W. Bidlingmaier & S.

Wattanachira
Editor

Open windrow
composting
manual
C. Bachert, W. Bidlingmaier, S. Wattanachira
BAUHAUS–UNIVERSITY WEIMAR / DEPARTEMENT OF WASTE MANAGEMENT

Editor:
P r o f . D r . - I n g . h a b i l . W e rn e r B i d l i n g m a i e r . B a u h a u s U n i ve r s i t ä t W e i m a r , G e r m a n y
P r o f . D r . - E n g . S u r a p h o n g W a t t a n a c h i r a , C h i a n g Ma i U n i ve r s i t y/ C e n t r e f o r E n vi r o n m e n t a n d
H a za r d o u s W a s t e Ma n a g e m e n t ( E HW M) , Th a i l a n d

Author:
Carsten Bachert
W er n e r B i d l i n g m a i e r
Suraphong W attanachira

Translation in Thai
M r s . L . W a t t a n a c h i r a , R a j a m a n g a l a U n i ve r s i t y o f Te c h n o l o g y L a n n a , C h i a n g Ma i , Th a i l a n d

With great thanks to:

• M r . T a n a n c h a i Y U N G Y U E N ( B A ) , K a s e t s a r t U n i ve r s i t y, B a n g k o k , Th a i l a n d , h e t o o k m o s t o f t h e
photographs
• D i p l . - I n g . A n t j e K l a u s - V o r r e i t e r , B a u h a u s - U n i ve r s i t y W e i m a r , G e r m a n y , s h e o r g a n i ze d t h e
c o n t a c t s i n Th a i l a n d
• D i p l . - I n g . C h r s i t i a n S p r i n g e r , B a u h a u s - U n i ve r s i t y W e i m a r , G e r m a n y , h e w a s r e s p o n s i b l e f o r
t h e l a yo u t
• D i p l . - I n g . J a s m i n H e i n ze , B a u h a u s - U n i v e r s i t y W ei m a r , G e r m a n y, s h e r e a d t h e p a p e r t o
eliminate mistakes

Bauhaus–University Weimar; Department of Waste Management, Germany

&
KNOTEN WEIMAR GmbH.

99423 Weimar, Coudraystraße 7, Germany

waste@uni-weimar.de

Published by

ORBIT e. V., Weimar, 2008

ISBN 3-935974-23-X
Open windrow composting manual

C. Bachert
W. Bidlingmaier
S. Wattanachira
Untitled
(author unknown)

In the soft warm bosom of a decaying compost windrow,

a transformation from life to death and back.

again is taking place.

Compost is far more than a healing agent

for the soil’s wounds.

Here in a dank and mouldy pile

the wheel of life is turning.

Nature made compost before

the first woman walked the earth,

before the first dinosaur reared its head

above a primal swamp.

The dead grass of meadow,

Seared by winter’s frost,

Is being composted by the dampness

of the earth beneath.

The birds, the insects and the animals

all contribute their bodies

to the vast and continuing cycle of rejuvenation.

C O N T E N T

Table of content

CHAPTER I INTRODUCTION.................................................................................... 1
Pre-face .................................................................................................................................................................. 1
Helpful information about the manual................................................................................................................ 2

CHAPTER II BASIC KNOWLEDGE – COMPOSTING .............................................. 4

Aerobic treatment – composting.......................................................................................................................... 4
Definitions composting, compost ........................................................................................................................ 4
Open windrow system ......................................................................................................................................... 5
Micro-organism ................................................................................................................................................... 8
Process factors....................................................................................................................................................... 9
Kind of substrate.................................................................................................................................................. 9
Temperature ......................................................................................................................................................... 9
Moisture............................................................................................................................................................. 10
Aeration ............................................................................................................................................................. 10
pH – Level ......................................................................................................................................................... 11
C/N – ratio ......................................................................................................................................................... 11

CHAPTER III DESIGN OF A COMPOSTING PLANT.............................................. 12

Construction elements of a composting plant ................................................................................................... 12
Input material supply ......................................................................................................................................... 12
Input material storage ........................................................................................................................................ 13
Pre-treatment...................................................................................................................................................... 13
Composting process........................................................................................................................................... 14
Compost preparation.......................................................................................................................................... 14
Compost storage ................................................................................................................................................ 14
Sieved structure storage ..................................................................................................................................... 14
Area requirements .............................................................................................................................................. 15
Design flashover values ..................................................................................................................................... 15
Area calculation ................................................................................................................................................. 18
Material flow ....................................................................................................................................................... 19
Mass balances ...................................................................................................................................................... 21

CHAPTER IV OPERATION AT A COMPOSTING PLANT ...................................... 24

Input material...................................................................................................................................................... 24
Suitable and unsuitable materials....................................................................................................................... 24

i
C O N T E N T

Additives............................................................................................................................................................ 28
Composition of the input material ..................................................................................................................... 29
Carbon – rich and nitrogen – rich input materials.............................................................................................. 30
Degeneration process .......................................................................................................................................... 30
Range of process factors (monitoring values).................................................................................................... 30
Changing of composting parameters.................................................................................................................. 32
during the composting process........................................................................................................................... 32
Compost ............................................................................................................................................................... 34
Compost quality................................................................................................................................................. 35
Fertilizer application .......................................................................................................................................... 35
Compost quality in Germany ............................................................................................................................. 36

CHAPTER V ANALYSES AT A COMPOSTING PLANT......................................... 38

Sample taking ...................................................................................................................................................... 40
Input material...................................................................................................................................................... 42
Compost ............................................................................................................................................................... 44
Temperature and fist probe ............................................................................................................................... 46
Temperature ....................................................................................................................................................... 46
Fist probe ........................................................................................................................................................... 47
Total windrow volume ........................................................................................................................................ 48
Rotting degree / Dewar – Test ............................................................................................................................ 49
Bulk density ......................................................................................................................................................... 51
Moisture content ................................................................................................................................................. 52
Organic carbon.................................................................................................................................................... 53

CHAPTER VI TROUBLE SHOOTING ..................................................................... 54

ii
C O N T E N T

List of figures
Figure I-1 Resource management.........................................................................................................................1
Figure II-1 Shapes of a windrow...........................................................................................................................5
Figure II-2 Manual stacking of a windrow [6].....................................................................................................6
Figure II-3 Open windrow composting with and without the use of boxes.......................................................7
Figure II-4 Forced aeration composting, source Composting and recycling municipal solid waste...............8
Figure II-5 Process of windrow turning ...............................................................................................................8
Figure II-6 Enlarged illustration of particles and interstices ...........................................................................10
Figure III-1 Wndrow dimensions depending on the aeration system..............................................................17
Figure III-2 Exemplary material flow at a big composting plant (turning windrows) – in a line.................19
Figure III-3 Exemplary material flow small composting plant (without input material supply) – rectangle
form .......................................................................................................................................................................20
Figure III-4 Exemplary mass balance with flashover values by mass percent ...............................................21
Figure IV-1 Categorisation of organic waste, modified to Source: BUND Hessen (1992) .............................25
Figure IV-2 Characteristic temperature curve..................................................................................................32
Figure IV-3 Volume reduction during the composting process, example form the pilot composting plant in
Phnom Penh [8] ..............................................................................................................................33
Figure V-1 Sample taking skittle ........................................................................................................................40
Figure V-2 Division of collective sample ............................................................................................................41
Figure V-3 Triangle and trapezoid shapes.........................................................................................................48
Figure V-4 Dewar flasks ......................................................................................................................................49
Figure V-5 Temperature curve dewar test.........................................................................................................50

iii
C O N T E N T

List of tables
Table III-1 Flashover design values....................................................................................................................16
Table IV-1 Suitable Additives .............................................................................................................................28
Table IV-2 Nitrogen- and carbon- rich input materials ...................................................................................30
Table IV-3 Monitoring values during the decomposition process ...................................................................31
Table IV-4 Compost applications .......................................................................................................................35
Table IV-5 Compost quality criteria in Germany .............................................................................................37
Table V-1 Analyses at a composting plant .........................................................................................................39
Table VI-1 Trouble shooting ...............................................................................................................................54

iv
P R E F A C E
Chapter

1
Chapter I Introduction

Pre-face
In times when mineral fertilizer is not available or too expensive, compost is the most important
source to provide nutrients for the plants and to adjust the soil conditions. Today many people
appreciate compost as a natural source for nutrients and humus.

To compost materials means also to close the natural circle of life.

Figure I-1 Resource management [11]

Composting systems can be simple and unsophisticated for countries in early stages of development or
mechanized and sophisticated for countries with relatively advanced technical development. In
developing countries these treatment of bio waste has many advantages: low equipment and operation
costs, in harmony with the environment, and in the end of the process a useful product. These manual
try to give a helping hand in designing and maintaining a composting plant in economically developing
countries. [5]

The degeneration of biological substance is a natural process. Composting as a kind of utilization of

bio waste is very old and was practised by Chinese people long time before Christ’s birth. To adjust the

1
P R E F A C E

process of maturation the understanding of the basic principles during the composting process are
necessary.

