Advanced

Wastewater
Treatment
Course #3201

Fleming Training Center

March 23 - 27, 2015
www.tn.gov/environment/water/fleming.shtml

Advanced Wastewater
Fleming Training Center

Course #3201
March 23-27, 2015
Monday, March 23:
8:30 Wastewater Overview
Activated Sludge
12:00 LUNCH
1:15 Activated Sludge - continued
Tuesday, March 24:
8:30 Nutrient Removal
11:00 LUNCH
12:15 Travel to Spring Hill WWTP
Wednesday, March 25:
8:30 Odor and Corrosion Control
9:30 Solids Removal from Secondary Effluents
11:00 LUNCH
12:15 Lab BOD

State of Tennessee
Fleming Training Center
2022 Blanton Dr.
Murfreesboro, TN 37129
Phone: 615-898-6507
Fax: 615-898-8064
E-mail: Amanda.Carter@tn.gov

Thursday, March 26:

8:30 BOD Math
9:30 Lab E. coli Testing
11:00 LUNCH
12:15 Fats, Oil and Grease Control
1:30 Residual Solids Management
Friday, March 27:
8:30 Lab E. coli Reading
9:30 Reclamation and Reuse
11:00 LUNCH
12:15 Exam and Course Evaluation

Advanced Wastewater Treatment

Section 1

Activated Sludge .1

Section 2

Nutrient Removal ..43

Section 3

Odor and Corrosion Control .....61

Section 4

Secondary Effluent Solids ..75

Section 5

BOD5 /cBOD5...89

Section 6

E. coli Testing .97

Section 7

Fats, Oils and Grease....109

Section 8

Biosolids ...125

Section 9

Reclamation and Reuse.151

Section 1
Activated Sludge

Section 1

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Activated Sludge Process

The term Activated Sludge comes from the sludge

particles teeming with active bacteria, fungi and
protozoans.

This fundamental process is the heart of activated sludge

treatment.

Organics + O2 + nutrients + inert matter

CO2 + H20 + new microorganisms + additional inert
matter

Activated Sludge
Advanced Wastewater Treatment

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TDEC - Fleming Training Center

Design Parameters for Various Activated

Sludge Processes

Performance problems can be caused by

Process

MCRT,
days

F:M ratio, lbs BOD

applied/d / lb MLVSS

MLSS, mg/L

Conventional

5 15

0.2 0.4

1500 3000

Complete Mix

5 15

0.2 0.6

2500 4000

Step Feed

5 15

0.2 0.4

2000 3500

Modified Aeration

0.2 0.5

1.5 5.0

200 1000

Contact Stabilization

5 15

0.2 0.6

1000 3000
4000 10000

Extended Aeration

20 30

0.05 0.15

3000 6000

Changes in influent characteristics

Hydraulic overloading

Mechanical equipment failures

High Rate Aeration

5 10

0.4 1.5

4000 10000

Pure Oxygen

3 10

0.25 1.0

2000 5000

Oxidation Ditch

10 30

0.05 0.30

3000 6000

Single Stage Nitrification

8 20

0.10 0.25

2000 3500

Separate Stage Nitrification

15 100

0.05 0.20

2000 3500

Septic flows
Toxic loads
Organic overloads

This page is enlarged at the end of this section.

Aeration equipment
Pump or lift stations
Valves

Insufficient operator training

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Storm water infiltration does NOT improve plant efficiency

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Biological Reactors - The tanks where aerobic, anaerobic,

or anoxic conditions are created to produce healthy
mixed liquor and facilitate biological treatment processes.

Clarifiers - Sedimentation tanks used to remove

settleable solids in water or wastewater.

System Components

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Overview - Activated Sludge

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TDEC - Fleming Training Center

Section 1

Return Activated Sludge (RAS)

Mixed Liquor - A mixture of raw or settled wastewater

and activated sludge contained in an aeration tank or
biological reactor.

Suspended Solids - Insoluble solids that either float on the

surface of, or are in suspension in, water, wastewater, or
other liquid.

Mixed Liquor Suspended Solids (MLSS) The

concentration (mg/L) of suspended solids in activated
sludge mixed liquor.

Return Activated Sludge (RAS) - Settled activated sludge

returned to mix with incoming raw or primary settled
wastewater.

Biological Reactor

Clarifier

Return Activated Sludge

An important test for controlling the activated sludge process

RAS
Pump

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TDEC - Fleming Training Center

Waste Activated Sludge (WAS)

Waste Activated Sludge (WAS) - Solids removed from the
activated sludge process.

Biological Reactor

Clarifier

WAS

WAS

Also called Mean Cell Residence Time (MCRT)

Mixed Liquor Volatile Suspended Solids (MLVSS) - The

organic fraction of the suspended solids in activated
sludge mixed liquor that can be driven off by combustion
at 550 C.

To solids
handling
process

To solids
handling
process
9

Solids Retention Time (SRT) - The average time

suspended solids are held in a biological wastewater
treatment system.

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Microorganisms

Types of microorganisms present in activated sludge

depend on

Microbiology

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Composition of the wastewater

Length of the systems MCRT
pH
Temperature
DO concentration

Microorganism population type affects both activated

sludge characteristics and treatment potential.

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Overview - Activated Sludge

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Section 1

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What are Microbes?

Why are they important?

Bacteria

Norwalk
virus

Protozoa
Viruses

Algae
Metazoa-

Can cause disease

Role in environment

Crawling ciliate on activated sludge

floc

worms, rotifers

Fungi

Most immediate
importance

Major decomposers in
nature
Essential in a balanced
ecosystem

Poliomyelitis
Cyanobacteria
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Why are they important?

Viruses and Bacteria

Role in treatment systems

Removed in water treatment

Key role in wastewater treatment
Major role in problems & solutions to solid waste

Viruses

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Size Range of Microorganisms

Ciliate

Bacteria are the main workers in wastewater treatment

They are one of the simplest forms of life, use soluble food and
are capable of self-reproduction
Individual cells come in sphere (coccus), rod (bacillus) and
spiral (spirillum) shapes and range in size from 0.5 to 5.0
microns
About 95% of microorganisms in mixed liquor for activated
sludge systems are the bacteria.
Dont want to see many spiral, they are disease-causing
bacteria
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Most are soil bacteria.

For WW Treatment, bacteria are the most important
microorganisms in the process.

Most important

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Examples of Bacteria Found

in Wastewater

Genetic material + protein

coat
Reproduce only by infecting
cells of other organisms
Pathogenic

Bacteria

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TDEC - Fleming Training Center

10 300 m
Bacteria
Human Hair
sized 70-100 m or
0.003-0.004 inch,
(0.001 in = 25 m)

0.5 5.0 m

Flagellate
10 200 m

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Overview - Activated Sludge

Amoeba
30 500 m
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TDEC - Fleming Training Center

Section 1

Bacteria

Under ideal conditions, a bacterium can grow to maturity and

reproduce by binary fission in less than 30 min.

Generation Time: replication in PURE culture:

Two Types of Bacteria

Binary fission is the process by which one mature cell

divides into two new cells.

Heterotrophic and autotrophic bacteria differ in the

source of nutrition they require.

Heterotrophic:

Bacillus sp. (BOD eating bacteria) 20-30 minutes

Nitrifiers 22-48 hours
Methanogens 10-30 days

Autotrophic

Video of Bacteria Reproducing

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Humans
Protozoa
Most wastewater bacteria

All animals are heterotrophs, as are most microorganisms

(the major exceptions being microscopic algae and bluegreen bacteria).
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Domestic waste generally provides a good balance for the

microorganisms, industrial waste may not, which could lead to
filament growth.

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Biochemistry

Heterotrophs can also be further classified based ont

their oxygen requirements:

BOD: TKN:P
100:5:1

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Heterotrophic

Nitrogen, Phosphorus, micronutrients

Source is the Sewage and wastewater
Ideal Balance

Carbohydrates- sugar, starch, cellulose

Protein
Fat

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Nutrients

Organic food source

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Heterotrophic

Need organic carbon as their food source.

Nitrifiers
Algae
Higher plants

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Heterotrophic

CBOD removers
Denitrifiers

Aerobes require free DO to function

Anoxic use nitrogen bound oxygen like nitrate (NO3-) and
nitrite (NO2-), no free DO
Anaerobes thrive in the absence of free DO, use sulfate (SO4-)
or carbon dioxide (CO2)
Facultative bacteria prefer free DO but can function in its
absence

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Rotting, by heterotrophic bacteria:

C6H12O6 + Bugs + O2
More Bugs + CO2+ H2O
Glucose

Energy and
Nutrients

What is the formula backwards?

C6H12O6+ O2
CO2+H2O+ energy

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Overview - Activated Sludge

Section 1

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Autotrophic

Photosynthesis!

Use carbon dioxide (inorganic) as a carbon source

Autotrophic organisms take inorganic substances into
their bodies and transform them into organic
nourishment.

Dissolved

Chunky

Microorganisms Eating

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Step 1 Adsorb
Step 2 Enzymes
break down organic
matter into soluble
particles
Step 3 Absorb
Step 4 Waste
products (nitrogen gas
for some, carbon
dioxide, water and
stable matter) and
reproduce

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Micrograph of Floc and Filaments

Bacteria have a little tail, they swim around and eat food
Once food runs low, they loose their tail and start leaving
behind waste product that is sticky (polysaccharide slime)
This sticky waste makes them stick to other bacteria and
creates heavy floc
If high slug of BOD, they dont loose their tail, they
continue to swim around and dont have sticky stuff to
attach to them, therefore, the dont floc and settle out.

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Example: oats in oatmeal

Our body uses both foods

We eat and our stomach and gut breaks the chunky
food down into smaller dissolved food that our cells in
our bodies can use.
If you had to stay in the hospital and could not eat, they
would feed you dissolved food in the form of sucrose, a
sugar water.

Microorganisms

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Example: sugar in oatmeal

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Matter is not created or

destroyed, but its form is
changed.
Carbon goes from Carbon
dioxide to organic carbon
(food) and back in a
treatment plant.

Two types of food

Autotrophic bacteria make their own food, either by

photosynthesis (which uses sunlight, carbon dioxide and
water to make food) or by chemosynthesis (which uses
carbon dioxide, water and chemicals like ammonia to
make food - these bacteria are called nitrogen fixers and
include the bacteria found living in legume roots and in
ocean vents).
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The Carbon Cycle

Nitrifiers like Nitrosomonas and Nitrobacter are important

autotrophic bacteria.

Food

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Filamentous bacteria are not

floc formers but are also
of interest in WW
treatment.
Small amounts of them can
improve floc structure,
acting as a back bone,
providing mass to help in
settling after treatment.
Large amounts can
negatively affect
performance of activated
sludge systems by keeping
floc apart and which makes
it light and fluffy, therefore,
not settling well.
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Overview - Activated Sludge

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TDEC - Fleming Training Center

Section 1

Protozoa Found in the Activated Sludge

Process

Protozoa

Single-celled animals that also reproduce by binary fission

Have complex digestive systems that ingest organic matter, which they use as an energy and
carbon source
Protozoans are much larger than bacteria, their size ranges from 10-500 microns
They are an important link in the activated sludge food chain because they consume bacteria
to fill a large part of their nutritional needs.

This seems not only to remove excess bacteria from WW, but appears to stimulate the growth of
healthy bacteria, which produce floc more quickly and aid in the clarification of the effluent

Form cysts
Beneficial in wastewater treatment
Indicators of health of system

Examples:

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Much less abundant than bacteria, but very

important.
Require DO
Flagellate has a whip-like tail and competes with
bacteria

Indicative of young sludge

Stalked ciliates as adults, attach to something; as a

baby, has little hairs (cilia) to move around and
move water and food into mouth
Euglena has green algae in it that makes oxygen
when the sun shines.

Amoeba
Free-Swimming Ciliates - Paramecium
Crawling Ciliates
Stalked Ciliates
Suctoria

Video of MLSS

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Protozoa Free Swimming Ciliate

(Paramecium)

Protozoa - Amoeba
Video of
Amoeba
eating

Amoebas dont like being in WW, they encyst themselves

to make it through the system
Look like donuts
Can be found during plant start up or after a plant is
recovering from an upset.
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Free swimming ciliates generally are younger

biomass organisms but are common in many plants.
Cilia covers entire shape
Sufficient D.O.
Asexually & Sexually
Paramecium- 4.7 hours growth rate
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Protozoa Stalked Ciliates

Resemble crabs or ladybugs

May have some cilia but majority of body does not contain any
Croppers of biomass
Cirri (A bundle or tuft of cilia serving as foot or tentacle in
certain ciliate protozoa) are 4-5 cilia fused together
Very efficient feeders
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Protozoa Crawling Ciliates

They feed by drawing cells into their mouth with small cilia that create a visible twirling motion in the
sample.
Can be sessile or colonial
Length of stalk indicates age
Some will have a myenome (contractile muscle fiber with in stalk)
Some species will produce a daughter cell which resembles a free-swimming ciliate
Size of oral opening may indicate health of system / more bacteria smaller opening and less bacteria larger
opening
Single (vorticella) vs colonial (epystylis) does not mean one is better than other, they are all individual
species and grow based on the environment

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Overview - Activated Sludge

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Section 1

TDEC - Fleming Training Center

Protozoa Suctoria

Fungi and Algae

Fungi

Algae

Soil organisms
Degrade dead organic
matter (saprophytic)

These are the true vampires of the wastewater world

Tentacles may recoil in presence of increased ammonia
Some will have a stalk and others may not

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Metazoa

Multi-cellular animals

Multicellular
Slower growing
Typically larger than
protozoa
Sexual and asexual
reproduction
Heterotrophic
All are motile

Examples:

Rotifer
Water Mite
Water Bear
Nematodes
Ostracods

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Old sludge organism

Feeds on smaller protozoa
Does not like ammonia

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8 legs- with 2 claws on each for

holding

Water bears are typically not seen

in industrial waste treatment
systems
They have been sent to space as
part of the NASA program

Not found in presence of ammonia

above 5ppm

Extremely aerobic

Over 80% are female

Longer Sludge age
Low BOD, Sufficient D.O.
Tardigrade food*
Some move like snails others
resemble free-swimming ciliates

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Metazoa Worms

Simple multi-celled organisms

Need aerobic environment
Consume solid food including
bacteria
In lagoons, they eat lots of algae
Means happy, healthy population

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Metazoa Water Bear (Tardigrade)

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Metazoa - Rotifer

Unless there has been an

upset to the plant

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Photosynthetic
Eutrophication can cause algal
blooms in receiving streams
Key in operation of
wastewater ponds: produce
oxygen needed by bacteria
Nuisance in clarifiers, basins,
etc.

Multicellular organisms
Diseases (tapeworms,
roundworms)
Beneficial in trickling
filters (increase air
penetration in biofilm and
help in sloughing)

Ascaris and egg

Prefer rotifers as a food source

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Trickling filter

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Overview - Activated Sludge

TDEC - Fleming Training Center

TDEC - Fleming Training Center

Section 1

Metazoa Nematode

Metazoa Bristle Worm

Aquatic earthworms.
Fast moving.
The poke around the floc.
Older sludge organisms that reproduce slowly.
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Aquatic earthworm
They eat bacteria and protozoa.
They are relative active. They have red spot that are
not visible here but can turn biomass red colored.
They have the capacity to make your biomass
disappear.
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Good Settling

Bacteria Population vs. Sludge Age

Rotifers

Stragglers

Pin Floc
Nematodes
Rotifers
Stalked Ciliates

Stalked Ciliates

Relative Predominance

Rotifers
Free-Swimming
Ciliates

Nematodes

Free-Swimming
Ciliates

Stalked Ciliates

Rotifers

Free-Swimming
Ciliates

Stalked Ciliates

Flagellates

Flagellates
Amoeba

Amoeba

This page is enlarged at the end of this section.

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Microorganisms Predominance
If conventional plant and you start to see more rotifers
and less free-swimming ciliates, you need to increase
wasting to make old sludge go away/

If extended aeration plant and you have pin floc and

nematodes, you are holding your sludge too long.

If you see a predominance of amoebas and flagellates in

the microbial population, this is an indication of young or
recovering sludge.

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F:M

High
Low

Free-Swimming
Ciliates
Flagellates
Amoeba

Low
High

MCRT
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Phases of Microorganisms Life

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46

Free-Swimming
Ciliates
Flagellates
Amoeba

Exponential
Growth

Declining
Growth

Endogenous
Respiration

Number of Microorganisms

45

Flagellates
Amoeba

Time

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Overview - Activated Sludge

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Section 1

TDEC - Fleming Training Center

Phases of Microorganisms Life

Exponential Growth The number of microorganisms in
a culture broth will grow exponentially until an essential
nutrient is exhausted. Typically the first organism splits
into two daughter organisms, who then each split to form
four, who split to form eight, and so on
Declining Growth As food supply declines, the
microorganisms work harder to get their food.
Reproduction rates gradually slow down.
Endogenous Respiration There is inadequate food to
maintain the biomass. Some microorganisms starve and
die others use their own stored energy to live.

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Food-to-Microorganism Ratio (F:M) - The ratio of

organic loading to microorganisms in the activated sludge
system

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Bulking
Most plants operate right before endogenous respiration

Exponential
Growth

Declining
Growth

Endogenous
Respiration

Clouds of billowing sludge that occur throughout the

secondary clarifiers and sludge thickeners when the
sludge does not settle properly.

Number of Microorganisms

In the activated sludge process, bulking is usually caused by

filamentous bacteria or bound water.

Bulking activated sludges can be caused by:

Elevated levels of hydrogen sulfide

Low F/M
Nutrient deficiencies

Time
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Filaments

Filaments

Microorganisms act as a
kind of skeleton for the
floc.

An overabundance of
filamentous
microorganisms can cause
bulking sludge.

Some filamentous organisms are good, but too many are

bad
Filamentous organisms can form a network or backbone
upon which clumps of activated sludge can gather

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This produces a floc with excellent settling characteristics

If filaments become excessive, a bridging mechanism

forms and prevents the numerous small clumps of sludge
from gathering or packing together

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If they are prevented from clumping together, sufficient particle

mass will not be produced to achieve good settling rates

Activated sludge with good settling characteristics do not

have a predominance of filamentous bacteria.
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Overview - Activated Sludge

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TDEC - Fleming Training Center

Section 1

Filaments

Filaments

Specific conditions can allow a particular filamentous

organism to dominate.

Conditions that promote filamentous organism growth:

Chlorination may be used

for temporary control of
filamentous organisms.

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Filaments

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Thiothrix filaments are usually

attached to the flocs.
The sulphur globules are
very characteristic.
The sulphides are oxidised
and elementary sulphur is
temporarily stored in the
cell as an intermediary
product.

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Foaming Problems
White, billowy foam is
often caused by
surfactants.

These are the bright globules

that can be microscopically
observed.

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Foaming Problems

Filamentous bacteria also cause foaming.

Nocardia

Cl2

Filaments

RAS Pump

Dose of 1 10 mg/L and so that chlorine will be in contact

with RAS for ~ 1 min before mixing with incoming settled WW

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57

Consistently low DO in biological reactors ~ 0.4 0.7

High-BOD wastewater (for example, high-sugar, low nutrient
industrial wastewater)
Low F:M
Elevated levels of H2S
Low pH

Identified by true branching

FOG encourages growth

Development of white,
billowy foam is also
common under start-up
conditions.

Thick Nocardia Foam

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Overview - Activated Sludge

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11

Section 1

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Nocardia
Nocardia can be controlled by

Maintaining an MCRT <1 day in warm weather

Works with pure oxygen systems

Can be very difficult in nitrifying plants

Physical removal and disposal by skimming and disposal

Spray with chlorine

Process Goals
Successful activated sludge process performance is
judged by effluent quality.

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Activated Sludge Process Goals

Activated Sludge Process Goals

May have oxygen demand if

CBOD removal
it bypasses the plant or makes
Nitrification (where required)
it through plant and into
TSS removal
receiving stream
Maintaining neutral pH
Minimizing the amount of solids produced
Optimizing the energy used

How do we accomplish this?

cBOD removal

Nitrification (where required)

TSS removal

Aerate with adequate RAS and MCRT

Good settling characteristics
May have to add chemicals

Maintaining neutral pH

Minimizing the amount of solids produced

Optimizing the energy used

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Aerate with adequate RAS

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May have to add chemicals

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BOD Distribution

Oxygen Consumed

Nitrogenous BOD

Biochemical Oxygen Demand (BOD) Measure of

quantity of oxygen used in biochemical oxidation of
organic matter.

Can be divided into:

Carbonaceous BOD

cBOD carbon-based compounds

nBOD nitrogen-based compounds

Conventional activated sludge processes are designed to

remove only cBOD from wastewater.

Time
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Overview - Activated Sludge

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TDEC - Fleming Training Center

Section 1

Organic Matter Tests

Nitrification Reaction

BOD Biochemical Oxygen Demand

COD Chemical Oxygen Demand

5-day test on organic matter than can be biologically metabolized by

bacteria in a 300 mL bottle

NH4 + 1.5 O2
Ammonia

A 2-hour test that measures all organic carbon with the exception of
certain aromatics (benzene, toluene, phenol, etc.) which are not
completely oxidized in the reaction.
COD is a chemically chelated/thermal oxidation reaction, and therefore,
other reduced substances such as sulfides, sulfites, and ferrous iron will
also be oxidized and reported as COD.
NH3-N (ammonia) will NOT be oxidized as COD.

