵𝑂𝐷𝑇 ∙ + 𝐵𝑂𝐷𝑇 [ + + ] (47)
𝑓𝐶𝑉−𝑋𝑆𝑃 𝑓𝐶𝑉−𝑋𝐻𝐸𝑇 𝑓𝐶𝑉−𝑍𝐸 𝑓𝐶𝑉−𝑋𝐼
𝑉𝑆𝑆 ∙ {(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑓𝐵𝑆 ∙ (1 − 𝑓𝐴𝐶 ) + (1 − 𝑌𝑆𝐵𝑆𝐴 ) ∙ 𝑓𝐵𝑆 ∙ 𝑓𝐴𝐶 + (1 − 𝑓)
=
∙ [𝑌𝐻𝐸𝑇 ∙ 𝑓𝐵𝑆 ∙ (1 − 𝑓𝐴𝐶 ) + 𝑌𝑆𝐵𝑆𝐴 ∙ 𝑓𝐵𝑆 ∙ 𝑓𝐴𝐶 ] ∙ 𝐴 + (1 − 𝑓) ∙ 𝑓𝑋𝐻𝐸𝑇 ∙ 𝐴}
+𝑉𝑆𝑆 ∙ {(1 − 𝑓𝑋𝑆𝑃 ) ∙ 𝐷 ∙ [(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝐵1 − 𝐶1 ] + 𝑓𝑋𝑆𝑃 ∙ 𝐷 ∙ [(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝐵2 − 𝐶2 ]}

Grouping the fXSP terms on LHS:

𝑓𝑋𝑆𝑃 ∙ 𝐷
𝐵𝑂𝐷𝑇 ∙ − 𝑉𝑆𝑆 ∙ 𝑓𝑋𝑆𝑃 ∙ 𝐷 ∙ {(1 − 𝑌𝐻𝐸𝑇 ) ∙ [(𝐵2 − 𝐵1 ) − (𝐶2 − 𝐶1 )]} (48)
𝑓𝐶𝑉−𝑋𝑆𝑃
𝑉𝑆𝑆 ∙ {(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑓𝐵𝑆 ∙ (1 − 𝑓𝐴𝐶 ) + (1 − 𝑌𝑆𝐵𝑆𝐴 ) ∙ 𝑓𝐵𝑆 ∙ 𝑓𝐴𝐶 + (1 − 𝑓)
∙ [𝑌𝐻𝐸𝑇 ∙ 𝑓𝐵𝑆 ∙ (1 − 𝑓𝐴𝐶 ) + 𝑌𝑆𝐵𝑆𝐴 ∙ 𝑓𝐵𝑆 ∙ 𝑓𝐴𝐶 ] ∙ 𝐴 + 𝐷 ∙ [(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝐵1 − 𝐶1 ]
= 𝑓𝑋𝐻𝐸𝑇 𝑓𝑍𝐸 𝑓𝑈𝑃
+ (1 − 𝑓) ∙ 𝑓𝑋𝐻𝐸𝑇 ∙ 𝐴} − 𝐵𝑂𝐷𝑇 [ + + ]
𝑓𝐶𝑉−𝑋𝐻𝐸𝑇 𝑓𝐶𝑉−𝑍𝐸 𝑓𝐶𝑉−𝑋𝐼

940 • Model Reference Biowin 6 Help Manual

Solving for fXSP:
𝑉𝑆𝑆 ∙ {(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑓𝐵𝑆 ∙ (1 − 𝑓𝐴𝐶 ) + (1 − 𝑌𝑆𝐵𝑆𝐴 ) ∙ 𝑓𝐵𝑆 ∙ 𝑓𝐴𝐶 + (1 − 𝑓)
∙ [𝑌𝐻𝐸𝑇 ∙ 𝑓𝐵𝑆 ∙ (1 − 𝑓𝐴𝐶 ) + 𝑌𝑆𝐵𝑆𝐴 ∙ 𝑓𝐵𝑆 ∙ 𝑓𝐴𝐶 ] ∙ 𝐴 + 𝐷
𝑓𝑋𝑆𝑃 = ∙ [(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝐵1 − 𝐶1 ] + (1 − 𝑓) ∙ 𝑓𝑋𝐻𝐸𝑇 ∙ 𝐴} (49)
𝑓𝑋𝐻𝐸𝑇 𝑓𝑍𝐸 𝑓𝑈𝑃
− 𝐵𝑂𝐷𝑇 [ + + ]
𝑓𝐶𝑉−𝑋𝐻𝐸𝑇 𝑓𝐶𝑉−𝑍𝐸 𝑓𝐶𝑉−𝑋𝐼
divided by

𝐷
𝐵𝑂𝐷𝑇 ∙ − 𝑉𝑆𝑆 ∙ 𝐷 ∙ {(1 − 𝑌𝐻𝐸𝑇 ) ∙ [(𝐵2 − 𝐵1 ) − (𝐶2 − 𝐶1 )]}
𝑓𝐶𝑉−𝑋𝑆𝑃

𝑉𝑆𝑆 ∙ {(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝑓𝐵𝑆 ∙ (1 − 𝑓𝐴𝐶 ) + (1 − 𝑌𝑆𝐵𝑆𝐴 ) ∙ 𝑓𝐵𝑆 ∙ 𝑓𝐴𝐶 + (1 − 𝑓)

∙ [𝑌𝐻𝐸𝑇 ∙ 𝑓𝐵𝑆 ∙ (1 − 𝑓𝐴𝐶 ) + 𝑌𝑆𝐵𝑆𝐴 ∙ 𝑓𝐵𝑆 ∙ 𝑓𝐴𝐶 ] ∙ 𝐴 + 𝐷
𝑓𝑋𝑆𝑃 = ∙ [(1 − 𝑌𝐻𝐸𝑇 ) ∙ 𝐵1 − 𝐶1 ] + (1 − 𝑓) ∙ 𝑓𝑋𝐻𝐸𝑇 ∙ 𝐴} (50)
𝑓𝑋𝐻𝐸𝑇 𝑓𝑍𝐸 𝑓𝑈𝑃
− 𝐵𝑂𝐷𝑇 [ + + ]
𝑓𝐶𝑉−𝑋𝐻𝐸𝑇 𝑓𝐶𝑉−𝑍𝐸 𝑓𝐶𝑉−𝑋𝐼
divided by
𝐷
𝐵𝑂𝐷𝑇 ∙ − 𝑉𝑆𝑆 ∙ 𝐷 ∙ {(1 − 𝑌𝐻𝐸𝑇 ) ∙ [(𝐵2 − 𝐵1 ) − (𝐶2 − 𝐶1 )]}
𝑓𝐶𝑉−𝑋𝑆𝑃

In this expression we have:

𝐴 = (1 − 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 )
𝐵1 = (1 − 𝑒 −𝑘1∙𝑡 )
𝐵2 = (1 − 𝑒 −𝑘2∙𝑡 )
𝑌𝐻𝐸𝑇
𝐶1 = (1 − 𝑓) ∙ ( ) ∙ {𝑘1 ∙ (1 − 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 ) − 𝑏𝐻𝐸𝑇 ∙ (1 − 𝑒 −𝑘1∙𝑡 )}
𝑏𝐻𝐸𝑇 − 𝑘1
𝑌𝐻𝐸𝑇
𝐶2 = (1 − 𝑓) ∙ ( ) ∙ {𝑘2 ∙ (1 − 𝑒 −𝑏𝐻𝐸𝑇 ∙𝑡 ) − 𝑏𝐻𝐸𝑇 ∙ (1 − 𝑒 −𝑘2∙𝑡 )}
𝑏𝐻𝐸𝑇 − 𝑘2
𝐷 = (1 − 𝑓𝑈𝑆 − 𝑓𝑈𝑃 − 𝑓𝐵𝑆 − 𝑓𝑋𝐻𝐸𝑇 − 𝑓𝑍𝐸 )

Once we have determined fXSP we can calculate CODT by substituting in either Eq. (40) or (42). Eq. (40) is
simpler:

Biowin 6 Help Manual Model Reference • 941

 𝑉𝑆𝑆
𝐶𝑂𝐷𝑇 = 𝑓 𝑓 𝑓 𝑓 ∙ (1 − 𝑓𝑈𝑆 − 𝑓𝑈𝑃 − 𝑓𝐵𝑆 − 𝑓𝑋𝐻𝐸𝑇 − 𝑓𝑍𝐸 ) (51)
[𝑓 𝑋𝐻𝐸𝑇 + 𝑓 𝑍𝐸 + 𝑓 𝑈𝑃 + 𝑋𝑆𝑃 𝑓𝐶𝑉−𝑋𝑆𝑃 ]
𝐶𝑉−𝑋𝐻𝐸𝑇 𝐶𝑉−𝑍𝐸 𝐶𝑉−𝑋𝐼

𝑉𝑆𝑆
𝐶𝑂𝐷𝑇 = 𝑓𝑋𝐻𝐸𝑇 𝑓𝑍𝐸 𝑓𝑈𝑃𝑓𝑋𝑆𝑃 ∙ (1 − 𝑓𝑈𝑆 − 𝑓𝑈𝑃 − 𝑓𝐵𝑆 − 𝑓𝑋𝐻𝐸𝑇 − 𝑓𝑍𝐸 ) (52)
[𝑓 + + + ]
𝐶𝑉−𝑋𝐻𝐸𝑇 𝑓𝐶𝑉−𝑍𝐸 𝑓𝐶𝑉−𝑋𝐼 𝑓𝐶𝑉−𝑋𝑆𝑃

COD versus BOD as a Modeling Parameter

The advantage of selecting COD as the parameter for quantifying the "strength" of organic material in the
influent, as opposed to BOD or TOC, is that it provides a consistent basis for description of the activated
sludge process. Marais and Dold (1985) outlined the rationale which makes COD the appropriate parameter.
It is worth reviewing this rationale briefly as selection of the COD parameter is fundamental to the
application of the models. Briefly, the suitability of COD is established by considering utilization of organic
substrate. In the process of metabolism the organic substrate serves two functions for the organisms as
shown schematically in Figure 1.1:
1. A portion of the organic material is oxidized to CO2 and water, providing energy for maintaining the
homeostatic balance for existing cell mass (osmotic pressure, ionic balance, membrane potential,
etc.) and for (2) below. The energy is provided by transferring electrons from the organic substrate
through the electron transport chain to the terminal electron acceptor (oxygen in the case of an
aerobic system, or nitrate under anoxic conditions). Under the substrate limited conditions usually
encountered in activated sludge systems, the organisms utilize a relatively fixed fraction of the
energy available from oxidation for the energy consuming processes.
2. The remaining portion of the organic material is converted into new heterotrophic cell mass,
utilizing energy available from process (1).
Regarding the relative proportions allocated between (1) and (2), this is quantified by the ratio
𝑐𝑒𝑙𝑙 𝑚𝑎𝑠𝑠 𝑓𝑜𝑟𝑚𝑒𝑑
𝑌𝐻 =
𝑠𝑢𝑏𝑠𝑡𝑎𝑟𝑒 𝑢𝑡𝑖𝑙𝑖𝑧𝑒𝑑

termed the yield coefficient. Therefore, if the electron donating potential of the organic substrate in the
activated sludge system influent (consisting of a broad spectrum of compounds) is measured it is possible to
quantify sludge production [from YH] and oxygen demand [from (1-YH)]. This observation provides the
rationale for selecting the COD parameter.
The electron donating capacity of organic material is measured in the COD test. In the test each mole of
oxygen (O2) accepts four electron equivalents (e- eq); therefore, the COD is a direct measure of the electron
donating potential. The link between electron equivalents (COD) of the substrate, the near constant yield of
organism mass per unit substrate COD, and the corresponding fixed oxygen requirement per unit substrate
COD metabolized, makes the COD a fundamental parameter in the analysis of activated sludge behavior.

Note: Regarding the COD of the waste sludge, this may be measured directly by the COD test or be
estimated from the VSS measurement. Because cell mass has an approximately constant composition and is

942 • Model Reference Biowin 6 Help Manual

made up of an essentially fixed number of electron equivalents (e- eq) per unit mass, the COD/VSS ratio is
near constant (approximately 1.48 mg COD/mg VSS).

A factor that adds impetus to the selection is that mass balances can be made in terms of COD. As electrons
cannot be created or destroyed in a biosystem operated at steady state, the mass of COD entering with the
influent per unit time must equal the sum of (1) the mass of COD leaving in the effluent, (2) the COD of the
wasted sludge, and (3) the oxygen consumed in the utilization of the organic material (from the oxygen
utilization rate measurement); that is, a mass balance is possible.
Characteristics of the COD as a measure of the "strength" of a wastewater are not realized by either the
BOD or the TOC parameters. The BOD measures only that portion of the e- eq in the substrate utilized for
energy generation and excludes the portion of the substrate e- eq transformed into new cell mass.
Therefore, BOD cannot be used as the basis for a mass balance. The TOC is deficient in that the ratio of
carbon/e- eq differs between organic compounds and therefore TOC is an inappropriate parameter when
dealing with the mixed substrate influents to wastewater treatment plants.

Figure 1.1: Schematic Representation of the Utilization of Substrate by Heterotrophic Organisms Showing the Division between
Substrate Oxidized for Energy Generation and Growth of New Cell Mass

References
Marais G.v.R. and P.L. Dold (1985) Biological removal of carbon, nitrogen and phosphorus in single sludge
systems". In Proc. Advances in Biological Wastewater Treatment Seminar (pp . 207-233). Rome Italy:
Instituto di Ricerca Sulle Acque (IRSA).

Biowin 6 Help Manual Model Reference • 943

Power in BioWin

Entering Power and Power Calculations

The objective of this chapter is to describe how power is modeled and output in BioWin. Power
requirements can be specified in every element in BioWin except the Influent, Mixer, and Splitter elements.
Along with individual elements, BioWin tracks power requirements for a number of categories or sources.
For example, Blower Power, Mixing Power, Mechanical Power, Pumping Power, Heating Power, Surface
aeration Power, Solid Liquid Separation/Disinfection (i.e. S/L sep./Disinfection) Power, and Heating
Ventilation and Cooling (HVAC) Power. This categorization allows the power requirements to be easily
displayed and itemized.

The following sections describe how the power requirements are determined or specified in each power
category:
1. Blower Power

Biowin 6 Help Manual Power in BioWin • 945

 2. Mixing Power
3. Mechanical Power
4. Pumping Power
5. Heating Power
6. Surface Aeration Power
7. S/L sep./Disinfection Power
8. HVAC Power

Blower Power Parameters and Calculations

This section describes how blower parameters are specified in BioWin as well as how Blower power is
calculated.

Defining Air Supply Groups and Local Blower Power Options

BioWin allows you to define blower air supply groups for a project via the Project|Plant|Air supply
groups/blower specs… command. Using this command, you can specify whether an aerated element is part
of a group of bioreactors / aerated zones that is supplied by a common blower. Note that any element that
can be aerated may be added to a group of reactors supplied by a blower, thereby contributing to that
blower’s power requirement. Invoking this command presents you with the Edit air supply groups dialog
box, shown below.

Dialog used to edit air supply groups

Note: The Edit air supply groups dialog box remains empty until an element that is or could be aerated is
placed on the drawing board. Once a configuration is built, all the elements that can be aerated (i.e. even
elements that are specified as unaerated) will be automatically added to an air supply group (i.e. #1 Air
supply group) and will appear in the Selected list. All reactors – even those that you intend to remain
unaerated – must be included in an air supply group. This has been implemented to ensure that if an

946 • Power in BioWin Biowin 6 Help Manual

unaerated reactor is made aerated at a later time, its air supply requirement will be properly considered and
captured in blower power calculations. Obviously, if a reactor remains unaerated, it will not contribute to
the power calculation of an air supply group.

Clicking the Add button will add a new air supply group (i.e. #2 Air supply group). Clicking the Delete…
button will delete the current air supply group specified in the drop list box.

Note: By default, all of the elements are placed in the current air supply group (Typically this is the default
air supply group “#1 Air supply group”). To place an element into a new air supply group (i.e. #2 Air supply
group) the element will first need to be removed from the current air supply group.

To removal an element from the air supply group specified in the drop list box, select the element and click
the left pointing arrow < to move it from the Selected list box into the Available list box (or double click the
element). Using the double arrows (i.e. <<) will move every item in the Selected list box over to the
Available list box. To move elements from the Available list box select the elements and click the right
pointing arrow > to move them to the Selected list (or to move a single element double click the element).
To move the entire group of elements use the >> button.
If you want a blower group to have parameters that are different from the global blower parameters (e.g.
blower efficiency, discharge pressure, etc.) or to have a different calculation basis than the Global
calculation method (e.g. Adiabatic/Polytropic, Linear, User defined), then you can click the Edit Blower
specification… button to open the Air supply group blower options dialogue box for the specified air supply
group in the drop list box (i.e. #1 Air supply group), shown below.

Dialog used to edit Air supply group blower options

In the Calculate power for group using radio button group, you may choose from four methods for
calculating blower power: Global power calculation method, Adiabatic/polytrophic power equation, Linear
power equation, or User defined equation.

Biowin 6 Help Manual Power in BioWin • 947

If Global power calculation method is selected, the method specified under Project|Plant|Global blower
calculation method…will be used to calculate blower power.

Note: the method specified in the Global blower calculation method is visible in brackets for the Global
power calculation method radio button (i.e. in the dialog box above the Global blower calculation method is
specified as User defined).

If Adiabatic/Polytropic power equation is selected, the adiabatic/polytropic power equation will be used to
calculate blower power.
If Linear power equation is selected, the linear power equation will be used to calculate blower power.
Selecting the User defined equation radio button, activates a text edit box for specifying the user defined
equation, a check box which allows the user to define constants, and a Check button, shown below. Detailed
information/help on specifying a user defined equation is provided in the Entering User Defined Equations
subsection of the Specifying Project Blower Calculation Method section.

Dialog used to specify a user defined equation for blower power

You also can specify Local blower parameters for the specified air supply group. If you click on the check box
for local blower parameters, then clicking the Edit local blower parameters… button opens the Blower
performance dialog box, shown below, allowing you to modify blower parameters.

Note: This changes the blower parameters on a local level only, that is, only for the current air supply group.

948 • Power in BioWin Biowin 6 Help Manual

Local blower parameters editor dialog

Specifying Global Blower Calculation Method

BioWin allows you to specify a global blower power calculation method for a project via the
Project|Plant|Global blower calculation method… command. Invoking this command presents you with the
Blower calculation dialog box, shown below.

Biowin 6 Help Manual Power in BioWin • 949

Dialog used to set the global power calculation method

In the Calculate blower power using radio button group, you may choose from three methods for calculating
blower power: Adiabatic/polytrophic power equation, Linear power equation, or User defined equation.

Note: If you wish, you can override this global blower calculation method in individual air supply groups.

Detailed information/help on specifying a user defined equation is provided in the Entering User Defined
Equations subsection of the Specifying Project Blower Calculation Method section.

Blower Power Calculations

Blower Power Parameters

Global Location: Project|Parameters|Aeration/Mass Transfer|Diffuser

Local Location: ‘Local Diffuser Parameters’ on Element “Model” tab

Name Default Value Unit Explanation

Diffuser Mounting 0.25 m The diffuser mounting height in the

Height reactor is used to determine the
discharge depth for the calculation of
static head.
‘A’ in diffuser 3 kPa This constant is used to determine the
pressure drop pressure drop across the diffusers for
the calculation of dynamic head.
‘B’ in diffuser 0 kPa/(m3/hr) This constant is used to determine the
pressure drop pressure drop across the diffusers for
the calculation of dynamic head.
‘C’ in diffuser 0 (kPa/(m3/hr))2 This constant is used to determine the
pressure drop pressure drop across the diffusers for
the calculation of dynamic head.

Global Location: Project|Parameters|Aeration/Mass Transfer|Blower

Local Location: ‘Local Blower Parameters’ on “Air supply groups blower options” tab

Name Default Value Unit Explanation

Intake filter pressure drop 3.5 kPa The sum of the pressure drop through
the intake piping and across the intake
filter. This parameter is used to
calculate blower intake pressure.

950 • Power in BioWin Biowin 6 Help Manual

 Pressure drop through 3 kPa The pressure drop through the
distribution system distribution system is used to calculate
(piping/valves) blower discharge pressure.
Adiabatic/polytropic 1.4 The adiabatic/polytropic compression
compression exponent (1.4 exponent is used when the
for adiabatic) adiabatic/polytropic power equation is
specified.
‘A’ in blower efficiency 0.75 This constant is used to determine
blower efficiency.
‘B’ in blower efficiency 0 hr/m3 This constant is used to determine
blower efficiency.
‘C’ in blower efficiency 0 (hr/m3)2 This constant is used to determine
blower efficiency.

Location: Project|Parameters|Physical/Chemical|Properties constants

Name Default Value Unit Explanation

‘A’ in Antoine equn. 5.2039 NIST calculated coefficient used to

calculate vapor pressure as per Antoine’s
equation.
‘B’ in Antoine equn. 1733.9260 NIST calculated coefficient used to
calculate vapor pressure as per Antoine’s
equation.
‘C’ in Antoine equn. -39.5 NIST calculated coefficient used to
calculate vapor pressure as per Antoine’s
equation.

Determining Blower Power Equation Variables

Blower power equations are based on estimates of:

• Intake Pressure (PIntake),
• Intake Airflow (Qa,Intake),
• Discharge Pressure (PDischarge), and
• Blower efficiency (BlowerEff).
These parameters (excluding Blower efficiency) can be tabulated in the ablum along with the blower power
for each defined air supply group by adding an Air Supply Group Table. See Add a Table Display (Pre-defined
Air Supply group table).

Blower Intake Airflow and Pressure

Biowin 6 Help Manual Power in BioWin • 951

In order to calculate the Intake Airflow and the Intake Pressure BioWin must determine the standard airflow
(i.e. air supply rate at 20°C and 101.325 kPa) required in each reactor. This airflow is then converted to
ambient air conditions with the following equation:

𝑃 𝑇𝑎,𝑖𝑛𝑙𝑒𝑡 (1)
𝑄𝑎,𝑎𝑚𝑏𝑖𝑒𝑛𝑡 = 𝑄𝑎,𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑 ∙ ( 𝑃𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑 ) ∙ (𝑇 )
𝑠𝑢𝑟𝑓𝑎𝑐𝑒 𝑎,𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑

where

𝑄𝑎,𝑎𝑚𝑏𝑖𝑒𝑛𝑡 = ambient airflow [m3/hr]

𝑄𝑎,𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑 = standard airflow required in each reactor (i.e. at 20°C,101.325 kPa) [m3/hr]

𝑃𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑 = standard atmospheric pressure [kPa]

𝑃𝑠𝑢𝑟𝑓𝑎𝑐𝑒 = surface pressure [kPa]

𝑇𝑎,𝑖𝑛𝑙𝑒𝑡 = inlet air temperature [K]

𝑇𝑎,𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑 = standard air temperature [K]

The surface pressure for a project is specified in Project|Parameters|Aeration/Mass Transfer… under the
Aeration tab.
The inlet air temperature is specified by invoking the Project|Plant|Inlet air conditions… command.
Detailed help on specifying inlet air conditions is provided in the Specifying Project Inlet Air Conditions
section of the Managing BioWin Projects chapter.