The adjustment of this natural process in a composting plant by optimizing the natural conditions this
handbook gives the knowledge about, the process of composting, the design of a composting plant,
the monitoring of the process, same facts about troubleshooting, and so on.

The monitoring of the composting process is very important to provide these optimal conditions in
the windrow and to get a good and useful product, the compost.

Helpful information about the manual

The composting manual consists of the following three levels:

Basic Level:
Level:

It is the lowest stages for maintaining a composting plant. With

this stage, it is possible to produce compost in a good quality and
short time.

Mainly this level is about, a good composition for the input

Head of workers material by volume; monitoring the temperature and moisture,
Project responsible person volume reduction during the composting process and the compost
volume determination.

Advanced Level:
Level:

This Level includes all the steps in the basic level.

Additionally this level is about, the bulk density, the composition

of the input material by mass, and the total mass as well as volume
and mass flow during the compost process.
Responsible engineer
Project manager
Compost plant Designer

Research Level:

This Level includes the basic and advanced level too.

The differences to the advanced level are the chemical analyses.

The optimizing of the nutrient content and suitable nutrients ratio
in the compost is the objective for this level.
Head of project

2
P R E F A C E

HELPFUL ICONS

Note the collected information in the

data collection sheet

Calculate the results with the given

formula

For more or detailed information look at

another page or chapter

p. 12 Page

3 Chapter

By using a coloured version, the colour

describes the level too

Treatment stage during the composting

process

3
B A S I C K N O W L E D G E
Chapter

2
Chapter II Basic knowledge –
composting

Aerobic treatment – composting

Definitions composting, compost
Degradation of biodegradable substance means the natural decomposition process. If man influences
the process is called composting. The final product of aerobic biological treatment is the compost.

Composting

„Composting is the biological decomposition of biodegradable solid waste under controlled aerobic conditions to a
state that is sufficiently stable for nuisance-free storage and handling and is satisfactorily matured for safe use in
agriculture”

Luis F. Diaz, 2003 [5]

Keywords of the definition

Biological decomposition

Only wastes of plant or animal origin can be broke down

biologically through the living activity of micro-organism.

p. 24
Biodegradable solid waste
4

This manual is mainly about use of plant origin for the
composting process. To adjust the fertilizer quality the addition
of animal origin can be useful.

4
B A S I C K N O W L E D G E

The composting of municipal solid waste (mix waste) as a kind

of pre-treatment before incineration or land filling does not
describe this manual.

p. 30

Under controlled aerobic conditions 4

The adjustment of the process by providing good conditions
for the composting process mainly, air (oxygen), water, and a
good input material composition, and the monitoring to get a
quality product.

p.35

Safe use in agriculture 4

The final product compost should be harmless for the nature
without dangerous compounds as heavy metals and the
decomposition process should be nearly finished.

Open windrow system

Put the material together to build a windrow or heap, the system is called windrow system.

Triangle Trapezoid

Figure II-1 Shapes of a windrow

Open windrow composting means that the windrow is normally not covered with a plastic foil or
something like this.

Look for the next figure to see a manual windrow building.

5
B A S I C K N O W L E D G E

1. Chop/shred waste 2. Mix different types of waste

thoroughly and spread hind-high

(hoe, shears, shredder)

3. Spray additives (as required)

4. Moisten if necessary

5. Add further layers of

waste in the same way 6. Finished compost heap

Figure II-2 Manual stacking of a windrow [6]

6
B A S I C K N O W L E D G E

It is possible to use boxes or to build a windrow without a box.

Figure II-3 Open windrow composting with and without the use of boxes

The use of boxes is more practical for small or middle composting plants. By using turning machines,
boxes are mostly unsuitable.

Two versions of windrow system are divided and practiced. The distinguishing feature is the aeration,
passive and forced.

Passive aeration systems

Passive aeration is at first the natural aeration. During the composting process, the carbon dioxide
concentration in the windrow rises and the oxygen concentration goes down. The concentration of
carbon dioxide is higher in the windrow than in the surrounding atmosphere. Because of this
difference and the higher temperature in the windrow, oxygen is able to enter into the windrow.
Therefore, it is possible that oxygen can enter the windrow up to layer thickness of 80 cm (general rule,
depend mainly on the structure material ration).

In addition, the used method known as the Chinese method with aeration through pipes counts to the
passive aeration systems. The moving force is the chimney effect. [5]

Forced aeration systems

During the composting process the oxygen concentration in the windrow is falling. To provide more
oxygen ventilation systems or material turning is useful. Ventilation systems forcing air up so the
pressure in the windrow is higher than the surrounding pressure or pulling the pressure in the windrow
down. Both systems are able to raise the oxygen concentration in the windrow by mechanically air
pumping.

7
B A S I C K N O W L E D G E

Figure II-4 Forced aeration composting, source Composting and recycling municipal solid waste [4]

Turing the material is also possible to lift up the oxygen concentration. The turning can be hand made
or with the use of machines.

Before turning After turning

Figure II-5 Process of windrow turning

Recommendation for aeration systems

The combination of the natural aeration and the turning of the windrows is a very good method. The
advantages of this combination are the avoiding of pips and the cost for machines (price and
maintenance). Using pips courses many problems, taking care by building and removing the windrows,
leachate in the pips, and so one. The disadvantage is the monitoring of the process to decide the
turning time for the windrows.

Micro-organism
The degeneration process of biodegradable solid waste depends on the living activity of micro-
organisms. That is why Mr. Luis F. Diaz gave an ecological definition of composting:

“Composting is a decomposition of process in which the substrate is progressively broken down by a succession of
a population of living organisms. The breakdown products of one population serve as a substrate for the
succeeding population. The succession is initiated by way of the breakdown of the complex molecules in the raw
substrate to simpler forms by microbes indigenous to the substrate”

8
B A S I C K N O W L E D G E

Luis F. Diaz, 2003 [5]

Bacteria, fungi, protozoa and actinomycea are the most common miro organism during the
composting process.
p. 32

4
During the process, the population of micro-organisms change because of the different temperature
stages in the process. Most of these active organism act in a special temperature range.

Process factors
As it was mentioned in the section before, micro-organisms degenerate the input material and the
breakdown products of the former population serve as substrate in the next stage of the
decomposition process. The degeneration process depends on different factors. These factors, and
their relation each other, influence the speed of the decomposition process, the stage of
decomposition, and the activity of micro-organisms.

These process factors are useful to monitor and control the composting process.

4
Find descriptions for the optimum of all process factors during the composting process in Chapter IV

Kind of substrate
As the definition of „composting“, describes the substrate has to be biodegradable. With the use of a
special input material or a mixture of different kinds of input materials, many properties for the
process and the quality of the compost are fixed, like the interstices volume, the moisture, or the
particle size of the input material. That is why the mixture of the input materials (used substrate) is the
most important step to produce good compost.
p. 28

4
For suitable and unsuitable input material, suitable mixtures look at Chapter IV

Temperature
The active organisms are the reason for the production of thermal energy. This energy is measurable in
the windrow or heap by the determination of the temperature inside a windrow. The temperature
influences the degeneration process mainly the speed of degeneration because the general rule is that
the activity of micro-organisms rise with an up growing temperature (the temperature should never rise
over 70°C).
p. 30

4
The temperature is a suitable value for the determination of the stage of degeneration and the rotting
degree.
9
B A S I C K N O W L E D G E

Moisture
Micro-organisms need water to survive. The providing of water is necessary to keep the degeneration
process running.

The problem is the very close relation between water and aeration. Both need interstices between the
particles and the interstices can be filled with “free” water or air. The amount, the size, and the
distribution of the interstices depend on the used input material. [5]

Particle

Interstices

Figure II-6 Enlarged illustration of particles and interstices p. 30

4
p. 30

4
Because of this relationship, the monitoring of the moisture is very important.

p. 10

Aeration 2
Aeration (passive or forced) has many different functions during the composting process:

Supply with Oxygen to keep the micro-organisms alive

Taking away the carbon dioxide

Reduction of water to dry the material

Leading away the heat to prevent temperatures over 70°C

The oxygen demand depends on the activity of micro-organisms.

Very important for the proving of oxygen is the mixture of the input material, especially the amount,
the size, and the distribution of the interstices.

Please note the every close relation between the moisture and the aeration, which is described in the
former section.

10
B A S I C K N O W L E D G E

pH – Level
The activity of the micro-organisms is close related to the pH – Level of the input substrate. Good for
biological activity are pH – Levels between 7 and 11.