Nitrosomonas

Oxygen

NO2- + 0.5 O2
Nitrite

Oxygen

NO2- + 2 H+ + H2O + Energy

Nitrite

Nitrobacter

Acid

Water

NO3- + Energy
Nitrate

TOC Total Organic Carbon

A quick (less than 15 min) test to more accurately measure low levels of
organic matter.
TOC doesn't differentiate between that portion of organic carbon,
which can be metabolized (assimilated) and which cannot.

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Total Oxygen Demand

pH

NBOD + CBOD = Total

Oxygen Demand

Nitrogenous oxygen demand

is a measure of the oxygen
required by the nitrifying
bacteria to convert ammonia
nitrogen to nitrite and nitrate.
The combined requirement to
decrease CBOD and
nitrogenous BOD makes up
the total oxygen requirement
for the nitrifying activated
sludge process.

NBOD

Total
Oxygen
Demand

CBOD

A measure of the hydrogen ion

concentration in a solution.
The pH scale typically runs
0 to 14, with 7 being neutral.
When neutral pH levels are not maintained, there may be

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Inability to maintain a healthy biomass;

Potential damage to process equipment; and/or
Increased cost because of chemical addition.

During nitrification, alkalinity is needed to buffer the pH.

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Typical Activated Sludge Values

Parameter
BOD5
TSS
Ammonia
pH

Influent
100 300 mg/L
100 300 mg/L
10 30 mg/L
6.5 8.5

Effluent
5 20 mg/L
5 30 mg/L
< 2 mg/L
~ 7.0

Activated Sludge Process Modes

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Section 1

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Activated Sludge Process Modes

Plug Flow

Plug-flow (conventional)
Complete mix
Contact stabilization
Step feed
Extended aeration
Oxidation ditches
High-rate aeration
High-purity oxygen
Sequencing batch reactors

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Air Line

Effluent
Influent

RAS
WAS

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Criteria for a Plug-Flow Reactor

Plug Flow

High length-to width ratio;

Air flow rate minimized to meet specific treatment needs;
and
Fairly high wastewater velocity through the reactor.

Influent
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Raw wastewater goes in as a plug and leaves as a plug

Smaller foot print needed
Highest DO requirement at inlet
Highest F:M at inlet
F:M decreases as you go through the process
You must have a primary clarifier, State wont let you
otherwise

To
Clarifier
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Plug Flow Design Parameters

Application

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Complete Mix

Domestic and Industrial

BOD Removal Efficiency 85 95%

Aeration Type

Diffused or Mechanical

MCRT

5 15 days

Aeration Time

4 12 hours

Influent

MLSS

1500 3000 mg/L

RAS Flow

25 75% of influent

F:M
Organic Loading

0.2 0.4 lbs BOD/d/lbs MLVSS

20 40 lbs BOD/d/1000 ft3

Effluent

RAS
WAS

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Section 1

Criteria for a Complete-Mix Reactor

Low length-to-width ratio

High air flow rate or mixing power
Low velocity through the reactor

Complete-mix

Conventional plant but modified

If you take an MLSS sample at one corner, it should be the
same at the opposite corner
Can handle toxic loads or organic loads dilutes them
out

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If organic loads stop coming in, this could become a problem

80

Complete Mix Design Parameters

Application

Primary reason to have one of these

Oxygen demand same throughout

Needs lots of air and/or mixing
Susceptible to growth of filamentous bacteria due to
nutrient deficiency
TDEC - Fleming Training Center

Contact Stabilization

Domestic and Industrial

BOD Removal Efficiency 85 95%

Aeration Type

Mechanical

MCRT

5 15 days

Aeration Time

3 10 hours

Influent

MLSS

2500 4000 mg/L

RAS Flow

25 100% of influent

F:M
Organic Loading

0.2 0.6 lbs BOD/d/lbs MLVSS

50 120 lbs BOD/d/1000 ft3

Effluent

RAS

WAS

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Contact Stabilization Design Parameters

Contact Stabilization

Application

Modification of Existing Plant

BOD Removal Efficiency 80 90%

Aeration Type

Diffused or Mechanical

MCRT

5 15 days

Aeration Time

0.5 1.5 hour Contact

3 6 hours Reaeration

MLSS

1000 3000 mg/L Contact

4000 10000 mg/L Reaeration

RAS Flow
F:M

50 150% of influent
0.2 0.6 lbs BOD/d/lbs MLVSS

Organic Loading
83

60 75 lbs BOD/d/1000
TDEC - Fleming Training Center

If toxic load comes in, it will shock the contact tank and
not affect the stabilization tank
Both contact tank and reaeration tank are aerated

Reaeration tank is for RAS.

Contact tank is where the organic load is applied

ft3

No new food is added

Organisms must use stored energy, once used up, they begin searching
for more food, this is when they are moved on to the contact tank
Attempts to have microorganisms take in and store large portions of
influent waste in a short period of time (30-90 minutes)
Can avoid a complete wash-out when high flows or toxic load comes
in

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Section 1

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Step Feed

Step Feed - Variations

Biological Reactor
Effluent

Influent

RAS
WAS
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Step Feed Design Parameters

Step Feed

Application

Domestic and Industrial

Aeration Type

Diffused

MCRT

5 15 days

Aeration Time

3 6 hours Flow
5 7.5 hours Solids

MLSS
RAS Flow

2500 3500 mg/L

25 75% of influent

F:M

0.2 0.4 lbs BOD/d/lbs MLVSS

Organic Loading

40 60 lbs BOD/d/1000 ft3

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Step Feed

89

16

Advantages over conventional operation:

BOD Removal Efficiency 85 95%

Mode 1 works more like a conventional activated sludge

process to handle ordinary domestic flows

Less aeration volume to treat same volume of wastewater

Better control in handling shock loads
Potential for handling lower applied solids to the secondary clarifier

Then you have the flexibility to switch to Mode 2, 3 or 4 depending

on the quantity of industrial waste flows, seasonal WW or
temperature variations
Mode 1 should provide the best treatment with the longest
detention time for microorganisms to have contact with food and
aeration

Mode 4 works more like a contact stabilization plant during

peak flows resulting from storms or when treating strong
industrial wastes
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Step Feed

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Section 1

Extended Aeration

Extended Aeration Design Parameters

Application

Smaller Communities and Package

Plants

BOD Removal Efficiency 85 95%

Effluent

Influent

RAS
WAS

91

Aeration Type

Diffused or Mechanical

MCRT

20 30 days

Aeration Time

18 36 hours

MLSS
RAS Flow

3000 6000 mg/L

50 150% of influent

F:M

0.05 0.15 lbs BOD/d/lbs MLVSS

Organic Loading

10 25 lbs BOD/d/1000 ft3

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Oxidation Ditch

Oxidation Ditch

Horizontal Rotors
(or other aeration mixing device)

Brush rotor first oxidation ditch

Effluent Weir
To
Clarifier

(or other aeration mixing device)

High MCRT and low F:M

Influent

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To control DO, play with depth of water

Some brush rotors were covered to keep down air-borne diseases

Simple to operate
Velocity of 1 ft/sec
Large tank volume and high oxygen demand are disadvantages

Horizontal Rotors

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Requires more aeration energy than conventional or complete mix

Well stabilized sludge
Very low effluent BOD
Adaptable to nutrient removal

94

Murfreesboro Wastewater Treatment

Plant

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High Rate Aeration

Influent

Effluent

RAS
WAS

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Section 1

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High Rate Aeration Design Parameters

Pure Oxygen

Application

Industrial

BOD Removal Efficiency 75 85%

Aeration Type

Mechanical or Diffused (rare)

MCRT

12 24 days

Aeration Time

2 4 hours

MLSS

4000 10000 mg/L

AKA High Purity Oxygen

The modification of the activated sludge process which allows the
closest match between the amount of oxygen supplied and the
oxygen uptake rate of the mixed liquor

Surface Aerator

Exhaust Gas

Oxygen Gas

RAS Flow

100 500% of influent

F:M
Organic Loading

0.4 1.5 lbs BOD/d/lbs MLVSS

100 1000 lbs BOD/d/1000 ft3

MLSS to
Clarifier

Influent

RAS
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Pure Oxygen Design Parameters

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Pure Oxygen Facility

BOD Removal Efficiency 85 95%

Oxygen for this process

can be supplied by:

Aeration Type

Mechanical

MCRT

3 10 days

Aeration Time

1 3 hours

Application

Domestic and Industrial

MLSS

2000 5000 mg/L

RAS Flow

25 50% of influent

F:M
Organic Loading

0.25 1.0 lbs BOD/d/lbs MLVSS

100 200 lbs BOD/d/1000 ft3

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100

Pure Oxygen Facility

101

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Sequencing Batch Reactor (SBR)

Liquid oxygen is a fire hazard, comes delivered at -300F

Continuously control oxygen feed rate depending on how
active the microorganisms are
Always has a covered tank to prevent costly pure oxygen
from going off into the atmosphere, keeps it in the tank
Nitrification ability limited due to accumulation of CO2 in
gas headspace which causes low pH in mixed liquor

Trucked-in liquid oxygen

(LOX)
Cryogenic oxygen
generation
Pressure-swing adsorption
generation

Compact, simplified process

Flexible; operational changes for nutrient removal
Higher maintenance skills for instruments, automatic
valves and monitoring devices

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Section 1

1. Fill reactor is filled with

wastewater.

3.

2. React the wastewater is

aerated.

4.

Influent

Effluent

Influent

1.

Sequencing Batch Reactor (SBR)

WAS

Effluent

Effluent

Influent

Influent

WAS

2.

WAS
103

104

Influent

Effluent

5.

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Sequencing Batch Reactor Design

Parameters

Sequencing Batch Reactor (SBR)

5. Idle a portion of the
waste sludge is
removed with adequate
sludge left in the tank
to provide biomass for
the next treatment
cycle.

** Some degree of treatment is taking place in any phase. **

105

4. Decant treated
wastewater is removed.

WAS

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WAS

3. Settle MLSS is
separated.

Effluent

Sequencing Batch Reactor (SBR)

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Application

Smaller Communities

BOD Removal Efficiency 85 95%

Aeration Type

Diffused

MCRT

N/A

Aeration Time

12 50 hours

MLSS

1500 5000 mg/L

RAS Flow

N/A

F:M
Organic Loading

0.05 0.3 lbs BOD/d/lbs MLVSS

25 lbs BOD/d/1000 ft3

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Criteria for choosing the optimal

activated sludge process variation:

Construction capital availability

Land availability
Influent flow and loading considerations
Operational expertise available

Aeration

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Section 1

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Aeration

Biological Reactors

Aeration is a process that occurs naturally, not just in an

aerator
Two purposes:

Biological reactors provide oxygen and promote contact

with waste.
RAS maintains the microorganism population

To keep biomass, food and

oxygen in contact (mixing)
Oxygen supplied to bugs

Influent

RAS
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110

Aeration

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Pure Oxygen System

In biological reactors, adequate DO must be maintained.

The typical concentration range for most reactors is:

1.0 to 4.0 mg/L

Pure oxygen systems use

aeration equipment similar
to a conventional plant

Adding dissolved oxygen to the mixed liquor creates the

highest single electrical demand at most activated sludge
facilities

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112

Pure Oxygen System

Surface Aerators

An advantage of pure oxygen systems is that a smaller

reactor size is required

Disadvantages of pure oxygen processes:

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20

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Horizontal Rotor Surface

Aerator

Surface Aerator

Higher capital costs

Higher operating costs
Systems are more prone to operational problems
Additional safety concerns

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Section 1

Surface Aerators

Surface Aerators

Surface aerators generate a lot of splashing and mist

For surface aerators, the most common way to control

the DO and mixing is through the use of variable-speed
motors.
Typically, a two-speed motor is used.

Deflector plate keeps most spray from going up

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116

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Waste Sludge Options

Secondary
Effluent

Influent
RAS

Waste Activated Sludge Systems

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118

Waste Sludge Options

Waste
from
Reactors

Decrease the MLSS concentration

Decrease the MCRT

Increase the F:M ratio

Increase the SVI

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Wasting Rates

Increasing the wasting rate will:

Waste
from
WAS
Line

Separate
Waste Line
From Clarifier

The most important feature of a WAS pumping

system is its flexibility to allow different wasting rates.

Develop a wasting strategy that works best for your

facility.

Objective of wasting is to maintain a balance between the

bugs under aeration and the amount of food coming in.

If WAS rates are constant and BOD increases in the plant

influent, the F:M ratio will increase as well.
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Section 1

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Filamentous Populations
Low

Process Control

High
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122

Organic Tests

Temperature vs. Population

CBOD/BOD tests provide

a good indication of the
organic strength of a
wastewater.
Because of fairly long
detention times,
BOD/COD variations are
typically only of concern if
they last 24 hours or
longer.
Correlation between
BOD and COD

123

Date

BOD, mg/L COD, mg/L

10/1/2007

125

240

10/2/2007

120

231

10/3/2007

145

279

10/4/2007

136

262

10/5/2007

110

212

10/6/2007

100

192

10/7/2007

94

181

10/8/2007

112

215

10/9/2007

117

225

10/10/2007

119

229

10/11/2007

128

246

10/12/2007

138

265

10/13/2007

155

282

During cold weather,

treatment quality degrades
because of the slower
growth rates of
microorganisms.
This can be remedied by
the increase MCRT to
allow microorganisms
more time in the system
to grow and reproduce.

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MCRT and Temperature

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Temperature affects the size of the microorganism

population.

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Sludge Volume Index

The SVI is a measure of sludge settleability

Acceptable SVI target levels are no greater than 150 mL/g
and ideally less than 100 mL/g
High SVIs are associated with:

Filamentous bacteria
Young sludge
Industrial wastewaters, with nutrient deficiencies

SVI =

Increase MLSS will increase

the MCRT
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Overview - Activated Sludge

SSV30, mL/L x 1000

MLSS, mg/L
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TDEC - Fleming Training Center

Section 1

pH

Nitrification

Optimum pH ranges:

Nitrification consumes bicarbonate alkalinity

To convert 1 mg of ammonia to nitrite, approximately 7
mg of alkalinity are consumed.

Minimum alkalinity levels

Conventional Process: 6.5 8.5

Nitrifying Process: 7.0 8.0

50 mg/L where pH is adjusted automatically

100 mg/L pH is adjusted manually

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BOD ratios

Nutrient Deficiencies

The minimum ratio of BOD to nitrogen to

phosphorus is 100:5:1.

This is very critical:

When essential nutrient ratios drop, less-desirable

microorganisms begin to dominate.

BOD:N:P = 100:5:1
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130

Toxins

Industrial Wastes

Influent wastewater may contain constituents that can be

toxic to activated sludge microorganisms.

Biological treatment processes cannot easily adjust to great

fluctuations of flows and waste

These types of constituents are:

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Metals
Inorganics
Organics

Industrial wastes could inhibit the activity of

microorganisms in a treatment plant
Examples of industrial wastes:

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Heavy metals
Toxic wastes
Low pH
Organic Materials

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Section 1

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Recognition of a Toxic Waste Load

Operational Strategy for Toxic Wastes

The first indication of a toxic waste load within the treatment

plant is recognized by observing the aeration basin DO levels.

As the toxic load moves into and through the aeration basin, the DO
will increase significantly.
A DO increase without an increase in air input indicates that a toxic
waste load is killing the microorganisms in the aeration tank, thus
reducing the oxygen uptake by the microorganisms

The second indication of a toxic waste reaching the plant may

be observed in the secondary clarifier effluent.

133

135

If this action is taken promptly, it isolates in the secondary

clarifiers most of the bacteria affected by the toxic waste

The operator then significantly increases the WAS flow to

purge the activated sludge process of the toxic waste and
the sick or dead microorganisms.

134

As the high organic load moves into and through the aeration basin,
the DO will decrease significantly.
A DO decrease without an air input decrease indicates that the high
organic waste load is too great for the available microorganisms to
properly assimilate and metabolize the waste (food to
microorganism ratio is out of balance because of greater BOD
(food)).

The effluent will be more turbid (less clear) indicating that the waste
flow has not been adequately treated.

TDEC - Fleming Training Center

TDEC - Fleming Training Center

Operational Strategy for High Organic

Loads

A second indication of high organic waste reaching the plant

may be observed in the secondary clarifier effluent.

The operators primary mission in the case of toxic

wastes is to save the activated sludge system.
When the operator at the plant recognizes a toxic waste
condition, the RAS flow rate is reduced significantly.

TDEC - Fleming Training Center

The first indication of a high organic waste load within the

treatment plant is recognized by observing the aeration basin
DO levels.

The effluent will be to have floc carryover (an indication of cell

death)
The degree of carryover will depend on the substance and quantity
of the toxic waste.

Recognition of a High Organic Load

The operators primary mission in the case of high

organic loads is to improve the microorganisms
treatment efficiency.
The RAS flow must be significantly increase to provide
more microorganisms to the aeration contact basin to
adequately treat the high organic waste.
The rate of RAS increase must be accomplished gradually
so that both design hydraulic and solids loading rates for
the secondary clarifiers are not exceeded.
In addition, every attempt should be made to increase the
air or oxygen input to maintain proper DO levels in the
aeration basins.
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Biological Treatment
Biological treatment processes can not easily adjust to
great fluctuations of flows and/or wastes (BOD)

Dissolved Oxygen Control

137

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Section 1

DO Requirements

Low DO

For low-BOD wastewater, the minimum airflow rate is

often based on mixing rather than DO requirements.

Signs that low-DO conditions may be present:

Typically, oxygen requirements are met when the DO in

the mixed liquor is at 2 mg/L or more.

Dominance of low-DO filamentous bacteria

Turbid effluent
Gray or black mixed liquor

Filamentous bacteria may indicate low DO conditions.

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140

Turbid Effluent

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Black Mixed Liquor

Low DO can lead to effluent turbidity.

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142

Uniform Mixing

Over Aeration

Reactors should be monitored to ensure mixing is

uniform

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Overaeration can ensure adequate DO is available but

wastes energy.

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Section 1

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Solids

Solids Inventory and Control

145

It is important to account for and control the solids in

the activated sludge process.

As BOD is reduced, additional microorganisms are

produced.

Measuring flow and solids concentration allows

calculation of mass balances.

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146

Settleability

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Uncontrollable Settling

The settleability test conducted on the MLSS is an

estimate of how well solids will settle in the secondary
clarifier

Good Settling with

Diluted Settleometer

Excess Old Sludge

Glutted System

Two types:

Controllable Settling

Hydraulic Overload
Inadequate Sludge Return

Poor Settling with Diluted

Settleometer

Uncontrollable Settling

Bulking Sludge

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Secondary
Influent
Qinf
TSSinf
BODinf

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Solids Wasted
MLSS
MLVSS
Qinf + QR

Secondary
Effluent
Qeff
TSSeff

WAS
QW

WAS, lbs/day = (TSSW, mg/L)(QW, MGD)(8.34 lbs/gal) TSSW

Example: WAS flow of 200 gpm with a WAS TSS of 8050

mg/L
(200 gpm)(1440 min/day) /1,000,000 = 0.288 MGD

RAS
QR
TSSR

149

Slime
Filamentous

148

Solids Inventory

India ink stain shows slime bulking due to

nutrient deficient waste (exocellular
lipopolysaccharide slime)

WAS, lbs/day = (8050 mg/L)(0.288 MGD)(8.34 lbs/gal)

WAS
QW
TSSW
TDEC - Fleming Training Center

= 19,335 lbs/day WAS

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TDEC - Fleming Training Center

Section 1

Good Settling

F:M Ratio

Rotifers

Stragglers

One of the most important process control parameters is

maintaining the optimum amount of solids to remove
BOD from influent wastewater.