To correct ambient airflow for humidity, BioWin first uses Antoine’s equation to calculate the vapour
pressure (Pvap):

𝐵 (2)
{𝐴−( )}
𝑃𝑣𝑎𝑝 = 10 𝑇𝑎,𝑖𝑛𝑙𝑒𝑡 +𝐶
× 100
where

A, B and 𝐶 = NIST calculated coefficients

100 = conversion from Bar to kPa
The A, B and C constants for Antoine’s equation are specified in
Project|Parameters|Physical/Chemical…under the Properties constants tab.

The vapour pressure and ambient airflow are then used to determine the ‘wet’ airflow (Qa,wet):

952 • Power in BioWin Biowin 6 Help Manual

 𝑃𝑠𝑢𝑟𝑓𝑎𝑐𝑒 +𝐼𝑛𝑙𝑒𝑡𝐴𝑖𝑟𝐻𝑢𝑚𝑑𝑖𝑡𝑦∙𝑃𝑣𝑎𝑝 (3)
𝑄𝑎,𝑤𝑒𝑡 = 𝑄𝑎,𝑎𝑚𝑏𝑖𝑒𝑛𝑡 ∙ { }
𝑃𝑠𝑢𝑟𝑓𝑎𝑐𝑒

Humidity is specified by invoking the Project|Plant|Inlet air conditions… command. Detailed help on
specifying inlet air conditions is provided in the S Specifying Project Inlet Air Conditions section of the
Managing BioWin Projects chapter.

Finally, this ‘wet’ airflow is corrected for the pressure drop through the intake filter (Pdrop,intake) to obtain the
intake airflow rate (Qa,Intake, m3/hr):

𝑃 (4)
𝑄𝑎,𝐼𝑛𝑡𝑎𝑘𝑒 = 𝑄𝑎,𝑤𝑒𝑡 ∙ ( 𝑃𝑠𝑢𝑟𝑓𝑎𝑐𝑒 )
𝐼𝑛𝑡𝑎𝑘𝑒

where

𝑃𝐼𝑛𝑡𝑎𝑘𝑒 = 𝑃𝑠𝑢𝑟𝑓𝑎𝑐𝑒 − 𝑃𝑑𝑟𝑜𝑝,𝑖𝑛𝑡𝑎𝑘𝑒 (5)

The global blower intake filter pressure drop is specified for every blower/air supply group in
Project|Parameters|Aeration/Mass transfer…under the Blower tab. This may be overridden for individual
air supply groups by
• Invoking the Project|Plant|Air supply group/blower specs…command.
• In the Air supply groups dialog box, select the desired Air Supply group, and click Edit blower
specifications to open the Air Supply group blower options dialog box.
• Check the Local blower parameters check box to activate the Edit local blower parameters…
button. Clicking this button opens the Blower dialog box where the intake filter pressure drop can
be edited for the current air supply group.

Blower Discharge Pressure

In order to calculate the Discharge pressure BioWin must determine the density of water at the specified
temperature of the stream, and both the static and the dynamic head that the blower must overcome. The
density is determined based on a temperature correlation equation. The static head (Hstatic, kPa) that the
blower must overcome is determined from the following equation:

𝜌𝐻20 ∙𝐷𝑑𝑖𝑠𝑐ℎ𝑎𝑟𝑔𝑒 ∙𝑔 (6)

𝐻𝑠𝑡𝑎𝑡𝑖𝑐 = 𝑃𝑠𝑢𝑟𝑓𝑎𝑐𝑒 + 1000

where

Biowin 6 Help Manual Power in BioWin • 953

 𝑃𝑠𝑢𝑟𝑓𝑎𝑐𝑒 = surface pressure denoted by the head space pressure or field pressure [kPa]

𝜌𝐻20 = density of water at the specified temperature of the stream [kg/m3]

𝐷𝑑𝑖𝑠𝑐ℎ𝑎𝑟𝑔𝑒 = discharge depth determined by subtracting the tank depth from the diffuser mounting
height [m]
𝑔 = gravitational constant [m/s2]

The dynamic head (𝐻𝑑𝑦𝑛𝑎𝑚𝑖𝑐 , kPa) the blower must overcome is defined as follows:

2
𝐻𝑑𝑦𝑛𝑎𝑚𝑖𝑐 = 𝐴 + 𝐵 ∙ 𝑄𝑎/𝑑𝑖𝑓𝑓 + 𝐶 ∙ 𝑄𝑎/𝑑𝑖𝑓𝑓 (7)

where

𝑄𝑎/𝑑𝑖𝑓𝑓 = airflow rate per diffuser [m3/hr]

𝐴 = diffuser pressure drop constant [kPa]

𝐵 = diffuser pressure drop constant [kPa/m3/hr]

𝐶 = diffuser pressure drop constant [(kPa/m3/hr)2]

Constants A, B and C can be specified globally for every diffuser in Project|Parameters|Aeration/Mass

Transfer… under the Diffuser tab. This may be overridden for each individual reactor that has aeration
capabilities in the Model tab of the respective reactors property dialog box by checking the Local diffuser
parameters check box and clicking on the Edit local diffuser parameters…button.

Note: The dynamic head is calculated for each reactor in the blower air supply group and the maximum
dynamic head is used in the final discharge pressure calculation.

In order to calculate the airflow rate per diffuser (i.e. in the case where constants B and C are specified in
Equation 7) the discharge pressure and airflow at the diffuser (PDischarge, diffusers, kPa) must be determined. The
discharge pressure at the diffuser is assumed to be equal to the static head:

𝜌𝐻20 ∙𝐷𝑑𝑖𝑠𝑐ℎ𝑎𝑟𝑔𝑒 ∙𝑔 (8)

𝑃𝐷𝑖𝑠𝑐ℎ𝑎𝑟𝑔𝑒,𝑑𝑖𝑓𝑓𝑢𝑠𝑒𝑟𝑠 = 𝐻𝑠𝑡𝑎𝑡𝑖𝑐 = 𝑃𝑠𝑢𝑟𝑓𝑎𝑐𝑒 + 1000

The standard airflow (i.e. air supply rate) is corrected for inlet humidity conditions:

954 • Power in BioWin Biowin 6 Help Manual

 𝑃𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑 +𝐼𝑛𝑙𝑒𝑡𝐴𝑖𝑟𝐻𝑢𝑚𝑑𝑖𝑡𝑦 ∙ 𝑃𝑣𝑎𝑝 (9)
𝑄𝑎,𝑤𝑒𝑡 = 𝑄𝑎,𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑 ∙ { 𝑃𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑
}

This wet airflow [m3/hr] is then corrected for the conditions at the diffusers output in the bioreactor:

𝑃𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑 𝑇𝑟𝑒𝑎𝑐𝑡𝑜𝑟 (10)

𝑄𝑎,𝑑𝑖𝑓𝑓𝑢𝑠𝑒𝑟 = 𝑄𝑎,𝑤𝑒𝑡 ∙ (𝑃 ) ∙ (𝑇 )
𝐷𝑖𝑠𝑐ℎ𝑎𝑟𝑔𝑒,𝑑𝑖𝑓𝑓𝑢𝑠𝑒𝑟 𝑎,𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑

where

𝑇𝑟𝑒𝑎𝑐𝑡𝑜𝑟 = temperature in the bioreactor [K]

Finally the airflow per diffuser [m3/hr/diffuser] is calculated as follows:

𝑄𝑎,𝑑𝑖𝑓𝑓𝑢𝑠𝑒𝑟 (11)
𝑄𝑎/𝑑𝑖𝑓𝑓 = # 𝑑𝑖𝑓𝑓𝑢𝑠𝑒𝑟𝑠

Note: Equations 8-11 are only utilized if a non-zero value is specified for the diffuser pressure drop
constants B and C.

The final Discharge Pressure [kPa] is calculated as the sum of the static head, the dynamic head and the
pressure drop through the distribution system:

𝑃𝐷𝑖𝑠𝑐ℎ𝑎𝑟𝑔𝑒 = 𝐻𝑠𝑡𝑎𝑡𝑖𝑐 + 𝐻𝑑𝑦𝑛𝑎𝑚𝑖𝑐 + 𝑃𝑑𝑟𝑜𝑝,𝑠𝑦𝑠𝑡𝑒𝑚 (12)

where

𝑃𝑑𝑟𝑜𝑝,𝑠𝑦𝑠𝑡𝑒𝑚 = pressure drop through distribution system (piping/valves) [kPa]

The global pressure drop through the distribution system is specified for every blower/air supply group in
Project|Parameters|Aeration/Mass transfer…under the Blower tab. This may be overridden for individual
air supply groups by
• Invoking the Project|Plant|Air supply group/blower specs…command.
• In the Air supply groups dialog box, select the desired Air Supply group, and click Edit blower
specifications to open the Air Supply group blower options dialog box.

Biowin 6 Help Manual Power in BioWin • 955

 • Check the Local blower parameters check box to activate the Edit local blower parameters…
button. Clicking this button opens the Blower dialog box where the pressure drop through the
distribution system can be edited for the current air supply group.

Blower Efficiency

Blower efficiency is calculated from the following equation:

2
𝐵𝑙𝑜𝑤𝑒𝑟𝐸𝑓𝑓 = 𝐴 + 𝐵 ∙ 𝑄𝑎,𝑖𝑛𝑡𝑎𝑘𝑒 + 𝐶 ∙ 𝑄𝑎,𝑖𝑛𝑡𝑎𝑘𝑒 (13)

where

𝐴 = blower efficiency constant [-]

𝐵 = blower efficiency constant [hr/m3]

𝐶 = blower efficiency constant [(hr/m3)2]

𝑄𝑎,𝑖𝑛𝑡𝑎𝑘𝑒 = intake airflow into the blower [m3/hr]

Constants A, B and C can be specified globally for every blower/air supply group in
Project|Parameters|Aeration/Mass transfer…under the Blower tab. This may be overridden for individual
air supply groups by :
• Invoking the Project|Plant|Air supply group/blower specs…command.
• In the Air supply groups dialog box, select the desired Air Supply group, and click Edit blower
specifications to open the Air Supply group blower options dialog box.
• Check the Local blower parameters check box to activate the Edit local blower parameters…
button. Clicking this button opens the Blower dialog box where the pressure drop through the
distribution system can be edited for the current air supply group.

Note: Blower efficiency is bounded between 0.001 and 0.99.

Blower Power Equations

Three power equation options are available in BioWin: the Adiabatic/Polytropic power equation, the Linear
power equation and a User defined power equation.

Adiabatic/Polytropic Power Equation

956 • Power in BioWin Biowin 6 Help Manual

The adiabatic/polytropic power equation is typically used to calculate the power (P) for screw compressors
as well as centrifugal and turbo blowers (Aerzen USA, 2015). Compression in these types of blowers is either
isentropic/adiabatic (i.e. without the gain or loss of heat) or polytropic (i.e. including heat transfer). The
adiabatic/polytropic power equation is defined as follows:

𝛾−1
𝑄𝑎,𝑖𝑛𝑡𝑎𝑘𝑒 𝛾 𝑃𝐷𝑖𝑠𝑐ℎ𝑎𝑟𝑔𝑒 𝛾
(14)
𝑃= ∙ 𝑃𝐼𝑛𝑡𝑎𝑘𝑒 ∙ ∙ [( ) − 1]
3600 𝛾−1 𝑃𝐼𝑛𝑡𝑎𝑘𝑒

where

𝑄𝑎,𝑖𝑛𝑡𝑎𝑘𝑒
= blower intake airflow [m3/hr]
𝑃𝐷𝑖𝑠𝑐ℎ𝑎𝑟𝑔𝑒
= blower discharge pressure [kPa]

𝑃𝐼𝑛𝑡𝑎𝑘𝑒 = blower intake pressure [kPa]

𝛾 = adiabatic/polytropic compression exponent (1.4 for adiabatic)

3600 = conversion from m3/hr to m3/s

The adiabatic/polytropic compression exponent can be specified globally for every blower/air supply group
in Project|Parameters|Aeration/Mass transfer…under the Blower tab. This may be overridden for
individual air supply groups by
1. Invoking the Project|Plant|Air supply group/blower specs…command.
2. In the Air supply groups dialog box, select the desired Air Supply group, and click Edit blower
specifications to open the Air Supply group blower options dialog box.
3. Check the Local blower parameters check box to activate the Edit local blower parameters…
button. Clicking this button opens the Blower dialog box where the compression exponent can be
edited for the current air supply group.

Note: The final adiabatic/polytropic blower power [kW] reported in BioWin is divided by the blower
efficiency (see Equation 13 for calculation of blower efficiency).

Linear Power Equation

The linear power equation is typically used to calculate the power (P) for rotary lobe blowers (Aerzen USA,
2015). Compression in these types of blowers is isochoric (i.e. at a constant volume) (Aerzen USA, 2015).
Blower power is proportional to the air flow and the change in pressure and is defined as follows:

Biowin 6 Help Manual Power in BioWin • 957

 𝑄𝑎,𝑖𝑛𝑡𝑎𝑘𝑒
𝑃= ∙ (𝑃𝐷𝑖𝑠𝑐ℎ𝑎𝑟𝑔𝑒 − 𝑃𝐼𝑛𝑡𝑎𝑘𝑒 ) (15)
3600

where

𝑄𝑎,𝑖𝑛𝑡𝑎𝑘𝑒 = blower intake airflow [m3/hr]

𝑃𝐷𝑖𝑠𝑐ℎ𝑎𝑟𝑔𝑒 = blower discharge pressure [kPa]

𝑃𝐼𝑛𝑡𝑎𝑘𝑒 = blower intake pressure [kPa]

3600 = conversion from m3/hr to m3/s

Note: The final linear blower power [kW] reported in BioWin is divided by the blower efficiency (see
Equation 13 for calculation of blower efficiency).

User Defined Power Equation

Detailed help on specifying a user defined power equation is provided in the Specifying Project Blower
Calculation Method section.of the Managing BioWin Projects chapter.

References
Aerzen USA. (2015) Aerzen USA Corporation Whitepaper: Aeration Blowers in Wastewater Industry in North
America. Coatesville, Pennsylvania.

Mixing Power

• Mechanical Mixing Power can be entered in the following elements:

• Bioreactor,
• Membrane Bioreactor,
• Media Bioreactor,
• Variable volume Bioreactor,
• Aerobic digester,
• Side stream reactor,
• Side stream Media Bioreactor,
• Submerged aerated filter,
• Shallow submerged aerated filter,

958 • Power in BioWin Biowin 6 Help Manual

 • Equalization tank,
• Single-tank SBR,
• SBR + 1 mix/settle prezone,
• SBR + 1 always-mixed prezone,
• SBR + 2 mix/settle prezone,
• SBR + 2 always-mixed prezone,
• Anaerobic Digester, and
• Model Builder Unit elements.
Within a specific element, mixing power can be specified in the Power tab of the element’s property dialog
box.

Sample Power tab in a Bioreactor element.

Power can be specified on a power per unit volume basis or on a fixed basis by checking or unchecking the
Power per unit vol check box, respectively. The user can enter a constant value for power or power per unit
volume by selecting the Constant value of radio button and entering a value in the text edit box.
Alternatively, the user can enter a power or power per unit volume pattern by selecting the Scheduled radio
button. This activates the Pattern…button. Clicking this button will open the Power Itinerary editor. By
default, the mixing power is set to 0, however if you open an existing file the mixing power will be set to the
value previously entered (i.e. 5 W/m3).

Mechanical Power
• Mechanical Power can be entered into the following elements:

Biowin 6 Help Manual Power in BioWin • 959

 • Trickling filter
• Grit tank
• Thermal Hydrolysis unit
• Ideal Clarifier
• Model Clarifier
• Ideal primary settling tank elements
Within a specific element, mechanical power is specified in the Power tab of the element’s property dialog
box.

Sample Power tab in an Ideal clarifier element.

Power can be specified on a power per unit flow basis or on a fixed basis by checking or unchecking the
Power per unit flow to this element check box, respectively. The user can enter a constant value for power
or power per unit flow by selecting the Constant value of radio button and entering a value in the text edit
box. Alternatively, the user can enter a power or power per unit flow pattern by selecting the Scheduled
radio button. This activates the Pattern…button. Clicking this button will open the Power Itinerary editor.

Pumping Power
Specifying Pumping Parameters
In BioWin, pumping power can either be calculated or specified for Pump elements.

960 • Power in BioWin Biowin 6 Help Manual

Within a pump element pumping power options are found in the Pumping power options tab, shown
below.

The Pumping power options tab of a Pump element

There are three methods for specifying Pump power options. You can choose to Calculate power, enter a
Constant power, or enter a Scheduled power by clicking on the corresponding radio button. If you select
the Constant power radio button then a value for power can be entered directly into the text edit box. If
you select the Scheduled power radio button, the Pattern… button becomes active so you can enter a time-
varying pattern for the power. Clicking this button presents you with the Edit pump power supply itinerary
dialog box.

Note: For each of the first two options, BioWin does not calculate the flow based on the power you have
entered. It is assumed that the required flow can be delivered by the pump. The first two options are for the
scenario of keeping track of the power consumed by existing pumps at a wastewater treatment facility.

If you specify to Calculate power, the Pipe & pump specifications button becomes active so you can enter
pump and pipe specifications for calculating power. Clicking this button presents you with the Pump and
pipe specifications dialog box, shown below, where the user can enter the static head, pipe length and pipe
inside diameter into the respective text edit boxes.

The Pump and pipe specifications dialog box

Biowin 6 Help Manual Power in BioWin • 961

Clicking the Pump efficiency… button opens the Pump efficiency dialog box, shown below, where the user
can specify the constants ‘A’, ‘B’, and ‘C’ in the overall pump efficiency equation. Values can be entered
directly into the text edit boxes.

Note: If you want one efficiency applied over the entire range of discharge flows, then the ‘B’ and ‘C’
coefficients can be set to zero.

The Pump efficiency dialog box

Clicking the Pipe/configuration details… in the Pump and pipe specifications dialog box presents you with
the Pipe Roughness and fittings dialog box, shown below, where the user can specify parameters for pipe
roughness and fittings.

The Pipe roughness and fittings dialog box

The method of specifying the pipe roughness for the length of pipe specified in the Pump and pipes
specifications dialog box may be selected from a number of pipe material options. You can specify pipe
material and thereby the roughness by clicking on the corresponding material radio button (i.e. PVC/HDPE,
Riveted steel, etc.). Selecting the Custom radio button activates the pipe roughness text edit box so a pipe
roughness value can be entered directly into the text edit box.

962 • Power in BioWin Biowin 6 Help Manual

The loss coefficient for the fittings (i.e. K(fittings)) can either be specified directly or calculated. If the
roughness factor for the fittings is known, it can be directly entered into the K(fittings) – Total minor losses
text edit box. To calculate K(fittings), enter the number of each type of fitting (i.e. Pipe entrance
(bellmouth), 90o bend, etc.) along the specified pipe length directly into the respective text edit boxes. Then
click the Calculate total K for fittings button. This changes the K(fittings) – Total minor losses text edit box
to show the calculated value.

Pumping Power Equations

The calculation of pumping power in BioWin is similar to the approach of RAE and AECOM (2010).

In order to determine the power requirements for a given pump element BioWin needs to calculate the
total system head to use in the pumping power equation.
Total system head [m] is defined as:

𝐻𝑇𝑜𝑡𝑎𝑙 = 𝐻𝑆 + 𝐻𝐷 (16)

where

𝐻𝑆
= static head [m]

𝐻𝐷 = dynamic head [m]

In BioWin, the static head is entered by the user in the Pipe and Pump specifications dialog box, shown
below.

The dynamic head [m] is calculated based on the generated friction within the system using the Darcy
Weisbach equation:

𝐾∙𝑣 2 (17)
𝐻𝐷 = 2∙𝑔

Biowin 6 Help Manual Power in BioWin • 963

where

𝐾 = loss coefficient

𝑣 = velocity in the pipe [m/s]

𝑔 = acceleration due to gravity [m/s2]

The loss coefficient accounts for both the loss through the pipe and the loss through the fittings:

𝐾 = 𝐾𝑓𝑖𝑡𝑡𝑖𝑛𝑔𝑠 + 𝐾𝑝𝑖𝑝𝑒 (18)

Kfittings is dependent on the fittings used for the specified length of pipe and is obtained from standard tables.
In BioWin this value is determined in the Pipe/configuration specifications dialog box, shown below.

In this dialog box, standard K values are specified for various fittings (i.e. Pipe entrance, 90o bend, butterfly
valve etc.). The user is required to specify the number of each type of fitting used in the specified length of
pipe by entering a number directly into the text edit boxes of the “Number” column. Clicking on the
Calculate total K for fittings button will sum the K values for the specified number of fittings and report the
total sum of the contributions from each of the fittings to the K(fittings) – Total minor losses text edit box.
Alternatively the user can directly enter a value for Kfittings into the text edit box.

Kpipe is dependent on the friction associated with the straight lengths of pipe and is defined as:

964 • Power in BioWin Biowin 6 Help Manual

 𝑓∙𝐿 (19)
𝐾𝑝𝑖𝑝𝑒 = 𝐷

where

𝑓 = friction coefficient

𝐿 = pipe length [m]

𝐷 = pipe diameter [m]

The friction coefficient is calculated using the Colebrook White equation:

If Re >= 2000 (20)

1 𝑘 2.51
= −2 𝐿𝑜𝑔10 (3.7 + )
√𝑓 𝑅𝑒√𝑓

If 𝑅𝑒 < 2000 (21)

64
𝑓=
𝑅𝑒

where

𝑅𝑒 = Roughness factor [m]

𝑅𝑒 = Reynolds number

The roughness factor k is a standard value obtained from standard tables and is based on the material of the
pipe. In BioWin, the roughness factor (k) is specified in the Pipe/configuration specifications dialog box,
shown above, by specifying the pipe material using the radio buttons in the Pipe roughness suggested
values radio button group. Alternatively the user can enter a user defined roughness factor by selecting the
Custom radio button and entering a value directly into the Pipe roughness text edit box.
The Reynolds number is calculated with the following formula:

𝑣∙𝐷 (22)
𝑅𝑒 = 𝜐

where

Biowin 6 Help Manual Power in BioWin • 965

 𝜐 = Kinematic viscosity [m2/s]

Kinematic viscosity is the ratio of dynamic viscosity to density. In BioWin the mixed liquor dynamic viscosity
(μ) of the liquid is dependent on the suspended solids concentration:

𝜇 = 𝜇𝐻2𝑂 × (1 + 𝐴 × 𝑀𝐿𝑆𝑆 𝑌 ) (23)

where

𝜇𝐻2𝑂 = the dynamic viscosity of water [Pa.s]

𝐴 = constant [m3/g]

𝑌 = constant

𝑀𝐿𝑆𝑆 = mixed liquor suspended solids concentration [g/m3]

The dynamic viscosity of water (𝜇𝐻2𝑂 ) is temperature dependent and calculated from:

𝐸
( 𝑎) (24)
𝜇𝐻2𝑂 = 𝐾𝑒 𝑅𝑇

where:

μH20 = the dynamic viscosity of water [Pa.s]

𝐾 = constant (initial value of dynamic viscosity) [Pa.s]

𝐸𝑎 = Activation energy [J mol-1]

𝑅 = Universal gas constant [ J K-1 mol-1]

𝑇 = Temperature [K]

The parameters for the dynamic viscosity calculation can be modified in

Project|Parameters|Physical/Chemical under the Properties constants tab.