Values under 7 are leading to a speed reduction during the first steps of degeneration. If the pH –
Level is under 5 a strong inhibition in the initial (until fast temperature rise) stage can be noticed.
Hence, the period between collection, storage, and treatment start at the plant should be short.
Uncontrolled natural anaerobic digestion, because of oxygen lack, during the collection and storage
timeframe leads to low pH – Levels. [2]

C/N – ratio
The ratio between carbon and nitrate atoms in the input material has a very close relation to the speed
of the degeneration process. It should be between 1:20 until 1:35 (carbon to nitrogen – optimum). If
the ratio is under 1:10 carbon is the up growing inhibition and if the ratio is over 1:40 to less nitrate is
available. Out of this range (1:10 until 1:40) the micro-organism population is not able to grow up. The
activity of the micro-organisms is the same but without an up growing population the time for the
degeneration process rise.

Very important for the C/N – ratio are not the results of the chemical analysis it is more the ratio of
biologically (short) available carbon and nitrate atoms.

11
 D E S G I N
Chapter

3
Chapter III Design of a
composting plant

Minimum requirements for a composting plant place:

Suitable access for delivery vehicles

Access to water

Covered with a roof

Water impervious surface or concrete

surface

Construction elements of a
composting plant

The following descriptions are basic, for more detailed information look at [3].
Often it is better to combine steps, especially for small plants.

Input material supply

1
The interface to notice all the incoming materials and the leaving materials like
the compost is the first point at the composting plant. It is a very important
point for big plants, for small plants, this station is not really necessary.

For the determination of the input volume, count the incoming delivery vehicles
and estimate the volume. To get better information use a big scale to measure
the mass of the trucks (full and empty). For the leaving materials like compost,
use the same method.

12
 D E S I G N

Input material storage

2
This part of the composting plant has different functions [3]

Optical controlling availability and

sorting of unsuitable materials

Buffer space for a high delivery of input

material or a process breakdown
(outage)

Continual flow rats for next steps

Separate storage availability for different

materials

The size of the storage area depends on the size of the composting plant and
the kind of input material.
p. 15

3
The storage time for garden waste or green waste should not be longer than one
day. In times (especially at small plants), if this is not possible, cover the material
with sieved structure as a bio filter to limit environmentally harmful emissions
and odour.

Structure material (fresh or sieved) is storable over weeks (without a roof).

For special situations like a small material flow or very good continual flow rates,
it is possible to run the plant without a storage area.

3 Pre-treatment
p. 9
The objective in this section at the plant is:
2

Adjustment of optimal conditions for
the composting process (reduction of
the particle size, mix of different input
material, optimal water content, and
optimal structure material content)

This is possible with machines or manual. As recommendation, it is suitable to

use small transportable machines for a few small plants.

This is the last chance to sort out unsuitable materials. Do not forget to think
about a place where the collection and storage of unsuitable materials is possible
(sometimes it is only a dustbin required; it depends on the pollution with
unsuitable materials in the input material).

13
 D E S I G N

4 Composting process
Design the composting process that optimal process conditions are measurable
and adjustable.
p. 9

2
Find the description of all parameters like the turning frequency, the moisture,
and so on, during the process in Chapter IV Operation at a composting plant.

The biggest influence on the required space is the composting time. The
required area for the composting process grow up with the needed process time.
Hence, optimal composting conditions lead to a short composting time and a
small space for the windrows.

5 Compost preparation
After the maturation process is mostly finished, the compost is ready for the
preparation, sieving the material to get the compost separated from the structure
material.
p. 35

4
The used diameter of the sieve depends on the operating range of the compost.
For example, a grass fertilizer needs a very small diameter and a soil conditioner
a big diameter.

6 Compost storage
Because of an inconstantly compost selling during a year, the compost storage
area is necessary. The area should be big enough to storage compost for about
1/3 (or 1/2) year. Cover the storage area with a roof to avoid the loss of
substances and nutrients during a heavy rain and to keep the moisture
constantly. Before selling the compost bagging, nitrogen addition and or
shredding can be adjusting the fertilizer quality (it is also possible to do this step
simultaneous to the compost preparation).

Sieved structure storage

The sieved structure is useful as mulching for tree and hedge or as
compensation if new structure material is not available, mostly during the cold
7 period because there are no cuttings of trees and hedges at this time. That
implies that the storage area has to be big enough to storage structure material
for about 1/3 of a year (composting process needs also structure during the cold
season). It is practical to storage this structure material together with new
structure material at the same area. Hence, the flashover value for the dwelling
time for the structure input material is so high.

14
D E S G I N

Area requirements
The next numbers give an approach to calculate the area for a composting plant. Because of the
complexity of the biological process, these numbers are not scientific values. All theses flashover values
came from practical experiences in Germany, Cambodia and Thailand as well as from the technical
literature.

Composting plants are divided in free categories. The belonging category depend on the operating
capacity

Small composting plants until 5,000 Mg/a

Middle composting plants until 10,000 Mg/a

Big composting plant until 25,000 Mg/a

DESIGN THE FOLLOWING DIFFERENT AREAS

Storage areas for the input material, the structure, and the
compost

Rotting area

Pre-treatment and preparation areas

Traffic ways for the machines and the workers

It is possible to calculate the required area for a composting plant with the given flashover values in the
next chapter. However, it would be much better to use measured and calculated values out of own
tests in your region.

Design flashover values

THE STORAGE AREAS

The calculation instructions are the same for all storage areas. Pay attention on the different kinds of
input materials and their different storage times. Calculate the complete input storage area with the
addition of the single calculated area for every kind of input material.

15
D E S I G N

Table III-1 Flashover design values

Average bulk Dumping

Dwell time
density height
Kind of material
[kg/m³] [m] [d]

Structure material 300 2,5 – 3 until 90

Green waste 300 - 600 2,0 ~ 1 – 3 (7 for
small plants)
Garden waste 200 – 600 2,0 ~ 1 – 3 (7 for
small plants)
Compost 650 2,5 until 90

Because of the wide range of the bulk density, the big amount of different kinds of input materials, the
close relation between the water content and the bulk density and their chancing during the seasons
(hot, rainy and cold period), flash over values cannot be given.
p. 38

5
It is possible to calculate the storage area for the input materials with an average of 600 kg/m³ but it is
better to measure own results in according to Chapter V Analyses at a composting plant.

If the composting plant is running with manual turning and sieving, the dumping height should be less
than 2 m.

The given dwelling time is a design value; structure material and compost are storable over one year.

About 30% by mass (design value) of the input material is compost.

ROTTING AREA

The process time is between eight and twelve weeks, depending on several conditions. The usage of
the average, 10 weeks, is suitable.

In addition, the dimensions of the windrows can be different. The windrow height and width depend
mostly on the used aeration method and the structure material ratio.

For the determination of the required area, a suitable value for the bulk density is 400 kg/m³.

16
D E S I G N

Height Length Height

Width Width

Natural aeration Forced aeration

and turning with pipes

Height ≤ 1.2 m ≤ 2.5 m

Width ≤ 1.8 m ≤ 3.5 m
Length unlimited

Figure III-1 Wndrow dimensions depending on the aeration system

Please note that the dimension of the windrows also depend on the used input material as well as the
use of machines or men. In addition, it is possible to build windrows with a trapezoid shape.

PRE-TREATMENT AND PREPARATION AREAS

Only for big composting plants, which uses many big machines this is an important point. Calculated
the area out of the technical drawings and add the area to the storage and rotting area.

For small composting plants without machines or small moveable machines, it is not necessary to
calculate this area.

TRAFFIC WAYS

For “normal” composting plants, it is enough to add 25% of the whole area (storage areas and rotting
area) as additional area for traffic ways.

17
D E S G I N

Area calculation
Preliminary remark

By the calculation of the total required area of a composting plant, the most influencing value is the
flow rate of the input material. The amount of input material in a year or a week is measurable with
waste analyses.

If some data are not available, it is possible to calculate the required area with flashover values out of
the former chapter.

For further information, look in the attachment in the table sheet and the example.

Required data Steps

Step 1:
Input material mass and bulk
density, dwell time and
Calculate the storage area
dumping height

Step 2:
Input material mass and bulk
density, dwell time and
Calculate the rotting area
dumping height

Step 3
Dimensions of the used
machines; for small plants not
If it is necessary, calculate the area for machines (pre-
necessary treatment, compost preparation, belts, big shredder,
turning machines, …)

Step 4:
Add 25% of the whole area
out of Step 1-3

Calculate the area for traffic ways.

Evaluation

Add the four kinds of areas together. The result is the

total required area for a composting plant.

Remarks

After the determination of the total area, think about

a practical material flow and draw a picture of the
new plant.

18
D E S I G N

Material flow
The adjustment of the material flow is important to avoid unnecessary ways and work. It is possible to
save time and money with a good and uncomplicated material flow. Some examples for a good
material flow are

Material flow in a line

It is a very easy and simple material flow.

The disadvantage is the long way back for the sieved structure
material (7).