Pin Floc
Nematodes
Rotifers
Stalked Ciliates

Stalked Ciliates
Rotifers

BOD = food
Activated sludge solids = microorganisms

Relative Predominance

F:M Ratio

Free-Swimming
Ciliates

Nematodes

Free-Swimming
Ciliates

Amoeba

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152

F:M Ratio

MLSS
MLVSS
Qinf + QR

Flagellates
Amoeba

Free-Swimming
Ciliates
Flagellates
Amoeba

F:M

High
Low

Free-Swimming
Ciliates
Flagellates
Amoeba

Low
High

MCRT
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TDEC - Fleming Training Center

Conventional = 0.2 0.5

Nitrifying less than or equal to 0.10

F:M based on BOD measurements does not give

immediate process control feedback
Running averages of F:M provide useful monitoring input
F:M can be based on COD measurements when
immediate process feedback is required

Target F:MCOD = Target F:MBOD

BOD:COD

154

F:M Example

TDEC - Fleming Training Center

F:M Ratio

BODinf

145 mg/L

Calculated F:M

Result

Action

Qinf

15 MGD

Less than target F:M

MLVSS

2500 mg/L

Increase wasting
rate

Aerator Volume

2 MG

Too many
microorganisms in
process

Greater than target

F:M

Not enough
microorganisms in
process

Reduce wasting rate

F:M = (BODinf, mg/L)(Qinf, MGD)(8.34 lbs/gal)

(MLVSS, mg/L)(Aerator Vol, MG)(8.34 lbs/gal)

F:M = (145 mg/L)(15 MGD)(8.34 lbs/gal) = 0.44

(2500 mg/L)(2 MG)(8.34 lbs/gal)

155

Flagellates
Amoeba

Target F:M values

153

Stalked Ciliates

F:M Ratio

F:M = (BODinf, mg/L)(Qinf, MGD)(8.34 lbs/gal)

(MLVSS, mg/L)(Aerator Vol, MG)(8.34 lbs/gal)

Secondary
Influent
Qinf
TSSinf
BODinf

Rotifers

Flagellates

Food (BOD, lbs/day) divided by Microorganisms (MLVSS, lbs)

151

Stalked Ciliates

Free-Swimming
Ciliates

TDEC - Fleming Training Center

Excess sludge to waste:

Excess M to waste = Current M F (Food)

(Microorganisms)
F:M Target

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Section 1

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F:M Ratio

Excess Sludge to Waste Example

Excess sludge to waste:

Excess M to waste = Current M F (Food)

(Microorganisms)
F:M Target

Aeration Vol = 1,300,000 gal

MLSS = 2980 mg/L
%VS = 70%
Qinf = 3,190,000 gpd
COD = 115 mg/L
Desired F:M = 0.15 lbs COD/day/lb MLVSS

Wastewater formula book, pg. 10 has this as three

different formulas:

Desired MLVSS, lbs = BOD or COD, lbs

Desired F:M ratio
Desired MLSS, lbs = Desired MLVSS, lbs
% Vol. Solids, as decimal
SS, lbs to waste = Actual MLSS, lbs Desired MLSS, lbs

157

Aeration Vol = 1,300,000 gal

Qinf = 3,190,000 gpd
COD = 115 mg/L
Desired F:M = 0.15

MLSS = 2980 mg/L

%VS = 70%
Desired MLVSS = 20,396.86 lbs

TDEC - Fleming Training Center

Given the following data, use the desired F:M ratio to

determine the lbs SS to be wasted:
Aeration Vol = 1,300,000 gal
Qinf = 3,190,000 gpd
COD = 115 mg/L
Desired F:M = 0.15

TDEC - Fleming Training Center

* CCSS is the average clarifier core SS

concentration of the entire water
column sampled by a core sampler.

MCRT

Mean Cell Residence Time

MLSS = 2980 mg/L

%VS = 70%
Desired MLVSS = 20,396.86 lbs
Desired MLSS = 29,138.37 lbs

SS, lbs to waste = Actual MLSS, lbs Desired MLSS, lbs

= (2980 mg/L)(1.3 MG)(8.34) 29,138.37 lbs
= 32,309.16 lbs 29,138.37 lbs
= 3170.79 lbs to waste

160

MCRT

TDEC - Fleming Training Center

Excess Sludge to Waste Example

Desired MLSS, lbs = Desired MLVSS, lbs

% Vol. Solids, as decimal
= 20,396.86 lbs
0.70
= 29,138.37 lbs desired MLSS
159

Desired MLVSS, lbs = BOD or COD, lbs

Desired F:M ratio
= (115 mg/L)(3.19 MGD)(8.34)
0.15
= 20,396.86 lbs desired MLVSS
158

Given the following data, use the desired F:M ratio to

determine the lbs SS to be wasted:

TDEC - Fleming Training Center

Excess Sludge to Waste Example

Given the following data, use the desired F:M ratio to

determine the lbs SS to be wasted:

The average time a given unit of cell mass stays in the biological
reactor.
Higher MCRTs create higher MLSS concentrations
Lower MCRTs create lower MLSS concentrations

MCRT, days = Suspended Solids in System, lbs

SS Leaving System, lbs/day

MLSS, lbs
(MLSS, mg/L)(Aerator Vol, MG)(8.34)

Solids in
System
Solids
Leaving
System

CCSS*, lbs
(CC SS, mg/L)(Final Clarifier Vol, MG)(8.34)

(WAS SS, mg/L)(WAS Q, MGD)(8.34)

WAS SS, lbs + S.E. SS, lbs

(SE SS, mg/L)(Plant Q, MGD)(8.34)

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Section 1

MCRT

MCRT

Given the following data, use the information below to

determine the MCRT, days:
Aeration Vol = 1.5 MG
MLSS = 2460 mg/L
Final Clar.Vol = 0.11 MG
WAS SS = 8040 mg/L
PE Flow = 3.4 MGD
SE SS = 18 mg/L
WAS Pump Rate = 60,000 gpd
CC SS = 1850 mg/L
MCRT = (2460 mg/L)(1.5 MG)(8.34) + (1850 mg/L)(0.11 MG)(8.34)
(8040 mg/L)(0.06 MGD)(8.34) + (18 mg/L)(3.4 MGD)(8.34)

Note that when using this equation, the highly variable

solids concentration throughout the clarifier sludge
blanket can make this calculation difficult
If Clarifier Core Suspended Solids (CCSS) sample is not
taken, but you are given the clarifier volume, add that to
your aerator volume before figuring your MLSS lbs.
Target MCRT

= 30774.6 lbs MLSS + 1697.19 lbs CCSS = 32471.79 lbs

4023.216 lbs/d WAS + 510.408 lbs/d SE SS 4533.624 lbs/d

= 7.2 days
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MCRT

High Rate = 5 10 days

Conventional = 5 15 days
Nitrifying = 8 20 days
Extended Aeration = 20+
TDEC - Fleming Training Center

MCRT

Given the following data, use the information below to determine

the MCRT, days(same as previous, just missing the CCSS sample:
Aeration Vol = 1.5 MG
MLSS = 2460 mg/L
Final Clar. Vol = 0.11 MG
WAS SS = 8040 mg/L
PE Flow = 3.4 MGD
SE SS = 18 mg/L
WAS Pump Rate = 60,000 gpd
MCRT = ( 2460 mg/L ) ( 1.5 MG + 0.11 MG ) ( 8.34 )
(8040 mg/L)(0.06 MGD)(8.34) + (18 mg/L)(3.4 MGD)(8.34)

MCRT/solids inventory must be adjusted as temperatures

change.
Temperature changes affect

Metabolic rates of microorganisms

Oxygen transfer rates
Solids settling rates

= ( 2460 mg/L ) ( 1.61 MG ) ( 8.34 ) = 33031.404 lbs

4023.216 lbs/d WAS + 510.408 lbs/d SE SS 4533.624 lbs/d

MCRT

RAS Rate

Low
High

30 40% of influent
Up to 150% of influent

= 7.3 days

165

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166

Conditions to Avoid in Activated Sludge

Temperature > 35C

TDS > 50,000 mg/L
Ammonia-N > 480 mg/L
Sulfide > 25 mg/L
Surfactants > 100 mg/L

167

TDEC - Fleming Training Center

TDEC - Fleming Training Center

Effects of Temperature on Activated

Sludge
>35C
>40C
>43C
>35C

168

Overview - Activated Sludge

Deterioration of biological floc

Protozoa disappear
Dispersed floc dominated by filaments
Sharp decrease in zone settle velocity of
activated sludge

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Section 1

TDEC - Fleming Training Center

Foam and Scum

Very Dark or Black Foam

Stiff White Foam

Foaming

Thick Scummy
Dark Foam
169

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170

White Foam

TDEC - Fleming Training Center

Bad Day at the Plant

Stiff white foam is typically an indication of a high F:M,

possibly caused by:

High influent BOD, low MLSS high F:M

Detergents (surfactants) not being fully metabolized

171

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White Foam

173

30

172

TDEC - Fleming Training Center

White Foam Scenario 1

For a long-term solution

to stiff white foam:

Excessive stiff white foam can become a nuisance and hazard for
your facility.

Find the cause of the

problem
Figure out a way to alter
or eliminate the cause

TDEC - Fleming Training Center

Cause: High F:M ratio from a new process startup

Solution: Build up the biomass in the aerators as quickly
as possible by:

Maximizing the RAS rate

Reducing WAS rate
Maintaining adequate DO levels throughout the aerators

174

Overview - Activated Sludge

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TDEC - Fleming Training Center

Section 1

White Foam Scenario 2

White Foam Scenario 3

Cause: High F:M ratio due to toxic slug in the influent

causing biomass to die off
Solution: Rebuild biomass as soon as possible

175

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177

Short-term: correct pH by adding chemicals

Long-term: determine the cause and correct it

Cause: High F:M due to cold temperatures

Solution: Raise MLSS in aerators by:

TDEC - Fleming Training Center

Maximizing the RAS rate

Reducing WAS rate
Maintaining adequate DO levels throughout the aerators

TDEC - Fleming Training Center

TDEC - Fleming Training Center

White Foam Scenario 7

Cause: High F:M by insufficient RAS to aerators
Solution:

179

Reducing WAS rate

Increasing the RAS rate

178

Cause: High F:M due to solids loss in effluent

Solution: Rebuild biomass as soon as possible

TDEC - Fleming Training Center

White Foam Scenario 5

White Foam Scenario 6

Cause: High F:M ratio due to nutrient deficiencies

Solution: Adjust ratio of BOD:N:P to maintain 100:5:1

176

Cause: High F:M caused by high or low pH

Solution:

Maximizing the RAS rate

Reducing WAS rate
Maintaining adequate DO levels throughout the aerators
Also, investigate the source of the toxic load to prevent future
problems

White Foam Scenario 4

Make sure RAS flow is going to aerators

Make sure RAS pumps are operating
Make sure RAS flow meter is working
Check clarifier sludge blanket level

180

Overview - Activated Sludge

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Section 1

TDEC - Fleming Training Center

Nocardia Foam

Nocardia Foam

Nocardia foaming is a thick, greasy, dark tan foam

181

TDEC - Fleming Training Center

Nocardia foam is caused by a longer MCRT and low F:M

ratio
To correct a Nocardia foam problem in a conventional
system, increase wasting to raise F:M.
Nocardia already present in your system must be
physically removed
Nocardia foam can cause problems with aerobic digesters
and be returned to the reactors through recycled water.

182

TDEC - Fleming Training Center

Dark Foam
Dark or black foam is typically the result of insufficient aeration or
industrial wastes.

Ashing

183

184

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Clarifier Covered in Ash

Ashing

Ashing may occur when:

185

32

TDEC - Fleming Training Center

TDEC - Fleming Training Center

Denitrification is beginning to occur in the clarifier

F:M is extremely low and beyond normal extended aeration
Mixed liquor contains excessive levels of grease
Ashing may be a symptom of overoxidized (overaerated)
mixed liquor.

186

Overview - Activated Sludge

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TDEC - Fleming Training Center

Section 1

Clarifier with Dense Pin Floc

Pinpoint and Straggler Floc

187

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188

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Pinpoint Floc

Possible Causes of Pinpoint Floc:

Old sludge with poor floc-forming characteristics

Excessive turbulence shearing the floc

Straggler floc is indicative of a low MCRT.

Pinpoint Floc Strategy

189

If tests indicate your sludge is old, decrease MCRT by

increasing the WAS flow rate

TDEC - Fleming Training Center

Overview - Activated Sludge

33

Section 1

TDEC - Fleming Training Center

Design Parameters for Various Activated

Sludge Processes
Process

MCRT,
days

F:M ratio, lbs BOD

applied/d / lb MLVSS

MLSS, mg/L

Conventional

5 15

0.2 0.4

1500 3000

Complete Mix

5 15

0.2 0.6

2500 4000

Step Feed

5 15

0.2 0.4

2000 3500

Modified Aeration

0.2 0.5

1.5 5.0

200 1000

Contact Stabilization

5 15

0.2 0.6

1000 3000
4000 10000

Extended Aeration

20 30

0.05 0.15

3000 6000

High Rate Aeration

5 10

0.4 1.5

4000 10000

Pure Oxygen

3 10

0.25 1.0

2000 5000

Oxidation Ditch

10 30

0.05 0.30

3000 6000

Single Stage Nitrification

8 20

0.10 0.25

2000 3500

Separate Stage Nitrification

15 100

0.05 0.20

2000 3500

3
34

TDEC - Fleming Training Center

Overview - Activated Sludge

TDEC - Fleming Training Center

Section 1

Bacteria Population vs. Sludge Age

Overview - Activated Sludge

35

Section 1

TDEC - Fleming Training Center

Good Settling
Rotifers

Stragglers

Pin Floc
Nematodes
Rotifers
Stalked Ciliates

Stalked Ciliates

Relative Predominance

Rotifers
Free-Swimming
Ciliates

Nematodes

Free-Swimming
Ciliates

Stalked Ciliates

Free-Swimming
Ciliates

Rotifers

Flagellates

Amoeba

High
Low
46
36

Stalked Ciliates

Flagellates
Amoeba

Flagellates
Amoeba

Free-Swimming
Ciliates
Flagellates
Amoeba

F:M
MCRT
TDEC - Fleming Training Center
Overview - Activated Sludge

Free-Swimming
Ciliates
Flagellates
Amoeba

Low
High

TDEC - Fleming Training Center

Section 1

Activated Sludge Vocabulary

______1.
______2.
______3.
______4.
______5.
______6.
______7.
______8.
______9.
______10.
______11.
______12.
______13.
______14.
______15.
______16.
______17.
______18.
______19.
A.
B.
C.
D.
E.
F.
G.
H.
I.

Absorption
Activated Sludge Process
Adsorption
Aeration Tank
Aerobes
Anaerobes
Anoxic
Biomass
Bulking
Coagulation
Ciliates
Composite Sample
Denitrification
Diffuser
Endogenous Respiration
Facultative
Filamentous Bacteria
Floc
F/M Ratio

______20.
Heterotrophic
______21.
Mean Cell Residence Time
(MCRT)
______22.
Mechanical Aeration
______23.
Mixed Liquor
______24.
Mixed Liquor Suspended
Solids (MLSS)
______25.
Mixed Liquor Volatile
Suspended Solids (MLVSS)
______26.
Nitrification
______27.
Oxidation
______28.
Protozoa
______29.
Reduction
______30.
Rotifer
______31.
Septic
______32.
Sludge Age
______33.
Sludge Volume Index
______34.
Supernatant
______35.
Zoogleal

Clumps of bacteria and particles or coagulants and impurities that have come
together and formed a cluster. Found in aeration tanks, secondary clarifiers and
chemical precipitation processes.
When the activated sludge in an aeration tank is mixed with primary effluent or
the raw wastewater and return sludge, this mixture is then referred to as mixed
liquor as long as it is in the aeration tank.
Bacteria that must have molecular (dissolved) oxygen (DO) to survive. Aerobes
are aerobic bacteria.
The clumping together of very fine particles into larger particles (floc) caused by
the use of chemicals (coagulants).
This test is a measure of the volume of sludge compared to its weight. The
volume occupied by one gram of sludge after 30 minutes settling.
The organic or volatile suspended solids in the mixed liquor of an aeration tank.
This volatile portion is used as a measure or indication of the microorganisms
present.
Describes the organisms that use organic matter for energy and growth.
Animals, fungi and most bacteria are these.
The taking in or soaking up of one substance into the body of another by
molecular or chemical action (as tree roots absorb dissolved nutrients in the soil)
The addition of oxygen, removal of hydrogen, or the removal of electrons from
an element or compound. In wastewater treatment, organic matter is oxidized
to more stable substances.

Overview - Activated Sludge

37

Section 1

J.
K.
L.
M.
N.
O.
P.
Q.
R.
S.
T.
U.
V.

W.
X.
Y.
Z.
AA.
BB.
CC.
DD.

38

TDEC - Fleming Training Center

A device (porous plate, tube, bag) used to break the air stream from the blower
system into fine bubbles in an aeration tank or reactor.
Oxygen deficient or lacking sufficient oxygen, but nitrate is available.
A condition produced by anaerobic bacteria. If sever, the wastewater produces
hydrogen sulfide, turns black, gives off foul odors, contains little or no dissolved
oxygen and the wastewater has a high oxygen demand.
Microscopic animals characterized by short hairs on their front ends.
These bacteria can use either dissolved molecular oxygen or oxygen obtained
from food materials such as sulfate or nitrate ions. In other words, these
bacteria can live under aerobic or anaerobic conditions.
Bacteria that do not need molecular (dissolved) oxygen (DO) to survive.
Suspended solids in the mixed liquor of an aeration tank.
A situation where living organisms oxidize some of their own cellular mass
instead of new organic matter they adsorb or absorb from their environment.
An expression of the average time that a microorganism will spend in the
activated sludge process.
Clouds of billowing sludge that occur throughout secondary clarifiers and sludge
thickeners when the sludge does not settle properly. In the activated sludge
process, this is usually caused by filamentous bacteria or bound water.
A measure of the length of time a particle of suspended solids has been retained
in the activated sludge process.
A class of protozoans distinguished by short hairs on all or part of their bodies.
A biological wastewater treatment process that speeds up the decomposition of
wastes in the wastewater being treated. Activated sludge is added to the
wastewater and the mixture (mixed liquor) is aerated and agitated. After some
time in the aeration tank, the activated sludge is allowed to settle out by
sedimentation and is disposed of (wasted) or reused (returned to aeration tank)
as needed. The remaining wastewater then undergoes more treatment.
Food to microorganism ratio. A measure of food provided to bacteria in an
aeration tank.
Liquid removed from settle sludge. This liquid is usually returned to the influent
wet well or to the primary clarifier.
The tank where raw or settled wastewater is mixed with return sludge and
aerated.
A group of motile microscopic organisms (usually single-celled and aerobic) that
sometimes cluster into colonies and often consume bacteria as an energy source.
The use of machinery to mix air and water so that oxygen can be absorbed into
the water.
A mass or clump or organic material consisting of living organisms feeding on the
wastes in wastewater, dead organisms and other debris.
Jelly-like masses of bacteria found in both the trickling filter and activated sludge
processes.
The gathering of a gas, liquid or dissolved substance on the surface or interface
zone of another material.

Overview - Activated Sludge

TDEC - Fleming Training Center

EE.
FF.

GG.
HH.

II.

Section 1

Bacteria that grown in a thread or filamentous form. A common cause of sludge

bulking in the activated sludge process.
An aerobic process where bacteria change the ammonia and organic nitrogen in
wastewater into oxidized nitrogen (usually nitrate). The second-stage BOD is
sometimes referred to as the nitrogenous BOD (first stage is called the
carbonaceous BOD)
A collection of individual samples obtained at regular intervals, usually every one
or two hours during a 24-hour period. Each individual sample is combined with
others in proportion to the rate of flow when the sample was collected.
The anoxic biological reduction of nitrate nitrogen to nitrogen gas. An anoxic
process that occurs when nitrite or nitrate ions are reduced to nitrogen gas and
nitrogen bubbles are formed as a results of this process. The bubbles attach to
the biological floc in the activated sludge process and float the floc to the surface
of the secondary clarifiers. This condition is often the cause of rising sludge
observed in secondary clarifiers or gravity thickeners.
The addition of hydrogen, removal of oxygen, or the addition of electrons to an
element or compound. Under aerobic conditions (no dissolved oxygen present),
sulfur compounds are reduced to odor-producing hydrogen sulfide (H2S) and
other compounds.

Review Questions
1. In the activated sludge process, microorganisms convert organic matter to
_______.
a. New cells, carbon dioxide and water
b. New cells, ammonia and water
c. Carbon dioxide, water and nitrate
d. Carbon dioxide, water and chlorine
2. The basic components of the activated sludge process are _______.
a. Thickeners and digesters
b. Screens and clarifiers
c. Sand filters and chlorine contact chambers
d. Biological reactors and clarifiers
3. Solids that settle to the bottom of clarifiers and are pumped back to the head of
biological reactors are referred to as _______.
a. RAS
b. WAS
c. TSS
d. Total residual chlorine

Overview - Activated Sludge

39

Section 1

TDEC - Fleming Training Center

4. The amount of time that microorganisms spend in the activated sludge process
before they are wasted is called the _______.
a. Total residual chlorine
b. MLSS
c. MCRT
d. WAS
5. The process of reproduction where one mature cell divides into two new cells is
known as _______.
a. Cellular deduction
b. Binary fission
c. Bacterial degradation
d. Resectioning
6. Protozoans are _______.
a. Bacteria
b. Microscopic plants
c. Single-celled animals
d. Worms
7. Conventional activated sludge processes are designed to remove soluble
carbonaceous BOD from wastewater.
a. True
b. False
8. Return activated sludge is typically pumped back to which of the following?
a. The headworks
b. Primary clarifier
c. Influent side of a biological reactor
d. Effluent side of a biological reactor
9. The measure of biochemical or organic strength of wastewater is referred to as:
a. Total residual chlorine
b. TSS
c. BOD
d. F:M
10. Potential visual indicators of low DO concentrations include _______.
a. Presence of filamentous bacteria
b. Turbid effluent
c. Dark gray to black mixed liquor
d. All of the above

40

Overview - Activated Sludge

TDEC - Fleming Training Center

Section 1

11. The MCRT for most conventional activated sludge processes is typically _______.
a. 5 15 days
b. 5 15 hours
c. 20 30 days
d. 20 30 hours
12. RAS flow is typically a percentage of plant influent flow that is based on ______.
a. Temperature and pH levels
b. BOD and nutrient concentrations
c. Mean cell residence time
d. Inert solids and metal concentrations
13. Nitrification is a two step process. At the end of the second and final step, to
what has ammonia been oxidized?
a. Nitrite
b. Nitrate
c. Ammonium hydroxide
d. Nitric acid

Answers to Vocabulary
1.
2.
3.
4.
5.
6.
7.
8.
9.