966 • Power in BioWin Biowin 6 Help Manual

Note:1Pa.s = 1 kg/(m.s) when calculating kinematic viscosity [m2/s] from dynamic viscosity and density
[kg/m3]

Finally, the power [kW] requirements for the pump are calculated with the following formula:

𝑄∙𝐻𝑇𝑜𝑡𝑎𝑙 ∙𝑔∙𝜌 (25)

𝑃= ( ) /1000
𝑃𝑢𝑚𝑝 𝐸𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦

where

𝑄 = flow through the pipe [m3/s]

𝑃 = density of water [kg/m3]

In BioWin, the density of the liquid is dependent on the suspended solids concentration:

𝜌 = 𝜌𝐻2𝑂 + 𝐴 ∙ 𝑀𝐿𝑆𝑆 (26)

where

𝜌𝐻2𝑂 = density of water [kg/m3]

𝐴 = constant [m3/g]

𝑀𝐿𝑆𝑆 = mixed liquor suspended solids concentration [g/m3]

The parameters for the density calculation can be modified in Project|Parameters|Physical/Chemical under
the Properties constants tab. The density of water is calculated as a function of temperature using an
empirical function based on ASCE library data.
If you hover your cursor over a Pump element, BioWin will display the Pump Energy Indicator in the bottom
right summary pane. The Pump Energy Indicator can also be plotted or tabulated in the Album. It is found
under the subsection Other in the Element Specific list in an Edit Table or Add parameter for plotting
dialog. See Data Output (charts, tables, reports) for instruction on adding charts and tables to the Album.
The Pump Energy Indicator [kw.hr/(ML.m] is used to benchmark pump efficiency based on both flow and
head and is calculated as follows:

𝑃⋅24⋅1000 (27)
𝑃𝑢𝑚𝑝 𝐸𝑛𝑒𝑟𝑔𝑦 𝐼𝑛𝑑𝑖𝑐𝑎𝑡𝑜𝑟 = 𝑄⋅𝐻𝑇𝑜𝑡𝑎𝑙

Biowin 6 Help Manual Power in BioWin • 967

where

𝑃 = pumping power [kW]

𝑄 = flow [m3/d]

𝐻𝑇𝑜𝑡𝑎𝑙 = total system head [m]

24 = conversion hr/d

1000 = conversion m3/ML

References
Royal Academy of Engineering (RAE) and AECOM (2010). The Mathematics of Pumping Water, AECOM
Design Build. http://www.raeng.org.uk/publications/other/17-pumping-water
Rheological Measurements of Disintegrated Activated Sludge. Travnicek, T et al, Pol. J. Environ. Stud. Vol 22,
No 4 (2013), 1209-1212Steady Rheological Properties of Rotating Biological Contactor (RBC) Sludge. Abu-
Jdayil, B et al, J. Water Resource and Protection, 2010, 2, 1-7
Biomass Concentration by Density Measurement: Activated Sludge and Membrane Bioreactor. Cano, G et al,
Journal of Water Sustainability, Volume 4, Issue 1, March 2014, 49-61

Heating Power and Power Recovery

The heating power requirement is determined for Anaerobic Digester and Thermal Hydrolysis flowsheet
elements. Typically, the main component of the heating power is the amount of energy required to heat an
influent stream to the desired operating temperature specified in the Anaerobic Digester and/or Thermal
Hydrolysis unit elements. Additional heating power may be required in an Anaerobic Digester element to
overcome a specified digester heat loss.
In both the Anaerobic Digester and Thermal Hydrolysis unit elements you can specify between one of two
heating methods:
Electrical heating which will incur an electricity cost, or
Heating via an external fuel source (i.e. natural gas, heating oil, diesel, or a custom fuel) which will incur a
cost for fuel.
BioWin also allows you to choose how biogas generated in an anaerobic digester is used. The overall
multiple options for biogas use are shown in the following diagram (and options for additional heating needs
are identified). Although not shown in the diagram, if heat recovery via a heat exchanger is specified the
overall heating requirements will be reduced. Digester biogas may be used in three main ways:

968 • Power in BioWin Biowin 6 Help Manual

Using the biogas in a Combined Heat & Power (CHP) engine. This pathway includes options for selling all or
left-over generated power; using or selling non-waste heat, and the method used for additional digester
heating if required (i.e. electrical or use of external fuel).
Burning the biogas in a boiler for heating and supplementing via electrical or external fuel sources if
insufficient gas is available. If there is any excess biogas after satisfying heating demands, there is an option
to sell it.
Either flaring off or selling all of the gas. For either option, the method used for digester heating (i.e.
electrical or use of external fuel) must be specified.

Potential Uses for Digester-Generated Biogas in BioWin

There are also options in BioWin for heating power recovery within the Anaerobic Digester and Thermal
Hydrolysis Unit elements. In an Anaerobic Digester element, a portion of the heating power may be
recovered via a Combined Heat & Power (CHP) engine. In both the Anaerobic Digester and Thermal
Hydrolysis Unit element a portion of the heating power may be recovered via a Heat Exchanger.
When the option to include a heat exchanger is specified, BioWin assumes that the hot digester (or THU)
output stream is used to heat the cool incoming stream in a counter-current heat exchanger. Users can
enter the efficiency of the exchanger as well as the temperature difference between the heat exchanger’s
hot exit stream and cold entry stream. A schematic representing the difference in temperature between the
hot exit and cold entry streams for the heat exchanger is shown below.

Biowin 6 Help Manual Power in BioWin • 969

Anaerobic Digester Element

Heating Power Parameters

Location: Project|Costs/Energy|Fuel/Chemical on “Calorific values of heating fuels” tab

Name Default Unit Explanation

Value

Calorific value of natural 48000 kJ/kg The calorific value of natural gas is
gas used to determine the energy of using
natural gas as a fuel source for
heating.
Calorific value of heating 42000 kJ/kg The calorific value of heating fuel oil is
fuel oil used to determine the energy of using
heating fuel oil as a fuel source for
heating.
Calorific value of diesel 46000 kJ/kg The calorific value of diesel is used to
determine the energy of using diesel
as a fuel source for heating.
Calorific value of custom 32000 kJ/kg The calorific value of custom fuel is
fuel used to determine the energy of using
custom fuel as a fuel source for
heating.

970 • Power in BioWin Biowin 6 Help Manual

Location: Project|Costs/Energy|Combined Heat and Power (CHP)

Name Default Unit Explanation

Value

Methane heat of 800 kJ/mol The methane heat of combustion is

combustion used to calculate the energy released
from the combustion of methane in
the biogas.
Hydrogen heat of 240 kJ/mol The hydrogen heat of combustion is
combustion used to calculate the energy released
from the combustion of hydrogen in
the biogas.
CHP engine heat price 0 $/kWh This parameter is used to calculate the
cost recovery from selling CHP engine
heat when CHP is not being used as
heat for the boiler.
CHP engine power price 0.15 $/kWh This parameter is used to calculate the
cost recovery from selling CHP engine
power.

Location: ‘Combined Heat & Power unit (CHP)’ on Anaerobic Digester “Power/Heat” tab

Name Default Unit Explanation

Value

Percent CHP engine to 33 % The percentage of power generated

power from CHP.
Percent CHP engine to 35 % The percentage of heat generated
heat from CHP.
Efficiency of heat use 0.55 % The percentage of heat generated
from CHP that is used to preheat the
boiler.

Specifying Digester Heating Options

The Heating/heat loss tab, shown below, allows users to enter options for heat loss, heating method as well
as heat recovery for the Anaerobic Digester.

Biowin 6 Help Manual Power in BioWin • 971

The Heating/heat loss tab of an Anaerobic digester element

When the option to include a heat exchanger is specified, BioWin assumes that the hot digester output
stream is used to heat the cool incoming stream in a counter-current heat exchanger. Users can enter the
efficiency of the exchanger as well as the temperature difference between the heat exchanger’s hot exit
stream and cold entry stream. A schematic representing the difference in temperature between the hot exit
and cold entry streams for the heat exchanger is shown below.

Schematic illustrating H/X Hot Stream Exit T – H/X Cold Stream Entry T

972 • Power in BioWin Biowin 6 Help Manual

Heating Power Requirements
The heating requirements for the Anaerobic Digester element include heating the influent stream to the
specified operational temperature and overcoming a user defined daily heat loss in order to maintain the
specified temperature.
The heating power [kW] required to heat the influent stream is calculated from:

(𝑇𝑅 −𝑇𝑖𝑛 )∙𝑄𝑖𝑛 ∙𝐶∙𝜌 (28)

𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑖𝑛 =
86400

where:

𝑇𝑅 = User specified operational temperature in the Anaerobic Digester element [oC]

𝑇𝑖𝑛 = Temperature of the influent stream [oC]

𝑄𝑖𝑛 = Flow of the influent stream [m3/d]

𝐶 = Heat capacity of water [J/(goC)]

𝜌 = Density of water [kg/m3]

86400 = Conversion for seconds/day

The heating power [kW] required to overcome daily heat loss is calculated from:

𝐻𝑙𝑜𝑠𝑠 ∙𝑉∙𝐶∙𝜌 (29)

𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑙𝑜𝑠𝑠 =
86400

where:

𝐻𝑙𝑜𝑠𝑠 = Digester Heat loss [oC/d]

𝑉 = Liquid Volume in the Digester [m3]

𝐶 = Heat capacity of water [J/(goC)]

𝜌 = Density of water [kg/m3]

86400 = Conversion for seconds/day

Note: When modeling digesters in series OR a digester followed by a THU unit, BioWin WILL account for the
temperature of the effluent leaving the heated process in the calculation of the heating power requirement

Biowin 6 Help Manual Power in BioWin • 973

for the subsequent element (i.e. the temperature leaving an element is reflected in the influent temperature
to the subsequent element). As such, reductions in the heating power requirements for the subsequent
reactor(s) may be observed.

Note: The overall heating power requirements will be impacted by the gas use option specified (e.g. heat
recovery via CHP, specifying to use the gas generated in the digester towards heating) as well as specifying
to recover heat via a heat exchanger.

Note: If the option to recover heat using a heat exchanger is specified the potential heat recovery will be
applied to the overall heating requirements before gas use options are evaluated.

Heating Power Equations when Flare/Sell All Specified for Gas Use

The Gas Use tab of an Anaerobic digester element with Flare/Sell all specified

When the option to Flare/Sell All gas generated in the digester is selected, the heating method can be
specified as either Electrical or via external fuel (i.e. Boiler (Fuel)), see diagram below. If Sell excess gas (all
gas/if “Flare/Sell all” selected) is selected, all of the biogas generated in the digester will be sold at a
specified Biogas sale price found in Project|Costs/Energy|Fuel/Chemical on the Heating fuel/Chemical
Costs tab. See Fuel (Heating and/or Sale) for the equations used to determine biogas availability and sale
costs when Sell all is specified.

974 • Power in BioWin Biowin 6 Help Manual

If the user also chooses to recover heat via a heat exchanger the overall heating power requirements will be
affected. See Heating Power Requirements for the equations used to determine the heating power required.
See Heat Exchanger for Power Recovery (AD) for the equations used to determine the heating power when
the option to include a heat exchanger is selected. The following section summarizes the equations used to
determine heating power based on the specified heating method when the option to Flare/Sell all is
selected for gas use.

Electrical Heating Method

When the option to Flare/Sell all is specified for gas use and an Electrical heating method is chosen without
any additional heat recovery via a heat exchanger, the following equation is used to calculate heating power
[kW]:

𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑖𝑛 +𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑙𝑜𝑠𝑠 (30)

𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔 = 𝐸𝑓𝑓𝑒

where:

𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑖𝑛 = Heating power required to heat the influent stream [kW]

𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑙𝑜𝑠𝑠 = Heating power required to overcome daily heat losses [kW]

𝐸𝑓𝑓𝑒 = Electrical heating efficiency [-]

Boiler (Fuel) Heating Method

Note: When the option to use Boiler (Fuel) is specified as the heating method, heating power requirements
will appear as zero in BioWin charts and tables. This is a result of using an external fuel source for heating
rather than electrical power, as such heating will not contribute to electrical power demands. BioWin will
determine the amount of fuel required to meet the heating demands and the associated fuel costs (see Fuel
(Heating and/or Sale)).

Biowin 6 Help Manual Power in BioWin • 975

When the option to Flare/Sell all is specified for gas use and the Boiler (Fuel) heating method is chosen
without any additional heat recovery via a heat exchanger, the following equations are used to calculate
heating power [kW].
The required heating power [kW] is determined from the following equation:

𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑖𝑛 +𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑙𝑜𝑠𝑠 (31)

𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔𝑅𝑒𝑞𝑢𝑖𝑟𝑒𝑑 = 𝐸𝑓𝑓𝑏

where:

𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑖𝑛 = Heating power required to heat the influent stream [kW]

𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑙𝑜𝑠𝑠 = Heating power required to overcome daily heat losses [kW]

𝐸𝑓𝑓𝑒 = Boiler efficiency [-]

Heating Power Equations when Boiler (heating influent) Specified for Gas Use

The Gas Use tab of an Anaerobic digester element with Boiler (heating influent) specified

The diagram below summarizes the options available when Boiler (heating influent) is specified for gas use.

976 • Power in BioWin Biowin 6 Help Manual

If the option to use the gas generated in the digester for heating is selected (i.e. Boiler (heating influent))
and the heat generated IS sufficient to meet the digester’s heating demands, then heating power will
appear as zero in BioWin charts and tables. The user will have the option to sell any excess gas. See Fuel
(Heating and/or Sale) for the equations used to determine excess biogas availability and sale costs.
If the option to use the gas generated in the digester for heating is selected (i.e. Boiler (heating influent))
and the heat generated is NOT sufficient to meet the digester’s heating demands, then supplemental
heating is required. Supplemental heating can be specified as either Electrical or via Boiler (Fuel).
In addition, users also have the option to include a heat exchanger which will impact the overall heating
requirements. See Heating Power Requirements for the equations used to determine the heating power
required. See Heat Exchanger for Power Recovery (AD) for the equations used to determine the heating
power when the option to include a heat exchanger is selected.
The potential power [kW] available from the biogas produced in the Anaerobic digester is calculated from
the following equation:

𝑜 𝑜
𝑃𝑂𝑓𝑓𝑔𝑎𝑠 = (𝑛𝐶𝐻4 ∙ 𝛥𝐻𝐶,𝐶𝐻4 + 𝑛𝐻2 ∙ 𝛥𝐻𝐶,𝐻2 )/86400 (32)

where:

𝑛𝐶𝐻4 = mols of methane present in the off gas [mol/d]

𝑛𝐻2 = mols of hydrogen present in the off gas [mol/d]

𝑜
𝛥𝐻𝐶,𝐶𝐻4
= methane heat of combustion [kJ/mol]

𝑜
𝛥𝐻𝐶,𝐻2 = hydrogen heat of combustion [kJ/mol]

Biowin 6 Help Manual Power in BioWin • 977

 86400 = conversion for seconds/day

Use of this biogas has an associated efficiency which gets applied to the potential power [kW] available as
follows:

𝑃𝑂𝑓𝑓𝑔𝑎𝑠−𝑎𝑣𝑎𝑖𝑙𝑎𝑏𝑙𝑒 = 𝑃𝑜𝑓𝑓𝑔𝑎𝑠 ∗ 𝐸𝑓𝑓𝑔𝑎𝑠 (33)

where:

𝐸𝑓𝑓𝑔𝑎𝑠 = Efficiency of gas use

The available power is subtracted from the overall heating requirements to determine if supplemental
heating is required as follows:

𝑃𝑆𝑢𝑝𝑝𝑙𝑒𝑚𝑒𝑛𝑡𝑎𝑙 = 𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑖𝑛 + 𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑙𝑜𝑠𝑠 − 𝑃𝑂𝑓𝑓𝑔𝑎𝑠−𝑎𝑣𝑎𝑖𝑙𝑎𝑏𝑙𝑒 (34)

where:

𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑖𝑛 = Heating power required to heat the influent stream [kW]

𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑙𝑜𝑠𝑠 = Heating power required to overcome daily heat losses [kW]

If the corresponding value of PSupplemental is POSITIVE, then additional heating is required and will be
calculated based on the heating method specified (equations provided below). If the corresponding value of
PSupplemental is NEGATIVE, then the gas available is sufficient for heating and any excess gas may be sold for a
specified price (See Fuel (Heating and/or Sale)).

Electrical Supplemental Heating Method

When supplemental heating is required and the Electrical heating method is specified the following
equation is used to calculate heating power [kW]:

𝑃𝑆𝑢𝑝𝑝𝑙𝑒𝑚𝑒𝑛𝑡𝑎𝑙 (35)
𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔 = 𝐸𝑓𝑓𝑒

where

𝐸𝑓𝑓𝑒 = Electrical heating efficiency [-]

978 • Power in BioWin Biowin 6 Help Manual

Boiler (Fuel) Supplemental Heating Method

Note: When the option to use Boiler (Fuel) is specified as the heating method, heating power requirements
will appear as zero in BioWin charts and tables. This is a result of using an external fuel source for heating
rather than electrical power, as such heating will not contribute to electrical power demands. BioWin will
determine the amount of fuel required to meet the heating demands and the associated fuel costs (see Fuel
(Heating and/or Sale)).

When supplemental heating is required and the option to use an external fuel source for heating is specified
the following equations are used to determine the required heating power and the amount of fuel needed
to meet the heating demands.
The required heating power [kW] is determined from the following equation:

𝑃𝑆𝑢𝑝𝑝𝑙𝑒𝑚𝑒𝑛𝑡𝑎𝑙 (36)
𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔𝑅𝑒𝑞𝑢𝑖𝑟𝑒𝑑 =
𝐸𝑓𝑓𝑏

where

𝐸𝑓𝑓𝑏 = Boiler efficiency [-]

Combined Heat and Power (CHP)

Combined Heat and Power (CHP) or cogeneration is the simultaneous production of electricity and heat
from a single fuel source (i.e. biogas) (EPA, 2015). In BioWin CHP is associated with the Anaerobic Digester
element. CHP generates:
• Electricity that can be used on site and/or sold back to the utility grid, and
• Heat that can either be recovered to offset heating requirements for the boiler or sold (EPA, 2015).
• Digester heating options are found within the Gas use tab of the Anaerobic Digester property dialog
box. Selecting the CHP check box activates the CHP Options group, shown below.

Biowin 6 Help Manual Power in BioWin • 979

The CHP options for an Anaerobic digester element

To specify what percentage of the CHP engine goes to generating power (i.e. the efficiency of generating
power) a percentage can be entered in the Percent CHP engine to power text edit box. To specify the
percentage of useful heat generated by the CHP engine a percentage can be entered in the Percent CHP
engine to heat text edit box. BioWin calculates the remaining Percent CHP engine exhaust/waste.
The user can also specify whether or not to transfer the heat generated by the CHP engine to the digester
input stream by checking the Use CHP heat for digester input stream checkbox. The efficiency of
transferring this heat to the digester input stream can be specified by entering a value in the Efficiency of
heat use text edit box.
The fate of the energy (e.g. whether it is all used onsite with any excess being sold back to the grid or it is all
sold back to the grid) produced by the CHP unit is specified in Project|Cost/Energy|Combined Heat and
Power (CHP)…. Invoking this command presents you with the Parameter editor dialog box, shown below.

980 • Power in BioWin Biowin 6 Help Manual

Parameters editor dialog used to set CHP parameters

Both the Methane heat of combustion and Hydrogen heat of combustion are used to determine how much
energy is produced from biogas generated in anaerobic digesters and potentially available for CHP
conversion. The division of this potential energy is specified locally in the anaerobic digester elements if
their CHP options are turned on.
The CHP engine heat price is the price at which heat generated from the CHP unit is sold only if the user
does not specify to use the CHP heat for the boilers in the anaerobic digester unit.
The CHP engine power price is the price at which CHP power is sold back to the utility grid.
In the CHP power use radio button group you may choose from two options for specifying CHP power use. If
you want to use CHP power onsite and sell any excess power back to the utility grid, then select On-site use
(sell any excess). If you want to sell all of the CHP power generated back to the utility grid, then select Sell
all CHP Engine power generated.
The diagram below summarizes the options available when CHP is specified for gas use.

Biowin 6 Help Manual Power in BioWin • 981

Heating Power Equations with CHP

The power [kW] generated from the biogas produced in the Anaerobic digester is calculated from the
following equation:

𝑜 𝑜
𝑃𝑂𝑓𝑓𝑔𝑎𝑠 = (𝑛𝐶𝐻4 ∙ 𝛥𝐻𝐶,𝐶𝐻4 + 𝑛𝐻2 ∙ 𝛥𝐻𝐶,𝐻2 )/86400 (37)

where

nCH4 = mols of methane present in the off gas [mol/d]

nH2 = mols of hydrogen present in the off gas [mol/d]

ΔHoC,CH4 = methane heat of combustion [kJ/mol]

ΔHoC,H2 = hydrogen heat of combustion [kJ/mol]

86400 = conversion for seconds/day

982 • Power in BioWin Biowin 6 Help Manual

The power credit [kW] generated through the use of the CHP engine is defined as:

𝑃𝑐𝑟𝑒𝑑𝑖𝑡,𝐶𝐻𝑃−𝑃𝑜𝑤𝑒𝑟 = %𝐶𝐻𝑃−𝑃𝑜𝑤𝑒𝑟 ∙ 𝑃𝑜𝑓𝑓𝑔𝑎𝑠 (38)

where
%𝐶𝐻𝑃−𝑃𝑜𝑤𝑒𝑟 = percent CHP engine to power
If the user specifies to use this power credit on site then this power is subtracted from the total
instantaneous power to give the net power. Power costs are determined using this net power (see Cost
Chapter).
The heat credit [kW] generated through the use of the CHP engine is defined as:

𝑃𝑐𝑟𝑒𝑑𝑖𝑡,𝐶𝐻𝑃−𝐻𝑒𝑎𝑡 = %𝐶𝐻𝑃−𝐻𝑒𝑎𝑡 ∙ 𝑃𝑜𝑓𝑓𝑔𝑎𝑠 (39)

where
%𝐶𝐻𝑃−𝐻𝑒𝑎𝑡 = percent CHP engine to heat

If the user specifies to use the heat credit generated towards heating the boiler than the heating credit is
defined as:

𝑃𝑐𝑟𝑒𝑑𝑖𝑡,𝐻𝑒𝑎𝑡𝑖𝑛𝑔 = 𝐸𝑓𝑓𝐻𝑒𝑎𝑡 𝑢𝑠𝑒 ∙ 𝑃𝑐𝑟𝑒𝑑𝑖𝑡,𝐶𝐻𝑃−𝐻𝑒𝑎𝑡 (40)

where

𝐸𝑓𝑓𝐻𝑒𝑎𝑡 𝑢𝑠𝑒 = efficiency of heat use

The available power credit is subtracted from the overall heating requirements to determine if supplemental
heating is required as follows:

𝑃𝑆𝑢𝑝𝑝𝑙𝑒𝑚𝑒𝑛𝑡𝑎𝑙 = 𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑖𝑛 + 𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑙𝑜𝑠𝑠 − 𝑃𝑐𝑟𝑒𝑑𝑖𝑡,𝐻𝑒𝑎𝑡𝑖𝑛𝑔 (41)

where

𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑖𝑛 = Heating power required to heat the influent stream [kW]

𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑙𝑜𝑠𝑠 = Heating power required to overcome daily heat losses [kW]

Biowin 6 Help Manual Power in BioWin • 983

If the corresponding value of PSupplementalis POSITIVE, then additional heating is required and will be
calculated based on the heating method specified (equations provided below). If the corresponding value of
𝑃𝑆𝑢𝑝𝑝𝑙𝑒𝑚𝑒𝑛𝑡𝑎𝑙 is NEGATIVE, then the heat generated by the CHP engine is sufficient for heating the digester
and the corresponding heating power requirements will be negligible (i.e. appear as zero) in BioWin.