Entrance
1 Writing table (big scale)

Storage
2 Structure / green + garden

Shredder
3 Grinding and mixing

Composting without Boxes

4

5
1 cm (diameter) sieve

Compost storage and packing

6 station (plastic bags)

Figure III-2 Exemplary material flow at a big composting plant (turning windrows) – in a line

19
D E S I G N

Material flow in a rectangle form

2 3 4

Storage
Structure / green + garden

Shredder
Grinding and mixing

Composting without Boxes

Storage area sieved structure

(2 areas, below and above)

Composting without Boxes

1 cm (diameter) sieve

Compost storage and packing

station (plastic bags)

6 5 4

Figure III-3 Exemplary material flow small composting plant (without input material supply) – rectangle form

20
D E S I G N

Mass balances
Preliminary remark

Use the advanced level to draw up an own mass balance. Additionally helpful information can be
found in the appendix. The use of the designed sheets for the calculation, the following text, the flow
plan, and the example are given to understand the calculation procedure.

Input Material 100%

1
65% water

Input material storage

2 3 and pre-treatment 100%

65% water

Water (and air) 80% Unsuitable materials 5%

Input in the composting process

95%

4 Composting process

Biological decomposition process

Discharge 32%

Biogas 143%

Contains mostly water and carbon dioxide

5 Compost preparation 32%

7 Sieved structure 10%

Compost 22%
6
35% water

Figure III-4 Exemplary mass balance with flashover values by mass percent, modified [2]

21
D E S I G N

The given example shows an easy mass balance. The objective is to get more information about the
required irrigation mass and the expected compost mass (or volume) after the composting process is
finished. With such mass balances, it is possible to get flashover values about the composting process
with different kinds of input materials.

The used balance was calculated with the following flashover values for the composting process.

Please note the given values in percent by mass.

p. 38

Required values for the draw up of a mass balance

5
To set up a mass balance do the next step with one heap or windrow during the whole composting
process. It is very important to record the data carefully. Look at Chapter V Analyses at a composting
plant, to get additionally helpful information about the tests.

Step 1:

Record the total mass and the moisture content of the input
material

Step 2:

Note the input material mass and the mass of unsuitable

materials after the storage and (or) pre-treatment area as well as
the moisture content.

Step 3:
3:

Record the irrigation of water by volume or mass.

At last step, record the mass and the moisture content of the
sieved materials (structure and compost).

Evaluation

Determinate values after the calculation procedure in the data

collection sheet or in the example.

Draw an easy material flow plan like the example (Figure III-4
Exemplary mass balance with flashover values by mass
percent) with the important steps at the composting plant and
calculated the values in percent by mass.

22
D E S I G N

Remarks

With such a balance it is now possible to say that about 22%

(numbers out of the example) of the input material by mass is
compost and the irrigation mass during the process is 30% of
the input material mass.

By 10.000 mg of input material the irrigation mass is about

3.000 mg and the expected compost volume is 2.200 mg.

Pay attention, the numbers can be quiet different for different

input materials, different surrounding conditions, and so on.

23
O P E R A T I O N
Chapter

4
Chapter IV Operation at a
composting plant

Input material
The input materials and the composition of them are very important for a fast composting process and
good product quality. As an easy rule says, “Good compost needs a good composition of the input
materials”.

Suitable and unsuitable materials

Organic waste consists primarily of organic substance. This term does not describe if the waste is
natural or artificial origin. In addition, the description does not indicate if the waste is compostable or
not. By the use of this definition also paints and oils belongs the category organic waste. [6]

In this manual and in special literature the name bio waste is used to describe waste, which can be
broke down by the activity of micro-organism (biological decomposable).

The division of bio waste in different categories depend on the water content. [6]

Suitable waste for anaerobic treatment like liquid waste and

waste with a high water content and/or less structure material

Suitable waste for aerobic treatment (composting) like solid

waste, particular bulky materials

Bio waste is allocated on the source. Hence, the bio waste can be divided in waste from households
(and markets), form gardens (and parks, roadsides) and from stockyards (and slaughterhouses).

The following information on bio waste concentrates on waste, which is suitable for composting.

This manual describes mainly the composition of green bio waste. To adjust the fertilizer quality, parts
from animal origin can be add as well.

24
O P E R A T I O N

Organic waste

Compostable Non-compostable

Plastics, products of the chemical

industry, oil …

Native
(biogenetic) Derivate organic
organic

Vegetables, fruit, Paper, cardboard

plants, cellulose

Structure
material Garden waste Kitchen waste

Bio waste

Composting

Compost

Figure IV-1 Categorisation of organic waste, modified [6]

25
O P E R A T I O N

SUITABLE INPUT MATERIALS

(Organic) kitchen waste

Leftovers form fruits, vegetables, and salad

Fruit remains

Coffee and tee bags, coffee and tee ground

with paper filters

Egg and nut shells

Bread crusts

Potato peelings

Cut flowers

Paper napkins (tissue), kitchen role and

packing paper

(Organic) garden waste

Grass cuttings

Leaves

Structure material
Bark

Tree and hedge cuttings, wood chips

Roots

Grinded coconut shells and shredded palm

leaves

Herbs / seeding weeds

Flowers and plants, part of plants and

diseases part of plants

Moss

Windfalls

Green cuttings (parks, sports ground)

26
O P E R A T I O N

UNSUITABLE INPUT MATERIALS

Recyclable materials
materials

Plastics, plastic foam, polystyrene and plastic

foil, plastic bottles and cups

Metals, cans, compound materials and used

glass

Drink cartons, paper in bulk, used and

polluted cardboard boxes

Harmful substances

Batteries, paints and oil

Medicines

Glue, alkaline solutions / acids

Pesticides and herbicides

Residual waste

Cooked and prepared food (meal, fish and

fruits) as well as leftovers (bones)

Nappies / hygiene articles

Glossy paper

Cigars and cigarettes ends

Pet litter

TOTALLY UNSUITABLE MATERIALS FOR COMPOSTING

Treated wood (painted, woos preservatives)

Kitchen waste with high fat content

Polluted input material in general

27
O P E R A T I O N

Additives
Additional materials, which increase the fertilizer quality, the speed of decomposition and/or reduce
the loss of nutrients, are called additives.

They are helpful but with a good input material composition, they are not necessary.

Table IV-1 Suitable Additives, modified [6]

Additive Application

Additives out of the composting process

Standard compost Rich in micro-organism for inoculation of the
input material during the starting phase
Mineral (inert) additives
Rock phosphate Phosphate becomes during the composting
flour process more soluble in water through the living
activity of micro-organisms
Useful for tropical soil with low availability of
phosphate
Sand In small amounts useful for its silica acid content,
which plays an important role in plant growth and
is set free by soil organisms
Lime Stabilizing the pH – Level
High calcium lack in the compost
Rock dust (basalt Contains minerals and trace elements
meal, calcium, clay Improves the biological stabilization of
granulate) decomposed material
Alginic chalk Fertilizer from harvested living chalk algae
Excellent bacteria nutrient
Suitable for neutralizing acidity of peat and bark
Algae flour Fertilizer from harvested living chalk algae
With much less calcium than alginic chalk
Trace elements source
Bone flour Consists mainly of phosphorous acidic chalk
Increase the content of calcium and phosphate in
the compost
Structure material
Blood meal Organic nitrogen fertilizer
is necessary to
Used if no animal waste is available Similar to
improve the
Horn flour Blood meal but with lower effect oxygen supply.
More suitable for the composting process Composting
Decomposable additives without structure
Animal dung (dairy Organic nitrogen fertilizer is not possible.
cow, horse, water Hence, structure
buffalo, sheep, pig, does not belong to
hen, duck rabbit) the additives.
Liquid manure Organic nitrogen fertilizer

28
O P E R A T I O N

Composition of the input material

p. 42

5
For analysing the composition of input material by volume or mass, look at Chapter V Analyses at a
composting plant.

Suitable compositions

The easiest composition by volume is to mix the garden (without the structure material) and the green
waste together and than mix the garden and green waste one by one with structure material.

Because the bio waste characteristics are quiet different, it is not possible to give exact numbers about a
suitable composition of the input materials. Hence, it depends on the maintaining person to find out
which mixture is suitable or not. However, it is only possible to give some ground rules.

Some rules for a suitable composition (percent by volume)

Do not add less than 40% and more than 60% as structure
material.

Garden waste or kitchen waste can be mixed until 60% (it is

possible to mix only garden waste with structure or only
kitchen waste with structure).

If only grass cutting available uses below 50%. If the

calculation is in percent by mass, structure material share shout
above 30%.

29
O P E R A T I O N

Carbon – rich and nitrogen – rich input

materials
Look in the following table (Table IV-2 Nitrogen- and carbon- rich input materials) to get information
about the C/N – ratio of some input materials.
p. 11

2
p. 53

5
Find a description of the C/N – ratio in the Chapter II Basic knowledge – composting and look in
Chapter V Analyses at a composting plant to get information about the analyses of the C/N – ratio.