H
V
DD
Y
C
O
K
BB
S

10.
11.
12.
13.
14.
15.
16.
17.
18.

D
U
GG
HH
J
Q
N
EE
A

19.
20.
21.
22.
23.
24.
25.
26.
27.

W
G
R
AA
B
P
F
FF
I

28.
29.
30.
31.
32.
33.
34.
35.

Z
II
M
L
T
E
X
CC

Answers to Review Questions

1.
2.
3.
4.
5.
6.
7.
8.
9.

A
D
A
C
B
C
A
C
C

10.
11.
12.
13.

D
A
C
B

Overview - Activated Sludge

41

Section 1

TDEC - Fleming Training Center

42

Overview - Activated Sludge

Section 2
Nutrient Removal

43

Section 2

TDEC - Fleming Training Center

Phosphorus and Nitrogen

Nutrient Removal

Phosphorus and nitrogen provide a

nutrient or food source for algae to grow

Algae in water is considered unsightly and

can cause taste and odor problems in
drinking water supplies
Dead and decaying algae can cause
serious oxygen depletion problems in
receiving streams

TDEC - Fleming Training Center

Fish kill
Unsightly appearance
Serious oxygen depletion
Taste and odor problems for drinking water supplies

TDEC - Fleming Training Center

44

Does not contain free or bound oxygen

compounds
Though, sulfate is considered to be in this
group

TDEC - Fleming Training Center

Eutrophication

Algal blooms can be caused by excess nutrient

levels.
Aquatic and marine dead zones can be caused by an
increase in chemical nutrients in the water, known
as eutrophication.
Chemical fertilizer is considered the prime cause of
dead zones around the world
The growth of excess algae in receiving streams is
not desirable. Algae can cause the following except

No free dissolved oxygen available

Chemically bound oxygen is present, such as
nitrite and nitrate

Anaerobic

Also called oxic

Free dissolved oxygen available

Anoxic

Nutrients

Aerobic

This oxygen can be free dissolved

oxygen or oxygen bound in other
substances like nitrate, nitrite or
sulfate
TDEC - Fleming Training Center

TDEC - Fleming Training Center

Oxygen Availability

Oxygen control is the key to

operating biological nutrient
removal processes
The microorganisms always require
some type of oxygen to support
their growth and reproduction

This can in turn cause fish kills

Oxygen Control

Combined with inorganic nitrogen greatly

increases algae growth

Nutrient Removal

Eutrophication is an increase in chemical

nutrients (compounds containing nitrogen or
phosphorus) in an ecosystem, and may occur
on land or in water.
However, the term is often used to mean the
resultant increase in the ecosystem's primary
productivity (excessive plant growth and
decay), and further effects including lack of
oxygen and severe reductions in water quality,
fish, and other animal populations.
Once algae blooms, it will die off and as the
algae decay bacteria will consume it and use up
all the oxygen.
TDEC - Fleming Training Center

TDEC - Fleming Training Center

Section 2

Eutrophication

Reversal of Dead Zones

Gulf of Mexico

Currently the most notorious dead zone is

a 8,543 mi region in the Gulf of Mexico,
where the Mississippi River dumps highnutrient runoff from its vast drainage
basin, which includes the heart of U.S.
agribusiness, the Midwest.
The drainage of these nutrients are
affecting important shrimp fishing
grounds.
This is equivalent to a dead zone the size
of New Jersey.

TDEC - Fleming Training Center

Dead zones are reversible.

The Black Sea dead zone, previously
the largest dead zone in the world,
largely disappeared between 1991 and
2001 after fertilizers became too costly
to use following the collapse of the
Soviet Union and the demise of
centrally planned economies in Eastern
and Central Europe.
Fishing has again become a major
economic activity in the region
TDEC - Fleming Training Center

Systems for Phosphorus Removal

Phosphorus Removal

Biological phosphorus removal

Lime precipitation
Filtration following aluminum sulfate

Generally speaking, phosphorous

levels in wastewater have dropped
due to phosphate detergent bans

TDEC - Fleming Training Center

Biological Phosphorus Removal

Most bacteria contain 1-2% Phosphorus

in their cell bodies
Phosphate accumulating organisms can
contain up to 5-7%

TDEC - Fleming Training Center

10

Biological Phosphorus Removal

Microorganisms found in
conventional activated sludge
processes use phosphorus within
their cell makeup

TDEC - Fleming Training Center

11

Nutrient Removal

Phosphorus is stored as a
polyphosphate.
The organisms store the maximum
amount of phosphorus in their cells
when they are in the aerobic zone
Then they are transferred to an
anaerobic zone

TDEC - Fleming Training Center

12

45

Section 2

TDEC - Fleming Training Center

Biological Phosphorus Removal

Biological Phosphorus Removal

To survive under anaerobic conditions,

the microorganisms must chemically
convert some of the carbon materials
in their cells to get the oxygen they
need for metabolism
The energy used in this process comes
from the polyphosphates they stored
in their cells

As a result, phosphorus is released from

the cell

TDEC - Fleming Training Center

13

TDEC - Fleming Training Center

Biological Phosphorus Removal

The sequence is repeated

Organisms are transferred to an anaerobic
stripping tank
Settled out in clarifiers and wasted with
biosolids

TDEC - Fleming Training Center

Anaerobic Selector

Primary
Effluent

15

TDEC - Fleming Training Center

Anoxic

Oxic

(Excess P
Uptake)

Clarifier

TDEC - Fleming Training Center

46

16

Lime Precipitation

(P released)

Aerobic Selector

RAS

Luxury Uptake of Phosphorus

Anaerobic

14

Biological Phosphorus Removal

They store much more than they need

for their life processes
This is called luxury uptake because
they take in more than they need
Then:

After releasing phosphorus, the

microorganisms are returned to the
aeration tank where food, oxygen
and phosphorus is plentiful
Since the bugs just used up
phosphorus to stay alive in the
anaerobic environment, the first
thing they want to do is take up and
store a large amount of phosphorus

17

Nutrient Removal

Lime is also known as calcium

hydroxide or Ca(OH)2
When lime is mixed with effluent
waters in a high enough concentration
to raise the pH to 11 or higher, a
chemical compound is formed
consisting of phosphorus, calcium and
the hydroxyl ion (OH-)
This compound can be flocculated to
form a heavier solid that can settle out
in a clarifier for phosphorous removal
TDEC - Fleming Training Center

18

TDEC - Fleming Training Center

Section 2

Lime Precipitation Sampling

Lime Feed System

Daily phosphorus tests should be

run on composite samples of
chemical clarifier effluent and also
secondary clarifier effluent to
compare results to determine:

Which pH setting works best?

Does the treatment plant meet effluent
discharge requirement for P?
Are you achieving your desired removal
efficiency?
TDEC - Fleming Training Center

19

Aluminum Sulfate Flocculation

The alum floc is difficult to settle out

and needs to be run through a pressure
filter or sand or mixed-media filter to
remove any remaining floc that does
not settle in the clarifier
TDEC - Fleming Training Center

TDEC - Fleming Training Center

When using
aluminum
sulfate as a
filtration aid,
dosages must be
precise
Operators must
rely on jar test
to accurately
dose their plant

21

TDEC - Fleming Training Center

22

Nitrogen

Nitrogen Removal

Nitrogenous compounds not only need to

be controlled to prevent algae growth, but
also:

To prevent adverse impact from ammonia

toxicity to fish life
Reduction of chlorine disinfection efficiency
Increase in DO depletion in receiving waters
Adverse public health effects

TDEC - Fleming Training Center

20

Aluminum Sulfate Flocculation

Aluminum sulfate can flocculate

effluent waters the same as lime
The compound that is created is
aluminum phosphate particles that
attach to each other and settle out

The lime feed system must operate

very reliably
Make frequent checks (several
times each shift) on the automatic
dry lime feed system, the mixing of
dry lime and water, the slurry
transfer to the rapid-mix basin and
the grit removal system that
removes sand from the lime slurry

23

Nutrient Removal

Mainly in groundwater being used for drinking

water where high levels of nitrate can hurt
newborn babies

Reduction in the waters suitability for reuse

TDEC - Fleming Training Center

24

47

Section 2

TDEC - Fleming Training Center

Systems for Nitrogen Removal

Nitrogen removal can be

accomplished by a variety of:

Systems for Nitrogen Removal

Operation Consideration

Physical Treatment Methods

Expensive

Sedimentation
Gas Stripping

Physical
Chemical and
Biological process

Chemical Treatment Methods

Ion Exchange
Biological Treatment Methods
Activated Sludge Process

Nitrification/denitrification
Ammonia stripping
Breakpoint chlorination

Trickling Filter Process

Rotating Biological Contactor Process

25

Land Treatment Process (Overland Flow)

Land Requirements.
Suitable Temperatures.
Wetland Treatment Systems
TDEC - Fleming Training Center
Control of plants.

Nitrification

26

Genera of Nitrifying Bacteria

The conversion of ammonia to

nitrate requires a large amount of
oxygen
Nitrification is a biological process
accomplished by two main types of
microorganisms

Operational control.
Additional cost for oxygen to
produce nitrification.

Oxidation Pond Process

TDEC - Fleming Training Center

Expensive

Breakpoint Chlorination

Most common:

System

Ammonia
Oxidizers

Nitrite Oxidizers

Nitrosomonas
Nitrobacter

Nitrosomonas
Nitrosococcus
Nitrosospira
Nitrosorbio

Nitrobacter
Nitrospira
Nitrococcus
Nitrospina
C - Ammonia oxidizers appear red
and Nitrospira appear green

TDEC - Fleming Training Center

27

TDEC - Fleming Training Center

Nitrification

48

Nitrification

These microorganisms are

autotrophic, which means they get
their food source from inorganic
sources, such as carbon dioxide
(CO2) and bicarbonate (HCO3-)
alkalinity

TDEC - Fleming Training Center

28

Step 1 Ammonia (NH3) or

ammonium (NH4+) gets converted
to nitrite (NO2-) by the
Nitrosomonas bacteria.

2NH4+ + 3O2 2NO2- + 2H2O + 4H

Ammonia

29

Nutrient Removal

Oxygen

Nitrite

TDEC - Fleming Training Center

Water

Strong Acid

30

TDEC - Fleming Training Center

Section 2

Nitrification

Nitrification

Step 2 The second step is

conversion of nitrite to nitrate
(NO3-) by the Nitrobacter bacteria.

2NO2Nitrite

O2

Oxygen

2NO3Nitrate

TDEC - Fleming Training Center

The proper conditions must exist for

Nitrosomonas to be able to separate the
nitrogen from the hydrogen in the
ammonium molecule and replace the
hydrogen with oxygen molecules.
There needs to be plenty of oxygen,
correct temperature and food for this
process to occur
Nitrobacter also rely on oxygen to
complete the stabilization of the nitrite
molecule into the more stable nitrate
substance

31

Effect of pH on the Rate of

Nitrification

TDEC - Fleming Training Center

Effect of Temperature on the

Rate of Nitrification

Growth rate increases

exponentially with
temperature

Optimum pH about 7.5 to 9.

TDEC - Fleming Training Center

33

Effect of Dissolved Oxygen on the

Rate of Nitrification

Maximum at 30-35C
Declines at 40C

Process variables that

an operator does can
adjust to compensate
for slower winter
growth rates in the
nitrification process

Adjust pH to higher
levels
Increase the MCRT
Increase the MLVSS

TDEC - Fleming Training Center

34

Nitrification

4.6 mg oxygen required per mg nitrogen oxidized

7.1 mg CaCO3 alkalinity depleted per mg nitrogen
oxidized

60-95F is optimum temperature for good

nitrification

TDEC - Fleming Training Center

32

35

Nutrient Removal

Can cause a pH drop if sufficient alkalinity is not

present

At lower temperatures, up to five times as much

detention time may be needed to accomplish complete
nitrification
Increase MLSS, MCRT and pH can help during winter
months

Alkalinity is the best water quality indicator to

monitor an enhanced nitrogen oxidation process

TDEC - Fleming Training Center

36

49

Section 2

TDEC - Fleming Training Center

Nitrification

Denitrification

Troubleshooting Example:

You ran tests on your effluent and you

have the following results:
Ammonia 3 mg/L
Nitrate 4 mg/L
Nitrite 21 mg/L

What do you think is happening here?

Biological denitrification is the

process where microorganisms
reduce nitrate (NO3-) to nitrogen
gas that is released to the
atmosphere
These bacteria are heterotrophic

2NH4+ + 3O2 2NO2- + 2H2O + 4H

Ammonia

Oxygen

2NO2Nitrite

Nitrite

O2

Water

Oxygen

TDEC - Fleming Training Center

Strong Acid

2NO3Nitrate

37

Denitrification

50

Step 1 Nitrate is reduced to nitrite

Step 2 Nitrite is reduced to nitric oxide (NO),
nitrous oxide (N2O) or nitrogen gas (N2)

TDEC - Fleming Training Center

40

Denitrification

This nitrogen
gas is the
released to the
atmosphere
once it gets to
an aerated tank
This can also
occur in primary
or secondary
clarifiers
TDEC - Fleming Training Center

39

Denitrification

38

Denitrification

When these microorganisms are

placed into an environment where
dissolved oxygen is not present but
there is food (BOD), they will reduce
nitrate to nitrogen gas by breaking the
bond between nitrogen and oxygen
This is how they get their oxygen
This reduction or breaking down is also
called microorganism dissimilation
TDEC - Fleming Training Center

TDEC - Fleming Training Center

41

Nutrient Removal

Optimum pH for denitrification is

7.5 to 9.0
Over the range of 5-30C, rate of
denitrification increases
exponentially with temperature
increases.
Denitrification can occur in
thermophilic range (50-60C).
Food concentration strongly
influences denitrification rate.
TDEC - Fleming Training Center

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TDEC - Fleming Training Center

Section 2

Denitrification

Nitrification vs Denitrification

2.9 mg oxygen released per mg

oxidized nitrogen removed
3.6 mg CaCO3 alkalinity recovered

Nitrification

Denitrification

TDEC - Fleming Training Center

43

Pre-anoxic zone with nitrate recycle

from aeration tank
On-Off aeration
Low D.O. operation

D.O. of 0.1 - 0.4 mg/L

D.O. of 0.4 mg/L appears below that
required by obligate aerobic low D.O.
filaments
Typical D.O. for low D.O. filaments is
0.5 1.0 mg/L
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45

44

Organic carbon source

with TCOD:TKN 7:1;
9:1 if P removal also.
Dissolved oxygen
concentration: optimal
N removal when rate of
nitrification equals rate
of denitrification at 0.5
mg/L
Floc size produces
D.O. penetrates floc,
separate zones within
theoretically to the center at
the floc
2.0 mg/L
Less D.O. provides anaerobic
center; anoxic if NO3- is available
TDEC - Fleming Training Center

46

Conventional or Plug Flow

Conventional or plug flow aeration

system
Complete mix activated sludge process
Contact stabilization
Extended aeration
Step-feed aeration
SBR
Attached Growth
Overland Flow
TDEC - Fleming Training Center

TDEC - Fleming Training Center

Process Modes for Biological

Nitrification/Denitrification

NO3 + cBOD N2
Get back 2.9 mg of O2 and 3.6 mg Alk

Factors Effecting Simultaneous

Nitrification/Denitrification (SNdN)

Denitrification Methods

NH4 + O2 NO2 + acid

NO2 + O2 NO3
Uses 4.6 mg of O2 and 7.1 mg of Alk

47

Nutrient Removal

This process is good

because of the flow
configuration and
detention time
pH levels may drop
during this
detention time
because nitrification
destroys alkalinity
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51

Section 2

TDEC - Fleming Training Center

Complete Mix

Contact Stabilization

Provides a uniform
dissolved oxygen
within the reactor
May be more
sensitive to pH
drops

This process is not ideal for

nitrification because:

TDEC - Fleming Training Center

49

Extended Aeration

An insufficient number of nitrifying

bacteria may be left in biomass from
separate RAS used in contact
stabilization
Main flow stream reactor is too small

TDEC - Fleming Training Center

50

Step Feed Aeration

Well suited for nitrification due to

long aeration time and the long
sludge age maintained

This can be used to accomplish

partial nitrification
Detention time is usually too short
to achieve complete nitrification
Biological Reactor

Effluent

Influent

TDEC - Fleming Training Center

SBR Stages
Operation

RAS

51

TDEC - Fleming Training Center

SBR Operating Guidelines

1.2 to 2 times ADF

Reactors

2 or more

Reactor Depth

10 to 20 ft (TWL)

Cycles/Day

2 to 6

F/M Ratio

0.02 to 0.05

MLSS Concentration
SRT

53

Nutrient Removal

2000 to 6000 mg/L

25-45 days

D.O. During React

52

52

of
Flow

TDEC - Fleming Training Center

WAS

1.0 to 3.0 mg/L

TDEC - Fleming Training Center

54

TDEC - Fleming Training Center

Section 2

SBR Advantages

SBR Advantages

Simplified process (final clarification

and RAS pumping not necessary)
Treatment occurring at all stages
Operating flexibility and control
(PLCs)
Compact-minimal footprint
Variety of WWTP sizes
Can retrofit existing WWTPs
TDEC - Fleming Training Center

55

SBR Limitations

TDEC - Fleming Training Center

Process control more complicated

Higher maintenance skills required

for instruments, monitoring devices,
valves, switches, etc.

Batch discharge may require

equalization before disinfection
TDEC - Fleming Training Center

57

Mixing during fill cycles is added

Preanoxic denitrification using BOD
in influent wastewater
Mixing during fill also improves
sludge settleability
Nearly all nitrate removed during
settle and decant steps (< 5 mg/L)

TDEC - Fleming Training Center

Nitrate concentration minimized

before settling
If enough nitrate is removed, an
anaerobic period can develop during
and after fill cycle
Readily degradable organics also
available for uptake and storage by
PAOs from influent wastewater

TDEC - Fleming Training Center

58

Nitrification using Attached Growth

Reactors: Trickling Filters

SBRs for Phosphorus Removal

56

SBRs for Nitrogen Removal

Very stable due to high sludge age

with long solids retention times
Quiescent settling enhances solids
separation (low effluent SS)
Operate as selector to minimize
sludge bulking potential
Reduced capital costs

59

Nutrient Removal

Most trickling filters not

designed for
nitrification
BOD must be low
(often 2-stage system)
Aerobic conditions
essential
Natural ventilation
often supplemented
with forced air
ventilation
Cover can decrease
temperature effects
and increase cold
weather performance.
BOD:N:P 100:5:1 key.

TDEC - Fleming Training Center

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53

Section 2

TDEC - Fleming Training Center

Denitrification with Attached

Growth Systems

Packed Tower for Nitrification

Tall trickling filter

with synthetic
media

Food source is needed for

denitrification units

Recirculation allows
for constant & even
distribution of WW

High carbon food

Constant flow &

appropriate oxygen
levels must be
monitored closely

Acetic acid
Citric acid
Methanol
Methane gas
Ethanol

Primary effluent

Diagram excerpted from Chapter 6: Nitrogen Remvoal. In Advance Waste Treatment.

TDEC - Fleming Training Center

61

Rotating Biological Contactors

Nitrate Recycle

Aerobic

Covers keep media insulated, protect biofilm from

rain, control odors
Monitor oxygen, alkalinity & nitrogen throughout
reactors
Nitrification takes place in the last stage or final
contactor in a series of contactors
Minimum 1-2 mg/L D.O. in solution at all times

TDEC - Fleming Training Center

64

Overland Flow

N2

Anoxic

63

Typical Biological Nutrient

Removal System

Anaerobic
Fermentation

62

Rotating Biological Contactors

Rotating shaft
surrounded by
HDPE media
(D=12 ft)
Zoogleal mass
grows on media
surface
Usually,
nitrification in last
unit(s) of train

TDEC - Fleming Training Center

TDEC - Fleming Training Center

Effluent

The water flows or trickles as sheet

flow through water-tolerant grass at
the soil surface effectively reduce
BOD and cause both nitrification
and denitrification to occur.

Return Sludge

Waste Sludge High

in Phosphorus
TDEC - Fleming Training Center

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65

Nutrient Removal

TDEC - Fleming Training Center

66

TDEC - Fleming Training Center

Section 2

Physical Nitrogen Removal Ammonia Stripping

Microbiological Summary

Energy
(cells)

BOD
O2
NH3

BNR System

CO2

N2
High P
solids

PO4-3

TDEC - Fleming Training Center

67

TDEC - Fleming Training Center

Physical Nitrogen Removal Ammonia Stripping

68

Physical Nitrogen Removal Ammonia Stripping

At normal temps and a pH of 7, ammonium ion

(NH4+) dominates
By feeding lime to increase pH to 10.8-11.5,
ammonium (NH4+) converts to dissolved ammonia
gas (NH3).