Note: If a Heat Exchanger is also used for heat recovery, the calculated heating credit will also be subtracted
from Equation 41.

Electrical Supplemental Heating Method

When supplemental heating is required and the Electrical heating method is specified the following
equation is used to calculate heating power [kW]:

𝑃𝑆𝑢𝑝𝑝𝑙𝑒𝑚𝑒𝑛𝑡𝑎𝑙 (42)
𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔 = 𝐸𝑓𝑓𝑒

where
𝐸𝑓𝑓𝑒 = Electrical heating efficiency [-]

Boiler (Fuel) Supplemental Heating Method

Note: When the option to use Boiler (Fuel) is specified as the heating method, heating power requirements
will appear as zero in BioWin charts and tables. This is a result of using an external fuel source for heating
rather than electrical power, as such heating will not contribute to electrical power demands. BioWin will
determine the amount of fuel required to meet the heating demands and the associated fuel costs (Fuel
(Heating and/or Sale)).

When supplemental heating is required and the option to use an external fuel source for heating is specified
the following equations are used to determine the power requirements and the amount of fuel needed to
satisfy the demands.
The required heating power [kW] is determined from the following equation:

𝑃𝑆𝑢𝑝𝑝𝑙𝑒𝑚𝑒𝑛𝑡𝑎𝑙 (43)
𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔𝑅𝑒𝑞𝑢𝑖𝑟𝑒𝑑 = 𝐸𝑓𝑓𝑏

where
𝐸𝑓𝑓𝑏 = Boiler efficiency [-]

Heating Power Equations with Heat Exchanger AD

When power recovery via a heat exchanger is specified, the following equations are used to calculate
heating power [kW].
The heating power recovered by the heat exchanger is as follows:

984 • Power in BioWin Biowin 6 Help Manual

 𝑇𝑜𝑢𝑡𝑙𝑒𝑡,𝑒𝑥 ∙𝑄𝑜𝑢𝑡 ∙𝐶∙𝜌 (44)
𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑟𝑒𝑐𝑜𝑣𝑒𝑟𝑒𝑑 = 86400
∙ 𝐸𝑓𝑓𝑒𝑥

where

𝑄𝑜𝑢𝑡 = Flow of the effluent stream [m3/d]

𝐶 = Heat capacity of water [J/(goC)]

𝜌 = Density of water [kg/m3]

𝐸𝑓𝑓𝑒𝑥 = Exchanger efficiency [-]

86400 = Conversion for seconds/day

𝑇𝑜𝑢𝑡𝑙𝑒𝑡,𝑒𝑥 = Temperature of the stream leaving the exchanger [oC]

The temperature of the stream leaving the exchanger is calculated as follows:

𝑇𝑜𝑢𝑡𝑙𝑒𝑡,𝑒𝑥 = 𝑇𝑅 − (𝑇𝑖𝑛 + 𝑇𝐴 ) (45)

where

𝑇𝑅 = User specified operational temperature in the Anaerobic Digester element [oC]

𝑇𝑖𝑛 = Temperature of the influent stream [oC]

𝑇𝐴 = Temperature difference between the heat exchanger’s hot exit stream and cold entry stream
[oC]
Finally, the heating power [kW] (when electrical heating is specified) or the required heating power (when
the external fuel source heating method) is specified is calculated as:

𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑖𝑛 +𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑙𝑜𝑠𝑠 −𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑟𝑒𝑐𝑜𝑣𝑒𝑟𝑒𝑑 (46)

𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔 𝑂𝑅 𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑅𝑒𝑞𝑢𝑖𝑟𝑒𝑑 = 𝐸𝑓𝑓

where

𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑖𝑛 = Heating power required to heat the influent stream [kW]

𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑙𝑜𝑠𝑠 = Heating power required to overcome daily heat losses [kW]

Biowin 6 Help Manual Power in BioWin • 985

 𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑟𝑒𝑐𝑜𝑣𝑒𝑟𝑒𝑑 = Heating power recovered by the heat exchanger

𝐸𝑓𝑓 = Boiler efficiency or Electrical Heating efficiency depending on which heating

method is specified

Note: If Electrical heating is specified, the equation above provides the heating power displayed in BioWin.
If the external fuel source heating method (i.e. Boiler (Fuel)) is specified, the heating power displayed in
BioWin will be zero since electrical power is not required. In this case, the required heating power calculated
above will be used to determine the amount of fuel required and the associated fuel costs. See Heating
Power Equations when Flare/Sell All Specified for Gas Use, Heating Power Equations when Boiler (heating
influent) Specified for Gas Use, or Heating Power Equations with CHP for a list of equations associated with
specifying Boiler (Fuel) as the heating method.

Note: If CHP is specified for Gas Use, the calculated heating credit will be subtracted from the numerator of
Equation 46.

Thermal Hydrolysis Unit Element

Heating Power Parameters

Location: Power recovery options on Element “Power” tab

Name Default Unit Explanation

Value

Exchanger efficiency 0.65 The efficiency of recovering heat from

the elements outflow.
o
H/X Hot Stream Exit T – 20 C The temperature difference between
H/X Cold Stream Entry T the hot sludge stream leaving the heat
exchanger and the cold water/steam
stream entering the heat exchanger.

Location: Project|Costs/Energy|Fuel/Chemical on “Calorific values of heating fuels” tab

Name Default Unit Explanation

Value

Calorific value of natural 48000 kJ/kg The calorific value of natural gas is
gas used to determine the energy of using
natural gas as a fuel source for
heating.

986 • Power in BioWin Biowin 6 Help Manual

 Calorific value of heating 42000 kJ/kg The calorific value of heating fuel oil is
fuel oil used to determine the energy of using
heating fuel oil as a fuel source for
heating.
Calorific value of diesel 46000 kJ/kg The calorific value of diesel is used to
determine the energy of using diesel
as a fuel source for heating.
Calorific value of custom 32000 kJ/kg The calorific value of custom fuel is
fuel used to determine the energy of using
custom fuel as a fuel source for
heating.

Heating Power Equations

Heating in the Thermal Hydrolysis Unit is required to increase the temperature of the influent stream to the
specified temperature in the unit. The heating power [kW] required to heat the influent stream is calculated
from:

(𝑇𝑅 −𝑇𝑖𝑛 )∙𝑄𝑖𝑛 ∙𝐶∙𝜌 (47)

𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑖𝑛 = 86400

where

𝑇𝑅 = User specified operational temperature in the Thermal Hydrolysis Unit [oC]

𝑇𝑖𝑛 = Temperature of the influent stream [oC]

𝑄𝑖𝑛 = Flow of the influent stream [m3/d]

𝐶 = Heat capacity of water [J/(goC)]

𝜌 = Density of water [kg/m3]

86400 = Conversion for seconds/day

Electrical Heating Method

When an Electrical heating method is chosen without any additional heat recovery via a heat exchanger, the
following equation is used to calculate heating power [kW]:

𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑖𝑛 (48)
𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔 = 𝐸𝑓𝑓𝑒

Biowin 6 Help Manual Power in BioWin • 987

where

𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑖𝑛 = Heating power required to heat the influent stream [kW]

𝐸𝑓𝑓𝑒 = Electrical heating efficiency [-]

Boiler (Fuel) Heating Method

Note: When the option to use Boiler (Fuel) is specified as the heating method, heating power requirements
will appear as zero in BioWin charts and tables. This is a result of using an external fuel source for heating
rather than electrical power, as such heating will not contribute to electrical power demands. BioWin will
determine the amount of fuel required to meet the heating demands and the associated fuel costs (see Fuel
(Heating and/or Sale)).

When the Boiler (Fuel) heating method is chosen without any additional heat recovery via a heat exchanger,
the following equations are used to calculate heating power [kW].
The required heating power [kW] is determined from the following equation:

𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑖𝑛 (49)
𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔𝑅𝑒𝑞𝑢𝑖𝑟𝑒𝑑 = 𝐸𝑓𝑓𝑏

where

𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑖𝑛 = Heating power required to heat the influent stream [kW]

𝐸𝑓𝑓𝑏 = Boiler efficiency [-]

Heat Exchanger for Power Recovery

A heat exchanger is used to transfer heat from one liquid/gas stream to another liquid/gas stream in an
attempt to lower the overall heating requirements.
Heating power recovery is available in the Thermal Hydrolysis Unit via a heat exchanger. Power recovery
options are specified in the Heating tab, shown below.

988 • Power in BioWin Biowin 6 Help Manual

The Heating tab of a thermal hydrolysis unit

The user can also choose to model power recovery in the form of a heat exchanger (h/x) by checking the
Heat exchanger on inflow/outflow check box. When the option to include a heat exchanger is specified,
BioWin assumes that the hot Thermal Hydrolysis Unit output stream is used to heat the cool incoming stream
in a counter-current heat exchanger. A value for Exchanger efficiency and H/X Hot Stream Exit T – H/X Cold
Stream Entry T (i.e. the difference in temperature between the heat exchangers hot exit stream and cold
entry stream) can be entered directly into the appropriate text edit boxes. A schematic representing the
difference in temperature between the hot exit and cold entry streams for the heat exchanger is shown
below.

Schematic illustrating H/X Hot Stream Exit T – H/X Cold Stream Entry T

Biowin 6 Help Manual Power in BioWin • 989

Heating Power Equations with Heat Exchanger
When the heat exchanger is activated in the THU element, the maximum change in the temperature of the
effluent stream is calculated as:

𝛥𝑇 = 𝑇𝑅 − (𝑇𝑖𝑛 + 𝑇𝐴 ) (50)

where

𝑇𝑅
= Operational temperature specified in the unit (oC)
𝑇𝑖𝑛
= Temperature of the influent stream (oC)
𝑇𝐴
= Temperature difference between the heat exchanger’s hot exit stream and cold entry stream
(oC)
The energy [kW] recovered from the effluent stream is then:

𝛥𝑇∙𝑄𝑜𝑢𝑡 ∙𝐶∙𝜌 (51)

𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑟𝑒𝑐𝑜𝑣𝑒𝑟𝑒𝑑 = 86400
∙ 𝐸𝑓𝑓𝐸𝑋

where

𝑄𝑜𝑢𝑡 = Flow of the effluent stream [m3/d]

𝐶 = Heat capacity of water [J/(goC)]

𝜌 = Density of water [kg/m3]

86400 = Conversion for seconds/day

𝐸𝑓𝑓𝐸𝑋 = Exchanger efficiency

Finally, the heating power [kW] (when electrical heating is specified) or the required heating power (when
the external fuel source heating method) is specified is calculated as:

𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑖𝑛 −𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑟𝑒𝑐𝑜𝑣𝑒𝑟𝑒𝑑 (52)

𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔 𝑂𝑅 𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑅𝑒𝑞𝑢𝑖𝑟𝑒𝑑 = 𝐸𝑓𝑓

where

𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑖𝑛 = Heating power required to heat the influent stream [kW]

990 • Power in BioWin Biowin 6 Help Manual

 𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑟𝑒𝑐𝑜𝑣𝑒𝑟𝑒𝑑 = Heating power recovered by the heat exchanger

𝐸𝑓𝑓 = Boiler efficiency or Electrical Heating efficiency depending on which heating

method is specified

Note: If Electrical heating is specified, the equation above provides the heating power displayed in BioWin.
If the external fuel source heating method (i.e. Boiler (Fuel)) is specified, the heating power displayed in
BioWin will be zero since electrical power is not required. In this case, the required heating power calculated
above will be used to determine the amount of fuel required and the associated fuel costs (see Fuel (Heating
and/or Sale)).

References
Environmental Protection Agency (EPA). (2015). Combined Heat and Power Partnership.
http://www.epa.gov/chp/index.html

Surface Aeration Power

Surface Aeration Power is determined and/or specified in the Brush Aerator and Surface Aerator Bioreactor
elements.
Within a specific element, surface aeration power is either calculated or entered depending on how the
method for aeration is specified in the Operation tab of the element’s property dialog box.

Sample Operation tab in a Bioreactor (brush aerators) element

There are two methods for specifying aeration: either by a DO setpoint or by a Power supply rate. The
aeration method is specified by clicking on the appropriate radio button. When DO setpoint is selected, the

Biowin 6 Help Manual Power in BioWin • 991

setpoint concentration must be specified. You may specify either a Constant setpoint or a Scheduled DO
setpoint pattern (clicking the Pattern… button will open the Edit DO setpoint itinerary dialog box). You may
wish to place a restriction on the maximum allowable power supply rate that may be used to achieve the
desired DO setpoint. This is a useful feature for investigating the ability of air equipment to achieve desired
DO setpoints.
When DO setpoint is selected, the surface aeration power (i.e. Ψ) is calculated from the following equation:

𝐶 ∗ −𝐶𝑠 (53)
𝑂𝑇𝑅 = 𝛹 ∙ 𝛼 ∙ 𝑂𝑇𝑅𝑠𝑡𝑑,𝑠𝑢𝑟𝑓𝑎𝑐𝑒 ∙ (𝐶 ∗∞,𝑠 )
∞,𝑆𝑡𝑑 −0

where

𝑂𝑇𝑅 = oxygen transfer rate determined from the oxygen utilization rate

𝛹 = power input

𝛼 = alpha

𝑂𝑇𝑅𝑠𝑡𝑑,𝑠𝑢𝑟𝑓𝑎𝑐𝑒 = surface aerator standard oxygen transfer rate

∗
𝐶∞,𝑠 = saturated concentration of dissolved oxygen at the gas/liquid interface

𝐶𝑠 = dissolved oxygen concentration

∗ = steady state dissolved oxygen concentration at 20oC and 1 atmosphere and the
𝐶∞,𝑆𝑡𝑑
supply gas oxygen concentration (dry basis)
When Power supply rate is selected, as shown below, the power supply rate (i.e. Ψ) must be entered. You
may specify either a Constant power supply rate or a Scheduled power supply rate pattern (clicking the
Pattern… button will open the Edit power supply rate itinerary dialog box).

992 • Power in BioWin Biowin 6 Help Manual

Sample Operation tab in a Bioreactor (brush aerators) element

Surface aerator model parameters can be modified globally for the project in the
Project|Parameters|Aeration/Mass transfer… menu on the Surface aerators tab. This can be overridden
locally in the selected element’s Model tab by checking the Local aerator parameters check box and clicking
the Edit local aerator parameters… button which opens the Surface aerators model parameters dialog box
shown below.

Biowin 6 Help Manual Power in BioWin • 993

Sample Surface aerators Model Parameter dialog box for a Bioreactor (brush aerators) element

S/L sep./Disinfection Power

Power associated with solid/liquid separation or disinfection can be specified in the
• Effluent,
• Dewatering unit,
• Point clarifier,
• Microscreen,
• Cyclone, and
• ISS Cyclone elements.
Within a specific element, S/L sep./Disinfection power is found in the Power/Costs tab of the element’s
property dialog box. The Power/Costs tab contains a check box where the user can specify if they would like
to include the element in the cost/power estimate. Checking the Include this ‘element/unit’ in power/cost
calculations activates an element specific Options (for power/cost calculations) group where element
specific power specification can be entered.

994 • Power in BioWin Biowin 6 Help Manual

Effluent Power
In the Power/Costs tab of the Effluent element, if the option to Include this effluent in power/cost
calculations is checked a fixed power per unit flow can be specified for filtration and/or UV disinfection by
checking the Filtration and/or UV Disinfection check boxes and entering a power value into the respective
text edit boxes. Additional options for specifying power are available by checking the Power check box. This
activates the Power supply rate group which contains an option to specify a fixed power or a power per unit
flow by checking the Power per unit flow to this element checkbox. The user can enter a constant value for
power or power per unit flow by selecting the Constant value of radio button and entering a value in the
text edit box provided. Alternatively, the user can enter a power or power per unit flow pattern by selecting
the Scheduled radio button. This activates the Pattern…button. Clicking this button will open the Power
Itinerary editor.

Power/Costs tab for the Effluent Element

Dewatering unit, Point Clarifier, Microscreen, Cyclone and ISS Cyclone Power
In the Power/Costs tab of the Dewatering unit, Point clarifier, Microscreen, Cyclone and ISS Cyclone
elements, power can be specified by checking the Include this unit in Power/cost calculation check box.
Checking the Power check box activates the Power specifications group which contains an option to specify
a fixed power or a power per unit flow by checking the Power per unit flow to this element checkbox. The
user can enter a constant value for power or power per unit flow by selecting the Constant value of radio
button and entering a value in the text edit box provided. Alternatively, the user can enter a power or power
per unit flow pattern by selecting the Scheduled radio button. This activates the Pattern…button. Clicking
this button will open the Power Itinerary editor.

Biowin 6 Help Manual Power in BioWin • 995

Sample Power/Costs tab in the Dewatering unit element.

Heating Ventilation and Cooling (HVAC) Power

BioWin allows you to specify Heating Ventilation and Cooling (i.e. HVAC) power requirements for a project
via the Project|Costs/Energy|HVAC… command. Invoking this command presents you with the HVAC
Power Requirements dialog box, shown below.

HVAC dialog used to set HVAC power

In the HVAC power consumption tab, you may choose from two options for specifying HVAC power. If you
want to use a constant HVAC power, then enter the desired power value in the Constant value of text edit
area.
If you want a time-varying power pattern, then select the Scheduled radio button. This will activate the
Pattern… button. Clicking this button presents you with the Edit HVAC power itinerary dialog box.

Displaying Power Demand and Energy Consumption

If the user elects to include power calculations BioWin can display the calculation results in Element
Information displays, Tables, and Charts.

996 • Power in BioWin Biowin 6 Help Manual

Element Information

A pre-defined Element Information table can be generated for any of the elements that contain power. An
Element Information display can be generated in one of two ways:
1. Right-click on the desired element and select either Add to album > Element info (Summary) or Add
to album > Element info (State variables)

2. Add a new page to the BioWin Album, right-click and select Element info… from the pop-up menu
shown below.

This opens up an Options dialog box, shown below. From the Elements drop down list choose which
element you would like to generate the Element information display. In the View type radio button group
select either State variable view or Summary view.

Biowin 6 Help Manual Power in BioWin • 997

Invoking either command will add an Element Information table to the BioWin Album. In the bottom section
of the Element Information display, element specific power information is displayed. Note: power categories
(i.e. mixing, mechanical, etc.) will change based on which categories are relevant to the selected element.

Tables
Power information can also be displayed in a Table in the BioWin Album. Power tables can be generated
semi-automatically or they can be completely customizable.

Add a Pre-defined Power Table Display

1. Right-click on the blank album pane where you wish to place the table.
2. Select Power Table from the resulting popup menu.

998 • Power in BioWin Biowin 6 Help Manual

 3. The Table Editor dialog will open.

4. Choose the element(s) you want to include in the table. By default, all of the elements appear in the
Selected lists for each of the power categories (i.e. blowers, mixing power, mechanical power etc.).
To remove an element(s) from the Selected list select the element(s) and click the left pointing
arrow. To remove all of the elements from the Selected list, click the double left pointing arrows.
You may also double click on an element to move from one list to another.
5. In the Options group specify if you would like to Show total (of displayed) and Show costs.

Biowin 6 Help Manual Power in BioWin • 999

 6. In the System wide display options group specify if you would like to Show total this activates
options to Show HVAC and Show CHP engine power. If you specify to Show costs and Show total,
then you can also choose to Show service charge and Show peak demand charge.
7. Click the Ok button to create the table and exit the table editor.

Example Power Table

Add a Pre-defined Air Supply group table

1. Right-click on the blank album pane where you wish to place the table.
2. Select Air supply group table from the resulting popup menu.

An Air supply group table summarizing the blower Power and the Intake Pressure, Discharge Pressure and
Intake Airflow used in the calculation of blower power will be automatically generated and added to the
Album.

1000 • Power in BioWin Biowin 6 Help Manual

Example Air Supply Group Table

Add an Element Specific Power Table Display

1. Right-click on the blank album pane where you wish to place the table.
2. Select Table from the resulting popup menu.

3. The Table Editor dialog will open.

Biowin 6 Help Manual Power in BioWin • 1001

 4. From the Elements tree view, select the element(s) that you wish to include in the table.
• You can expand individual element groups, select specific elements, click on them and push the
right-pointing arrow to move them to the Selected elements list; or move entire element groups
over at once by clicking on the element group (e.g. Bioreactor) and clicking the right-pointing
arrow.
• Note that if the element you have selected has multiple outputs (e.g. a secondary clarifier), all
outputs are added to the Selected elements list by default. If you do not want one of the
outputs (e.g. the underflow of a secondary clarifier), simply click on the entry in the Selected
elements list and press the Delete key on your keyboard.
• If you want to change the order in which the Selected elements will appear in the table, move
the elements around by clicking on them and clicking the up/down arrows. You can change the
order of a group of elements, by using the Ctrl or Shift key to select the group and then clicking
the up or down arrow. Finally, you can move a selection directly to the top or bottom of the list
by holding the Ctrl key while you click the up or down arrow.

1002 • Power in BioWin Biowin 6 Help Manual

 5. Choose the variables you want to include in the table from the Element specific list under the ninth
subcategory (i.e. --- 9. Power/Costs---). [Type “9” in the element specific list to scroll to the
Power/Cost group.] If you want to add more than one variable from a given group, you may do so:
To select a continuous group, click the first variable of the group, and while holding the Shift key,
click the last variable of the group. To select non-continuous variables, hold the Ctrl key and click the
desired variables in succession. You may also simultaneously select variables from multiple lists.
6. Once you have selected the variables you want in the table, move them to the Selected variables list
by clicking the right-pointing arrow.
7. If you want to change the order in which the Selected variables will appear in the table, move the
variables up or down by clicking on them and clicking the up/down arrows. You can change the
order of a group of variables, by using the Ctrl or Shift key to select the group and then clicking the
up or down arrow. Finally, you can move a selection directly to the top or bottom of the list by
holding the Ctrl key while you click the up or down arrow.
8. If you wish to re-add certain variables, place a check in the box labeled Duplicates, and re-add the
variables.
9. Select Concentrations. Mass rates and Both are irrelevant for the Power information.
10. If you want to add a blank line between table entries, click the Add blank line button. The blank line
will show as a short dashed line in the Selected elements list. The blank line can be moved up or
down in the list just like other elements. Multiple lines may be added to the list.
11. If you want BioWin to display the total of a table’s columns, click the Add total so far button. The
word “Total” will be added to the Selected elements list. The Total can be moved up or down in the
list just like other elements. Multiple totals may be added to the list; if a total will always totalize
the rows preceding it.
12. Click OK to finish.