Table IV-2 Nitrogen- and carbon- rich input materials, modified [4] [6]

With this
Kind of waste C:N – Kind of waste C:N – information, it
ratio ratio is possible to
Nitrogen – rich waste Carbon – rich waste adjust the
Liquid manure 2–3 Fruit wastes 35 C/N – ration
if it is
Chicken droppings 10 Leaves 40 – 60
necessary by
Grass cuttings 12 – 15 Straw, oats 48 - 60
changing the
Vegetable waste 13 Bark 100 – 130
composition
Kitchen waste 23 Bush pruning 100 – 150 of the input
Potato plants 25 Sawdust 100 – 500 material [2].
Horse dung 25 Paper / cardboard 200 – 500

Degeneration process
Range of process factors (monitoring values)
The keeping of the monitoring values is important to have optimal conditions for the composting
process. If this is not possible, the composting process takes more time or stops. In problematic
situations can be found some solutions in Chapter VI Trouble shooting.

As proposal, it is good to copy the table sheet with the monitoring values and put it on the first side to
keep an eye on it every time. p. 9

2
Find the description of the given parameters in Chapter II Process factors.
p. 38

5
For the determination of the monitoring values look at Chapter V Analyses at a composting plant.

30
O P E R A T I O N

Monitoring values

Table IV-3 Monitoring values during the decomposition process [11]

Parameter Composting

Environment Aerobic (with air)

Turning frequency Depend on the used method

1. weekly method;
turn the windrows every week
2. temperature method;
turn the windrow if the temperature sinks
below 40° to 30° degrees
Temperature in the feedstock never rise above 70°degrees
no rise above 40°C after turning the compost
can be safely used or stored
Moisture Optimum according to the fist probe analyses
(Chapter V
Rotting degree Determination of the rooting degree (Chapter V

Rotting degree / Dewar – Test)

Water content 40 – 70 %WS

pH -value 7 – 11 (light alkaline)

Air avoiding volume 30 – 50 % (interstices volume in the windrow,

depend on the composition of the input material)

C : N -ratio 20 – 35

31
O P E R A T I O N

Changing of composting parameters

during the composting process
Monitoring the composting process is necessary for a good compost product and a short composting
time. The knowledge about the temperature curve or the development of the total volume can greatly
help to understand the underlining principals for composting. In addition, problems during the rotting
process can be found and solved to get a satisfactory product.

TEMPERATURE

The temperature is the most important monitoring value during the composting process because it is
very easy to measure and it shows the success of the process. Degradation of organic substance,
through the living activity of micro-organism because of the self heating capacity, is the reason for
differences in the temperature in the windrow (heap) centre (nucleus) and the surrounding
temperature. The temperature curve goes also hand in hand with the mineralization and rotting
processes.

The figure shows the characteristic temperature curve during the composting process in South – East
Asia.

80°C (176°F)

65°C (149°F)

50°C (122°F)

35°C (95°F)

20°C (68°F)
Degradation Conversation Maturation

Figure IV-2 Characteristic temperature curve, modified [2]

As the figure shows, the composting process can be divided into three phases [2]

A degeneration phase

A conversation phase

A maturation phase

High temperatures during the degradation phase are very important because if the temperature
reaches and even surpasses 60 – 70°C the destruction of weed seed and pathogens takes place. The
length of the first phase is decided by: [2]

A suitable composition of the input materials with regard to

the particle size and homogeneity

Good environmental factors like a suitable moisture content,

existence of oxygen and climatic influences

32
O P E R A T I O N

The time to reach the maximum temperature is about 2 – 5 days. At this stage of the composition
process, the lightly breakable substance (hydro carbonate) is degraded.

The degradation of components, which are difficult to break down, occurs during the conversation
phase. The duration time depends on ambient conditions. Hence, no specific timeframe can be
given for this stage.

During the maturation phase, the activity of bacteria slows down. At this period, soil organism and
worms populate the material and mix the mineral with the organic components. Clay-hums
complexes are formed, which increases the nutrient content of the compost (especially plant
available nutrients). At the end of this period (the final temperature do not rise above 40°C), the
material is ready for compost preparation.

TOTAL VOLUME, TOTAL MASS AND BULK DENSITY

During the composting process, the total volume and the total mass of the windrow decreases.
Because of the abrasion by other materials and of maceration, the size of particles decreases. Hence,
the total volume becomes smaller and the bulk density increases. [5]

100 750
feedstock amount by mass [%]
90 700
feedstock amount by volume [%]
Feedstock amount in [%] regarding the input

80 bulk density [WM with 25%MC] 650

660
650
640
70 600
600

bulk density [g/lFS]

60 550
550

50 500

40 450
470

30 400

370
20 350

10 300

0 250
0 2,5 5 7,5 10 12,5 15
Composting time in weeks
Input Final compost

Figure IV-3 Volume reduction during the composting process, example form the pilot composting plant in Phnom Penh [8]

Bio-oxidation through the living activity of micro-organism to carbon dioxide is the reason for the
mass reduction.

33
O P E R A T I O N

MICROBIOLOGICAL AKTIVITY

The direct determination of the microbiological activity is not possible. The temperature development
as well as the total volume or mass reduction can be used to measure the activity.

As both figures show, at the first phase of the composting process (degeneration phase) the
degradation of easy decomposed organic materials takes place and the activity of micro-organism
increases rapidly. From there, the temperature increases to a high level and decomposition rate is very
high. This leads to a rapid reduction in volume and mass. Because of the high activity, the oxygen
demand is high.

During the conversation phase, the activity of micro-organism becomes less intensive. The
temperature level drops and the decomposition rate becomes slower too. At this phase, components
that are more refractory remain. Consequently, the total volume and mass reduction increases slower.
The oxygen demand decreases as well. If the temperature in this stage does not rise over 40°C the
compost can be used safely or stored.

At the end, the maturation stage, the temperature and the other indicators for the microbiological
activity decline. If the lack of degradable organic substance as limiting factor is reasonable, the
completion of the composting process and the increase of stability are reached. The material is ready
for the compost preparation.

Pay attention, the former descriptions are all for optimal composting conditions. A lack of water inside
the windrow, for example, leads to a decreasing activity and a falling temperature without finishing the
composting process. If water is add the composting process starts again.

Compost
Advantages of the compost use as soil conditioner

Increase of nutrient and organic content in the soil

Improvement of the soil texture (better aeration and water

retention)

Compost, the product out of the composting process, has different possibilities in use. However,
before the compost is ready for sale or use, a basic quality should be guaranteed. The product quality
depends on a number of factors like the input material, the maintaining and monitoring of a plant and
the compost preparation).

The largest market for the compost is the agriculture industry but sometimes it is difficult to get in this
market. Hence, study the minimum requirements and analyse the compost carefully.

“[..]Experiences indicate that the compost mass can be safely used or stored after the temperature has
finally dropped to about 40°C.”[5]

34
O P E R A T I O N

Compost quality
Minimum requirements of compost quality

Save use in agriculture and horticulture

Low content on potential harmful substances

Constantly good compost quality

Well-balanced nutrients content

Storage able

Fertilizer application
The application of compost depends on the stage of maturation. Pay attention, never mix fresh
compost with the soil and cover this layer with soil because the natural decomposition process is not
finished. With a lack of oxygen (by covering the compost – soil mixture with soil) anaerobic processes
start and this is harmful for the plants.

The main application of compost is soil conditioning and fertilizing.

Application Description

Soil conditioner Use a 1 – 2 cm thick layer of compost and cover

the soil
Work the compost slightly into the soil
Mulching 3 cm thick compost layer
5 – 10 cm thick sieved structure layer
Use (compost or structure) layer and cover the
area around trees, hedges, …,
Hence fertilizer 2 cm thick compost layer to cover the soil
Flower fertilizer Use maximum 4 l of compost for 1 square meter
Grass fertilizer Sieve the compost with a 0.5cm (diameter) and
use 2 l of compost for 1 square meter.
Vegetables It depends on the vegetable
fertilizer As flashover value use a 2 cm layer and work the
compost slightly into the soil
Room plants 1 part of compost
1 part of potting soil
Mix the two parts for fertilizing
Table IV-4 Compost applications, modified [9]

35
O P E R A T I O N

“Golden rules” for the use of compost

Never use only compost for seeding plants or vegetables, mix

the compost with soil, because the fertilizer is to strong for
young plant and germs.

Do not storage the compost more than one year because the
valuable humus – clay complexes degenerate into their
inorganic components.

Never use musty or festered compost.

Do not use to much compost, because the fertilizer effect is

may be too strong.

The given examples are flashover values from Germany. It is also possible to analyse the soil and
in interdependency between the soil conditions and the plant requirements, to calculate the
amount of compost, which is needed for optimal plant growing.

Compost quality in Germany

In according to the German Federal Quality Association Compost find attached in the table the quality
guidelines for compost in Germany.

For more or detailed information, look at special German literature.