Ammonia nitrogen in the

gaseous ammonia (NH3)
form has a natural
tendency to leave the
wastewater and go into
the atmosphere
The bulk of ammonia in
wastewater comes in the
form of ammonium
(NH4+), which needs to
be converted to ammonia
by raising the pH

At 25 and pH 11, the percentage of ammonia is about

98%

Wastewater pumped to top of packed bed media

(wood or plastic).
Water droplets fall on media, releasing ammonia
gas as large amounts of air move through tower.

Calcium carbonate scale can plug media void spaces

& build up inside channels, pipes and pumps. Clean
with hot water or muriatic acid.

Diagram excerpted from Chapter 6: Nitrogen Removal. In Advance Waste Treatment.

TDEC - Fleming Training Center

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TDEC - Fleming Training Center

Chemical Nitrogen Removal Breakpoint Chlorination

Chemical Nitrogen Removal Breakpoint Chlorination

Ammonia nitrogen can be oxidized to

nitrogen gas (N2) through the use of
chlorine
Enough chlorine is added until the ammonia
nitrogen has been oxidized to nitrogen gas
Unfortunately, this takes a large amount of
chlorine to remove ammonia

For every 1 mg/L of ammonia nitrogen, 10 mg/L

of chlorine is needed

Therefore, this is normally used to remove

small amounts of ammonia still left in the
wastewater
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70

Zone 1- formation
of chloro-organic &
chloramine
compounds
Zone 2-destruction
of chloro-organic &
chloramine
compounds
Zone 3-formation of
free chlorine
residual
Diagram excerpted from Chapter 6: Nitrogen Removal. In Advance Waste Treatment.

71

Nutrient Removal

TDEC - Fleming Training Center

72

55

Section 2

TDEC - Fleming Training Center

Chemical Nitrogen Removal

Ion Exchange

Lemna Duckweed System

The ion exchange process is used to

remove undesirable ions from water
and wastewater.
The nitrogen removal process
involves passing ammonia-laden
wastewater downward through a
series of columns packed with
natural or synthetic ion exchange
resins
TDEC - Fleming Training Center

TDEC - Fleming Training Center

74

Allows evaluation of biological conditions

with or without DO available
Simple and cheap

TDEC - Fleming Training Center

Portable pH meter
ORP probe
Immerse probe in tank and read

Responds to chemical ion concentrations

75

ORP Control (Goronzy, 1992)

56

Sludge settleability
Filamentous organisms growth
Effluent BOD
Effluent suspended solids

TDEC - Fleming Training Center

76

Operations

Process

Range, mV

eAcceptor

cBOD oxidation

+50 to +200

O2

Poly-P production

+40 to +250

O2

Nitrification

+150 to +350

O2

Denitrification

-50 to +50

NO3-

Poly-P breakdown

-40 to -175

NO3-, SO4=

Sulfide formation

-50 to -250

SO4=

Acid formation

-40 to 200

Organics

Methane formation

-200 to -350

Organics

TDEC - Fleming Training Center

Oxidation Reduction Potential

The key to successful process

control of enhanced biological
systems is for liquid-solids
separation
Operators are not only able to
control nutrient removal, but also

Use of aquatic duckweed plants for

wastewater treatment
Used effectively as a polishing pond
after a conventional wastewater
treatment pond
The duckweed cover the polishing
ponds surface, preventing sunlight to
get to the algae and the algae die off
Duckweed are capable of removing
phosphorus and nitrogen from the
water

73

Enhanced Biological (Nutrient)

Control

Many operators have a tendency to

overreact to situations

77

Nutrient Removal

When making a process change,

remember that all processes reflect
changing influences of process recycle
flows as well as immediate changes
associated with influent conditions or
chemical reactions
After making a change, you should wait at
least 2-3 times the overall MCRT before
deciding if the change was beneficial

TDEC - Fleming Training Center

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TDEC - Fleming Training Center

Section 2

Biological Nutrient Removal

Review Questions
1.

Phosphorous is removed from wastewater treatment plant effluent so that

it will not combine with nitrogen and kill algae in receiving waters.
a. True
b. False

2.

The main reason lime is preferred over alum for the precipitation of
phosphorous is the lower cost of lime.
a. True
b. False

3.

Chemicals used to remove phosphorous from wastewater include all but:

a. Aluminum sulfate
b. Calcium hydroxide
c. Chlorine
d. Lime
e. None of the above

4.

Lime feeding equipment should be routinely checked:

a. Every hour
b. Several times during each shift
c. Once each shift
d. Three times a week
e. Once a week

5.

In the lime precipitation process for phosphorous removal, the pH of the

combined wastewater and lime slurry should be _______ or above.
a. 5
b. 7
c. 8
d. 9
e. 11

6.

Important variables the operator must control in the luxury uptake

process include all but:
a. Detention time in the anaerobic tank
b. Dissolved oxygen level in the stripping tank
c. Predominance of anaerobic microorganisms in the activated sludge
d. Primary effluent supply to the aeration tank
e. Stripping tank sludge recycle rate

Nutrient Removal

57

Section 2

58

TDEC - Fleming Training Center

7.

The key to operating selectors and biological nutrient removal systems is:
a. Mixing
b. Nitrogen
c. Oxygen
d. Phosphorous

8.

Generally speaking, phosphorous levels in wastewater have dropped due

to:
a. Better phosphorous removal processes
b. Changes in drinking water consumption
c. Increased phosphorous uptake by plants and aquatic life
d. Phosphate detergent bans

9.

After making a change in the operation of a biological treatment process,

how long does it take to properly evaluate whether the change was
beneficial?
a. One MCRT interval
b. Two to four days
c. Two to three times the MCRT
d. Until jar tests have been completed

10.

Nitrification is the process by which bacteria reduce nitrate to gaseous

nitrogen forms, primarily nitrous oxide and nitrogen gas.
a. True
b. False

11.

The recommended dissolved oxygen level for nitrification in a suspended

growth reactor is 2.0 to 4.0 mg/L.
a. True
b. False

12.

An anoxic reactor is one which is lacking in dissolved molecular oxygen

but may contain chemically bound oxygen.
a. True
b. False

13.

If cold temperatures are limiting the efficiency of a nitrification process,

the operator should increase the organic loading on the unit or decrease
the number of microorganisms.
a. True
b. False

Nutrient Removal

TDEC - Fleming Training Center

Section 2

14.

For nitrogen to be biologically removed from an effluent, the process must

consist of both nitrification and denitrification.
a. True
b. False

15.

pH levels may increase during nitrification because nitrification destroys

alkalinity.
a. True
b. False

16.

Nitrification is inhibited at low wastewater temperatures.

a. True
b. False

17.

Some of the harmful effects of discharging treatment plant effluent

containing nitrogen include all but:
a. Ammonia toxicity to fish in receiving waters
b. Increased dissolved oxygen depletion in receiving waters
c. Potential health hazards to newborn infants
d. Reduction in nutrients available to algae
e. Reduction of chlorine disinfection efficiency

18.

Which of the following activated sludge process modes is best suited for
nitrification in a suspended growth reactor?
a. Complete mix
b. Contact stabilization
c. Convention or plug flow
d. Modified aeration
e. Step-feed aeration

19.

Which of the following cant be used as a food source in an attached

growth (fixed film) reactor?
a. High carbon food
b. Methane gas
c. Methanol
d. Primary effluent
e. Secondary effluent

20.

An anaerobic or anoxic process will show an alkalinity loss whereas a

nitrifying process will show an alkalinity gain.
a. True
b. False

Nutrient Removal

59

Section 2

TDEC - Fleming Training Center

21.

Bulking activated sludge can be caused by all but:

a. Elevated levels of sulfide
b. High pH
c. Low BOD loading rates
d. Nutrient deficiencies
e. Septic wastewaters

22.

The required basic features of anoxic zones is:

a. Ability to completely drain basin for inspection and maintenance
b. Provisions for the buildup of an adequate sludge blanket
c. Sufficient mixing of contents to maintain the microbial solids in
suspension without transferring oxygen to the biomass
d. Recycling facilities to automatically control the MCRT
e. All of the above

23.

Disadvantage(s) of mechanical aeration include:

a. Creation of excessive turbulence
b. High heat loss in cold weather
c. High maintenance requirements
d. Noisy operation
e. A and C

24.

Acceptable SVI target levels are ideally less than _____ mL/g.
a. 200
b. 150
c. 120
d. 100

25.

The Sludge Volume Index (SVI) is a measure of:

a. Clarifier removal efficiency
b. Sludge settleability
c. Sludge volume in relation to clarifier volume
d. Sludge wasted in relation to sludge recycled

Answers:
1.
B
2.
A
3.
C
4.
B
5.
E
6.
C
7.
C

60

8.
9.
10.
11.
12.
13.
14.

D
C
B
A
A
B
A

15.
16.
17.
18.
19.
20.
21.

Nutrient Removal

B
A
D
C
E
B
B

22.
23.
24.
25.

C
B
D
B

Section 3
Odor and Corrosion Control

61

Section 3

TDEC - Fleming Training Center

WhatisOdor?
Itsmellslikemoneytome!
Freshwastewaterdoesnothaveanoffensive
odor

OdorandCorrosionControl

Chemical/physicalinteractionwitholfactory
hairs
Complex dependsonhumidity,temperature,
pH
Subjective notwopeopleperceiveodorsalike
Anaerobicdecompositionoforganic
compoundscontainingsulfurornitrogen
Twomajorculprits H2SandNH3
TDEC FlemingTrainingCenter

TDEC FlemingTrainingCenter

NeedforOdorControl

CharacteristicOdors

Withincreasedpopulation,collectionsystemsare
beingstretchedfartherandfartherawayfromthe
WWTP
Longercollectionsystemscreatelongerflowtimesto
reachtheWWTP
Increasedtraveltimescancausethewastewaterto
becomesepticandthereforecauseodorandcorrosion
problems

Alsowithincreasepopulation,thebufferzone
initiallyaroundaWWTPisbeingencroachedupon
withneighborhoodsbeingbuiltaroundWWTP
Goodhousekeepingisaneffectivemeansfor
controllingodors
TDEC FlemingTrainingCenter

OdorMeasurement

Formula
Ammonia
Cadaverine
Dibutylamine
Hydrogen
Sulfide
Indole
Thiocresol

NH3
H2N(CH2)5NH2
(C4H9)2NH
H2S
C2H6NH
CH3C6H4SH

Typical
ThresholdOdor,
Comments
mg/L
0.037
Sharp,pungent
0.24
Putrid,decaying
flesh

Fishy
0.00047
Rotteneggs

0.0001

Fecal
Skunk,rancid

Summaryofodorswecandetectfromvarioussubstancesandthethreshold
odorconcentration(thelevelatwhichournosefirstdetectsanodor)
TDEC FlemingTrainingCenter

SulfurCycle

Difficulttodefinenature,
cause,extentwithjust
thehumannose
FYI Tasteandodorare
closelyrelated

ThresholdConcentration
Level
Odorisdiluteduntilno
longerdetectable
Odorpanel(groupof
people)
Olfactometer(instrument)
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TDEC FlemingTrainingCenter

Odor and Corrosion Control

TDEC - Fleming Training Center

Section 3

TheMainCharacters

H2S HydrogenSulfide

H2SandNH3 areeasilyidentifiedandgiveoff
mostoffensiveodors
Difficulttomeasureinliquidphase
Volatile,tendtooffgaswhendisturbed
Moreeasilymeasuredinatmosphere

Colorless,combustible,toxicgas;heavierthanair
(S.G.=1.19)
Characteristicrotteneggodor
Butathighconcentrationsitisnotnoticeable

Cancausealmostinstantaneousunconsciousness,
permanentbraindamage(atconcentrations
commonlyfoundinunventedliftstations),oreven
death
AnaerobicbacteriareduceSO42 toHS

Manytypesoftest/monitoringdevices
Colorchangestripordisc
Electronicdevice(withorw/ohighalarm)
Datalogforrecordoflongtermexposure

HS goesintoequilibriumwithairlayer
Inwater,HS noproblem
Inair,HS becomesH2S

TDEC FlemingTrainingCenter

H2S HydrogenSulfide

TDEC FlemingTrainingCenter

SulfatetoSulfideConversion

HydrogensulfidecausesmostproblemsatapH<5
AtapHbelow5,allsulfideispresentinthegaseous
H2Sforandmostofitcanbereleasedfromwastewater
andmaycauseodors,corrosion,explosiveconditions
andrespiratoryproblems.

TDEC FlemingTrainingCenter

SulfatetoSulfideConversion

DO
ORP
BOD
Detentiontime
Temperature
SulfurConcentration

TDEC FlemingTrainingCenter

10

pHChart

DO,ORP,BOD,andDetentionTimeareall
related
AsDOincreases,ORPincreases(andviceversa)
BODaffectstheamountofDOinwastestream
DetentiontimesupportstheoxidationofBOD

Astemperatureincreases,reductionrateof
SO42 toHS increases
Reactionratedoublesevery10C(upto40C)
Areaswithhighertempshavemoreproblemsthan
areaswithlowertemps

Sulfurconcentrationrarelyalimitingfactor
TDEC FlemingTrainingCenter

11

TDEC FlemingTrainingCenter

Odor and Corrosion Control

12

63

Section 3

TDEC - Fleming Training Center

H2SToxicity

H2SCorrosion

Easilydetectableatlowconcentrations
Rotteneggodor

Willfatigueolfactorysystemevenatlow
concentrations
Ifyousmellhydrogensulfideandthenitgoesaway,
movequicklytoawellventilatedarea

Higherconcentrationswillmaskolfactorysystem
entirely
Alwaysuseagasmeter,thenoseisnotalwaysreliable

H2Sisbiologically
convertedtoH2SO4 inthe
presenceofwaterand
oxygen
Corrosionoccurs:pipe
crown,liftstations,
headworks,sludge
storageanddewatering,
andothers

Lengthofexposurevs.Concentration
Longtermexposureto10ppm vs.30min.at600ppm

DeathsduetoH2Spoisoninghavebeenreported
TDEC FlemingTrainingCenter

13

H2SCorrosion

14

NH3 Ammonia

H2SO4 attacks:

Toxic,distinctodor
Verycorrosive,especiallytocopper
Primarilyoccursinlimestabilizationprocess

Concrete
Pipefailure,trenchcollapse

Metal

IncreaseinpHwillincreaseNH3

Manholeladders,supportstructures

Electronics
Copperwiringconvertedtononconductivecopper
sulfide

TDEC FlemingTrainingCenter

TDEC FlemingTrainingCenter

15

Mostcommontreatmentisacidbased
scrubbers

TDEC FlemingTrainingCenter

16

PossibleControlStrategies
Minimizehydraulicdetentiontimeinpipesandwetwells
MaintainDOinthewastewater
Ensuringsufficientflowvelocitiestopreventsolids
depositioninpipelinesandchannels
Routinelycleaningstructurestoremoveslime,grease
andsludgeaccumulation
Treatingliquidandsolidsrecyclestreams
Changingorenforcingseweruseordinance
Routinelyandfrequentlydisposingofscreeningsandgrit
Immediatelyremovingfloatingscum/solids
Promptlyandthoroughlycleaningprocessunitsasthey
areremovedfromservice

ControlStrategies

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17

TDEC FlemingTrainingCenter

Odor and Corrosion Control

18

TDEC - Fleming Training Center

Section 3

ControlStrategies

ChemicalControls

Thereare2majormethodsofodorcontrol

Trytokeepsulfidesinaqueoussolution

Chemicaladditiontothewastewater
Mechanicalcontrolbyodorousairtreatment,
whereodorousvaporscanbecontainedand
collected

TDEC FlemingTrainingCenter

ManipulatesfactorsthatcontributetoH2S
formation:
DO
BOD
ORP
pH,etc.

19

ChemicalControls

TDEC FlemingTrainingCenter

Chlorine Cl2

Chlorination
Oxygenandaeration
Ozone
Chromate
Metallicions
Nitratecompounds
pHcontrol

Oftenusedtodestroyhydrogensulfideatthe
pointofapplication
8to10lbsCl2 for1lbH2S
DangeroustohandleCl2;bleachaddstocost
Strongbactericide
Reducesbacteriaresponsibleforsulfideproduction
byinhibitingthegrowthofbiofilminsidesewer
lines
CouldalsoneutralizebacteriainWWTP

TDEC FlemingTrainingCenter

21

Chlorine Cl2

TDEC FlemingTrainingCenter

22

Chlorine Cl2

Chlorinationisoneoftheoldestandmost
effectivemethodsusedforodorcontrol

ReactionbetweenCl2 andH2S

Chlorineisaveryreactivechemicalandoxidizes
manycompoundsinwastewater

ReactionbetweenCl2 andNH3

TDEC FlemingTrainingCenter

20

H2S+4Cl2 +4H2O H2SO4 +8HCl

23

NH3 +Cl2 NH2Cl+HCl(monochloramine)

NH2Cl+Cl2 NHCl2 +HCl(dichloramine)
NHCl2 +Cl2 NCl3 +HCl(trichloramine)

TDEC FlemingTrainingCenter

Odor and Corrosion Control

24

65

Section 3

TDEC - Fleming Training Center

Chlorine Cl2

Chlorine Cl2

Themostimportantrolesthatchlorineplaysin
controllingodorsareto
Inhibitthegrowthofslimelayersinsewers
Destroybacteriathatconvertsulfatetosulfide
Destroyhydrogensulfideatthepointofapplication
Thiscontrolsrequireslesschemicalthantryingtooxidize
theodoronceformed

Dosesashighas12mg/LCl2 forevery1mg/L
H2S(insolution,notintheatmosphere)maybe
neededtocontrolthegenerationofhydrogen
sulfideinsewers
DangeroustohandleCl2;bleachaddstocost

Thismeansthatchlorineshouldbeaddedinthe
collectionsystempriortotheplant
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HydrogenPeroxide H2O2

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HydrogenPeroxide H2O2

Widelyused,relativelysafetohandle
Nontoxicbyproduct(O2)

Reactsin3possiblewaystocontrolodors
Oxidantaction
ConvertsH2Stosulfatecompounds(SO4)

addstowastestreamDO

Oxygenproducing

Requiresgoodmixing,longcontacttime
typicaltohavemultiplefeedpoints
Canneed15minutesto2hoursofcontacttime

Lessthan5lbH2O2 per1lbH2S

Keepssystemaerobic

Bactericidaltothesulfatereducingbacteria
Killsbacteriathatproduceodors

Usuallya2:1to4:1ofH2O2 toS2 isneededfor

control
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HydrogenPeroxide H2O2

66

28

ORPAdjustment

Benefit:increasesDOandslowssulfide
formation
Typical5lbO2 to1lbH2S
Onlysuitableforforcemains
RequiresstorageandhandlingofliquidO2

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TDEC FlemingTrainingCenter

AlloftheoxidizingagentswillincreaseORP
ozonemaybeexception

Anothermethodmaybetoaddnitrate
upstream
BacteriaprefertotakeO2 fromnitrateinsteadof
sulfate
ReactionalsoaddsDOtosystemandraisesORP
Bioxide tradename,inwideuse

29

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Odor and Corrosion Control

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TDEC - Fleming Training Center

Section 3

Chromate CrO42

Ozone O3
Powerfuloxidizingagentthateffectively
removesodors
Toxic
Mustbegeneratedonsite($$$)
Veryshortcontacttime,lessthan1min
Rarelyused

Effectivelyinhibitthesulfatereductionto
sulfide.
Causeserioustoxicconditionsthatlimittheir
usefulness.

Although,WaterAuthorityofDicksonCounty
installedanozonegeneratorinMarch2012atone
oftheirliftstations.