Example Element Specific Power Table

Charts
Power/Energy Consumption plots can be generated semi-automatically in BioWin. These include:
• Power Demand Distribution plots
• Pie plot of instantaneous power demand

Biowin 6 Help Manual Power in BioWin • 1003

 • Bar plot of instantaneous power demand
• Time Series plots
• Instantaneous power by category
• Total and net instantaneous power
• Energy consumption (Daily)
• Energy consumption (Monthly)
• Energy consumption (Yearly)
• Energy consumption
Monthly peak demand plot
For power demand distribution and time series plots, you are only required to select the elements that you
want included in the plots. BioWin then performs the necessary calculations and generates the plot. You
then may customize the appearance of the chart using BioWin's powerful chart and series formatting tools.
The Monthly peak demand chart gets generated automatically. This chart shows past current values for the
monthly peak demand history and will move forward in time if a dynamic simulation is selected.

Add a Power/Energy Consumption Plot to the Album

If you want to add a Current Power Distribution plot:
1. Right-click on an album chart and click Add Series in the resulting popup menu.
2. Click on the Power/Energy consumption tab of the Add parameters for plotting dialog box.

1004 • Power in BioWin Biowin 6 Help Manual

 The Power/Energy consumption (from album) dialog

3. Choose the element(s) you want to include in the plot. By default, all of the elements appear in the
Selected lists for each of the power categories (i.e. blowers, mixing power, mechanical power etc.).
Note the power categories displayed in the Power/Energy consumption tab will vary depending on
your specific configuration.
4. To remove an element(s) from the Selected list of a power category select the element(s) and click
the left pointing arrow. To remove all of the elements from the Selected list, click the double left
pointing arrows. If all of the elements are removed from the Selected list of a power category the
respective category will not be included in the plot.
5. In the Power Demand Distribution group, you can choose a Pie or a Bar plot by selecting the
appropriate radio button.

Biowin 6 Help Manual Power in BioWin • 1005

 6. Use the Labels (marks) radio button group to specify if the distribution plot labels should show
Name and kW or Name and %.
7. When you are satisfied with the list of selected elements and the plot and label type, click the
Instantaneous power distribution button to generate a pie or bar chart illustrating the current
power demand distribution for the project.
8. Click the Close button to finish.

Example Current Power Distribution plots

Note: If the option to Include HVAC power is checked HVAC will also appear as a category in the Power
Distribution plots

If you want to add one of the time series power/energy consumption plots [Instantaneous power
consumption (by category), Total instantaneous power, Net instantaneous power, Energy consumption (i.e.
daily, monthly, yearly, and total)]:
9. Right-click on an album chart and click Add Series… in the resulting popup menu.
10. Click on the Power/Energy consumption tab of the Add Parameters for plotting dialog box.

1006 • Power in BioWin Biowin 6 Help Manual

 The Power/Energy consumption (from album) dialog

11. Choose the element(s) you want to include in the plot. By default, all of the elements appear in the
Selected lists for each of the power categories (i.e. blowers, mixing power, mechanical power etc.).
Note the power categories displayed in the Power/Energy consumption tab will vary depending on
your specific configuration.
12. To remove an element(s) from the Selected list of a power category select the element(s) and click
the left pointing arrow. To remove all of the elements from the Selected list, click the double left
pointing arrows. If all of the elements are removed from the Selected list of a power category the
respective category will not be included in the plot.
13. In the Time series plots group, select which Axis you would like to plot the time series on (e.g. left)
by choosing either the Left or Right radio button.

Biowin 6 Help Manual Power in BioWin • 1007

 14. To generate a time series of the instantaneous power in each power category click the
Instantaneous power by category button.
15. To generate a time series for the total and net instantaneous power, select the appropriate axis (e.g.
left) and click the Total and net instantaneous power button. Note the net power deviates from the
total power only when CHP is specified in the Anaerobic Digester element and the user chooses to
use the power generated through CHP onsite (See Plotting Power with CHP example).
16. To track the total amount of power consumed per day or the daily energy consumption, select the
appropriate axis (e.g. right) and click the Energy consumption (Daily) button.
17. To track the total amount of power consumed per month or the monthly energy consumption,
select the appropriate axis (e.g. right) and click the Energy consumption (Monthly) button. Note this
will add a series that plots the accumulated energy consumption each day of the month. This series
will automatically reset at the start of each month.
18. To track the total amount of power consumed per year or the yearly energy consumption, select the
appropriate axis (e.g. right) and click the Energy consumption (Yearly) button. Note this will add a
series that plots the accumulated energy consumption each day of the year. This series will
automatically reset at the start of each year.
19. To track the total amount of power consumed over time or the energy consumption, select the
appropriate axis (e.g. right) and click the Energy consumption button. Note this will add a series that
plots the accumulated energy consumption over time.
20. When you are satisfied with your time series selection click the Close button to finish.

1008 • Power in BioWin Biowin 6 Help Manual

Example Power/Energy Consumption Time Series Plots (with Daily and Monthly Energy Consumption)

Note: If the option to Include HVAC power is checked HVAC will also appear as a category in the Power
Distribution plots.

Example Energy Consumption Time Series Plot (with Daily, Monthly, Yearly and Total Energy Consumption)

Note: Over the first simulated month the Monthly energy consumption, Yearly energy consumption, and
Total energy consumption series will overlap. Over the first simulated year the Yearly energy consumption,
and Total energy consumption series will overlap.

If you want to add a Monthly peak demand plot:

21. Right-click on an album chart and click Add Series in the resulting popup menu.
22. Click on the Power/Energy consumption tab of the Add parameters for plotting dialog box.

Biowin 6 Help Manual Power in BioWin • 1009

The Power/Energy consumption (from album) dialog

23. Choose the Monthly peak demand button.

24. Click the Close button to finish.

1010 • Power in BioWin Biowin 6 Help Manual

Example Monthly peak power demand plot

Note: This plot shows the peak 15-minute power demand for each month over the most recent 12 months
of simulation; this facilitates calculating and checking demand charges for the subsequent month. Although
a current value bar plot is shown indicating the past monthly current values of the peak demand, this plot
will move forward in time during a dynamic simulation. After a month of simulation, a new bar will appear
indicating the last month’s peak demand. It can also be re-formatted to take the form of a line plot if
desired.

Plotting Power with CHP - Example

Specifying CHP in the Anaerobic Digester element will modify the look of various plots and series depending
on the division of the energy generated (i.e. % to power, % to heat), the fate of the heat generated (e.g.
whether it is used to heat the digester input stream) and the fate of the energy generated (e.g. whether it is
used onsite with any excess being sold back to the grid or it is all sold back to the grid).
The following section illustrates the changes that occur to both steady state and dynamic power/energy
consumption plots when CHP is turned on.
For more information on CHP please see the following sections: Specifying Project Combined Heat and
Power Parameters, Anaerobic Digester Power/Heat, Combined Heat and Power (CHP).

Steady State Example

When CHP is not specified in the Anaerobic Digester element (i.e. there is no power recovery), power
demand distribution plots will resemble those shown below. Note in this example an electrical heating

Biowin 6 Help Manual Power in BioWin • 1011

method is specified in the Anaerobic Digester element. For detailed instructions on creating a pie or bar
chart illustrating the power demand distribution see Add a Power/Energy Consumption Plot to the Album

Example Current Power Distribution plots without CHP

Turning on CHP will result in the addition of a new power category (i.e. CHP engine generated power) to a
power demand distribution bar plot, as shown below. The power produced by CHP is shown as a negative
value since it is representative of power that is generated while the other power categories represent power
that will be consumed.

Note: the power generated through CHP will not be displayed in a pie plot of the power demand
distribution. Therefore, it is best to use a bar chart for steady state simulations with CHP.

1012 • Power in BioWin Biowin 6 Help Manual

Example Current Power Distribution bar plot with CHP

What if we want to offset the power required for heating? In the Anaerobic Digester element we can specify
to use the useful heat generated by the CHP engine to heat the digester input stream and enter an efficiency
for this heat use. This will result in a reduction in heating power as shown in the plot below. Note this
reduction in heating power will be shown in both pie and bar charts. However it is recommended that a bar
plot is used when CHP is specified.

Example Current Power Distribution bar plot with CHP and the option to use useful heat from CHP to reduce heating power.

Biowin 6 Help Manual Power in BioWin • 1013

Dynamic Example
Power/Energy Consumption plots without CHP

When CHP is not specified in the Anaerobic Digester element (i.e. there is no power recovery) the total and
net instantaneous power series will overlap. In the figure below, the red total power demand series is
underneath the orange net power demand series. Note in the dynamic examples below, an electrical
heating method is specified in the Anaerobic Digester element.

Note: The total and net instantaneous power series will still overlap when CHP is specified AND the option
to Sell all CHP Engine power generated is selected.

Example instantaneous power by category time series plot without CHP

Power/Energy Consumption plots with CHP (Use CHP Engine power generated onsite, sell excess)

When CHP is turned on AND the option to use the CHP Engine power generated on-site (sell any excess) is
selected, the power generated through CHP will be included as a category (i.e. Power (CHP)) in the
Instantaneous power by category plot. The net instantaneous power will be less than the total power since
it includes the power generated through CHP (i.e. Net power demand = Total power demand – Power
Generated with CHP). The energy consumption plots will also show less energy consumption than the
energy consumption without CHP.

1014 • Power in BioWin Biowin 6 Help Manual

Example instantaneous power by category time series plot and energy consumption with CHP (Use CHP onsite, sell excess)

When CHP is turned on AND the option to use the CHP engine power generated on-site (sell and excess) is
selected AND the option to use the heat generated through CHP for the boiler is selected, then a reduction
in heating power will be shown. This will result in a reduction in the total and net power demand as well as
the energy consumption.

Biowin 6 Help Manual Power in BioWin • 1015

Example instantaneous power by category time series plot and energy consumption with CHP (Use CHP onsite, sell excess + use useful
heat from CHP)

Power/Energy Consumption plots with CHP (Sell all CHP Engine power generated)

When CHP is turned on AND the option to Sell all CHP Engine power generated is selected, the power
generated through CHP will be included as a category (i.e. Power (CHP)) in the Instantaneous power by
category plot. The total and net instantaneous power will overlap since none of the CHP power generated is
used on site. The Energy consumption will also remain the same as that determined without CHP.

1016 • Power in BioWin Biowin 6 Help Manual

Example instantaneous power by category time series plot and energy consumption with CHP (Sell all power)

When CHP is turned on AND the option to Sell all CHP Engine power generated is selected AND the option to
use the useful heat generated through CHP for the boiler is selected, then a reduction in heating power will
be shown. This will also reduce the energy consumption.

Biowin 6 Help Manual Power in BioWin • 1017

Example instantaneous power by category time series plot and energy consumption with CHP (Sell all power + use useful heat from
CHP)

1018 • Power in BioWin Biowin 6 Help Manual

Operating Costs in BioWin

Operating Costs
The objective of this chapter is to describe how to enter the information required to calculate operating
costs in BioWin, and how to display operating costs for your simulation scenarios. BioWin tracks operating
costs in four separate categories:
• Costs associated with energy consumption.
• Costs associated with consumption of chemicals / consumables.
• Costs associated with consumption and selling of fuel.
• Costs associated with sludge disposal.
This chapter describes the methods to enter information related to these categories in BioWin, and how to
display information that will be useful in the analysis of your plant.

Biowin 6 Help Manual Operating Costs in BioWin • 1019

The following sections describe how to enter information for each of the three main categories in BioWin:
• Power / Energy consumption
• Chemicals
• Fuel (Heating and/or Sale)
• Sludge

Power / Energy consumption

This section describes how to enter energy costs in BioWin.

How to Enter Electricity Costs

BioWin allows you to specify electricity costs for a project via the Project|Costs/Energy|Electricity…
command. Invoking this command presents you with the Electricity costs dialog box, shown below.

Dialog used to set the electricity costs

In the Energy Consumption tab, you may choose from three options for specifying electricity costs. If you
want to use a constant electricity cost, then enter the desired cost value in the Constant value of text edit
area.
If you want a time-varying cost pattern, then select the Scheduled radio button. This will activate the
Pattern… button. Clicking this button presents you with the Edit Electricity cost itinerary dialog box. You can
use this option to create any electricity cost pattern you wish.
If you want a seasonal and time varying cost pattern, then select the Seasonal radio button. This will
activate the Details… button. Clicking this button presents you with the Seasonal electricity cost dialog box,
shown below.

1020 • Operating Costs in BioWin Biowin 6 Help Manual

Dialog used to set the seasonal electricity costs

The Seasonal electricity cost dialog box allows you to define the day and month for the start of a season (i.e.
summer or winter); on-peak, mid-peak, off-peak electricity rates and time periods; as well as a rate
classification for weekends.
In the Summer/Winter options groups you can specify the start date for the Summer or Winter season by
expanding the Start date drop box and using the calendar to select the month and day.
In the Rates group you can edit the electricity cost for On-peak, Mid-peak, and Off-Peak electricity use by
entering a value directly into the respective text edit boxes.
In the Period definitions group you can use the spin edit boxes to change the start times for Period 1-4. Use
the drop list boxes to define Period 1-4 as either On-peak, Mid-peak or Off-Peak. The default Summer and
Water start dates and the four Period definitions follow the schedule set out in the following figure
(HydroOne, 2015). The seasons and daily periods can be adjusted to match those used by your local energy
provider.

Biowin 6 Help Manual Operating Costs in BioWin • 1021

Default Season start dates and Period definitions (HydroOne, 2015)

In the Year round group you can specify whether or not to define the weekends as Off-peak by either
checking or unchecking the Weekends Off-peak check box. Unchecking the Weekends Off-peak check box
activates the check boxes for Saturdays Off-peak and Sundays Off-Peak. If you uncheck these boxes the
period definitions defined for each season will be used to determine the rates for the weekends instead of
the seasonal off-peak rate.
On the Other charges tab shown below, you can enter information for supply costs. A Service charge cost
can be entered into the text edit box. Under the Demand charge group, both a peak demand charge and
base demand can be entered into the text edit boxes.

Note: the Service charge and demand charge are specified on a monthly basis. The peak demand charge for
month “n” is calculated by multiplying the user specified Peak demand charge value ($/kW) by the plant
peak power demand (kW) observed over a 15 minute period in month “n-1”.

Obviously, when you start a simulation, there is no “previous month” for BioWin to sample for a peak power
demand, so it uses the user-specified Base demand as the “previous month” peak power demand for
calculating the first month’s peak demand charge.
Note: the monthly peak demand history can be plotted for a project by selecting the Monthly Peak demand
button in the Power/Energy consumption tab of the Add parameters for plotting dialog (see Add a
Power/Energy Consumption Plot to the Album).

1022 • Operating Costs in BioWin Biowin 6 Help Manual

Dialog used to set other electricity charges

Specifying Power (Activating Electricity Costs)

Electricity costs will only be used if a power demand is specified for the project flowsheet. This involves
specifying one or more of the following:
• Heating Ventilation Air Conditioning (HVAC) Power
• Blower Power (i.e. air supply groups)
• Element specific power

HVAC Power
HVAC power can be specified in Project|Costs/Energy|HVAC…. For help on entering HVAC power in
BioWin please see the HVAC Power subsection in the Entering Power and Power Calculations section of the
Power in BioWin chapter.

Blower Power
Blower power can be specified by defining a blower air supply group for a project via the Project|Plant|Air
supply groups/blower specs…command.

Note: As a configuration is built, all the elements that can be aerated (i.e. even elements that are specified
as unaerated) are automatically added to an air supply group (e.g. #1 Air supply group). For help on
specifying Blower power in BioWin please see the Blower Power subsection in the Entering Power and
Power Calculations section of the Power in BioWin chapter.

Element Specific Power

In most elements, power can be specified on the Power (or Power/Costs) tab of the elements Property
Dialog box. In the Anaerobic Digester and Thermal Hydrolysis unit, Heating power will only contribute to
power demand if Electrical heating is specified in the Heating (or Heating/Heat loss) tab.

Note: some elements contain a pre-specified default power input. For help on entering power in BioWin
please see the Entering Power and Power Calculations section of the Power in BioWin chapter.

Selling Power/Heat Generated through CHP back to the Utility Grid

If Combined Heat and Power (CHP) is specified for power recovery in an Anaerobic Digester element, then
users may choose to either:
• use the CHP power generated on-site and sell any excess back to the utility grid
• sell all CHP power generated back to the utility grid
• sell heat generated through CHP (This option is only available if the heat generated through CHP is
not used to heat the boiler)

Biowin 6 Help Manual Operating Costs in BioWin • 1023

These options are found in Project|Costs/Energy|Combined Heat and Power (CHP)…. Invoking this
command presents you with the Parameter editor dialog box, shown below.

Parameters editor dialog used to set CHP parameters

The CHP engine heat price is the price at which heat generated from the CHP unit is sold only if the user
does not specify to use the CHP heat for the boilers in the anaerobic digester unit (See Anaerobic Digesters).
The CHP engine power price is the price at which CHP power is sold back to the utility grid.
In the CHP power use radio button group, you may choose the fate of CHP power use. If you want to use
CHP power onsite and sell any excess power back to the utility grid, then select On-site use (sell any excess).
If you want to sell all of the CHP power generated back to the utility grid, then select Sell all CHP Engine
power generated.
More information on specifying CHP in BioWin can be found in the Heating Power subsection under the
Entering Power and Power Calculations section of the Power in BioWin chapter.

References
Hydro One Inc., 2015. Electricity Rates.
http://www.hydroone.com/MyHome/MyAccount/UnderstandMyBill/Pages/ElectricityRates.aspx

Chemicals
This section describes how to enter chemical costs in BioWin.

Specifying Project Chemical Costs

BioWin allows you to specify chemical (i.e. methanol, ferric, aluminum) costs for a project via the
Project|Costs/Energy|Fuel/Chemical… command. Invoking this command presents you with the Heating
fuel/Chemical Costs dialog box, shown below.

1024 • Operating Costs in BioWin Biowin 6 Help Manual

Dialog used to set the chemical costs

Note: These specified costs will only be used if the user chooses to include the methanol addition element
and/or the metal addition element in chemical cost calculations by checking the corresponding check box in
the Costs tab of the methanol addition element (See Costs (Methanol)) and/or metal addition element (See
Costs (Metal Addition)) property dialog box. For example, the Costs tab for the Methanol addition element
is shown in the figure below.

The Costs tab of a Methanol addition influent element

Biowin 6 Help Manual Operating Costs in BioWin • 1025

Users can specify whether the cost of methanol addition should be included in chemical cost estimates by
checking the Include this element in chemical costs calculation check box.
Dialog used to set the calorific values of heating fuels

Specifying Element Specific Chemical Costs

Chemical costs can be specified locally on the Costs (or Power/Costs) tab of the following elements property
dialog box:
• Stream (SV) influent
• Effluent
• Dewatering unit
• Point clarifier
• Microscreen
• Cyclone
• ISS Cyclone
For example, the Costs tab, shown in the figure below, is used to specify the costs associated with the
Stream (SV) Influent.

The Stream Costs tab of a Stream (state variable) Influent element

Checking the Include this element in chemical costs calculation check box activates the Chemical cost text
edit box. Users can specify a chemical cost on a unit volume basis by entering a value into the text edit box.
The Power/Costs tab of the Effluent’s property dialog box, shown below, allows the user to specify costs
associated with the Effluent element.

1026 • Operating Costs in BioWin Biowin 6 Help Manual

The Power/Costs tab of an Effluent element

Checking the checkbox Include this effluent in power/cost calculations activates the Effluent options (for
power/cost calculations) group. A chemical cost can be specified for Chlorine disinfection by checking the
Chlorine disinfection check box and specifying a value in the text edit box.
The Power/Costs tab of the Dewatering unit’s property dialog box, shown below, allows you to specify cost
information for the dewatering unit.

The Power/Costs tab of a Dewatering unit element

Checking the Include this unit in power/cost calculation check box will activate the Options (for power/cost
calculation) group. To specify chemical costs for the dewatering unit check the Chemicals/other check box
and entering a value in the text edit box.

Biowin 6 Help Manual Operating Costs in BioWin • 1027

For help on entering chemical costs for a specific element see the Element Descriptions section of the
Building Configurations chapter.

Fuel (Heating and/or Sale)

This section describes how to specify both fuel costs for heating and costs associated with selling fuel.

Specifying Project Fuel (Heating and/or Sale) Costs

BioWin allows you to specify heating fuel (i.e. natural gas, heating oil, diesel, custom fuel) costs and fuel sale
costs (i.e. biogas sale price) for a project via the Project|Costs/Energy|Fuel/Chemical… command. Invoking
this command presents you with the Heating fuel/Chemical Costs dialog box, shown below.

Dialog used to set the heating fuel costs and biogas sale price

Note: These specified heating fuel costs will only be used if the user chooses the Boiler (Fuel) heating
method in the Heating/Heat loss tab of an Anaerobic Digester element (see Specifying Digester Heating
Options) or in the Heating tab of a Thermal Hydrolysis unit element (see Thermal Hydrolysis Unit Heating).
For example, the Heating/Heat loss tab for the Anaerobic digester element is shown in the figure below.