36
O P E R A T I O N

Table IV-5 Compost quality criteria in Germany [7]

Criteria Description

Hygiene A hygienically unreproachabel product with assure

the exclusion of germs
Impurities Content of impurities (glass, plastic, metal) lager
than 2mm is maximum of 0,5% by mass of dry
matter
Stones Stone content shall not exceed 5% by mass
Plant compatibility Mature compost in the intended rage of application
no content of phytotoxical substances (no nitrogen
immoblilsation)
Degree of Matured Compost: stage IV or V (Dewar – Test /
decomposition rotting degree)
Water Content Loose material ≤ 45 %DS
Bagged material ≤ 35 %DS
VM Matured compost ≤ 20%VM
Heavy metals Zinc (Zn) 400 mg/kg DS
Lead (Pb) 150 mg/kg DS
Copper (Cu) 100 mg/kg DS
Chromium (Cr) 100 mg/kg DS
Nickel (Ni) 50 mg/kg DS
Cadmium (Cd) 1,5 mg/kg DS
Mercury (Hg) 1,0 mg/kg DS
Declarable 1.) compost type and input material
parameters 2.) maximum particle size
3.) bulk density
4.) salt content
5.) pH value
6.) plant nutrients
7.) total content: N, P2O2, K2O, MgO, CaO
8.) soluble content: N, P2O2, K2O
9.) organic matter (VM)
10.)net mass
11.) name and address of the responsible dealer
12.)advice for correct application

All these criteria can be analysed e.g. according with the German regulations, which can be found in
the book: “Methods book for analysis of compost” [7]. If the analyses were sending to labs, check the
analyses regulations.

37
A N A L Y S E S
Chapter

5
Chapter V Analyses at a composting
plant

The following table (Table V-1 Analyses at a composting plant) gives an overview, which analyses are
important for the maintenance of a composting plant and in which timeframe they have to be done.

Descriptions and remarks for all tests are in the next pages. To get a better understanding use the
description of a test and the sample in the data collection sheet.

Most of the given samples at the data collection sheet show real examples analysed at the composting
plant at assumption college Thonburi, Bangkok Thailand. Hence, look at the appropriate chapters to
get more information about composting and suitable solutions. These examples are at first given to get
an imagination about the calculation procedure and to show that often it is not as it was expected.

The data collection sheets for every test find at the last pages with examples.

Please note the importance of sample taking at the page after the next page.

The chemical analyses (pH – value, C, N, P, K,) could be done e.g. according with German
regulations, which can be found in the book: “Methods book for analysis of compost” (check the lab
about the analysing procedure, that the analysed results can be compared with German results and
values at this manual). [7]

38
A N A L Y S E S

Table V-1 Analyses at a composting plant

Analysis Time
Page
start daily weekly End

sample taking 40

input material
Composition B 48
total windrow Volume B 42
bulk density A 51
moisture content A 52
pH - Value R
total C R
total N R

operation
Temperature B 46
fist probe B 47
total windrow Volume B 48
rotting degree B 49
bulk density A 51
moisture content A 52

Compost
total Compost Volume B 44
bulk density A 51
moisture content A 52
pH – Value R
total C R
total N R
EC R
Available P R
Exchangeable K R

Explanation

B Basic level p. 3
A Advanced level
R Research level 1

39
A N A L Y S E S

Sample taking

Preliminary remark

The compost sample should, supply a representative sample, be able to be carried out, and not require
a major technical expenditure. [7]

If you like to analyse every parameter in according to the German regulations out of the table sheet
you need about 20 l of fresh material.

Materials

Use only materials for sample taking and transport, which are not able to change the results of the
analyses you want.

Carrying out the sample taking

Take the samples from the entire profile section as a fine layer
(not less than 30l) or use a drill (next item). Put the material on
a cleaned concrete surface or a plastic foil.

Figure V-1 Sample taking skittle

If a drill, (screw borer) is available take 5 borings out of one
cross section and put the material on a cleaned concrete
surface or a plastic foil.

Individual samples

It is taken out in one work step like a sample out of one cross section. The minimum amount of
individual samples can be calculated with the following formula:

G [kg] = 0.06 * d [mm]

d … particle size

The coarser and less uniform the material, the larger the sample, which has to be collected.
[7]

40
A N A L Y S E S

Collective samples, reduction of the collected material

A collective sample consists of well mixed (put the individual samples together and mix them with a
shovel) individual samples. To reduce the amount use of the following method:

Step 1:

Put all the individual samples together and mix the

samples very well on a plastic foil (or a cleaned
concrete surface).

Step 2:

Divide the well-mixed material in quarters by drawing

a line with a shovel. Choose a quarter (25% of the
material) and put it away.

Figure V-2 Division of collective sample

Step 3:

Do Step 2 repeatedly until you have reached the

required volume.

Transport

The samples shout be transported in well-sealed PE containers and should be in the laboratory after 24
hours. If it is possible, try to transport the samples cooled.

Remark

Any deviations from the described methods should be noted very carefully.

These steps are very important to avoid analysing mistakes.

41
A N A L Y S E S

Input material

Preliminary remark

The data collection sheet “composition input material” is divided in three parts like the three levels.
For every part or level, a separate data collection sheet was designed. p. 24

4
Look at the Chapter IV Input material about a good mixture for the input material. Do not forget to
name the windrow with a sign.

Ratio of input material by volume

Testing procedure

Step 1:

Measure the dimensions of the bucket (or something like

this) you use for transporting the input material and
calculate the volume of the bucket

Kitchen waste
Describe the different kinds of input materials after their
(Only green cabbage) optical properties.

Step 2:

Fill the buckets up to the top and count every bucket to

build the windrow.

By using pre-treatment, count the buckets before the

treatment.

Evaluation

Calculate the volume of the different kinds of waste and

the input material ratio by volume.

Calculate the amount of piled waste as it is described in the

data collection sheet “total windrow volume”.

42
A N A L Y S E S

Bulk density and total mass

Testing procedure
p. 51

Step 3:
5

Measure the bulk density of every kind of input material.
p. 52

5

If it is possible, analyse the MC of the input material.

Evaluation

Calculate the input mass of the different kinds of waste and

the input material ratio by mass.

Calculate the total mass of the piled waste

Remark

If a big scale is available, it is also possible to measure the

whole charge. Then calculate the total mass by sum up all
charges.

Chemical analyses

Remark

Inscribe the samples carefully and note the given name in the
table. Also, make a note of the laboratory.

Take the sample as it is described in this chapter.

Look after the testing procedures in the laboratories and

compare these with the German regulations. If they are
different, use specific literature to compare the results with the
expectations.

For the determination of the organic carbon look at the test in

this chapter.

43
A N A L Y S E S

Compost

Preliminary remark

The data collection sheet “compost” is also divided in three parts like the data collection sheet
“composition input material”. p. 24

4
Look at Chapter IV Input material for good compost properties.

Total compost volume

Testing procedure

Step 1:

Measure the dimensions of the bucket you use for

transporting the compost.

Step 2:

Note in the sheet from which windrow the compost is.

Fill the buckets up to the rim and count every bucket of

compost

Evaluation

Calculate the total volume of compost by multiply the
number of buckets with the bucket volume.

44
A N A L Y S E S

Bulk density and total mass

Testing procedure p. 51

Step 3:
3: 5

Measure the bulk density of compost.
p. 52

5

If it is possible analyse the MC of the compost

Evaluation

Calculate the input mass of the compost by multiply the bulk

density with the total volume.

Chemical analyses

Remarks

Inscribe the samples carefully and note the given name in the
table. Also, make a note of the laboratory.

Take the sample as it is described in this chapter.

Look after the testing procedures in the laboratories and

compare these with the German regulations. If they are
different, use specific literature to compare the results with the
expectations.

p. 53

5

For the determination of the organic carbon, look at the test in
this chapter.

45
A N A L Y S E S

Temperature and fist probe

Temperature
p. 9

Preliminary remark
2
The temperature is a very important indicator in the composting process. Measure the temperature in
nucleolus (centre) minimum three times per windrow. The outside temperature is also important to
judge the rise and fall during a week.

Testing procedure

Step 1:

Divide the windrow in (minimum) tree section to measure the

temperature on the same point every day

Step 2:

Put the thermometer into the windrow and wait five minutes if
you use a normal thermometer without an electronic display.
Then pull the thermometer out of the windrow and look
immediately for the temperature.

By using a thermometer with electronic display wait, until the

temperature value is constant.

Remark

In the same data collection sheet please collect also the data
about, the fist probe, the irrigation of water, and so on (look at
the sample in the data collection sheet or in the description of
the moisture content).

46
A N A L Y S E S

Fist probe
Preliminary remark
p. 10

The importance of water for the composting process

2
It is very easy and fast test to measure the moisture content of a compost windrow. Please note your
results (wet, dry, good) in the data collection sheet “temperature, fist probe, and irrigation of water”.

Testing procedure

Step 3:

Remove the first dry layer of a composting windrow and

take a sample with the fist out of the windrow.