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TDEC FlemingTrainingCenter

32

NitrateCompounds NO3

MetallicIons
Ironorzinc(mainly)hasbeenusedtoprecipitatesulfide
compounds.
Reactwithsulfidesandsettleout
Sulfurispermanentlyremovedfromwastestream
Zincisrarelyusedanymoreduetoeffluentandsludge
limitations

Hasatoxiceffectonbiologicaltreatmentsuchassludge
digestionandthereforehaslimitations
Inexpensive,safetohandle
Typicallyfedupstreamofproblemarea

Thefirstchemicalsusedintheanaerobic
breakdownofwastesarenitrateions
Ifenoughnitrateionsarepresent,thesulfate
ionswillnotbebrokendown
Thecostofthistypeoftreatmenttohalt
hydrogensulfideproductionisveryhighand,at
present,isnotpractical

Avg.4to5lbsironfor1lb sulfur

Disadvantages sludge,lowpH
Addedbenefit canalsoprecipitateoutphosphorus
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PotassiumPermanganate KMnO4
Verycostly
Rarelyusedinthisapplication
Noncorrosive,stable
Effectiveforwiderangeofodorcausingagents
Precipitatesoutsulfidecompounds

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TDEC FlemingTrainingCenter

34

pHControl Continuous
IncreasingthepHofthewastewaterisan
effectiveodorcontrolmethodforH2S
ByincreasingthepHabove9,biologicalslimes
andsludgegrowthareinhibited.
AnysulfidepresentwillbeintheformofHS ion
orS ionratherthanasH2Sgas,whichisformed
andreleasedatlowpHvalues

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Odor and Corrosion Control

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Section 3

TDEC - Fleming Training Center

pHControl ShockTreatment

pHControl

Shortterm,highpH(greaterthan12.5)slug
dosingwithsodiumhydroxideiseffectivein
controllingsulfidegenerationforperiodsofup
toamonthormoredependingonsewer
temperatureandsewerconditions

SmallpHdropcancauselargeshiftin
equilibrium(vaporvs.aqueous)
Limeandcausticsodamostcommonlyusedto
keeppHup
ContinuouscontroldisruptsWWTP
ShockpHtreatmentusedinstead
pHto12for10to20minorsotodestroybiofilm

Pipecrowncorrosionsometimescontrolledby
sprayingwithcausticsoda
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MetalPrecipitation
Reactwithsulfidesandsettleout
Sulfurispermanentlyremovedfromwastestream
Zincisrarelyusedanymoreduetoeffluentandsludge
limitations

Inexpensive,safetohandle
Disadvantages sludge,lowpH
Typicallyfedupstreamofproblemarea
Avg.4to5lbsironfor1lbsulfur
Addedbenefit canalsoprecipitateout
phosphorus
39

Safety

Personalprotectiveequipment
Properlockout/tagoutprocedures
Handlingchemicals
Secondarycontainment

68

Attempttoremoveorneutralizetheambient
vaporH2S
Covers,scrubbers,ventilation,anduseofnon
corrosivelinersorcoatings

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Covers

Safetyitemsthatshouldbeconsideredwhen
workingwithorinstallingchemicalodorcontrol
systemsinclude:

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MechanicalControls

Mostcommontreatmentmethod
Iron(orzinc)addedtowastestream

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41

Installedoverproblemareaandgeneratedgas
isventedoffandtreated
Inanaerobicdigesters,H2Sisremovedand
remainderofgasisusedasfuel
Materialsshouldbecorrosionresistant
Workwellforodorcontrol

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Odor and Corrosion Control

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TDEC - Fleming Training Center

Section 3

Scrubbers

ChemicalMistOdorControlSystem
Wetscrubber,nomedia
Bleachisrecirculated

Combinedwithcoverandventilation
Gasiscollectedandventedouttoscrubber

Packedbedofnoncorrosivemedia
Chemicalmisteddownfromtop
Gaspulledupfrombottom

Somearemultistage:separatesectionsfor
oxidation,pH,etc.
Effectiveforodorandcorrosioncontrol

KMnO4 andH2O2 canalso

beused
NaOHonlyusedwhenH2S
concentrationingasphase
ishigh

Softenedwaterisusedto
minimizescaling

Liftstations,clearwells,andother
Diagram excerpted from Chapter 1: Odor Control. In Advance Waste Treatment.
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44

PackedTowerScrubberwith
CountercurrentAirFlow
Oxidantused:

Chlorine
Sodiumhydroxide
Bleach
Hydrogenperoxide
Toremovehydrogensulfide

Sulfuricacid,diluted
Toremoveammonia

Diagram excerpted from Chapter 1: Odor Control. In Advance Waste Treatment.

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PackedTowerScrubber
withCrossAirFlow

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46

MoreScrubbers?
Biofilters
Mediaiscompostor
woodchips
H2Siscontrolled
biologically

Activatedcarbonfilters
Absorbsulfidesandother
odorcausingcompounds
Doesnothavethesame
capacityforodorremoval
ifregenerated
Diagram excerpted from Chapter 1: Odor Control. In Advance Waste Treatment.
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Odor and Corrosion Control

48

69

Section 3

TDEC - Fleming Training Center

ElectrolyticChemicalScrubber
UsingaBrineSolution

AnActivatedCarbonSystem

Diagram excerpted from Chapter 1:Odor Control. In Advance Waste Treatment.

Diagram excerpted from Chapter 1: Odor Control. In Advance Waste Treatment.

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TDEC FlemingTrainingCenter

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Ventilation
Wetwells,coveredtanks,coveredchannels
Introducesoxygentovaporphaseandkeeps
liquidphasefrombecominganaerobic
Bonus! providessafeenvironmentfor
operatorsandminimizesbuildupofflammable
orexplosivegases

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LinersandCoatings

ElectronicsProtection

Veryeffectiveatcontrollingcorrosion
Linersusedwidelytorepairdamagedpipes
Manytypes:

Degreeofprotectiondependsonseverityof
corrosionpotential
Achievedbyairtightenclosures,airconditioned
workspaces,corrosionresistantcoatings,and/or
nitrogenpurgedsystems

Slipliners
Curedinplacepipe
Specialtyconcrete
Epoxies

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53

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Odor and Corrosion Control

54

TDEC - Fleming Training Center

Section 3

MaskingAgents

MaskingAgents

Counteractants

Considerthis:

imposestronger,morepleasantodorover
problem

Nevermaskthe
odorofatoxic
substance
Notasubstitutefor
goodoperationor
housekeeping
Odorproblems
shouldbe
controlledattheir
source

Neutralizers
attempttocombinewithodorandreduceits
effect

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ProcedurestoSolveOdorProblems
Evaluationofplantperformance
Examinationofengineeringordesignfeatures
ofplant
Identificationofsourceorcauseofproblem
Onsiteinspectionandinvestigationofthe
problemareas

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Odor and Corrosion Control

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Section 3

TDEC - Fleming Training Center

Odor Control
Review Questions

72

1.

The most common source of sulfide in wastewater is biological activity in

the collection sewer or treatment plant
a. True
b. False

2.

The threshold odor level is the average level at which odors are
considered objectionable as measured by an odor panel
a. True
b. False

3.

Treatment plant operators develop educated noses and are usually able
to detect odors most other people would not notice.
a. True
b. False

4.

Adsorption is the taking in or soaking up of one substance into the body

of another substance.
a. True
b. False

5.

At a pH below 5, all sulfide present in wastewater is in the gaseous form.

a. True
b. False

6.

In a biological odor removal tower, odors will not be removed from the
gas stream until a biomass is established on the filter media.
a. True
b. False

7.

Chemical mist and packed bed odor control units are examples of wet
scrubber systems.
a. True
b. False

8.

Regenerated carbon has the same capacity for odor removal as new
carbon.
a. True
b. False

Odor and Corrosion Control

TDEC - Fleming Training Center

9.

Section 3

Besides chlorine, what other chemical(s) are used to control or prevent

odors?
a. Chlorophenol
b. Dichloramine
c. Hydrogen peroxide
d. Sodium hypochlorite
e. Both C and D

10.

Microorganisms that can use either molecular (atmospheric) or combined

(bound) oxygen are called:
a. Anaerobes
b. Facultative organisms
c. Obligate aerobes
d. Strictly aerobic microorganisms
e. Strictly anaerobic microorganisms

11.

Hydrogen sulfide causes the most serious problems at what pH range?

a. Less than 5
b. 5 to 7
c. 7, neutral
d. 7 to 9
e. Greater than 9

12.

Odors
a.
b.
c.
d.
e.

13.

Conditions that favor hydrogen sulfide production are also associated with
other problems such as:
a. Corrosion of concrete pipelines and manholes
b. Explosive gas mixtures
c. Respiratory hazards for operators
d. All of the above
e. None of the above

14.

Ways
a.
b.
c.
d.
e.

in AIR cannot be treated by:

Absorption
Adsoprtion
pH adjustment
Ozonation
None of the above

that chlorine controls odors include(s):

Destroying bacteria that convert sulfate to sulfide
Destroying hydrogen sulfide at the point of application
Inhibiting the growth of slime layers in sewers
All of the above
None of the above

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Section 3

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15.

Steps followed (not in order) in procedures used when attempting to solve

odor problems include:
a. Evaluation of plant performance
b. Examination of engineering or design features of plant
c. Identification of source or cause of problem
d. On-site inspection and investigation of the problem areas
e. All of the above

16.

Offensive-smelling inorganic gases found in treatment plants include:

a. Ammonia
b. Hydrogen sulfide
c. Mercaptans
d. Methane
e. A and B

17.

Safety items that should be considered when working with or installing

chemical odor control systems include:
a. Personal protective equipment
b. Proper lockout/tagout procedures
c. Handling of chemicals
d. Secondary containment
e. All of the above

18.

Oxidants commonly used in packed bed scrubber systems include all but:
a. Chlorine
b. Hydrogen peroxide
c. Ozone
d. Sodium hydroxide
e. Sodium hypochlorite

Answers:
1.
A
2.
B
3.
B
4.
B
5.
A

74

6.
7.
8.
9.
10.

A
A
B
E
B

11.
12.
13.
14.
15.

A
C
D
D
E

Odor and Corrosion Control

16.
17.
18.

E
E
C

Section 4
Secondary Effluent Solids

75

Section 4

TDEC - Fleming Training Center

Physical-Chemical
Treatment

Solids Removal

Secondary Effluent

TDEC - Fleming Training Center

Coagulation/Flocculation
Process

Nonsettleable
solids resist settling
due to particle size
& natural forces
between particles
Suspended,
colloidal (fine silt,
bacteria, viruses) &
dissolved (color,
chemicals)

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Destabilization adds chemicals to

change or neutralize charge of
particles

Certain chemical reactions occur quickly

resulting in the formation of very small
particles, usually called pinpoint floc

Including bacteria

TDEC - Fleming Training Center

The main purpose is to bring together

microfloc particles
TDEC - Fleming Training Center

Secondary Effluent Solids

The speed of the paddles becomes

very important

Flocculation follows coagulation and

consists of gentle mixing of the
wastewater

WW solids tend to have negative

charge

Flocculation Process

During the coagulation phase, chemicals

are added to the wastewater and rapidly
mixed with the water

Coagulation/Flocculation
Process

TDEC - Fleming Training Center

Coagulation/Flocculation
Process

Coagulation: clumping together of

very fine particles into larger particles
(microfloc) caused by the use of
chemicals (coagulant) added during
rapid mixing
Flocculation: gathering together of fine
particles after coagulation to form
larger particles (floc) by gentle mixing
Liquid/solids separation (gravity, DAF)

Too rapid a speed may mechanically

break up the floc
Too slow a speed may not provide
enough mixing and may promote dead
spots within the tank where mixing
does not occur
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TDEC - Fleming Training Center

Section 4

Liquid/solids Separation

Chemical Treatment

Liquid/solids separation step follows

flocculation and is almost always
conventional sedimentation by gravity
settling

Regardless of the form of chemical

treatment process, the most important
process controls are:

Although other processes are used

occasionally like DAF, gravity filtration
and membrane filtration

TDEC - Fleming Training Center

Chemical Treatment

Often, filters are installed after chemical

treatment to produce a highly polished
effluent
Chemicals can also be used as a bandaid effectively during problem situations

TDEC - Fleming Training Center

10

Aluminum Sulfate (Dry)

Aluminum Sulfate (Liquid)
Ferric Chloride
Lime
Polymers

TDEC - Fleming Training Center

12

Secondary Effluent Solids

The cationic (positively charged)

metals salts adsorb onto negatively
charged wastewater solids and
neutralize their negative charges

TDEC - Fleming Training Center

Aluminum Sulfate
(Alum)

11

Aluminum (3+) (alum) or iron

(3+)(ferric) metal salts are used to
coagulate wastewater solids

Reduce sludge bulking

Upstream equipment failure
Accidental spills entering the plant
Seasonal overloads

Chemicals Used to Improve

Settling

TDEC - Fleming Training Center

Chemical Treatment

Provide enough mixing energy to

completely mix the chemical with the
water
Control the mixing intensity during
flocculation
Control the chemical dose

Al2(SO4)3 14 H2O
Reacts with alkalinity in water to form
aluminum hydroxide as the precipitate
Works best at pH of 5.8 to 8.5 with
sufficient alkalinity
Dry alum: powder, lump form
Liquid alum: pH < 4; very corrosive
1 mg/L alum consumes 0.5 mg/L
alkalinity
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Section 4

TDEC - Fleming Training Center

Alum

Alum will support a bacterial growth

and cause sludge deposits in feed
lines if wastewater is used to transport
the alum to the point of application

13

Alum

These growths can clog feed lines

By keeping a velocity high enough to
scour the lines continuously, this
problem can be reduced

TDEC - Fleming Training Center

14

Ferric Chloride
(FeCl3)

15

Highly corrosive
Liquid is 35-45% strength; will crystallize at
30F
Effective over wider pH range than alum;
works better in cold water, forming heavier,
denser floc
Reacts with alkalinity to form iron hydroxide
(Fe(OH)3)
1 mg/L consumes 0.6 mg/L alkalinity
Decomposes in presence of light, producing
hydrochloric acid

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17

78

Full face respirator

Acid resistant goggles/
face shield
Rubber gloves and boots
Rubber suit/apron
Emergency eye wash and
shower (within 25 ft of
storage and feed
systems)

TDEC - Fleming Training Center

Lime (Ca(OH)2)

16

Chemical Handling Safety

A 1% solution will have a pH of 3.5

Overdosing of alum may decrease the
pH to a point that will reduce
biological activity
A lower pH may also allow chlorine to
further decrease the pH and affect the
aquatic life in the receiving streams

Calcium hydroxide or quicklime

Coagulate solids or adjust pH
Quicklime must be mixed with water
(slaked) before used
Heat generated when water is added
Inspect mixers and pumps daily for
wear
Irritates skin, eyes, lungs on contact
TDEC - Fleming Training Center

A Polymer Map

Polymers fed in
very small doses

Solutions made in
water prior to use.
High to very high
MW polymers
require several
hours to hydrate.

Polymer ionic charges charge density

TDEC - Fleming Training Center

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Secondary Effluent Solids

TDEC - Fleming Training Center

< 1%

TDEC - Fleming Training Center

Section 4

Polymers

Advantages

Little effect on pH

Make work better

in cold water with
low turbidity

19

Jar Testing Equipment

Disadvantages

Produces less
sludge

Overfeeding can
clog filters

Must clean up
spills immediatelyslick & often
corrosive (low pH)

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20

21

Accurately controls
dosage
Known amount of
chemical and water (1)
mixed using high
speed mixer (2)
Solution held in day
tank (3)
Metered output
ensures proper dosage
into WW (4)
Safety: dust dangerous
if inhaled or on contact
with skin/eyes

May draw directly

from storage tank
or diluted in
smaller tank then
fed

Positive
displacement
metering pump

TDEC - Fleming Training Center

22

Positive Displacement
Pumps

TDEC - Fleming Training Center

Liquid Chemical Feed

System

Dry Chemical Feed System

Most valuable tool

in operating &
controlling chemical
treatment process
Simulates
coag./floc. with
different chemicals
and/or doses
Full scale plant
operation may not
match results

TDEC - Fleming Training Center

Screw Feeder

Top: flexible rubber,

plastic or metal
diaphragm draws
liquid in and out.
When raised, suction
is exerted. When
depressed, liquid is
forced through the
discharge valve.

23

Bottom: easy to
adjust piston stroke
to regulate chemical
TDEC - Fleming Training Center
feed.

24

Secondary Effluent Solids

Maintains desired
output by varying
speed and/or amount
of time screw rotates
as chemical is
discharged
Must keep screw
clean
Chemical may cake
in hopper

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Section 4

TDEC - Fleming Training Center

Rectangular Sedimentation
Clarifiers

Mechanical Flocculators

25

Done in same or
separate tank as
sedimentation
Tapered flocculation
Paddle speed critical
Top: variation in paddle
size to control floc
shearing
Bottom: variable speed
drive unit

TDEC - Fleming Training Center

Circular Clarifiers

27

29

80

26

Rectilinear flow
Influent enters one end
Flow hits baffle & moves
by gravity to opposite
end where effluent
overflows outlet weirs
Settled sludge moved by
flights or bridge to
hopper
On return scraper skims
scum into trough

TDEC - Fleming Training Center

Tube Settler Module

Sludge collected at
center of conical base
Scum and oil removed
by radial arm at
surface
PM & visual inspection:
worn parts, corrosion,
proper operation
Hazards due to slips,
trips, drowning,
exposure to diseases,
electrocution

TDEC - Fleming Training Center

28

Causes of Short Circuiting

Water density due

to temperature or
suspended solids
differences
Strong winds
High inlet/outlet
velocities

TDEC - Fleming Training Center

TDEC - Fleming Training Center

Factors Considered in
Clarifier Design

Weir Overflow Rate, gpd/ft

Surface Overflow Rate, gpd/ft2

Detention Time, hrs

Solids Loading Rate, lbs/day/ft2

30

Secondary Effluent Solids

Shallow depth
sedimentation
Reduces settling time
Tubes of steel or
fiberglass
Allows basin to settle
larger flow
Requires more frequent
sludge removal

TDEC - Fleming Training Center

TDEC - Fleming Training Center

Section 4

Wastewater Filtration

31

Microscreens

Microscreens
Gravity Filtration
Synthetic Media Filter
Continuous Backwash, Upflow &
Deep-Bed Granular Media Filtration
Surface Filtration
Cross Flow Membrane Filtration
TDEC - Fleming Training Center

32

Gravity Filter Configurations

33

Deep bed filtration

One or more
materials and/or
grades of material
Most are rapid sand
filter with gravity flow
from top down
Most operate on
batch basis
Underdrain collects
filtered WW

Gravity Filter Configurations

TDEC - Fleming Training Center

34

Rapid Sand Filter

Straining occurs over

submerged section of
microfabric
20-25 m PE, PPE,
stainless steel wire, copper
or Teflon screen
Filters out very small SS,
decreases turbidity &
improves effectiveness of
disinfection
Blinding or clogging due to
iron or magnesium: clean
withCenterhot water or steam
TDEC - Fleming Training

Backwashing indicated by headloss

Backwashing a sand filter, treated water is used in
order to avoid contamination of the filter bed
Incomplete cleaning leads to formation of mudballs
After a proper washing, the head loss should be less
than 0.5 foot at start-up
For depth filtration the multimedia filter, the finer,
denser media (sand) is placed on the bottom with the
course, lighter media (anthracite) on the top.
The coarse media removes larger solids that would
quickly clog the finer media
The fine media will surface strain solids that penetrate
the full depth of the coarse media bed

TDEC - Fleming Training Center

Filter Operating Strategy

Calcium scaling can occur within the filter and on the

surface of the sand media granules when calcium ions
and sulfate or carbonate ions are present in the filter
influent flow.
Usually this happens when lime or sulfuric acid are
used for pH control.
Prevention or controlling of scaling can be
accomplished in several ways:
Use caustic in place of lime, or hydrochloric acid in place of
sulfuric acid in neutralization
Use scale retardant/dispersant available from water
treatment chemical suppliers
Keep sand bed moving whenever the influent flow is off by
introducing clean water, or wash the sand with clean water
for four hours before securing the filter.

35

TDEC - Fleming Training Center

36

Secondary Effluent Solids

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81

Section 4

TDEC - Fleming Training Center

Synthetic Medium Filter

Synthetic Medium Filter

Schreiber Fuzzy Filter:

wastewater flows upward
through polyvalinadene
media between a lower
fixed plate & upper
movable plate.
To clean, upper plate is
raised mechanically.
Flow to filter continues as
air is introduced to
scour/wash media
periodically (external
blower). Freed solids
continuously exit filter
during washing.

Clayton County, GA NE STP uses

five 7 X 7 filters handling up to
15 MGD at 30 gpm/sq ft.