1028 • Operating Costs in BioWin Biowin 6 Help Manual

The Heating/heat loss tab of an Anaerobic Digester element

Users can specify which heating fuel to use in the drop down menu provided in the Boiler options group.
BioWin calculates both the amount of fuel required to meet heating demands and the associated cost of this
fuel (see equations below). In order to calculate the cost of the fuel the overall heating requirements must
first be determined. See Heating Power Equations when Flare/Sell All Specified for Gas Use, Heating Power
Equations when Boiler (heating influent) Specified for Gas Use, Heating Power Equations with CHP for
descriptions of how heating power is calculated in the Anaerobic Digester based on which gas use option is
specified. See Heating Power Equations for a description of how heating power is determined in the Thermal
Hydrolysis Unit. Note if heat recovery via a heat exchanger is specified, the overall heating power
requirements will be affected (see Heating Power Requirements with Heat Exchanger).
Once the heating power requirements are determined (based on the appropriate heating power equation
section listed above), the amount of fuel (i.e. kg/d) required to meet the heating demands in an Anaerobic
Digester or Thermal Hydrolysis Unit is calculated as follows:

𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔𝑅𝑒𝑞𝑢𝑖𝑟𝑒𝑑 (1)
𝐹𝑢𝑒𝑙 𝑓𝑜𝑟 𝐻𝑒𝑎𝑡𝑖𝑛𝑔 = ∙ 86400
𝐶𝑎𝑙𝑜𝑟𝑖𝑓𝑖𝑐 𝑉𝑎𝑙𝑢𝑒

where

𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔𝑅𝑒𝑞𝑢𝑖𝑟𝑒𝑑 = Heating power required based on boiler efficiency [kW or kJ/s]

𝐶𝑎𝑙𝑜𝑟𝑖𝑓𝑖𝑐 𝑉𝑎𝑙𝑢𝑒 = Calorific value of specified fuel source [kJ/kg]
86400 = Conversion for seconds/days

Biowin 6 Help Manual Operating Costs in BioWin • 1029

The calorific value for the heating fuel options provided in the Anaerobic Digester are found in
Project|Costs/Energy|Fuel/Chemical… on the Calorific values of heating fuels tab.
The hourly cost of providing fuel ($/hour) for heating is dependent on the form of the fuel (i.e. gas or liquid).
If Natural gas is specified as the fuel source the cost is calculated as follows:

𝐹𝑢𝑒𝑙 𝑓𝑜𝑟 𝐻𝑒𝑎𝑡𝑖𝑛𝑔 ∙𝐶𝑎𝑙𝑜𝑟𝑖𝑓𝑖𝑐 𝑉𝑎𝑙𝑢𝑒∙𝐹𝑢𝑒𝑙 𝐶𝑜𝑠𝑡 (2)

𝐹𝑢𝑒𝑙(𝐻𝑒𝑎𝑡𝑖𝑛𝑔) =
1000000∙24

where
𝐹𝑢𝑒𝑙 𝑓𝑜𝑟 𝐻𝑒𝑎𝑡𝑖𝑛𝑔 = Amount of fuel required to meet heating demands [kg/d]

𝐶𝑎𝑙𝑜𝑟𝑖𝑓𝑖𝑐 𝑉𝑎𝑙𝑢𝑒 = Calorific value of specified fuel source (i.e. natural gas) [kJ/kg]

𝐹𝑢𝑒𝑙 𝐶𝑜𝑠𝑡 = Specified cost of heating fuel (i.e. natural gas) [$/GJ]

1000000 = Conversion for GJ/kJ

24 = Conversion for d/hr

When a liquid fuel source (i.e. excluding natural gas) is selected the hourly costs of providing fuel ($/hour) is
calculated as follows:

𝐹𝑢𝑒𝑙 𝑓𝑜𝑟 𝐻𝑒𝑎𝑡𝑖𝑛𝑔 ∙𝐹𝑢𝑒𝑙 𝐶𝑜𝑠𝑡∙1000 (3)

𝐹𝑢𝑒𝑙(𝐻𝑒𝑎𝑡𝑖𝑛𝑔) =
𝐹𝑢𝑒𝑙 𝐷𝑒𝑛𝑠𝑖𝑡𝑦 ∙24

where

𝐹𝑢𝑒𝑙 𝑓𝑜𝑟 𝐻𝑒𝑎𝑡𝑖𝑛𝑔 = Amount of fuel required to meet heating demands [kg/d]

𝐹𝑢𝑒𝑙 𝐶𝑜𝑠𝑡 = Specified cost of heating fuel [$/L]

𝐹𝑢𝑒𝑙 𝐷𝑒𝑛𝑠𝑖𝑡𝑦 = Density of liquid heating fuel [kg/m3]

1000 = Conversion for L/m3

24 = Conversion for d/hr

The density of liquid fuels is found in Project|Costs/Energy|Fuel/Chemical… on the Density of liquid heating
fuels tab.
The specified biogas sale price will only be used when the option to Sell excess gas (all gas if “Flare/Sell all”
selected) is chosen in the Anaerobic Digester element. Note this option is only available if Boiler (heating
influent) OR Flare/Sell all is specified for Gas Use in the digester element. The calculation of biogas sales is
dependent on which of the above options is selected for Gas Use.

1030 • Operating Costs in BioWin Biowin 6 Help Manual

Note: when the option to sell biogas is specified the sale credit of biogas is grouped into the Fuel (Heating
and/or Sale) cost category. This category appears as “Fuel (Heating and/or Sale)” in steady state charts and
pre-defined tables AND “Fuel (Heating)” in dynamic charts. Adding an Element specific chart or table to the
Album will show the Fuel cost (Heating) and Digester gas sales credit as separate items. Adding an Element
info (Summary) table to the Album also shows the Fuel cost (Heating) and Digester gas sales credit as
separate items.

In order to calculate the sales credit from selling biogas when Flare/Sell all is specified for gas use, the
potential power [kW or KJ/s] available from the biogas produced in the Anaerobic digester (𝑃𝑂𝑓𝑓𝑔𝑎𝑠 )
must first be determined:

𝑜 𝑜
𝑃𝑂𝑓𝑓𝑔𝑎𝑠 = (𝑛𝐶𝐻4 ∙ 𝛥𝐻𝐶,𝐶𝐻4 + 𝑛𝐻2 ∙ 𝛥𝐻𝐶,𝐻2 )/86400 (4)

where

𝑛𝐶𝐻4 = mols of methane present in the off gas [mol/d]

𝑛𝐻2 = mols of hydrogen present in the off gas [mol/d]

𝑜
𝛥𝐻𝐶,𝐶𝐻4
= methane heat of combustion [kJ/mol]
𝑜
𝛥𝐻𝐶,𝐻2 = hydrogen heat of combustion [kJ/mol]

86400 = conversion for seconds/day

The digester gas sales credit is then calculated as follows:

𝑃𝑂𝑓𝑓𝑔𝑎𝑠 ∙𝐵𝑖𝑜𝑔𝑎𝑠 𝑠𝑎𝑙𝑒 𝑝𝑟𝑖𝑐𝑒∙86400 (5)

𝐷𝑖𝑔𝑒𝑠𝑡𝑒𝑟 𝑔𝑎𝑠 𝑠𝑎𝑙𝑒𝑠 𝑐𝑟𝑒𝑑𝑖𝑡 =
1000000∙24

where

= specified value found in Project|Costs/Energy|Fuel/Chemical…on the Heating

𝐵𝑖𝑜𝑔𝑎𝑠 𝑠𝑎𝑙𝑒 𝑝𝑟𝑖𝑐𝑒
fuel/Chemical Costs tab [$/GJ]

86400 = conversion for s/d

1000000 = conversion for GJ/KJ

24 = conversion for hr/d

Biowin 6 Help Manual Operating Costs in BioWin • 1031

In order to calculate the sales credit from selling biogas when Boiler (heating influent) is specified for gas
use, Equation 4 is used to determine the potential power available from the biogas produced in the
Anaerobic digester. Using this biogas to heat the influent has an associated efficiency which gets applied to
the potential power [kW or KJ/s] available as follows:

𝑃𝑂𝑓𝑓𝑔𝑎𝑠−𝑎𝑣𝑎𝑖𝑙𝑎𝑏𝑙𝑒 = 𝑃𝑜𝑓𝑓𝑔𝑎𝑠 ∗ 𝐸𝑓𝑓𝑔𝑎𝑠 (6)

where

𝐸𝑓𝑓𝑔𝑎𝑠 = Efficiency of gas use

The available power is subtracted from the overall heating requirements (See the Heating Power section for
the equations used to calculate heating power requirements) to determine if excess biogas (in the form of
potential power) is available:

𝑃𝑒𝑥𝑐𝑒𝑠𝑠 = 𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑖𝑛 + 𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑙𝑜𝑠𝑠 − 𝑃𝑂𝑓𝑓𝑔𝑎𝑠−𝑎𝑣𝑎𝑖𝑙𝑎𝑏𝑙𝑒 (7)

where
𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑖𝑛 = Heating power required to heat the influent stream [kW]
𝑃𝐻𝑒𝑎𝑡𝑖𝑛𝑔,𝑙𝑜𝑠𝑠 = Heating power required to overcome daily heat losses [kW]

Note: If a heat exchanger is specified heating requirements will change and will need to be accounted for in
Equation 7. See Heating Power section for the equations used to determine heating requirements when
heat recovery via a heat exchanger is specified.
If 𝑃𝑒𝑥𝑐𝑒𝑠𝑠 is POSITIVE excess biogas is available for sale and the biogas sale price is determined as
follows:

𝑃𝑒𝑥𝑐𝑒𝑠𝑠 ∙𝐵𝑖𝑜𝑔𝑎𝑠 𝑠𝑎𝑙𝑒 𝑝𝑟𝑖𝑐𝑒∙86400 (8)

𝐷𝑖𝑔𝑒𝑠𝑡𝑒𝑟 𝑔𝑎𝑠 𝑠𝑎𝑙𝑒𝑠 𝑐𝑟𝑒𝑑𝑖𝑡 = 1000000∙24

where

𝐵𝑖𝑜𝑔𝑎𝑠 𝑠𝑎𝑙𝑒 𝑝𝑟𝑖𝑐𝑒 = specified value found in Project|Costs/Energy|Fuel/Chemical…on the Heating

fuel/Chemical Costs tab [$/GJ]
86400 = conversion for s/d

1000000 = conversion for GJ/KJ

1032 • Operating Costs in BioWin Biowin 6 Help Manual

 24 = conversion for hr/d

Sludge
This section describes how to enter sludge disposal costs in BioWin.
Costs associated with sludge disposal can be specified in the Power/Costs tab of the Sludge elements
property dialog box.

The Costs tab of a Sludge element

Checking the Include this sludge output in power/cost calculations checkbox activates the Sludge Options
(for power/cost calculations) group. Sludge disposal costs can be specified on the basis of the dry mass of
total suspended solids in the sludge stream by checking the Sludge disposal (dry) check box and entering a
value in the text edit box. Sludge disposal costs can be specified on the basis of the volumetric flow rate of
the sludge stream by checking the Sludge disposal (volumetric) check box and entering a value in the text
edit box. Sludge disposal costs can be specified on the basis of the wet mass of total suspended solids in the
sludge stream by checking the Sludge disposal (wet tonne) check box and entering a value in the text edit
box.

Biowin 6 Help Manual Operating Costs in BioWin • 1033

Displaying Cost Information
Once the cost is obtained via one or more of the methods above the cost information can be shown through
one of many BioWin displays including Element Information, Tables, and Charts.

Element Information

A pre-defined Element Information table can be generated for any of the elements that contain costs. An
Element Information display can be generated in one of two ways:
Right-click on the desired element and select either Add to album > Element info (Summary) or Add to
album > Element info (State variables)

Add a new page to the BioWin Album, right-click and select Element info… from the pop-up menu shown
below.

This opens an Options dialog box, shown below. From the Elements drop down list choose which element
you would like to generate the Element information display. In the View type radio button group select
either State variable view or Summary view.

1034 • Operating Costs in BioWin Biowin 6 Help Manual

Invoking either command will add an Element Information table to the BioWin Album. In the bottom
section of the Element Information display, element specific cost information is displayed.

Note: cost categories (i.e. Power cost, Cost (Chemicals) etc.) will change based on which categories are
relevant to the selected element.

Biowin 6 Help Manual Operating Costs in BioWin • 1035

Tables
Cost information can also be displayed in a Table in the BioWin Album. Cost tables can be generated
automatically or they can be completely customizable.

Add a Pre-Defined Cost Table Display

1. Right-click on the blank album pane where you wish to place the table.
2. Select Cost Table from the resulting popup menu.

1036 • Operating Costs in BioWin Biowin 6 Help Manual

 3. A Cost Table summarizing the costs associated with each of the three main categories will be
automatically generated and added to the Album.

Add an Element Specific Cost Table Display

1. Right-click on the blank album pane where you wish to place the table.
2. Select Table from the resulting popup menu.

3. The Table Editor dialog will open.

Biowin 6 Help Manual Operating Costs in BioWin • 1037

 4. From the Elements tree view, select the element(s) that you wish to include in the table.
• You can expand individual element groups, select specific elements by clicking on them and
push the right-pointing arrow to move them to the Selected elements list; or move entire
element groups over at once by clicking on the element group (e.g. Bioreactor) and clicking the
right-pointing arrow.
• If the element you have selected has multiple outputs (e.g. a secondary clarifier), all outputs are
added to the Selected elements list by default. If you do not want one of the outputs (e.g.
the underflow of a secondary clarifier), simply click on the entry in the Selected elements list
and press the Delete key on your keyboard.
• If you want to change the order in which the Selected elements will appear in the table,
move the elements around by clicking on them and clicking the up/down arrows. You can
change the order of a group of elements, by using the Ctrl or Shift key to select the group and
then clicking the up or down arrow. Finally, you can move a selection directly to the top or
bottom of the list by holding the Ctrl key while you click the up or down arrow.
5. Choose the variables you want to include in the table from the Element specific list under the
ninth subcategory (i.e. --- 9. Power/Costs---). If you want to add more than one variable from a
given group, you may do so: To select a continuous group, click the first variable of the group, and
while holding the Shift key, click the last variable of the group. To select non-continuous variables,
hold the Ctrl key and click the desired variables in succession. You may also simultaneously select
variables from multiple lists.

1038 • Operating Costs in BioWin Biowin 6 Help Manual

 6. Once you have selected the variables you want in the table, move them to the Selected variables
list by clicking the right-pointing arrow.
• If you want to change the order in which the Selected variables will appear in the table, move
the variables up or down by clicking on them and clicking the up/down arrows. You can change
the order of a group of variables, by using the Ctrl or Shift key to select the group and then
clicking the up or down arrow. Finally, you can move a selection directly to the top or bottom of
the list by holding the Ctrl key while you click the up or down arrow.
7. If you wish to re-add certain variables, place a check in the box labeled Duplicates, and re-add the
variables.
8. Select Concentrations. Mass rates and Both are irrelevant for the Cost information.
9. If you want to add a blank line between table entries, click the Add blank line button. The blank line
will show as a short dashed line in the Selected elements list. The blank line can be moved up or
down in the list just like other elements. Multiple lines may be added to the list.
10. If you want BioWin to display the total of a table’s columns, click the Add total so far button. The
word “Total” will be added to the Selected elements list. The Total can be moved up or down in the
list just like other elements. Multiple totals may be added to the list; if a total will always totalize
the rows preceding it.
11. Click OK to finish.

Charts
Costing plots are also generated automatically in BioWin. These include:
• Steady state/current value Cost Distribution plots
• Pie plot of current cost distribution
• Bar plot of current cost distribution

Biowin 6 Help Manual Operating Costs in BioWin • 1039

 • Dynamic Time Series plots
• Energy costs
• Consumption charge
• Service charge
• Peak demand charge
• Total (consumption + demand + service)
• Cumulative total cost (Yearly)
• Additional Plots
• Energy consumption charge ($/kwh)
• Sludge disposal costs
• Instantaneous sludge disposal costs
• Cumulative sludge disposal costs (Yearly)
• Chemical costs
• Instantaneous chemical costs
• Cumulative chemical costs (Yearly)
• CHP power credit
• Instantaneous CHP power credit
• Cumulative CHP power credit (Yearly)
• Fuel costs
• Instantaneous fuel costs
• Cumulative fuel costs (Yearly)
• Total costs
• Instantaneous total operating cost
• Cumulative total operating cost (Yearly)
For cost distribution and time series plots, you are only required to select the chart options or the series you
want included in the plots. BioWin then performs the necessary calculations and generates the plot. You
may customize the appearance of the chart using BioWin's powerful chart and series formatting tools.

Adding a Costs Plot or Series to the Album

If you want to add a Cost Distribution plot:
1. Right-click on an album chart and click Add Series in the resulting popup menu.
2. Click on the Costs tab of the Add parameters for plotting dialog box.

1040 • Operating Costs in BioWin Biowin 6 Help Manual

 The Costs (from album) dialog

3. In the Cost Distribution group, you can choose a Pie or a Bar plot by selecting the appropriate radio
button from the Plot type options.
4. Use the Labels (marks) radio button group to specify if the distribution plot labels should show
Name and value or Name and %.
5. When you are satisfied with the plot and label type, click on the Current cost distribution button to
generate a pie or bar chart illustrating the current cost distribution for the project.
6. Click the Close button to finish.

Biowin 6 Help Manual Operating Costs in BioWin • 1041

Example Cost Distribution plots

If you want to add a time series plot of the consumption costs, sludge disposal costs, chemical costs or
CHP power credit:
7. Right-click on an album chart and click Add Series… in the resulting popup menu.
8. Click on the Costs tab of the Add Parameters for plotting dialog box.

1042 • Operating Costs in BioWin Biowin 6 Help Manual

 The Costs (from album) dialog

9. In the Time series plots group, select the series you would wish to plot.
Energy costs
• To generate a time series for energy consumption ($/hour), click the Use charge button. The energy
consumption series represents the product of the total power demand (kW) and the specified
Electricity costs ($/kwh).
• To track the service charge ($), click the Service charge button. This plots the Service charge
specified under Project|Costs/Energy|Electricity… in the Other Charges tab. Note the service
charge gets automatically plotted to the right axis.
• To track the peak demand charge ($), click the Peak demand charge button. For the first month
(until a month boundary is crossed) of simulation, this series plots the product of the Peak demand

Biowin 6 Help Manual Operating Costs in BioWin • 1043

 charge and the Base Demand specified under Project|Costs/Energy|Electricity… in the Other
Charges tab. For the subsequent months of operation, the base demand is determined from the
peak demand observed in the previous month (the simulator samples the power demand every 15
minutes to determine the peak demand). The Peak demand charge is automatically plotted to the
right axis.
• To generate a time series of the Total energy costs ($/hour), click the Total (consumption + +
demand + service) button. This plots the sum of the Use charge, the Service charge and the Peak
demand charge. The Service charge and Peak demand charge are converted from ($/month) to
($/hour).
• To track the total cost of power over a year or the yearly energy consumption cost, click the
Cumulative total cost (Yearly) button. This will add a series, plotted to the right axis, which
accumulates the cost of energy consumption each day of the year. This series will automatically
reset at the start of a new year.

Example Energy costs plot

Additional plots
• To generate a time series illustrating the specified electricity consumption charge, click the Energy
Consumption Charge ($/kwh) button.

Example Energy Consumption Charge plot

1044 • Operating Costs in BioWin Biowin 6 Help Manual

 • If you wish to show the electricity use charge for the most recent day only, select the Scrolling (One
day only) checkbox and click the Energy Consumption Charge ($/kwh) button.

Example Scrolling (One day only) Energy consumption plot (pink line)

Sludge disposal costs

• To generate a time series of the instantaneous sludge disposal costs, click the Instantaneous sludge
disposal costs button.
• To track the total cost of sludge disposal per year, click the Cumulative sludge disposal costs
(Yearly) button. This will add a series, plotted to the right axis, which accumulates the cost of sludge
disposal each day of the year. This series will automatically reset at the start of a new year.

Example Sludge Handling Costs plot

Chemical costs
• To generate a time series of the instantaneous chemical costs, click the Instantaneous chemical
costs button.

Biowin 6 Help Manual Operating Costs in BioWin • 1045

 • To track the total cost of chemicals per year, click the Cumulative chemical costs (Yearly) button.
This will add a series, plotted to the right axis, which accumulates the sludge disposal cost each day
of the year. This series will automatically reset at the start of a new year.

Example Chemical Costs plot

CHP Power credit

• To generate a time series of the instantaneous CHP power credit costs, click the Instantaneous CHP
power credit button.
• To track the total power credit costs over a year, click the Cumulative CHP power credit (Yearly)
button. This will add a series, plotted to the right axis, which accumulates the power credit each day
of the year. This series will automatically reset at the start of a new year.

Example CHP Power credit plot

1046 • Operating Costs in BioWin Biowin 6 Help Manual

Note: CHP power credit costs only apply when the user chooses to Sell all CHP Engine power generated. This
is specified under Project|Costs/Energy|Combined Heat and Power (CHP)…

Fuel costs
• To generate a time series of the instantaneous fuel costs, click the Instantaneous fuel costs button.
• To track the total fuel costs over a year, click the Cumulative fuel costs (Yearly) button. This will add
a series, plotted to the right axis, which accumulates the fuel costs day of the year. This series will
automatically reset at the start of a new year.

Example Fuel Costs plot

Note: Fuel costs only apply when the user specifies Boiler (Fuel) as the Heating method in the Anaerobic
Digester and/or Thermal Hydrolysis unit elements.

Note: Fuel costs include the cost of fuel required for heating AND the costs recovered from selling biogas in
the Anaerobic Digester element if the option to Sell excess gas (all gas if “Flare/Sell all” selected) is specified.

Total costs
• To generate a time series of the instantaneous total operating costs, click the Instantaneous total
operating cost button.
• To track the total operating cost over a year, click the Cumulative total operating cost (Yearly)
button. This will add a series, plotted to the right axis, which accumulates the total operating costs
each day of the year. This series will automatically reset at the start of a new year.

Biowin 6 Help Manual Operating Costs in BioWin • 1047

 Example Total Costs plot

10. When you are satisfied with your time series selection click the Close button to finish.

Displaying Costs with CHP - Example

Specifying CHP in the Anaerobic Digester element will modify the look of various plots and series depending
on the division of the energy generated (i.e. % to power, % to heat), the fate of the heat generated (e.g.
whether it is used to heat the boiler) and the fate of the energy generated (e.g. whether it is used onsite
with any excess being sold back to the grid or it is all sold back to the grid).
The following section illustrates the changes that occur to steady state and dynamic costs plots as well as
the automatically generated cost table when CHP is turned on.
For more information on CHP please see the following sections: Specifying Project Combined Heat and
Power Parameters, Anaerobic Digester Power/Heat, Combined Heat and Power (CHP).

Steady State Example

Costs Distribution without CHP

When CHP is not specified in the Anaerobic Digester element (i.e. there is no power recovery), the cost
distribution plots and the cost table will resemble those shown below.

Note: In this example the Boiler (Fuel) heating method is specified in the Anaerobic Digester element. For
detailed instructions on creating a pie or bar chart illustrating the cost distribution see Adding a Costs Plot or
Series to the Album. For detailed instructions on creating a cost table see Add a Pre-Defined Cost Table
Display.

1048 • Operating Costs in BioWin Biowin 6 Help Manual

Example Cost Distribution plots without CHP

Example Cost Table without CHP

Cost Distribution with CHP

Biowin 6 Help Manual Operating Costs in BioWin • 1049

Use CHP power on-site, sell excess
When CHP is turned on AND the option to use CHP power on-site (sell any excess) is selected, cost
distribution plots as well as the cost table will look similar to those without CHP. However, the power and
fuel costs will be lower with CHP than without CHP (shown below) as a result of the power and fuel savings
from CHP.

Example Cost Distribution plots with CHP (Use on-site, sell excess)

Example Cost Table with CHP (Use on-site, sell excess)

Sell all CHP engine power generated

1050 • Operating Costs in BioWin Biowin 6 Help Manual

When CHP is turned on AND the option to sell all CHP engine power generated is selected, a new cost
category (i.e. CHP power sales) will be added to the cost distribution bar chart and the cost table, as shown
below.
CHP power sales represents the product of the CHP engine power price ($/kWh) specified in
Project|Costs/Energy|Combined Heat and Power (CHP)… and the total power generated from CHP (see the
Combined Heat and Power (CHP) section in the Power in BioWin chapter). The CHP power sale is shown as a
negative value since it represents a cost saving.

Note: CHP power sales will not be displayed in a pie plot of the cost distribution. Therefore, it is best to use
a bar chart for steady state simulations with CHP when the option to sell all CHP engine power generated is
selected.

Example Cost Distribution plots with CHP (Sell all CHP power generated)

Example Cost Table with CHP (Sell all CHP power generated)

Use CHP Heat for Digester Input Stream

If the user specifies to use CHP heat for the digester input stream AND an Electrical Heating method is
specified, power costs will be reduced as a result of the savings in heating costs. If Boiler (Fuel) is specified as
the heating method, fuel costs will be reduced as a result of the heating credit. Both options will be evident
in the cost distribution plot and the cost table.