Step 4:

Close the fist and press the sample in the fist.

Evaluation

If water comes out of the fist the material, it is too wet.

If the material crumbles or fall apart when you open the

fist the material is too dry.

By realising the hand, the material should be hold together

and feel moist.

Remarks

If the result shows that, the material it is, too wet stop
irrigation and open the windrow or turn the windrow.

If the material is too dry irrigate and note the volume of

used waster in the table sheet

47
A N A L Y S E S

Total windrow volume

Preliminary remark

To calculate the total windrow volume approximately, use the following easy method.

Testing procedure

Step 1:

If it is a triangle windrow measure, the length, the bottom

width, and the height.

If it is a trapezoid windrow measure, the length, the bottom

width, the top width, and the height.

Figure V-3 Triangle and trapezoid shapes

Evaluation

Calculate the volume as it is described in the data collection

sheet “total windrow volume”

48
A N A L Y S E S

Rotting degree / Dewar – Test

Preliminary remark

The self-heating capability of fresh compost substance through the degeneration processes is used to
measure the compost degeneration quality. Very important for this test is an optimum and standardize
water content. This can be checked by fist probe.

Testing procedure p. 47

Step 1: 5

Sieve the fresh original sample to < 10mm and check the
water content of the sieved material with the “fist probe”
(if the material is too wet dry the material to adjust the
water content, if it’s too dry add water)

Step 2:

Fill the sieved and checked fresh material without

pressure in the dewar vessel. To the material, bump the
vessel with careful pushes on the ground.
Figure V-4 Dewar flasks

Step 3:

During the test, take the vessel to an air-conditioned room

with 20°C room temperature. Every day measure
minimum two times with a difference of eight hours per
day, the temperature.

The test is over after the temperature goes down.

Normally it takes two until five days to finish the test.

49
A N A L Y S E S

Evaluation

not finished
If the maximum temperature is below 40°C degrees, the

compost is ready to work out.
40°C

finished
Figure V-5 Temperature curve dewar test

Remarks

In according to the German regulations [7] to compost quality

was divided in 5 stages of rotting degree. The criterion to judge
to compost quality is also the maximum temperature (Tmax).

Rotting degree I: Tmax = 60 – 70°C

Rotting degree II: Tmax = 50 – 70°C

Rotting degree III: Tmax = 40 – 50°C

Rotting degree IV: Tmax = 30 – 40°C

Rotting degree V: Tmax = 20 – 30°C

Please note, “compost with rotting degree II and III is designated as fresh compost, compost with
rotting degree IV and V as finished compost” [7].

50
A N A L Y S E S

Bulk density

Preliminary remark

The bulk density is defined as mass per unit volume. Therefore, it is possible to calculate the total
volume by knowing the bulk density and the total mass of a windrow.

Be careful and take the samples from the entire cross section of the windrow. Do not disperse the
volume by filling the bucket and do not compact the material in the bucket.

Testing procedure

Step 1:

Measure the mass of the empty bucket and measure the

dimensions to calculate the volume and record the data’s
in the collection sheet.

Step 2:

Fill the bucket carefully. Do not use too much or too less
material out of the windrow.

Step 3:

Measure the mass of the full bucket and record the data’s.

Repeat Step 2 and 3 minimum 2 times per windrow.

Evaluation

Calculate the bulk density as it is described in the data

collection sheet “bulk density”.

51
A N A L Y S E S

Moisture content

Preliminary remark
p. 10
The importance of water for the composting process
2
The moisture content is the mass of water in the windrow/sample to the mass of the dry substance in
percent.

To measure the optimal moisture conditions the fist probe is useful as a first approach. Some materials
like paper and wood are able to save quiet lot water and so the bulk density of dry and wet material can
be varying.

Testing procedure

Step 1:

Measure the mass of the empty suitable (porcelain, aluminium)

vessel. The used scale should be able the measure exactly 0.1g.

Step 2:

Fill a fresh representative sample in the vessel and measure the

mass of the fresh sample including the vessel.

Dry the sample in an oven until the mass of the sample is

constant (normal rule after 24 hours) by 105°C / 221°F.

Step 3:

Measure the mass of the dry material including the vessel.

Evaluation

Calculate the moisture content as it is described in the data

collection sheet

52
A N A L Y S E S

Organic carbon

Preliminary remark

In according to the German regulations the organic carbon can be calculated out of the result of the
determination of the volatile matter. That is why the following description is at first about the volatile
matter and afterwards about the calculation of the organic carbon.

Testing procedure p. 52

Sample preparation:
preparation: 5

Dry the unscreened fresh material by 105°C in an oven until
the dried mass is constant.

Use a suitable grinder to grind the material of at least 30g dry

substance.

Step 1:

Measure the tare mass of the empty porcelain vessel. The scale
shout be able to read 1 mg exactly.

Measure the mass of the porcelain vessel including the

prepared sample (approx. 5g dried and ground sample)

Step 3:

Burn up the material at 550°C in a box type furnace, until the

mass is constant.

Cool down the hot porcelain vessel with a desiccators and

afterwards measure the mass again.

Evaluation

Calculate the volatile matter at first.

Multiply the volatile matter with the factor 0.58 to calculate the
organic carbon.

53
T R O U B L E S H O O T I N G
Chapter

6
Chapter VI Trouble shooting

Problems with the composting process, maybe the answer is in this chapter:
Table VI-1 Trouble shooting

Problem Reason What to do

Bad smell / odour Aeration is to less Turn the windrow and mix wet
sections with dry material
Too much water inside the
windrow Add structure material to lift up
the natural aeration

Cover the windrow during

heavy rain periods (only if the
composting plant is not covered
with a roof)

Stop irrigation and open the

windrow until the moisture is
optimal again

A lot of animals in the The ratio of cooked waste or Avoid cooked waste and parts
windrow parts from animal origin is to from animal origin
high
Loosen up the material by
turning the windrow

Slowly decomposition Bad composting conditions Adjust the process factors

process

Slow temperature in the low pH-Level Reduce the storage time for the
initial phase input material

Add stone flour (CaCO3) to rise

the pH-Level

54
T R O U B L E S H O O T I N G

Low temperature during To less “green” waste Change the composition of the
the composting process input material because the
structure content is to high

High temperatures at the Degeneration of strong Sieve the material and storage
end of the process degradable substrate the compost separately and
monitor the temperature

High temperatures in the Degeneration process is not Do not pack the compost into
compost “finished” bags wait until the temperature
goes down

Bad compost quality high moisture content dry the compost

Less nutrients because of the Add dung (manure) to lift up the

input material nitrogen content

55
References
[1] Bidlingmaier, W., Gallenkemper, B.: Grundlagen der Abfallwirtschaft, Lecture script
Department of waste management institute at Bauhaus – University Weimar, Germany.

[2] Bidlingmaier, W.: Biologische Verwertungstechnologien. Lecture script Department of waste

management institute at Bauhaus – University Weimar. Weimar. Germany.

[3] Bidlingmaier, W., 2000: Biologische Abfallverwertung. Die Deutsche Bibliothek. Eugen.
Germany.

[4] Diaz, L. F., Savage, G.S., Eggert, L. L., Golueke, C. G., 1993: Composting and Recycling
municipal solid waste. Lewis Publishers. Florida. USA..

[5] Diaz, L. F., Savage, G.S., Eggert, L. L., Golueke, C. G., 2003: Solid Waste Management for
Economically Developing Countries. Second Edition. Cal Recovery. Concord, California.
USA.

[6] GTZ, GFA – Umwelt, IGW Engineer Consulting Witzenhausen, 1990: Utilization of
organic waste in (peri-) urban centres. Report Supraregional Sectoral Project. Bonn /
Eschborn. Germany.

[7] Federal Compost Quality Assurance Organisation, 1994: Methods Book for the Analysis of
Compost. Abfall Now. Stuttgart. Germany.

[8] Heller, C., 2002: Analyse und Optimierung des Betriebsablaufes und Erstellung eines
Betriebshandbuches für die Pilot-Kompostierungsanlage Stung Mean Chey in Phnom Penh
(Kambodscha). Diploma Thesis Department of waste management at Bauhaus – University
Weimar. Weimar. Germany

[9] Thuringia Ministry of Agriculture, Nature protection and Environment,: Thüringer

Kompostfibel. Germany.

[10] Knoten Weimar: Quality critera for compost in Europe and Germany.
www.bionet.de/en/waste/print

[11] Klauß – Vorreiter, A.., 2003: Integrated waste management master plan for Assumption
College Thonburi, Draft Knoten Weimar An - Institute at Bauhaus – University Weimar.
Weimar. Germany.