TDEC - Fleming Training Center

37

38

Bottom Feed Cylindrical

Filter

TDEC - Fleming Training Center

40

41

82

TDEC - Fleming Training Center

Membrane Filtration

Membrane filtration processes are classified

on the basis of the size of the particle they
separate from the wastestream

TDEC - Fleming Training Center

Cloth membrane as filter media

removes fine particles
Each disk has 6 pie-shaped
sections mounted vertically to
hollow tube that collects filtered
effluent
Low head-gravity feed
Filter is static during filtering
Backwashes automatically base
on water level differential
Disks rotate only during cleaning
Maintains continuous filtration
during backwash

Membrane Filtration

Surface Filtration: Disk

Filters

Continuous backwash,
upflow, deep bed silica
sand media filter
Do not have to be taken
out of service for
backwashing
Fewer and/or smaller
filters due to
continuous
operation

39

Closed, self contained

unit
Small footprint
No odors or flies
Filter media is
compressible, so
porosity can be altered
Media life: > 10 yrs
No media loss

Microfiltration (MF)
Ultrafiltration (UF)
Nanofiltration (NF)
Reverse Osmosis (RO)

The separation technique involves a thin,

semipermeable membrane that acts as a
selective barrier that separates the particles
on the basis of molecular size
TDEC - Fleming Training Center

42

Secondary Effluent Solids

TDEC - Fleming Training Center

TDEC - Fleming Training Center

Section 4

Cross Flow Membrane

Filtration

Cross Flow Membrane

Filtration

WW pumped at high
velocity along surface
Driving force is
pressure differential
between WW side and
effluent side
Table: particle size &
mw retention
capacities for KOCH
membranes

45

Membrane Configuration

Have pores between UF and RO

Effective at removing salts

The tightest membrane process that allows

only water to pass through the membrane
Retains salts and higher molecular weight
components
Used for tertiary treatment producing water
with low BOD/COD and of near-potable
water quality
TDEC - Fleming Training Center

47

Membranes are housed in various types

of modular units
The basic types of membrane
configurations are:

46

Hollow Fiber Cartridge

Water
Alcohols
Salts
Sugars
TDEC - Fleming Training Center

44

Reverse Osmosis

Emulsified oils
Metal hydroxides
Proteins
Starches
Suspended solids

Examples of molecules that pass through the pores

Nanofiltration

Most common
Pore sizes range from 0.005-0.1 micron
Examples of particles that are retained are:

Cross Flow Membrane

Filtration

Have pores ranging from 0.1-2.0 microns

Less common

Ultrafiltration membranes

TDEC - Fleming Training Center

43

Microfiltration membranes

Tubular
Hollow fiber
Spiral
Plate and frame
Ceramic Tube or Monolith
TDEC - Fleming Training Center

Spiral Wound Module

Semi-permeable polymer
membrane
Water (permeate) passes through,
but solids are rejected
Membrane fouling due to oils and
greases
Chemically cleaned in place using
water, caustics, surfactants, &
acids prescribed by manufacturer
(2-3 times/week)
5-40 psi
3-10 yr membrane life
TDEC - Fleming Training Center

Pack large surface

area into compact
design.

Membrane cast on
non-woven polyester
flat sheets & put into
spiral modules.

Operate at 50-150 psi.

48

Secondary Effluent Solids

TDEC - Fleming Training Center

83

Section 4

TDEC - Fleming Training Center

Membrane Bioreactors

49

84

Membrane Bioreactors

Membrane
immersed in WW
Flat plate
microfiltration
Eliminates need
for secondary
clarification and
filtration
MLSS: 15,00030,000 mg/L

TDEC - Fleming Training Center

50

Secondary Effluent Solids

Sludge age > 40 days

Cleaned 2-3
times/year in place
>99.9% removal
bacteria & viruses

TDEC - Fleming Training Center

TDEC - Fleming Training Center

Section 4

Solids Removal from Secondary Effluents

Review Questions
1.

Coagulation is a process of gentle mixing to ensure contact between the

coagulant chemicals and the suspended particles.
a. True
b. False

2.

Dry alum is corrosive unless it absorbs moisture.

a. True
b. False

3.

The settling rate of particles is faster at a warmer temperature than it is at

a lower temperature.
a. True
b. False

4.

The conventional single-media filter bed commonly used in potable water

systems is generally unsatisfactory in removing solids found in wastewater
because of plugging.
a. True
b. False

5.

In a dual-media filter, the finer, denser sand is placed over the coarse
media, anthracite.
a. True
b. False

6.

Downflow filters are designed to remove suspended solids by either the

surface-straining method or the depth filtration method.
a. True
b. False

7.

The cause of mudball formation in a filter is inadequate oil and grease

removal by earlier processes.
a. True
b. False

8.

Growth of algae and slime in gravity filters can be controlled with

occasional applications of chlorine ahead of the filter.
a. True
b. False

Secondary Effluent Solids

85

Section 4

86

TDEC - Fleming Training Center

9.

The rate of flow through a granular media filter is expressed as the

surface loading rate.
a. True
b. False

10.

The performance of treatment chemicals during a jar test does not

depend on:
a. Chemical concentration
b. Mixing intensity
c. Method of application
d. Time of day sample is collected
e. Time of reaction

11.

The most critical water quality indicator influencing the performance of

polymers is:
a. Ammonia
b. Conductivity
c. Hardness
d. pH
e. Phosphate

12.

What could be the possible causes of the floc being too small in a
chemical coagulation and flocculation system?
a. Change in pH
b. Chemical feed pump adjusted too low
c. Improper chemical dosage
d. Paddle speed in flocculators too fast
e. All the above

13.

Which of the following tests should not be run daily for process control
when chemicals are used to reduce effluent suspended solids?
a. Chemical dosage
b. Chemical viscosity
c. Influent and effluent suspended solids
d. pH
e. All the above

14.

A jar test cannot be used to determine:

a. The most economical dosages
b. The pH of the sample
c. The plant response to wastewater changes by using lab equipment
d. What the clarity will probably be in the plant effluent
e. None of the above

Secondary Effluent Solids

TDEC - Fleming Training Center

Section 4

15.

Short-circuiting in a clarifier may be caused or made worse by:

a. Differences in the density of suspended solids in the influent
b. High inlet and outlet velocities
c. Strong winds blowing across the surface of the tank
d. Temperature differences within the tank
e. All of the above

16.

What is the one invariable requirement in all jar test procedures?

a. Chemicals of the highest possible purity should be used
b. Jar test apparatus must have at least 6 jars
c. pH of the samples must be within the range of 6.5 to 8.5
d. Test conditions should match actual plant conditions

17.

Clarifier efficiency is determined using:

a. Effluent grab samples
b. Influent and effluent 24-hour composite samples
c. Nephelometric measuring devices
d. 24-hour sludge accumulation (volume) measurements
e. None of the above

Answers:
1.
B
2.
B
3.
A
4.
A
5.
B

6.
7.
8.
9.
10.

A
B
A
A
D

11.
12.
13.
14.
15.

D
E
B
B
E

Secondary Effluent Solids

16.
17.

D
B

87

Section 4

TDEC - Fleming Training Center

88

Secondary Effluent Solids

Section 5
BOD5 /cBOD5

89

Section 5

TDEC - Fleming Training Center

TDEC Fleming Training Center

TDEC Fleming Training Center

Biochemical Oxygen Demand

This test measures waste loadings to treatment plants

BIOCHEMICAL OXYGEN
DEMAND

and evaluates the BOD-removal efficiency of treatment

systems.
The test measures the molecular oxygen utilized during a
specified incubation period for the biochemical
degredation of organic material (carbonaceous demand)
and the oxygen used to oxidize inorganic material such as
sulfides and ferrous iron.

Advanced Wastewater Treatment

It also may be used to measure the amount of oxygen used to

oxidize reduced forms of nitrogen (nitrogenous demand) unless

their oxidation is prevented by an inhibitor.

+ Food + Oxygen (O2)

(Bacteria)

TDEC Fleming Training Center

Measured
Indirectly

Measured
Directly

Carbon Dioxide
(CO2)

TDEC Fleming Training Center

Biochemical Oxygen Demand

Sampling and Storage

The method consists of:

Filling typically a 300-mL bottle with sample and dilution water until
overflowing
Measuring initial DO
Capping and incubating at 20 1C for 5 days 6 hours in the dark
to prevent photosynthesis that can produce DO
Measuring final DO
Oxygen depletion is calculated as Biochemical Oxygen Demand

Grab samples if analysis is begun within 2 hours of

collection, cold storage is unnecessary

If analysis is not started within 2 hours of sample collection, keep

sample at or below 6C (40 CFR 136) from the time of collection.

Standard Methods states 4C, but since 40 CFR 136 states 6C, go with

the Federal Rule of 6C

Begin analysis within 6 hours of collection.

Composite samples keep samples at or below 6C

during compositing.
Limit compositing period to 24 hrs

TDEC Fleming Training Center

TDEC Fleming Training Center

Sample Preparation and Pretreatment

Preparation of Seed Suspension

Check pH, if it is not between 6.0-8.0, adjust sample temp to 20

It is necessary to have present in each BOD bottle a

3C, then adjust pH to 7.0-7.2 using sulfuric acid or sodium

hydroxide

population of microorganisms capable of oxidizing the

biodegradable organic matter in the sample.

Always seed samples that have had their pH adjusted

Domestic wastewater, unchlorinated or otherwise undisinfected

If possible, avoid samples containing residual chlorine by

effluents from biological wastewater treatment plants, and surface

waters receiving wastewater discharges usually contain
satisfactory microbial populations.
The preferred seed is obtained from a biological treatment system
processing the waste.
In this case, use supernatant from settled domestic wastewater,
effluent from primary clarifiers, diluted mixed liquor from an aeration
basin, undisinfected effluent, or receiving water from below the
point of discharge.

sampling ahead of chlorination process

If sampling after disinfection, samples MUST be seeded

Samples supersaturated with DO samples containing DO

concentrations above saturation at 20C

To prevent loss of oxygen during incubation on such samples, reduce

DO to saturation by bringing sample to about 20 3C in partially filled

bottle while agitating by vigorous shaking or by aerating with clean,
filtered compressed air
No need to shake samples that are no supersaturated.
Recommend documenting initial DO and put on bench sheet that sample

When effluent or mixed liquor from biological treatment process is used

was supersaturated with DO

90

as a seed source, inhibition of nitrification is recommended.

BOD5/cBOD5

TDEC - Fleming Training Center

TDEC Fleming Training Center

Section 5

TDEC Fleming Training Center

Preparation of Dilution Water

Dilution Water Criteria

Check to ensure that the DO is at least 7.5 mg/L before using

Preferably run two blanks, beginning and ending of

water for BOD tests.

sample set

Add phosphate buffer, magnesium sulfate, calcium chloride

Dilution water blanks must meet quality control limits, <0.2

and ferric chloride solution to source water.

mg/L DO (preferably <0.1 mg/L)

Commercially available already mixed.

Otherwise discard and prepare fresh solution

Mix thoroughly and bring temperature to 20 3C.

Prepare dilution water immediately before use unless dilution

No seed or nitrification inhibitor is added for dilution water

water blanks show that the water is acceptable after longer

storage times

blank
Run one nitrification inhibitor (NI) blank per quarter or with

If the dilution water blanks show a DO depletion greater than 0.20

a new lot of NI, whichever is more frequent

mg/L, obtain a satisfactory water by improving purification or use water

from another source.

Total of two blanks

One dilution water blank at beginning
One dilution water blank at end

Water needs to be free of heavy metals, for example copper

If you purchase your water for dilution water, you should get a
certificate of analysis to show it is tested for and free of metals

TDEC Fleming Training Center

TDEC Fleming Training Center

Preparation of Dilutions

Preparation of Dilutions

Make at least 3 dilutions of prepared sample estimated to

Samples should be homogeneous

Mix sample while removing aliquot

produce a residual DO of at least 1.0 mg/L and a DO

uptake of at least 2.0 mg/L after a 5-day incubation.
Recommended sample volumes:

Pipette as fast as possible to prevent loss of solids

Pipette each sample dilution separately

Raw\settled sewage = 1.0 - 5.0 %

When pouring sample or dilution water into bottles, allow

8mg/L

Polluted river water = 25 - 100 %

10

Use wide bore pipette

Industrial wastes = 0.1 - 1.0 %

Oxidized effluent = 5.0 - 25 %

the water to flow down the sides of the bottle to prevent

air bubbles from becoming trapped in the bottle

6mg/L
1mg/L

First Dilution
2mg/L O2 demand

TDEC Fleming Training Center

Last Dilution
1mg/L O2 remaining

11

TDEC Fleming Training Center

12

Dilutions Prepared Directly in BOD Bottles

Addition of Seed Suspension

Fill each BOD bottle approximately 2/3

If seeding is used, add seed suspensions to the dilution

full with dilution water.

Add appropriate amounts of seed
suspension and nitrification inhibitor to
the individual bottles.

vessels or to individual BOD bottles before final dilution

Generally below samples will provide a suitable amount of

microorganisms
1-3 mL of settled raw wastewater or primary effluent
1-2 mL of at 1:10 dilution of MLSS

When a bottle contains more than 67%

(201 mL) of sample after dilution, nutrients

may be limited in the diluted sample and
subsequently reduce biological activity.
In such samples, add the nutrient, mineral
and buffer solutions directly to diluted
sample at a rate of 1 mL/L or use
commercially prepared solutions designed
to dose the appropriate bottle size.

Do not filter seed suspension before use

Always record the exact volume of seed suspension before use
The DO uptake attributable to the seed added to each bottle

generally should be between 0.6-1.0 mg/L, but the amount of seed

should be adjusted from this range to that required to provide GGA
results of 198 30.5 mg/L BOD

BOD5/cBOD5

91

Section 5

TDEC - Fleming Training Center

TDEC Fleming Training Center

13

TDEC Fleming Training Center

14

Addition of Nitrification Inhibitor

Addition of Nitrification Inhibitor

Seed all samples to which

Nitrification inhibitor
Prevents Nitrosomonas from oxidizing ammonia to nitrite,
preventing nitrogenous oxygen demand in the sample (CBOD
measurement).

nitrification inhibitor has been added.

The amount of seed should be
consistent with that required to
achieve GGA test results in the
range of 198 30.5 mg/L
If using 2-chloro-6(trichloromethyl)pyridene (TCMP)
do not add TCMP to BOD bottles
before they are at least 2/3 filled with
diluted sample

TDEC Fleming Training Center

Nitrification:
Nitrosomonas + NH3 + O2 NO2 Nitrobacter + NO2- + O2 NO3 Nitrogenous demand observed if these microbiologically mediated

reactions occur.

15

TDEC Fleming Training Center

Sealing of Bottles

Calibration

Complete filling of each bottle by adding enough dilution

Winkler titration - best; most accurate

Relies on chemistry

water that insertion of the stopper leaves no bubbles in

the bottle.
Mix the sample by turning the bottle manually several
times unless a DO probe having a stirrer is used
immediately to measure initial DO concentration.
As a precaution against drawing air into the dilution bottle
during incubation, use a water seal.

16

Probe: Air-saturated water

Reagent water at 20C shaken/aerated to saturate
Maximum DO at 20C ~ 9.00 mg/L
Meter result shouldnt vary greatly from the saturation point
Correct for pressure and/or altitude differences

By adding water to the flared mouth of special BOD bottles

Place a paper or plastic cup or foil cap over flared mouth

of bottle to reduce evaporation of the water seal during

incubation.

TDEC Fleming Training Center

17

TDEC Fleming Training Center

18

Calibration

Determination of Initial & Final DO

Probe: Water-saturated air (most common)

Air-calibration chamber calibrate at sample temperature.
Minimizes errors caused by temperature differences.
Keep interior of the chamber just moist -- not filled with water.
Typical for probes
Probe is stored in a constant humidity environment
Container should be sealed somehow (to maintain constant
humidity)

Determine the initial DO on all sample dilutions, dilution

92

water blanks and where appropriate, seed controls.

Replace any displaced contents with sufficient diluted sample or

dilution water to fill the bottle, stopper all bottles tightly, and water
seal before beginning incubation.
After preparing dilution, measure initial DO within 30 minutes.

Determine the final DO after 5 days 6 hours of

incubation in all sample dilutions and in all blanks and

checks

BOD5/cBOD5

TDEC - Fleming Training Center

TDEC Fleming Training Center

Section 5

19

TDEC Fleming Training Center

Sample Incubation

Quality Control Checks

Incubate at 20C 1C the stoppered and sealed BOD

Minimum residual DO and minimum DO depletion:

Only bottles, including seed controls, giving a minimum DO
depletion of 2.0 mg/L and a residual of 1.0 mg/L after 5 d of
incubation are considered to produce valid data

bottles containing desired dilutions, seed controls, dilution

water blanks and GGA checks.
Exclude light to avoid growth of algae in the bottles during
incubation

20

Because at least 2.0 mg oxygen uptake/L is required to give a

meaningful measure of oxygen uptake and at least 1.0 mg/L must

remain throughout the test to ensure that insufficient DO does not affect
the rate of oxidation of waste constituents.
Exceptions occur for reporting purposes only when the depletions for
tests using undiluted samples in all bottles fall below 2.0 mg/L and when
the residual in all dilutions is less than 1.0 mg/L
When using membrane electrodes for measuring DO, make

frequent calibration checks to ensure accurate DO readings.

TDEC Fleming Training Center

21

TDEC Fleming Training Center

22

Quality Control Checks

Quality Control Checks

Glucose-glutamic acid check

The GGA check is the primary basis for establishing accuracy and
precision of the BOD test and is the principal measure of seed
quality and set-up procedure.
Add nitrification inhibitor if seed is obtained from a source that is
nitrifying.
The resulting average BOD must fall in the range of 198 30.5
mg/L
Consistently high values can indicate the use of too much seed
suspension, contaminated dilution water or the occurrence of
nitrification
Consistently low values can indicate poor seed quality or quantity
or the presence of a toxic material.

Dilution water quality check

With each batch of samples incubate one or more bottles of dilution
water that contains nutrient, mineral and buffer solutions but no
seed or nitrification inhibitor.
This dilution water blank serves as a check on quality of unseeded
dilution water and cleanliness of incubation bottles.
Determine initial and final DO
The uptake in 5 days must not be more than 0.20 mg/L and
preferably not more than 0.10 mg/L
If the water blank exceeds 0.20 mg/L, discard all data for tests using this

dilution water or clearly identify such samples in data records.

If low values persist, prepare a new mixture of GGA and check the

sources of dilution water and source of seed.

TDEC Fleming Training Center

23

TDEC Fleming Training Center

Quality Control Checks

24

Calculations

Seed control
Determine the BOD of the seed suspension as for any other
sample
This is the seed control
Ideally, make 3 dilutions of seed such that the smallest quantity
gives at least 2.0 mg/L DO depletion and the largest quantity
results in at least 1.0 mg/L DO residual after 5 days of incubation.
Determine the DO uptake per milliliter of seed added to each bottle
using either the slope method or the ratio method.
For the ratio method, divide the DO depletion by the volume of the seed

in milliliters for each seed control bottle having a 2.0 mg/L depletion and
greater than 1.0 mg/L minimum residual DO and average the results.
Seed dilutions showing widely varying depletions per milliliter of seed (
30%) suggest the presence of toxic substances or large particulates in
the seed suspension.
In this case, check or change the seed source.

BOD5/cBOD5

93

Section 5

TDEC - Fleming Training Center

TDEC Fleming Training Center

25

TDEC Fleming Training Center

Calculations

Calculations

Plug data into equation:

If DO depletion is less than 2.0 mg/L and sample

concentration is 100% (no dilution except for seed,

nutrient, mineral and buffer solutions), actual seedcorrected, DO depletion may be reported as the BOD
even if it is less than 2.0 mg/L
When all dilutions result in a residual DO<1.0 mg/L, select
the bottle having the lowest DO concentration (greatest
dilution) and report

P = 2/300 = 0.00667
BOD5, mg/L = (7.3 5.2)
0.00667
BOD5, mg/L = 315 mg/L

TDEC Fleming Training Center

BOD, mg/L >

27

TDEC Fleming Training Center

Reporting

Reporting

Average the test results for all qualified bottles within each

Identify results in the test reports when any of the

dilution series

28

following quality control parameters is not met

Report the results as BOD5, if nitrification is not inhibited.

Dilution water blank exceeds 0.20 mg/L

Report results as CBOD5 if nitrification is inhibited.

GGA check falls outside acceptable limits

Test replicates show more than 30% difference between high and

Samples showing large differences between the

low values

computed BOD for different dilutions, for example, greater

than 30% may indicate the presence of a toxic substance
or analytical problems.

TDEC Fleming Training Center

Seed control samples do not meet the above criteria in all dilutions
Minimum DO is less than 1.0 mg/L

29

TDEC Fleming Training Center

Common Sources of Error

Common Sources of Error

Not adjusting pH to within 6.5 7.5

Adjustment not required if effluent is between 6.0-8.5
If pH is adjusted, samples must be seeded

Subtracting blanks
Not seeding when required
Seed strength not constant

Improper calibration of DO meter

Not analyzing GGA samples

Incubation temperatures not constant

Not evaluating for toxicity

Initial DOs above saturation

Improper calculations

Depletion criteria not met

Not depleting 2.0 mg/L
Final DO <1.0 mg/L

94

26

Water quality issues

BOD5/cBOD5

30

BOD Sample Analysis Report

TDEC - Fleming Training Center

Sample

Bottle
Number

Sample
mL's

Percent
Dilution

P = A/300

Seed
mL's
Added

Initial DO
D1

Analyst

Final DO
D2

Analyst

Section 5

DO
Depletion
D1 - D2

Seed
Control
Factor

Results
Read

BOD5,
mg/L

Report
BOD

Date

Dilution
Blank

Take DO depletion for each seed

control bottle and divide it by the
volume of seed used to get your
mg/L DO depletion per mL of seed.

Seed
Control
Average

GGA

Raw

Final

BOD5/cBOD5

95

Section 5

TDEC - Fleming Training Center

96

BOD5/cBOD5

Section 6
E. coli Testing

97

Section 6

TDEC - Fleming Training Center

Buttheirpresencemay
indicatethepresenceof
pathogenicorganisms

Comprisesalltheaerobic
andfacultativeanaerobic
gramnegative,
nonsporeforming,rod
shapedbacteriathat
fermentlactosewithin
48hours~35C
Coliformbacteriacanbe
splitintofecalandnon
fecalgroups
Thefecalgroupcangrow
athighertemperatures
(45C)thanthenonfecal
coliforms

Sampling

TDEC - Fleming Training Center

ColiformBacteria

TDEC - Fleming Training Center

MPNofcoliform
bacteriaareestimated
toindicatethe
presenceofbacteria
originatingfromthe
intestinesofwarm
bloodedanimals
Coliformbacteriaare
generallyconsidered
harmless

Clean,sterilizedborosilicate
glassorplasticbottlesor
sterileplasticbags.
Leaveampleairspacefor
mixing.
Collectsamples
representativeofwastewater
tested.
Useaseptictechniques;avoid
samplecontamination.
Testsamplesassoonas
possible.