Biowin 6 Help Manual Operating Costs in BioWin • 1051

Do not use CHP Heat for Digester Input Stream
Heat will only be sold if the user elects not to use CHP heat for the digester input stream AND a cost for CHP
engine heat price ($/kWh) is specified under Project|Costs/Energy|Combined Heat and Power (CHP)….
The cost savings from heat sales can be determined by viewing the Cost Table. In the Cost Table, shown
below, the difference between the sum of the Power, Chemical and Sludge costs and the Total cost is
indicative of the cost savings from heat sales (i.e. $59.06/hour - $48.65/hour = $10.41/hour savings).

Example Cost Table with CHP (Use on-site, sell excess + sell heat generated)

Dynamic Example
Cost plots without CHP
When CHP is not specified in the Anaerobic Digester element (i.e. there is no power recovery) the energy
costs and total operating costs will resemble those shown below.

1052 • Operating Costs in BioWin Biowin 6 Help Manual

CHP (Use onsite, sell excess)

When CHP is turned on AND the option to use the CHP Engine power generated on-site (sell any excess) is
selected, there will be a reduction in the Energy Consumption, Cost (Consumption, Demand & Service
charges) and the Cumulative cost (Power) as a result of the power savings. Consequently, the total and
cumulative operating costs (i.e. Cost (Total) and Cumulative cost (Total)) also will be reduced.

Note: There will also be a reduction in Fuel costs also contributing to the reduction in total and cumulative
operating costs.

Biowin 6 Help Manual Operating Costs in BioWin • 1053

When CHP is turned on AND the option to use the CHP engine power generated on-site (sell and excess) is
selected, AND the option to use the heat generated through CHP for the digester input stream, then there
will be an additional reduction in energy consumption and fuel costs. The plots for Energy Consumption,
Cost (Consumption, Demand & Service charges), Cumulative cost (Power), Cost (Total) and Cumulative cost
(Total) will reflect the lower costs and energy consumption resulting from the heat savings.
When CHP is turned on AND the option to use the CHP engine power generated on-site (sell and excess) is
selected AND the option to not use the heat generated through CHP for the digester input stream is
selected AND a cost for selling heat is specified, then the operating costs (i.e. Cost (Total) and Cumulative
cost (Total)) will be reduced as a result of the sale of heat generated from the CHP engine.

Cost plots with CHP (Sell all CHP Engine power generated)

When CHP is turned on AND the option to Sell all CHP Engine power generated is selected, users will have
the ability to plot the instantaneous and yearly cumulative CHP power credit costs (i.e. CHP power credit
(sale) and Cumulative credit (CHP power)). The instantaneous and cumulative operating costs (i.e. Cost
(Total) and Cumulative cost (Total)) will be reduced as a result of the cost savings from the sale of CHP
power.

1054 • Operating Costs in BioWin Biowin 6 Help Manual

When CHP is turned on AND the option to Sell all CHP Engine power generated is selected AND the option
to use the heat generated through CHP for the digester input stream is selected, then a reduction in both
fuel and energy costs (i.e. Energy consumption, Cost (Consumption, Peak & Service charges), Cumulative
cost (Power), Cost (Total) and Cumulative cost (Total)) will be shown as a result of heat savings. This will
further reduce the total operating costs (i.e. Cost (Total) and Cumulative cost (Total)).
When CHP is turned on AND the option to Sell all CHP Engine power generated is selected AND the option
to not use the heat generated through CHP for the digester input stream is selected AND a cost for selling
heat is specified, then the operating costs (i.e. Cost (Total) and Cumulative cost (Total)) will be reduced as a
result of the sale of heat generated from the CHP engine.

Biowin 6 Help Manual Operating Costs in BioWin • 1055

Glossary of Terms

Album
The BioWin Album is a fully integrated means for displaying information in graphical (i.e. charts) and tabular
formats. Pages of the album may contain multiple charts and/or tables. Users of previous versions of
BioWin should note that the album is a much more powerful and elegant replacement for Grapher which
was a separate application used for charting.

BOD
Biochemical Oxygen Demand is a measure of wastewater strength. The test measures the portion of organic
substrate utilized for energy generation and ignores the portion transformed into new cell mass. Therefore,
BOD cannot be used as the basis for a mass balance.

Chart
The term "chart" refers to a container for a series. Chart formatting refers to the appearance of axes, chart
titles, background, legend, etc.

COD
Chemical Oxygen Demand is a measure of wastewater strength. Specifically, the electron donating capacity
of organic material is measured in the test.

Cycle Offset
You step into a cycle by a time amount equal to that of your offset. In other words, you start at time
"offset" in a cycle.
For example, if you have a 6 hour cycle (2h Fill, 2h Reaction, 2h Settle/Decant) the SBR receiving the next
feed should have an Cycle Offset of 4 hours. You will begin the simulation of this SBR in the Settle/Decant
phase allowing to start the Fill phase after 2 hours.

Biowin 6 Help Manual Glossary of Terms • 1057

Cycle Time
Cycles are made up of a sequence of events at various times. The first event value is used until the second
event time is reached. Then the second event value is used until the third event time is reached and so on.
This continues until the last event time is reached. When this happens, the last event value is used until the
cycle time is reached. At this point, the cycle begins to repeat.
If you change the cycle length during a dynamic simulation (by pausing the simulator), the dynamic
simulation will resume at a point in the new cycle as if the new cycle had been applied at the very beginning
of the simulation.

Database
The database is an "in-memory" representation of data generated during dynamic simulations. You can
control the amount of information saved to the database by setting up data monitoring for only the
variables, compounds, and parameters you are interested in for certain elements in your configuration.

Drawing Board
The main section of the BioWin window where you lay out the process configuration that you will be
simulating. For users of previous versions of BioWin, it should be noted that the drawing board replaces the
Configure and Simulate windows.

Element Information Display

These are element-specific information displays which may be added to the album. There are two types: (1)
State variable, and (2) Summary. The first type lists state variables and their values in an element. The
second type lists general and element-specific (e.g. Solids Loading Rate for a settler) compounds and their
values. For users of previous versions of BioWin, it should be noted that the two types of element
information displays replace Model Data Windows and Summary Data Windows, respectively.

Event
An event is a row in an itinerary. It consists of an event time and one or more values. The event time is the
time at which the value is set.

Explorer
The BioWin Explorer is used for displaying information about the elements in the current configuration. An
expanding/collapsing tree view in the left section groups the elements by type. Clicking on a branch of this
tree view displays information in the right section.

Itinerary
BioWin uses itineraries for scheduling element operating conditions. There are many itinerary editors which
facilitate scheduling influent flow, D.O. setpoints, air flowrates, temperature, and flow splitting/routing.

1058 • Glossary of Terms Biowin 6 Help Manual

Radio Button

Example of a Radio Button Group

Radio button groups are used to select one option from a number of mutually exclusive dialog box options.
The appropriate radio button in a group may be selected using the keyboard by pressing Tab until the input
focus moves to one of the radio buttons in the group, and then using the arrow keys to change the selected
radio button, or by pressing the keyboard character corresponding to the underlined character in the radio
button group and then using the arrow keys to change the selected radio button. To change the selected
option using the mouse, click on the radio button corresponding to the desired option. A radio button
cannot be deselected like a check box.

Recursion
This occurs in your configuration flow network when you attempt to connect a node splitter and a node
mixer in a closed loop, i.e. there are no elements with volume in the loop between the two node elements.

Series
The term "series" refers to a graphical display of data. Series are contained in charts. Series styles include
Line, Fast Line, Point, Bar, Area, Pie, and Surface.

Spin Edit

Example of a Spin Edit Box

A spin edit box quite often is used to control dialog box options that use numeric values such as sizes. The
value in the box may be changed with the mouse in two ways: directly by clicking in the box and typing in a
value, or by clicking on the up/down arrows to increase or decrease the value by a predefined increment
controlled by the program. Using the keyboard, the value may be changed by moving the focus to the spin
edit box and then either directly typing in a value or using the keyboard up/down arrow keys. Note that
typically there is some limit that the option may be set to and if a value exceeding this limit is entered using
the direct method then the value will default to the limit.

SRT
Solids Retention Time (or Sludge Age) is the average length of time that solids remain in a system. It is
calculated by dividing the sludge mass in the defined system by the mass removed daily via sludge wasting.

Biowin 6 Help Manual Glossary of Terms • 1059

Status Bar
The section at the very bottom of BioWin's main window that contains information on menu items and tool
icons when the mouse is held over them. It also displays information about the simulation status of the
current configuration.

Summary Panes
Areas near the bottom of BioWin's main window used for viewing summary information about elements
when you hold your mouse over them on the drawing board.

Table
Tables are highly customizable information displays which may be added to the album. Users of previous
versions of BioWin should note that tables replace Custom Data Windows.

1060 • Glossary of Terms Biowin 6 Help Manual

 Add a Process Rate Series 616
Add a SBR Profile Series 632
Add a Settling Tank Profile Series 636
Add a Settling Tank State Point Analysis Chart 634

Index Add a Shadow to a Chart Title Frame 659

Add a Shadow to the Chart Legend Frame 668
Add a SOTE (%) Series 630
Add a Special Series From the Album 589
Add a Table Display (Concentrations and/or mass
rates) 568
Add a Table Display (Pre-defined Air Supply group
table) 573
Add a Table Display (Pre-defined Cost table) 573
Add a Table Display (Pre-defined Power table) 572
“ Add a Table Display (Process rates) 570
“PolyP bound cations” Is No Longer A State Add a Time Series from the Album 582
Variable - Equation Discarded 136 Add a Time Series from the Drawing Board 626
Add a Trickling Filter Profile Series 632
A Add an Axis Title 641
Add an Element Info Display From The Album 576
About the Manual 13 Add an Element Info Display From the Drawing
Access Element Properties from the Drawing Board 577
Board 211 Add an Element Specific Cost Table Display 1041
Activated Sludge Processes 753 Add an Element Specific Power Table Display 1004
Activated Sludge vs. Anaerobic Digestion 788 Add an Image to a Chart Title Frame 657
Add a Biofilm Reactor Details Table Display 577 Add an Imported Series 614
Add a Chart Title 654 Add an N2O emissions plot 624
Add a Chart To The Album 581 Add Dividing Lines to a Legend 662
Add a Color Gradient to the Chart Legend 667 Add function 607
Add a constant function 608 Add To Notes 579
Add a Costs Plot or Series to the Album 597 Add/Remove a Series in the Legend 685
Add a Current Value Series 587 Adding a Border to the Chart 671
Add a Fill Pattern and Color to a Chart Title Frame Adding a Composite Time Series 584
656 Adding a Costs Plot or Series to the Album 1044
Add a Frame to the Chart Legend 665 Adding a Gradient to the Chart Background 673
Add a Frame to the Chart Title 656 Adding a Power/Energy consumption Plot to the
Add a Function Series 604 Album 591
Add a General “Current Value” Series from the Adding a Surface Series 585
Album 618 Adding a Tool 678
Add a General “X-Y Scatter” Series from the Adding element information to the Album 30
Album 620 Adding elements to the drawing board 23
Add a Gradient to a Chart Title Frame 658 Adding Labels to a Chart 686
Add a Page to the Album 563 Adding tables to the Album 27
Add a Power/Energy Consumption Plot to the Additional State Variables Included - Review
Album 1007 Inputs 135
Add a Pre-defined Air Supply group table 1003 Additional State Variables Included AND/OR
Add a Pre-Defined Cost Table Display 1040 Parameters Should Be Changed And New
Add a Pre-defined Power Table Display 1001 Parameters Added 136

Biowin 6 Help Manual Index • 1061

Adiabatic/Polytropic Power Equation 959 Applying a Chart Template 159
Adjust Chart Three-Dimensional Appearance 676 Area Series Procedures 715
Adjust the Appearance of Chart Walls 674 Arrange the Pie Series Slices 714
Adjusting the Chart Position 683 Attachment/Detachment 901
Adjusting the Chart Size 683 Automatic Logging Options 154
Adsorbed hydrocarbon COD 858 Available Functions and Operators 96, 203
Aeration and Gas Transfer Model 864 Average function 609
Aeration Parameters 865 Avoiding Modified Vesilind Settler Model
Aeration Parameters Can Now Also Be Global 137 Problems 894
Aerobic Denit half sat. no longer used check your Axis Label Procedures 644
parameters 137 Axis Scale Procedures 639
Aerobic Digester 448 Axis Title Procedures 641
Aerobic Digester Dimensions 449
Aerobic Digester Model 453 B
Aerobic Digester Operation 450
Background 924
Aerobic Digester Power 452
Background on Anaerobic Model Development
Air Flow Rate Itinerary 170
785
Alarm conditions 130
Bar Series Procedures 705
Alarm Options 74
Basic Parameters and Relationships 882
Alarms 130
Basis for BOD Calculations 926
Album Chart Sub-Menu 578
Beta Itinerary 177
Album Menus 562
Biofilm Density 901
Album pages and panes 562
Biofilm parameters at a glance 902
Album Table Displays 568
Biofilm, media and liquid volume exceeds tank
Album Toolbar 568
volume. Increase the assumed biofilm
Alkalinity determination 837
thickness to address this problem. 131
Alkalinity Is No Longer A State Variable - Equation
Biological inhibition due to pH 838
Discarded 136
Biological Processes 844, 850, 852
All Alkalinities Will Be Converted 135
Biological/Chemical Models 753
Alpha Itinerary 177
Bioreactor 267
Anaerobic Digester 454
Bioreactor Dimensions 268
Anaerobic Digester Dimensions 455
Bioreactor Model 271
Anaerobic Digester Element 973
Bioreactor Operation 269
Anaerobic Digester Gas use 461
Bioreactor Power 271
Anaerobic Digester Heating/heat loss 464
Bioreactors 267
Anaerobic Digester Initial Values 459
BioWin Album 561
Anaerobic Digester Model options 466
BioWin Date / Time Formats 647
Anaerobic Digester Operation 456
BioWin Examples 55
Anaerobic Digester Outflow 457
BioWin Explorer 723
Anaerobic Digester Power 460
BioWin in Brief 4
Anaerobic Digestion Processes 784
BioWin Model for Mass Transfer 871
Anaerobic model introduced. Additional state
BioWin Number Formats 645
variables included 138
BioWin Tutorials 14
Anaerobic Processes 785
Blower Discharge Pressure 955
Anaerobic selector modification (including P
Blower Efficiency 958
removal) 30
Blower Intake Airflow and Pressure 954
Anion or Cation limitation for growth 134
Blower Power 1027
Applied User defined equation - Example 100

1062 • Index Biowin 6 Help Manual

Blower Power Calculations 952 Change the Axis Label Font 649
Blower Power Equations 958 Change the Axis Label Format 645
Blower Power Parameters 952 Change the Axis Label Style 645
Blower Power Parameters and Calculations 948 Change the Axis Major Tick Formatting 652
BOD Associated with Active Biomass 935 Change the Axis Minor Tick Formatting 653
BOD Associated with Colloidal Slowly Change the Axis Tick Label Options 644
Biodegradable COD (XSC): 929 Change the Axis Title Angle 642
BOD Associated with Particulate Slowly Change the Axis Title Area Size 641
Biodegradable COD (XSP): 932 Change the Axis Title Border 643
BOD Associated with Readily Biodegradable COD Change the Axis Title Font 642
Components: 927 Change the Bar Series Border 707
BOD Calculations in BioWin 924 Change the Bar Series Color 706
BOD Influent 223 Change the Bar Series Pattern 708
Boiler (Fuel) Heating Method 978, 991 Change the Bar Series Shapes and Positions 709
Boiler (Fuel) Supplemental Heating Method 982 Change the Chart Axis Formatting 651
Brush Aerator Bioreactor 319 Change the Chart Legend Background Color and
Brush Aerator Bioreactor Dimensions 321 Pattern 665
Brush Aerator Bioreactor Model 323 Change the Chart Legend Font 666
Brush Aerator Bioreactor Operation 322 Change the Chart Legend Vertical Spacing 662
Bubble Size 883 Change the Chart Major Grid Formatting 651
Building Configurations 207 Change the Chart Minor Grid Formatting 653
Change the Chart Title Alignment 654
C Change the Chart Title Font Properties 657
Change the Chart Title Position 655
Cabinet Models 197
Change the Fast Line Series Appearance 697
Cabinet Models provided with BioWin 206
Change the Legend Position 663
Calcium or Magnesium limited conditions occured
Change the Line Series Border 700
132
Change the Line Series Color 699
Calculated pH and specified pH are quite different
Change the Line Series Pattern and Mode 701
from each other 134
Change the Line Series Point Border 703
Calculating CODT in the BOD Influent Element 938
Change the Line Series Point Color 702
Calibration to Design and Engineering Criteria 903
Change the Line Series Point General Appearance
CH4 production rate no longer reported for
702
activated primaries 138
Change the Pattern Color: 692
Change a Series Color 696
Change the Pie Series Border 712
Change a Series Style 684
Change the Pie Series Color and Pattern 712
Change Axis Position for a Series 685
Change the Pie Series General Appearance 711
Change the Appearance of Legend Symbols 664
Change the Pie Series Three-Dimensional
Change the Area Series Border 716
Appearance 713
Change the Area Series Color 716
Change the Point Series Border 705
Change the Area Series General Appearance 716
Change the Point Series General Appearance 704
Change the Area Series Lines Format 717
Change the Point Series Pattern 705
Change the Area Series Point Border 719
Change the Series Label Color 691
Change the Area Series Point General Appearance
Change the Series Label Font 692
718
Change the Series Label Frame 690
Change the Area Series Point Pattern 719
Change the Series Label Gradient 693
Change the Axis Inner Tick Formatting 652
Change the Series Label Number Format 688
Change the Axis Label Border 649
Change the Series Label Shadow 694

Biowin 6 Help Manual Index • 1063

Change the Series Label Style 687 Context Sensitive Help on a Window Menu
Change the Series Order 669 Command 13
Change the Series Plotting Order 696 Control Area Placement for Multiple Area Series
Change the Series Type 669 718
Change to Chart 581 Control Bar Placement for Multiple Bar Series 710
Change to Element info… 580 Conversion Notes 135
Change to Table… 580 Copy 579
Changing Chart Master Options 161 Copy Elements on the Drawing Board 209
Changing model parameters 27 Copying, Pasting, and Printing Equations 205
Changing the Chart Background Color 670 Cost Distribution with CHP 1054
Changing the Paper Orientation 682 Cost plots with CHP (Sell all CHP Engine power
Changing the Paper Size or Source 683 generated) 1058
Chart Axis Procedures 639 Cost plots without CHP 1056
Chart Formatting Procedures 638 Costs 223
Chart Legend Procedures 659 Costs (Album) 596
Chart Options 668 Costs (Metal Addition) 250
Chart Panel Options 670 Costs (Methanol) 240
Chart Template Options 157 Costs (SSO) 244
Chart Title Procedures 654 Costs Distribution without CHP 1052
Charts 1006, 1043 Count function 609
Charts in BioWin 581 Create a Time series chart 35
Check Simulate Data 551 Create a Time series chart with many series 36
Checking influent data 17 Creating a Chart Template 157
Checking that all data have been specified 27 Creating a Word Report 735
Checking the system set-up 50 Creating an Excel™ Report 736
Chemical Phosphorus Removal Example 818 Creating Charts & Adding Series 581
Chemical Phosphorus Removal with Aluminum Creating Project Reports 734
Salts 814 Cumulative function 610
Chemical Phosphorus Removal with Iron Salts 810 Current Value (Album) 587
Chemical Precipitation Reactions 810 Current value chart 36
Chemicals 1028 Curve fit function 610
CHP (Use onsite, sell excess) 1057 Custom Export Utility 124
Clarifiers 483 Customizing BioWin 138
COD and BOD in BioWin 924 Customizing the Project Appearance 138
COD Influent 213 Customizing the Work Environment 144
COD versus BOD as a Modeling Parameter 943 Cyclone 526
Combined Heat and Power (CHP) 982 Cyclone Flow Split 530
Common Series Procedures 684 Cyclone Operation 528
Conclusion 885 Cyclone Power/Costs 532
Configuration Sheets 742
Connect Elements with Pipes 210 D
Connecting elements with pipes 25
Data Interval 113
Consider Turning On Ammonia Stripping Model
Data Output (charts, tables, reports) 561
and Gas Phase Modelling 132
Database Inventory 115
Considerations 841
Default tags 153
Context Sensitive Help in BioWin 12
Defining Air Supply Groups and Local Blower
Context Sensitive Help on a Dialog Box 12
Power Options 948

1064 • Index Biowin 6 Help Manual

Definition of Non-State Variables 916 E
Delete a Display 566
Edit Table Entries 574
Delete a Page from the Album 564
Edit the Series List 695
Delete a Series From a Chart 685
Editing the charts 38
Delete an Element from the Drawing Board 209
Effluent 250
Delete current… 581
Effluent Power 998
Detailed Description of Functions 607
Effluent Power/Costs 252
Determination of the Overall Mass Transfer
Effluents 250
Coefficient at Field Conditions 875
Electrical Heating Method 978, 990
Determination of the Overall Transfer Coefficient
Electrical Supplemental Heating Method 981
for Other Components 877
Electricity Cost Itinerary 179
Determination of the Overall Transfer Coefficient
Element Descriptions 213
for Oxygen in Diffused Aeration Systems 876
Element Info - Pre-defined Table in Album 574
Determination of the Overall Transfer Coefficient
Element Information 1000, 1038
for Oxygen in Surface Aerated Vessels 875
Element Specific Power 1027
Determination of the Steady State Saturation
Enter Head Space Volume For Digesters 136
Concentration at Field Conditions 873
Entering Model Constants 197
Determining Blower Power Equation Variables
Entering Model Equations 199
953
Entering Model Processes 198
Dewatering Unit 513
Entering Power and Power Calculations 947
Dewatering Unit Operation 515
Entering User defined equations 91
Dewatering Unit Power/Costs 518
Equalization Tank 478
Dewatering Unit Split Method 516
Equalization Tank Dimensions 480
Dewatering unit, Point Clarifier, Microscreen,
Equalization Tank Operation 481
Cyclone and ISS Cyclone Power 998
Equalization Tank Power 482
Diffuser Parameters 867
Equation Editor Popup Menu 93, 200
Diffusion 901
Equation Editor Syntax 92, 200
Digester gas now reported in m3/hr for SI units
Equation Editor Text Editing Features 93, 200
system 137
Error calculating pacer element flow 134
Disabling a Chart Tool 679
Error: Possible flow race condition. Volume
Display Options 146
bound may be violated - check results 134
Displaying Cost Information 1038
Error: Unable to calculate diffuser density 134
Displaying Costs with CHP - Example 1052
Error: Unable to schedule electricity use costs 134
Displaying Power Demand and Energy
Example 937
Consumption 999
Examples 838
Divide function 609
Excel Report Chart Templates 745
DO In Tank Is Higher Than Specified Setpoint Due
Excel Report Template Formatting 738
To DO In Input (Even Without Aeration) 133
Explorer Appearance 725
DO Setpoint Itinerary 170
Exponential average function 610
Double Exponential Parameters 897
Export Chart Series Data 680
Double Exponential Settling Model 894
Export Options 679
Drawing Board 138
Export… 580
Drawing Board Options 75
Exporting as Email Attachment 681
Drawing Board Table Displays 577
Exporting Charts 679
Duplicate a Page in the Album 564
Exporting Data 123
Dynamic Example 1017, 1056
Exporting to a File 681
Dynamic Simulation 554
Exporting To GFX Files 126
Dynamic simulations 37, 41, 45