56
Index
compost mass................................................................ 22
compost preparation...................................................... 14
A compost quality............................................................. 35
abrasion ......................................................................... 33 compost storage ............................................................ 14
activity of micro-organism .............................................. 4 compostable waste ........................................................ 24
additional materials ....................................................... 28 composting...................................................................... 4
additives ........................................................................ 28 composting parameters ................................................. 32
advantages of the compost ............................................ 34 composting plant place
aeration................................................................ 7, 10, 34 minumum requirements............................................. 12
Chinese method ........................................................... 7 composting process................................. 7, 14, 30, 32, 33
forced........................................................................... 7 composting time...................................................... 14, 32
natural.......................................................................... 7 conditions........................................................................ 5
recommendation .......................................................... 8 conditons
aerobic............................................................................. 4 air ................................................................................ 5
aerobic treatment ....................................................... 4, 24 water............................................................................ 5
air .................................................................................. 10 construction elements.................................................... 12
algae flour ..................................................................... 28
alginic chalk .................................................................. 28 D
anaerobic ................................................................. 11, 24
analyses at a composting plant ...................................... 38 decomposition............................................................. 4, 5
animal dung................................................................... 28 decomposition rate ........................................................ 34
animal origin ................................................................... 4 degeneration.................................................... 8, 9, 10, 11
application of compost .................................................. 35 degeneration process..................................................... 30
area................................................................................ 15 degradation ................................................................... 33
area calculation.............................................................. 18 design flashover values ................................................. 15
areas at a composting plant Deward – test ................................................................ 49
pre-treatment........................................................ 15, 17 dimensions of windrows ............................................... 16
rotting area........................................................... 15, 16 dumping height............................................................... 16
storage areas .............................................................. 15 dwell time ...................................................................... 16
traffic ways .......................................................... 15, 17
F
B
fertilizer..................................................................... 4, 28
bad smell ....................................................................... 54 fertilizer application ...................................................... 35
bio waste ....................................................................... 24 fertilizer quality............................................................. 24
biodegradable substance.................................................. 4 fist probe ....................................................................... 47
bio-oxidation ................................................................. 33 flashover values ................................................ 14, 15, 18
blood meal..................................................................... 28 compost application................................................... 36
bone flour ...................................................................... 28 flow rat.......................................................................... 13
buffer space ................................................................... 13
bulk density ............................................................. 33, 51
G
C garden waste ................................................................. 26
gardens.......................................................................... 24
C/N - ratio ............................................................... 11, 30 German Federal Quality Association Compost............. 36
biologically (short) available ..................................... 11 good product ................................................................. 24
carbon to nitrogen – optimum.................................... 11 green bio waste ............................................................. 24
carbon............................................................................ 11
carbon - rich materials................................................... 30
chemical analyses.......................................................... 38
H
clay-hums ...................................................................... 33 harmful emissions ......................................................... 13
compost ............................................... 4, 9, 12, 34, 36, 44 harmful substances........................................................ 27
German quality criteria .............................................. 36 heap................................................................................. 5

57
heavy metals.................................................................... 5 operating capacity ......................................................... 15
high temperatures .......................................................... 32 optical controlling ......................................................... 13
horn flour....................................................................... 28 optimal conditions......................................................... 30
households..................................................................... 24 optimal moisture content............................................... 52
organic carbon............................................................... 53
organic content.............................................................. 34
I organic substance.......................................................... 24
inhibition ....................................................................... 11 organic waste ................................................................ 24
initial stage .................................................................... 11 oxygen .......................................................................... 10
input material .............................. 9, 10, 11, 18, 24, 29, 42 oxygen demand ............................................................. 34
input material storage .................................................... 13
input material supply..................................................... 12 P
input materials............................................................... 15
carbon rich ................................................................. 30 paints............................................................................. 24
nitrogen rich............................................................... 30 parks.............................................................................. 24
suitable................................................................. 24, 26 particle size ..................................................................... 9
totally unsuitable........................................................ 27 pathogens ...................................................................... 32
unsuitable............................................................. 24, 27 pH ................................................................................. 11
input volume ................................................................. 12 phases
interstices .................................................................. 9, 10 conversation .............................................................. 32
irrigation........................................................................ 46 degeneration .............................................................. 32
irrigation mass............................................................... 22 maturation ................................................................. 32
plant origin...................................................................... 4
preparation .................................................................... 17
K pre-treatment........................................................... 13, 17
kitchen waste................................................................. 26 problems ....................................................................... 54
process factors................................................................. 9
process time .................................................................. 16
L
level R
A- advanced level ........................................................ 2
B - basic level .............................................................. 2 range of process factors................................................. 30
R - research level ......................................................... 2 recyclable materials ...................................................... 27
lightly breakable substance ........................................... 33 residual waste................................................................ 27
lime ............................................................................... 28 rock dust........................................................................ 28
liquid manure ................................................................ 28 rock phosphate flour ..................................................... 28
living activity ................................................................ 33 rotting area .................................................................... 16
rotting degree .......................................................... 31, 49
rotting processes ........................................................... 32
M
markets .......................................................................... 24 S
mass balances ................................................................ 21
mass reduction............................................................... 33 sample taking ................................................................ 40
material flow ..................................................... 13, 19, 22 collective samples...................................................... 41
in a line ...................................................................... 19 individual samples..................................................... 40
in a rectangle form ..................................................... 20 materials .................................................................... 40
material flow plan ......................................................... 22 transport..................................................................... 41
maximum temperature............................................. 33, 50 sand............................................................................... 28
microbiological aktivity ................................................ 34 self-heating capability................................................... 49
micro-organism ....................................... 8, 11, 24, 32, 34 sieve diameter ............................................................... 14
micro-organisms........................................................ 9, 10 sieved structure storage................................................. 14
mineralization................................................................ 32 sieving........................................................................... 14
moisture..................................................................... 9, 10 slaughterhouses............................................................. 24
moisture content ............................................................ 52 soil organism................................................................. 33
monitoring values.................................................... 30, 31 stockyards ..................................................................... 24
mulching........................................................................ 14 storage area ............................................................. 13, 15
garden waste.............................................................. 13
green waste................................................................ 13
N structure material....................................................... 13
natural decomposition ................................................... 35 storage times ................................................................. 15
nitrate ............................................................................ 11 structure material ........................................ 13, 14, 26, 28
nitrogen - rich materials ................................................ 30 substrate .......................................................................... 9
nutrients............................................................. 28, 33, 34 suitable compositions.................................................... 29
suitable input materials ................................................. 26
suitable waste................................................................ 24
O surrounding temperature ............................................... 32
odour ....................................................................... 13, 54

58
 T V
temperature.............................................. 9, 32, 34, 46, 49 volatile matter ................................................................ 53
maximum............................................................. 33, 50 volume reduction .......................................................... 34
surrounding................................................................ 32
windrow nucleus........................................................ 32
temperature development ........................................ 32, 34 W
thermal energy................................................................. 9 waste ............................................................................... 4
thermometer .................................................................. 46 water ................................................................. 10, 24, 52
total mass....................................................................... 33 weed seed...................................................................... 32
total volume................................................................... 33 windrow ...................................................................... 5, 7
total windrow volume.................................................... 48 height......................................................................... 16
totally unsuitable materials............................................ 27 length......................................................................... 17
traffic ways.................................................................... 17 trapezoid.................................................................... 48
trapezoid windrow..................................................... 5, 48 trapezoid................................................................ 5, 17
trapezoid windrows ....................................................... 17 triangle....................................................................... 48
triangle windrow ....................................................... 5, 48 trinagle......................................................................... 5
trouble shooting............................................................ 54 width.......................................................................... 16
windrow system .............................................................. 5
windrow systems
U in boxes ....................................................................... 7
unsuitable input materials........................................ 13, 27 without boxes .............................................................. 7
worms ........................................................................... 33

59
List of attachment content
1. Data sheet: area calculation
2. Data sheet: area calculation, example
3. Data sheet: material flow
4. Data sheet: material flow example
5. Data collection sheet: input material composition (3 pages)
6. Data collection sheet: input material composition, first step (3 pages)
7. Data collection sheet: input material composition, example with pre-treatment (3 pages)
8. Data collection sheet: input material composition, example without pre-treatment (3 pages)
9. Data collection sheet: compost (3 pages)
10. Data collection sheet: compost, first step (3 pages)
11. Data collection sheet: compost example(3 pages)
12. Data collection sheet: temperature and fist probe
13. Data collection sheet: temperature and fist probe, example
14. Data collection sheet: total heap volume
15. Data collection sheet: total heap volume, example
16. Data collection sheet: total heap volume, first step
17. Data collection sheet: Dewar - test
18. Data collection sheet: Dewar – test, example
19. Data collection sheet: bulk density
20. Data collection sheet: bulk density; example
21. Data collection sheet: bulk density, first step
22. Data collection sheet: moisture content
23. Data collection sheet: moisture content, example
24. Data collection sheet: moisture content, first step
25. Data collection sheet: organic carbon /volatile matter
26. Data collection sheet: organic carbon /volatile matter, example
27. Data collection sheet: organic carbon /volatile matter, first step

60