Biowin 6 Help Manual Index • 1065

F Growth and Decay of Ordinary Heterotrophic
Biomass 754
Factors Impacting HAO Interactions 815
Growth and Decay of Phosphorus Accumulating
Factors Impacting HFO Interactions 812
Biomass 779
Fast Line Series Procedures 696
Growth and Decay of Propionic Acetogenic
File Location Options 155
Biomass 794
First Always-Mixed Prezone Setup 376
Growth and Decay of Sulfur Oxidizing Biomass
First Mix/Settle Prezone Setup 412
803
Flow Balance 552
Growth and Decay of Sulfur Reducing Biomass
Flow Specifications Could Not Be Achieved 131
806
Flowsheet Tools 60
Growth Processes 859
Flux Based Models 887
GSST Air Flow Rate Itinerary 189
Flyby panes 902, 914
GSST Dimensions 427
Formulation for OTE 883
GSST DO Setpoint Itinerary 189
Formulation for OTR 882
GSST Granules 429
Formulation for SOTR 882
GSST Initial Values (mixed mode bulk) 436
Formulation of Diffuser Density, DD% 883
GSST Model Options 439
Formulation of SOTE 882
GSST Operation 430
Fuel (Heating and/or Sale) 1032
GSST parameters 911
Function Series (Album) 603
GSST Power Options 438
Further Reading: Gas-Liquid Mass Transfer Model
GSST Waste 435
868

H
G
Heat Exchanger for Power Recovery 991
Gas Hold-Up 884
Heat loss Itinerary 180
Gas-Liquid Mass Transfer 848, 851, 857
Heating Power and Power Recovery 971
General considerations for using ASMs 193
Heating Power Equations 990
General Mixer 539
Heating Power Equations when Boiler (heating
General Operation 57
influent) Specified for Gas Use 979
General Options 144
Heating Power Equations when Flare/Sell All
General Parameters 842, 863
Specified for Gas Use 977
General Plot (Album) 618
Heating Power Equations with CHP 985
Granular Sludge Sequencing Tank 425
Heating Power Equations with Heat Exchanger
Grit Removal Tank 472
993
Grit Removal Tank Dimensions 474
Heating Power Equations with Heat Exchanger AD
Grit Removal Tank Operation 475
987
Grit Removal Tank Power 478
Heating Power Parameters 973, 989
Grit Removal Tank Split Method 476
Heating Power Requirements 976
Growth and Decay of Ammonia Oxidizing Biomass
Heating Ventilation and Cooling (HVAC) Power
770
999
Growth and Decay of Anaerobic Ammonia
Help and Manual 7
Oxidizing Biomass 776
Help Contents Tab 9
Growth and Decay of Methanogenic Biomass 797
Help Favorites Tab 10
Growth and Decay of Methylotrophic Biomass
Help Search Tab 9
763
Help, Tutorials and Examples 7
Growth and Decay of Nitrite Oxidizing Biomass
Henry’s Law constants temperature dependencies
773
875

1066 • Index Biowin 6 Help Manual

Heterotrophic Growth through Fermentation 789 Influents 213
Hide/Show a Series 696 Inlet Air Humidity Itinerary 179
High Air Flow / Diffuser 133 Inlet Air Temperature Itinerary 178
High function 610 Input Type 225, 242
High Nitrification Rate / High Temperature Internal Recycle Flow Rate Itinerary 174
Conditions 32 Introduction 844, 899, 905, 908
High Rate P Removal System 31 Introduction to Excel Report Templates 737
Home Page 1 Introduction to Gas-Liquid Mass Transfer 868
How to Customize BioWin 20 Invoking the Equation Editor 92, 199
How to Enter Electricity Costs 1024 Iron RedOx Reactions and Precipitation of
How To Print The Manual 14 Vivianite and FeS 827
HVAC Power 1027 ISS Cyclone 532
HVAC Power Itinerary 180 ISS Cyclone Flow Split 535
Hydraulic Retention Time Calculation 86 ISS Cyclone Operation 534
Hydrogen Production Now Reported As A Fraction ISS Cyclone Power/Costs 537
137 Itinerary Editors 165
Hydrolysis, Biological adsorption, Ammonification
and Assimilative denitrification 767 K
Keeping track of things and generating reports 19
I
Kinetic Parameters 755, 764, 768, 770, 774, 777,
Ideal Clarifier 494 780, 790, 795, 798, 803, 807, 813, 816, 823,
Ideal Clarifier Dimensions 496 827, 830
Ideal Clarifier Operation 497
Ideal Clarifier Power 500 L
Ideal Clarifier Split Method 498
Layout 13
Ideal Primary Settling Tank 483
ldeal Clarifier Model 500
Ideal Primary Settling Tank Dimensions 485
Learning Objectives 14
Ideal Primary Settling Tank Model 493
Legend Styles 660
Ideal Primary Settling Tank Operation 486
Legend Text Styles 661
Ideal Primary Settling Tank Power 493
Limitations 6
Ideal Primary Settling Tank Split Method 491
Line Series Procedures 698
Ideal Separation Models 886
Linear Power Equation 959
Impact of Diffuser Density 879
Liquid Outflow Itinerary 175
Import Wizard 117
Liquid Phase Mass Transfer Coefficient 884
Importance of pH Modeling 832
Low / High pH Inhibition 133
Imported Series (Album) 614
Low function 611
Importing Data 117
Low pH in digester - may be acidic 133
Importing Data for Plotting - Example 119
Ind. #1 - Soluble biodegradable volatile COD 844
Ind. #2 - Soluble biodegradable volatile COD 849 M
Ind. #3 - Soluble biodegradable volatile COD 852 Main Simulator Window 57
Industrial COD Influent 230 Main Window Menus 58
Inert conversion Add-on 206 Main Window Status Bar 62
Influent Itinerary 182 Main Window Summary Panes 61
Influent Type 215, 231 Managing BioWin Projects 65
Influent Type (Metal Addition) 246 Managing Data 113
Influent Type (Methanol) 237 Managing Models 192

Biowin 6 Help Manual Index • 1067

Managing Other Windows 64 Model Clarifier Split Method 510
Mass Balance Window 725 Model Description 832, 909
Mass transfer Parameters 864 Model Details Information 63
Mass Transfer Theories under Turbulent Flow Model Formulation (Anaerobic Processes) 786
Conditions 869 Model Formulation (Fixed Film Processes) 901
Mass Transfer Theory 869 Model Formulation (Sidestream Treatment
Mechanical Power 962 Processes) 906
Media Bioreactor 281 Model Options 66
Media Bioreactor Dimensions 283 Model Parameter Editors 161
Media Bioreactor Model 287 Model Reference 753
Media Bioreactor Operation 285 Model usage 900
Media Bioreactor Power 286 Modeling Coarse Bubble Diffuser Performance
Membrane Bioreactor 273 881
Membrane Bioreactor Dimensions 274 Modeling Fine Pore Diffuser Performance 877
Membrane Bioreactor Model 279 Modeling Fixed Film Processes 899
Membrane Bioreactor Operation 276 Modeling Granular Sludge Sequencing Tanks 908
Membrane Bioreactor Power 278 Modeling Metal-Colloidal Coagulation Reactions
Membrane Bioreactor Split Method 277 822
Metal Addition Influent 245 Modeling of Industrial Components 844
Metal Addition with a Model Clarifier Element Modeling of pH and Alkalinity 832
826 Modeling Sidestream Treatment Processes 904
Metal Addition with an Ideal Primary Clarifier Modified Vesilind Parameters 893
Element 825 Modified Vesilind Settling Model 888
Methane Production Now Reported As A Fraction Monitoring Data 114
136 More than 10% of effluent N is stripped as
Methanol addition 236 ammonia 132
Method 1 927 Move a Page in the Album 564
Method 2 928 Moving average function 611
Microscreen 522 Multiply and offset 613
Microscreen Flow Split 524 Multiply function 611
Microscreen Operation 523 Multiply with a Constant 612
Microscreen Power/Costs 526
Mixers 537 N
Mixing Power 960
N and P associated with endogenous residue are
Model Builder 191
now modeled as a fraction of Ze 138
Model Builder Reactor Dimensions 258
N2O Emissions (Album) 622
Model Builder Reactor Initial Values 262
Name an Element on the Drawing Board 209
Model Builder Reactor Model 265
Named Ranges 740
Model Builder Reactor Operation 259
Navigating in the Explorer 724
Model Builder Reactor Power 264
New program version - Check pacer element
Model Builder Unit 257
settings 137
Model Builder Unit Outflow 261
New program version – re-simulate to get
Model Calibration 903
meaningful results. 137
Model Clarifier 506
Nitrogen Limited Conditions Occurred 132
Model Clarifier Dimensions 508
Number Formats in BioWin 688
Model Clarifier Model 512
Numerical Parameters 71
Model Clarifier Operation 509
Model Clarifier Power 512

1068 • Index Biowin 6 Help Manual

O Power/Energy Consumption plots with CHP (Use
CHP Engine power generated onsite, sell
Old file - review model builder models carefully
excess) 1017
138
Power/Energy Consumption plots without CHP
Open Box Pipe Style 468
1017
Opening and Saving Model Files 196
Precipitation of Brushite, Hydroxy-Apatite and
Opening Files from Previous Versions 135
Struvite 830
Operating Costs 1023
Pre-Configured File Cabinet 55
Operating Costs in BioWin 1023
Print Options 148, 681
Other Chart Options and Procedures 668
Print Preview the Chart 681
OUR And Denitrification Rate No Longer Reported
Print… 579
For Anaerobic Digesters 137
Printing Album Pages 567
Printing the Drawing Board 212
P
Process name not found - removed 136
Percent Removal Itinerary 176 Process rate (Album) 616
pH (or IS) Could Not Be Calculated 134 Process rate (Drawing Board) 631
pH Inhibition 762, 766, 772, 775, 778, 783, 793, Project Air Supply Groups/Blower Specifications
796, 800, 805, 809 103
Phosphorus Limited Conditions Occurred 132 Pumping Power 962
Physical and operational data 15 Pumping Power Equations 965
Pie Series Procedures 711 Pumping Power Options 547
Pipe Options 77, 140 Pumps 545
Pipes 467
Place an Element on the Drawing Board 207 R
Plotting Power with CHP - Example 1014
Rates Window 728
Plug Flow Channel 541
Rearranging and moving elements on the drawing
Plug Flow Channel Dimensions 543
board 24, 208
Plug Flow Channel Operation 544
Recording Project Notes 81
Point Clarifier 501
Recording results and modifying the Album 40, 44
Point Clarifier Operation 503
Recursive Configuration 131
Point Clarifier Power/Costs 506
References 103, 789, 842, 862, 898, 904, 907,
Point Clarifier Split Method 504
915, 945, 960, 971, 994, 1028
Point Separation Models 886
References and Additional Reading 885
Point Series Procedures 704
Remove a Chart Axis 639
Popups and Jumps 11
Rename a Series 684
Power (per unit flow) Itinerary 172
Rename an Album Page 564
Power (per unit volume) Itinerary 173
Report Options 150
Power / Energy consumption 1024
Resize Panes 566
Power in BioWin 947
Resize Table Columns 574
Power Itineraries 171
Resize the Summary Panes 62
Power Itinerary 171
Rigid Interface Theories 869
Power Supply Rate Itinerary 171
Router Itinerary 190
Power use / Energy consumption 947
Running a dynamic simulation 18
Power/Energy consumption (Album) 591
Running a steady state simulation 17
Power/Energy Consumption plots with CHP (Sell
Running Simulations 551
all CHP Engine power generated) 1019
Running Simulations in BioWin 551

Biowin 6 Help Manual Index • 1069

Running the SBR simulation to reach a steady SBR with Two Always-Mixed Prezones 371
state 52 SBRs 341
Second Always-Mixed Prezone Setup 378
S Second Mix/Settle Prezone Setup 413
Selecting a Printer 682
S/L sep./Disinfection Power 997
Selecting Multiple Elements on the Drawing Board
Saving a Chart Template 159
24, 207
SBR + 1 Always-Mixed Prezone 355
Selling Power/Heat Generated through CHP back
SBR + 1 Always-Mixed Prezone Dimensions 357
to the Utility Grid 1027
SBR + 1 Always-Mixed Prezone Initial Values 366
Series Available from the Album 582
SBR + 1 Always-Mixed Prezone Model Options
Series Available from the Drawing Board 625
369
Series Formatting Procedures 683
SBR + 1 Always-Mixed Prezone Power 368
Series Label Styles 686
SBR + 1 Always-Mixed Prezone SBR Zone
Series Labeling Procedures 686
Operation 362
Series Options 678
SBR + 1 Always-Mixed Prezone Underflow 365
Series Styles in BioWin 581
SBR + 1 Mix/Settle Prezone Dimensions 393
Set Axis Scale Increment 640
SBR + 1 Mix/Settle Prezone Initial Values 402
Set Axis Scale Maximum and Minimum Values 640
SBR + 1 Mix/Settle Prezone Model 405
Set Axis Scale Type 640
SBR + 1 Mix/Settle Prezone Power 404
Set up the configuration and influent data 34
SBR + 1 Mix/Settle Prezone SBR Zone Operation
Setting Project Options 66
397
Setting the Unit System 141
SBR + 1 Mix/Settle Prezone Underflow 401
Setting up a settler profile in the Album 40
SBR + 2 Always-Mixed Prezone Power 387
Setting up a State Point Chart 41
SBR + 2 Always-Mixed Prezones Dimensions 373
Setting up Channels 817
SBR + 2 Always-Mixed Prezones Initial Values 385
Setting up charts 35
SBR + 2 Always-Mixed Prezones Internal Recycle
Setting up Chemically Enhanced Primary
Flows 384
Treatment 825
SBR + 2 Always-Mixed Prezones Model 388
Setting up the One-Unit Configuration 47
SBR + 2 Always-Mixed Prezones SBR Zone
Settling Tank Profile Series (Drawing Board) 636
Operation 380
Settling Tank State Point Chart (Drawing Board)
SBR + 2 Always-Mixed Prezones Underflow 384
633
SBR + 2 Mix/Settle Prezone Power 422
Settling Velocity Switching Functions 891
SBR + 2 Mix/Settle Prezones Dimensions 409
Shallow Submerged Aerated Filter (SSAF) 309
SBR + 2 Mix/Settle Prezones Initial Values 420
Shallow Submerged Aerated Filter Dimensions
SBR + 2 Mix/Settle Prezones Internal Recycle
310
Flows 419
Shallow Submerged Aerated Filter Model 314
SBR + 2 Mix/Settle Prezones Model 423
Shallow Submerged Aerated Filter Operation 312
SBR + 2 Mix/Settle Prezones SBR Zone Operation
Shallow Submerged Aerated Filter Power 313
414
Side Stream Media Bioreactor 288
SBR + 2 Mix/Settle Prezones Underflow 418
Side Stream Media Bioreactor Dimensions 289
SBR Air Flow Rate Itinerary 188
Side Stream Media Bioreactor Model 293
SBR DO Setpoint Itinerary 187
Side Stream Media Bioreactor Operation 291
SBR Profile Series (Drawing Board) 631
Side Stream Media Bioreactor Power 292
SBR with 2 Mix/Settle Prezones 407
Side Stream Mixer 537
SBR with Always-Mixed Prezone(s) 354
Sidestream Modeling Uses the Full ASDM Process
SBR with Mix/Settle Prezone(s) 390
Model 907
SBR with One Mix/Settle Prezone 391
Sidestream reactor 335

1070 • Index Biowin 6 Help Manual

Sidestream Reactor Dimensions 336 Specifying Project Liquid Temperature 90
Sidestream Reactor Model 339 Specifying Project Model Parameter Values 65
Sidestream Reactor Operation 337 Specifying Pumping Parameters 962
Sidestream Reactor Power 339 Specifying the flow distribution information 48
Simplistic User defined equation - Example 98 Specifying the SBR operational information 49
Simulation Status Information 62 Specifying the SBR physical information 49
Single Always-Mixed Prezone Setup 360 Specifying the sludge wastage information 49
Single Mix/Settle Prezone Setup 396 Split Itinerary 169
Single-Tank Sequencing Batch Reactor 341 Splitter 518
Sludge 1037 Splitter Flow Split 520
Sludge Effluent 253 SSO (Source Separated Organics) Influent 241
Sludge Power/Costs 255 Standard BioWin Itineraries 168
Sludge Settling Velocity 890, 896 Steady State Balance 552
Solid-Liquid Separation / Clarifier Models 885 Steady State Example 1014, 1052
Solids Retention Time Calculation 82 Steady State Performance 34
Soluble hydrocarbon COD 858 Steady state simulations 41, 44
Some Default Parameters Have Changed – Check Steady State Solver Options 73
All Project Parameter Tabs: Kinetic, Stoich., Step Middle Pipe Style 470
Biofilm, Other – Typically Update to New Step Pipe Style 470
Defaults 135 Stoichiometric 795, 799, 808
SOTE (%) Series (Drawing Board) 629 Stoichiometric Parameters 757, 765, 769, 771,
Special BioWin Itineraries 181 774, 777, 781, 791, 804
Special Series (Album) 589 Stopping a Steady State Simulation 559
Special Series (Drawing Board) 628 Straight Pipe Style 469
Specified D.O setpoint above 90% saturation Stream (State Variable) Influent 220
value - using 90% of saturation value 132 Stream Input Type 221
Specified DO setpoint cannot be achieved - STSBR Dimensions 342
specify a lower value 133 STSBR Initial Values 349
Specifying Digester Heating Options 974 STSBR Model Options 352
Specifying Element Specific Chemical Costs 1030 STSBR Operation 345
Specifying Global Blower Calculation Method 951 STSBR Power Options 351
Specifying Methanol Influent Concentrations 239 STSBR Underflow 348
Specifying pH and Alkalinity 837 Submerged Aerated Filter (SAF) 302
Specifying physical and operational data 26 Submerged Aerated Filter Dimensions 304
Specifying Power (Activating Electricity Costs) Submerged Aerated Filter Model 308
1027 Submerged Aerated Filter Operation 306
Specifying process temperature(s) 27 Submerged Aerated Filter Power 307
Specifying Project Blower Calculation Method 91 Subtract function 612
Specifying Project Chemical Costs 1028 Suggested Approach 47
Specifying Project Combined Heat and Power Sulfur Modeling 802
Parameters 112 Summary 935
Specifying Project Details 80 Surface Aeration Power 994
Specifying Project Electricity Costs 107 Surface Aerator Bioreactor 315
Specifying Project Fuel (Heating and/or Sale) Surface Aerator Bioreactor Dimensions 316
Costs 1032 Surface Aerator Bioreactor Model 318
Specifying Project Fuel/Chemical Costs 110 Surface Aerator Bioreactor Operation 317
Specifying Project HVAC Power 113 Surface aerator Parameters 868
Specifying Project Inlet Air Conditions 90 Surface Renewal/Penetration Theories 870

Biowin 6 Help Manual Index • 1071

Surface Series Color Mode 722 Time Series (Drawing Board) 626
Surface Series Drawing Mode 721 Tips for Complex Systems 556
Surface Series Gridline Appearance 720 Titration of Acids and Bases 838
Surface Series Procedures 719 Toolbars 59
Switch Display Types 565 Tools Options 678
Switching Functions 763, 766, 770, 773, 776, 779, Trend function 612
783, 794, 797, 801, 806, 809 Trickling Filter 294
System Settings Options 156 Trickling Filter Dimensions 295
Trickling Filter Model 301
T Trickling Filter Operation 299
Trickling Filter Power 300
Tables 1001, 1040
Trickling Filter Profile Series (Drawing Board) 632
Tag & Table Reference for Examples Shipped With
TUTORIAL 1 - BioWin Familiarization 14
BioWin 747
TUTORIAL 2A - Building a Configuration 21
Tags 738
TUTORIAL 2B - A Nutrient Removal Refresher 30
Tanks 472
TUTORIAL 3 - Nitrification Dynamics and Setting
Temperature Itinerary 173
up Charts 33
The air flow rate required to achieve the DO
TUTORIAL 4 – Secondary Clarifier Simulation 39
setpoint is below the specified minimum air
TUTORIAL 5 - Aeration System Simulation 43
flow rate 132
TUTORIAL 6 – Setting Up an SBR System 46
The Air Flow Required To Achieve The DO
Typefaces and conventions used in this manual 13
Setpoint Exceeds The Maximum Air Flow
Types of Models 885
Rate 132
The Biofilm Model Uses the Full ASDM Process
U
Model 901
The desired air flow rate was adjusted to within Unable to convert Alkalinity 136
the range specified 133 Unable to match pH / alkalinity specification 134
The interface and loading a file 15 Underflow Rate Itinerary 174
The oxygen transfer rate under field conditions is Undo Drawing Board Actions 211
given by: 876 Unit System 70
The Power Supply Requested Exceeds The Units for Air Flow 884
Maximum Power Supply Rate 133 Un-monitoring Data 115
The Power Supply Required To Achieve The DO Useful BioWin Interface Tools and Techniques 161
Setpoint Exceeds The Maximum Power User Defined Power Equation 960
Supply Rate 133 U-Shape Pipe Style 471
The System 46 Using Add-on Modules (Builder Models) 193
The tutorial 2A system 22 Using Project Templates 143
The tutorial 3 system and the influent data 33 Using The BioWin Help System 7
The tutorial 4 system 39 Using the Drawing Board 207
The tutorial 5 system 43
Thermal Hydrolysis Unit 440 V
Thermal Hydrolysis Unit Element 989
Variable Volume/Batch Bioreactor 325
Thermal Hydrolysis Unit Heating 444
Variable Volume/Batch Bioreactor Dimensions
Thermal Hydrolysis Unit Model 446
326
Thermal Hydrolysis Unit Operation 442
Variable Volume/Batch Bioreactor Initial Values
Thermal Hydrolysis Unit Power 443
330
Tick Formatting Procedures 650
Variable Volume/Batch Bioreactor Model 334
Time Series (Album) 582
Variable Volume/Batch Bioreactor Operation 327

1072 • Index Biowin 6 Help Manual

Variable Volume/Batch Bioreactor Outflow 329
Variable Volume/Batch Bioreactor Power 333
Variable XXX No Longer Available - Check Your
Graphs 137
Verifying Equations 98, 205
Very old file - check carefully. 137
View Element Information in the Summary Panes
61
Viewing information and simulation results 17
Viewing the stable SBR response 53

W
Warning: High Ionic Strength (Activity
Coefficients) 134
Wastewater Fractions 217, 233
Wastewater Fractions (BOD Influent) 227
Wasting Rate Itinerary 176
Water chemistry concentrations are now
reported in mmoles/L 138
Welcome 3
Welcome to BioWin 3
Welcome to the Online Help System for BioWin 7

Y
Your own time series charts 37

Z
Zoom In on a Drawing Board Area 211

Biowin 6 Help Manual Index • 1073