ApprovedMethods

TDEC - Fleming Training Center

Bacteriological
Analysis

TDEC - Fleming Training Center

ColiformBacteria

MembraneFiltration

Coliform(fecal)

Numberper100mL

Multipletub/multiplewell(Colilert)
Membranefiltration
mColiBlue24
ModifiedmTEC agar

TDEC - Fleming Training Center

Membranefiltration
E.coli

TDEC - Fleming Training Center

Numberper100mL

6
M-ColiBlue24 Membrane Filtration Method, Hach Company, www.Hach.com

98

E. coli Testing

TDEC - Fleming Training Center

Section 6

Waterbathorair
incubatoroperatingat
appropriate
temperature
Vacuumpump
UVsterilizerorboiling
waterbath
1015Xdissecting
microscope;should
havefluorescent
illuminator
Alcoholburner

TDEC - Fleming Training Center

MembraneFiltrationEquipment

TDEC - Fleming Training Center

MembraneFiltration

M-ColiBlue24 Membrane Filtration Method, Hach Company, www.Hach.com

A100mLvolumeofsampleisfilteredthrougha47mm
membranefilterusingstandardtechniques.
Filteristransferredtoa50mmpetriplatecontainingan
absorbentpadsaturatedwithmFC Broth.
Invertfilterandincubateat44.50.2Cfor24hrs.
Countbluecolonies.
Interferences
None,butexcessparticulatesmaycausecoloniestogrow
togetheronacrowdedfilterorslowthesamplefiltrationprocess.

10

FecalColiform

TDEC - Fleming Training Center

FecalColiform

TDEC - Fleming Training Center

FecalColiform

11

E. coli Testing

Maximumholdtimeis8hrs at<10C
Idealsamplevolumeyields2060colonies
Samples<20mL,add10mLsteriledilutionwater
tofilterfunnelbeforeapplyingvacuum.
Sanitizefunnelbetweensamples.
Visuallydeterminecolonycountsonmembrane
filters.
Verifyusing1015Xbinocularwidefield
microscope.

TDEC - Fleming Training Center

Sterilegraduated
cylinder
Sterilepipets
SterileMFfiltrationflask
Steriledilutionwater
Sterilesamplevessels
Samplescontaining
chlorinemustbetreated
with3%sodium
thiosulfatesolution
mFCBroth

TDEC - Fleming Training Center

MembraneFiltrationSuppliesand
Glassware

12

99

Section 6

TDEC - Fleming Training Center

Fecalcoliformsappearblue.
Colonies=colonyformingunit
=cfu

NPDESpermitlimit:
monthlyaverageof200
cfu/100mL;dailymaximum
of1000cfu/100mL.

Escherichiacoli(E.coli)
Colilert

13

TDEC - Fleming Training Center

Incubationtimeis24 2
hrs.
Fecalcoliformdensity
reportedasnumberof
coloniesper100mLof
sample.

TDEC - Fleming Training Center

FecalDataInterpretation

14

Colilert &Colilert18

TechniquesforMeasuring

MPNMethod

MostProbableNumber(MPN)

Addsubstratetoa
100mLsample
Ifmakingdilutions,
usesterileDIwater,
notsterilebuffered
water.

TDEC - Fleming Training Center

mColiBlue24
mTECAgar

15

Colilert &Colilert18

Colilert &Colilert18
Sealsamplein
QuantiTray
TDEC - Fleming Training Center

Shakesample
vigorously.Waitfor
bubblestodissipate.
PourintoQuantiTray.

17

100

16

E. coli Testing

Incubateat350.5C
for18hrs(Colilert
18)OR24hrs
(Colilert)

TDEC - Fleming Training Center

MembraneFilter

TDEC - Fleming Training Center

IdexxQuantiTray

18

TDEC - Fleming Training Center

Section 6

TDEC - Fleming Training Center

Examinetrayfor
appropriatecolor
change
Yellowisanindicator
oftotalcoliforms

Colilert &Colilert18

Left: The 97 well QuantiTray 2000 will count up

to 2419 cfu without dilution.
Right: The 51 well QuantiTray will count up to
200 cfu without dilution.

19

Examinepositivetotal
coliformfor
fluorescenceusinga
UVlightinadark
environment
Fluorescenceisa
positiveindicatorfor
E.coli
CalculateMPNvalue
accordingtothetable
providedwiththe
QuantiTray

TDEC - Fleming Training Center

Colilert &Colilert18

20

TDEC - Fleming Training Center

TDEC - Fleming Training Center

Colilert &Colilert18

21

22

ModifiedmTECAgarwith
MembraneFiltration

23

E. coli Testing

MembraneFilter modifiedmTECagar
Filtersampledilutionsthrougha47mmdiametersterile,
white,gridmarkedfilter(0.45mporesize)
PlacesampleinapetridishwithmodifiedmTECagar
Invertdishandincubatefor35 0.5Cfor2hours
Resuscitatesinjuredorstressedbacteria

Thenincubateat44.5 0.2Cfor22hours
Afterincubation,removetheplatefromthewaterbathordry
airincubator

TDEC - Fleming Training Center

Escherichiacoli(E.coli)

TDEC - Fleming Training Center

EPAMethod1603

24

101

Section 6

TDEC - Fleming Training Center

EPAMethod1603

EPAMethod1603

Initialprecisionandrecovery
Ongoingprecisionandrecovery
Matrixspike
Negativecontrol
Positivecontrol
Filtersterilitycheck
Methodblank
Filtrationblank
Mediasterilitycheck

25

EPAMethod1603

Negativecontrol
Shouldbeanalyzedwheneveranewbatchofmediaorreagents
isused

Positivecontrol

27

Methodblank
Filtera50mLvolumeofsterilebuffereddilutionwaterandplace
onamodifiedmTEC agarplateandincubate.
Absenceofgrowthindicatesfreedomofcontaminationfromthe
targetorganism.
Rundaily.

TDEC - Fleming Training Center

Run1per20samples

TDEC - Fleming Training Center

Ongoingprecisionandrecovery

Placeatleastonemembranefilterperlotoffiltersonatryptic
soyagar(TSA)plateandincubatefor24 2hoursat35C 0.5
C.
Absenceofgrowthindicatessterilityofthefilter.
Rundaily.

28

Filtersterilitycheck

Shouldbeperformedbyeachlabbeforethemethodisusedfor
monitoringfieldsamples

Matrixspike

26

EPAMethod1603

Initialprecisionandrecovery

Runafterevery20fieldandmatrixspikesamplesoroneper
weekthatsamplesareanalyzed

TDEC - Fleming Training Center

QCTests:

TDEC - Fleming Training Center

Countandrecordthe
numberofredormagenta
colonies(verifywith
stereoscopicmicroscope)
SeetheUSEPA
microbiologymethods
manual,PartII,SectionC,
3.5,forgeneralcounting
rules

Shouldbeanalyzedwheneveranewbatchofmediaorreagents
isused

EPAMethod1603

Thelabshouldtestmediasterilitybyincubatingoneunit(tubeor
plate)fromeachbatchofmedium(TSA,modifiedmTECand
verificationmedia)asappropriateandobservingforgrowth.
Absenceofgrowthindicatesmediasterility.
Rundaily.

102

Escherichiacoli(E.coli)
mColiBlue24with
MembraneFiltration

TDEC - Fleming Training Center

Mediasterilitycheck

TDEC - Fleming Training Center

Filtera50mLvolumeofsterilebuffereddilutionwaterandplace
onaTSAplateandincubateatjustat35C 0.5Cfor24 2
hours.
Absenceofgrowthindicatessterilityofthebufferandfiltration
assembly.
Rundaily.

29

Filtrationblank

30

E. coli Testing

TDEC - Fleming Training Center

Section 6

31

ExpectedReactionsofVarious
Microorganisms

E.coli O157:H7willnotproduceabluecolony,butwillgrowasa
redcolony

TDEC - Fleming Training Center

Variablereactionmaybepositivefortotalcoliformwhenincubated
longerthan25hours
TDEC - Fleming Training Center

C.freundii

Escherichiacoli willproduceabluecolony

32

Pseudomonasaeruginosa

E.cloacae
E.aerogenes
K.pneumoniae

Samplesandequipmentknownorsuspectedto
haveviableE.coliattachedorcontainedmustbe
sterilizedpriortodisposal.

Knownnegativereaction(nogrowth)after2425hours

Enterobacterspecies

Citrobacterspecies

Ifyourmonthlygeometricmeanislessthan126,
thismeansyourdisinfectionisadequate.

ExpectedReactionsofVarious
Microorganisms

Totalcoliformswillproducearedcolony

Klebsiellaspecies

Incubationat35 0.5Cfor24 2hrs.

E.colidensityreportedasnumberofcolonies
per100mLofsample.
E.coliappearblue
NPDESpermitlimit:monthlyaverageof126
cfu/100mL

33

Proteusvulgaris
Aeromonashydrophila

Somestrainsofthefollowingmicroorganismsareknownto
produceafalsepositivetotalcoliformreaction(aredcolony,
butnotatruetotalcoliform)

Yersiniaenterocolitica

Serratia species
Hafnia alvei
Vibriofluvialis
Aeromonas species
Proteusvulgaris
Providencia stuartii

Leclercia adecarboxylata
Ewingella americana
Staphylococcusspecies
Proteusmirabilis

TDEC - Fleming Training Center

Maximumholdtimeis8hrs at<10C
Idealsamplevolumeyields2080colonies
Runaminimumof3dilutions
Samples<20mL,add10mLsteriledilutionwater
tofilterfunnelbeforeapplyingvacuum.
Sanitizefunnelbetweensamples.
Visuallydeterminecolonycountsonmembrane
filters.
Verifyusing1015Xbinocularwidefield
microscope.

E.colimColiBlue24

TDEC - Fleming Training Center

E.colimColiBlue24

34

MColiBlue24 TroubleShootingGuide,HachCompany,www.Hach.com

35

E. coli Testing

Temperaturesaredocumentedtwicedaily,atleast4hours
apart
ThermometersarecertifiedatleastannuallyagainstNIST
thermometers
Reagentsforstoragerequirementsandexpirationdates
E.colicoloniesidentifiedcorrectly
Calculationsarecorrect
HoldingTimesaremet
Samplecollection
Analysisstart
Endtimes

TDEC - Fleming Training Center

ForColilert:IDEXXLaboratories,www.idexx.com
FormTECAgarandmColiBlue24 media:HachCompany,
www.Hach.com
EPAMethod1603:E.coliInWaterByMembraneFiltration
UsingModifiedThermotolerantEscherichiacoliAgar
(ModifiedmTEC),September2002,EPA821R02023

AllBacteriologicalChecks

TDEC - Fleming Training Center

E.coliInformation

36

103

Section 6

TDEC - Fleming Training Center

GeometricMean

GeometricMean
GeometricMean (X1)(X2)(X3)(Xn)1/n

YouhaverunyourE.colisamplesforthemonth
andneedtofigureyourgeometricmean.
Yourresultsareasfollows:

37

GeometricMean (X1)(X2)(X3)(Xn)1/n

Step3:Punchthebutton,thentypeinthenumberfromStep1,
&thenpunch=.
6000yx0.25=8.8011

TDEC - Fleming Training Center

60x100x1x1=6000(DoNotclearoutyourcalculator)

39

GeometricMean
=0.25

TDEC - Fleming Training Center

(20)(20)(210)(350)=29,400,000
(29,400,000)0.25 =73.6

41

104

Step3:Punchtheyx buttonandthentypeinthenumberfromStep1,
thenpunch=.

6000yx 0.25=8.8011

TDEC - Fleming Training Center

60x100x1x1=6000(DoNotclearoutyour
calculator)

38

Now,tryoneonyourown:
20,20,210,350

Step1:1/n 1dividedthenumberoftestresults.Forour
exampleabove,therearefourtestresults.

Step2:Multiplyallofthetestresultstogetherandpunchthe=
buttononthecalculator.Remembertocount0asa1.

Step2:Multiplyallofthetestresultstogetherandpunchthe=button
onthecalculator.Remembertocount0asa1.

GeometricMean

GeometricMean

1 4=0.25(writethisnumberdown,youwilluseitinStep3)

1 4=0.25(writethisnumberdown,youwilluseit
inStep3)

E. coli Testing

GeometricMean=73.6

TDEC - Fleming Training Center

60cfu
100cfu
0cfu
0cfu

TDEC - Fleming Training Center

Step1:1/n 1dividedthenumberoftestresults.Forourexample
above,therearefourtestresults.

40

Membrane Filtration Method

E. coli Testing

Each ampule contains enough medium for one test. Medium packaged in
PourRite Ampules has a shelf-life of one year. Ampules are shipped with a
Certificate of Analysis and have an expiration date printed on the label.

Hach PourRite Ampules contain prepared selective media. This eliminates the
measuring, mixing, and autoclaving needed when preparing dehydrated media.
The ampules are designed with a large, unrestrictive opening that allows media
to pour out easily. Simply break off the top of the ampule and pour the medium
onto an absorbent pad in a petri dish.

Convenient Packaging

In the initial step, an appropriate sample volume passes through a membrane

filter with a pore size small enough (0.45 micron) to retain the bacteria present.
The filter is placed on an absorbent pad (in a petri dish) saturated with a culture
medium that is selective for coliform growth. The petri dish containing the filter
and pad is incubated, upside down, for 24 hours at the appropriate temperature.
After incubation, the colonies that have grown are identified and counted using
a low-power microscope.

Method

The Membrane Filtration (MF) method is a fast, simple way to estimate bacterial
populations in water. The MF method is especially useful when evaluating large
sample volumes or performing many coliform tests daily.

Bacteria_MF Coliform.fm

Bacteria, Coliform
Page 1 of 28

The volume of sample to be filtered will vary with the sample type. Select a maximum sample size to give 20 to 200
colony-forming units (CFU) per filter. The ideal sample volume of nonpotable water or wastewater for coliform testing yields 2080
coliform colonies per filter. Generally, for finished, potable water, the volume to be filtered will be 100 mL.

When the sample is less than 20 mL (diluted or undiluted), add 10 mL of sterile dilution water to the filter funnel before applying
the vacuum. This aids in distributing the bacteria evenly across the entire filter surface.

Tips and Techniques

Introduction

* USEPA accepted
** USEPA approved

Scope and Application: potable water, nonpotable water, recreation water, and wastewater

m-Endo, m-FC, m-FC/RA, m-TEC, modified m-TEC, M-EI, m-ColiBlue24,

and Pseudomonas Broth

Methods 8074, 8367*, and 10029**

Bacteria, Coliform

Bacteria, Coliform
Page 18 of 28

an alcohol or Bunsen burner.

Let the forceps cool before use.

2. Invert ampules two

or three times to mix
broth. Break open an
ampule of m-ColiBlue24
Broth using an ampule
breaker. Pour the
Note: Do not touch the pad or
contents evenly over the
the inside of the petri dish.
Note: To sterilize the forceps, absorbent pad. Replace
dip them in alcohol and flame in the petri dish lid.

1. Use sterilized forceps

to place a sterile,
absorbent pad in a sterile
petri dish. Replace the lid
on the dish.

3. Set up the Membrane

Filter Apparatus. With
sterile forceps, place a
membrane filter, grid side
up, into the assembly.

Simultaneous Total Coliform and E.coli Screening

Bacteria_MF Coliform.fm

4. Shake the sample

vigorously to mix. Pour
100 mL of sample or
diluted sample into the
funnel. Apply vacuum
and filter the sample.
Rinse the funnel walls
three times with 20 to
30 mL of sterile buffered
dilution water.

Method 10029

The m-ColiBlue24 Broth can be used to analyze drinking water, bottled water,
beverages; surface, well, and groundwater, waste water, recreational waters,
and process water for ultrapure, chemical processing and pharmaceutical
applications.

Using m-ColiBlue24 Broth PourRite Ampules

Bacteria, Coliform

TDEC - Fleming Training Center

Section 6

105

106

6. With a slight rolling 7. Invert the petri dish

motion, place the filter,
and incubate at
grid side up, on the
35 0.5 C for 24 hours.
absorbent pad. Check for
trapped air under the
filter and make sure the
filter touches the entire
pad. Replace the petri
dish lid.

E. coli Testing

Bacteria_MF Coliform.fm

Note: Sometimes only the

center of a colony will be
colored. Therefore, a colony
with any amount of red color
should be counted as red and a
colony with any amount of blue
should be counted as a blue
colony. Red colonies may vary
in color intensity. Blue colonies
may appear blue to purple.
Count all the red and blue
colonies as total coliforms.
Count all the blue to purple
colonies as E. coli.

8. Remove the petri dish

from the incubator and
examine the filters for
colony growth. Colonies
are typically readily
visible; however, a
stereoscopic microscope
or other 1015X
magnifier may be useful.
Red and blue colonies
indicate total coliforms
and blue colonies
specifically indicate E.
coli.

Bacteria, Coliform
Page 19 of 28

A few varieties of the non-coliform bacteria Pseudomonas, Vibrio, and Aeromonas

spp. may grow on m-ColiBlue24 Broth and form red colonies. Such bacteria can
be readily distinguished from total coliforms by the oxidase test. Pseudomonas,
Vibrio, and Aeromonas spp. are oxidase-positive. Total coliforms and Escherichia
coli are oxidase-negative. If your sample contains high levels of interfering
bacteria, you can perform an oxidase test to confirm which red colonies are
total coliforms.

The m-ColiBlue24 Broth is formulated so that coliforms other than E. coli grow as
red colonies. The percentage of red colonies that are false positives
(non-coliforms) is comparable to the percentage of sheen colonies grown on mEndo Broth that are false positives (non-coliforms); therefore, confirmation is not
required.

Optional Testing of Red Colonies

5. Turn off the vacuum

and lift off the funnel top.
Using sterile forceps,
transfer the filter to the
previously prepared petri
dish.

Bacteria, Coliform

Section 6
TDEC - Fleming Training Center

TDEC - Fleming Training Center

Section 6

W t
Wastewater
t Microbiological
Mi bi l i l T
Tests
t
Sample

Test Method

Reporting

100 mL Effluent

Colilert with
QuantiTray

E. coli/100 mL

100 mL Dilution Water

mFC Broth

Fecal Coliforms/100 mL

25 mL Effluent

mFC Broth

Fecal Coliforms/100 mL

100 mL Effluent

mFC Broth

Fecal Coliforms/100 mL

50 mL Effluent

mColiBlue24

E. coli/100 mL

100 mL Effluent

mColiBlue24

E. coli/100 mL

QC Sample

mColiBlue24

E. coli/100 mL
E. coli Testing

Number

107

Section 6

TDEC - Fleming Training Center

108

E. coli Testing

Section 7
Fats, Oils and Grease

109

Section 7

TDEC - Fleming Training Center

Introduction
ReviewinformationpresentedinTennesseeOiland

GreaseControlDocument,June2002,TDEC.

Fats,Oiland
GreaseControl

Editors:JenniferPetersDoddandRogerD.Lemasters,

TDEC.

FlemingTrainingCenter
Purpose:Toolformunicipalitiestocreateregulations

andenforcementplansdealingwithoilandgreaseon
alocallevel.
TDEC FlemingTrainingCenter

TDEC FlemingTrainingCenter

Background

Background

Oilandgreaseinsewerscausingproblemsformany

Federalpretreatmentregulations(40CFR403.5(b)(6))

TNcities.

specificallyprohibitpetroleumoil,nonbiodegradable
cuttingoil,orproductsofmineralorigininamounts
thatwillcauseinterferenceorpassthrough.

Contributingfactors:
increaseinrestaurants
agingcollectionsystem
decreaseindisposaloptions

Fewcitieshaveregulationsthatspecifylimitsand

enforcementofoilandgreasedischargesfrom
restaurants.

TDEC FlemingTrainingCenter

TDEC FlemingTrainingCenter

Background

Contents

Minimizingoilandgreasedischargestocollection

Introduction

systemwillreducesewerblockagesandsewage
backupintoservicelaterals.

Fats,Oil,andGreaseLimits
PreventingGreasefromEnteringtheSewerCollection

System
Guidancedocumentfocusesonedibleoilandgrease

GreaseSeparationDevices

fromrestaurantsandotherfoodprocessors(prisons,
churches,schools,etc.)

DisposalOptions
Education
Appendices

TDEC FlemingTrainingCenter

110

Fats, Oil and Grease

TDEC FlemingTrainingCenter

TDEC - Fleming Training Center

Section 7

CharacteristicsofOil&Grease

CharacteristicsofOil&Grease
Duetoitsstructure,grease

Foundinwastewaterasanemulsionorfreefloating

collectsoncoolinternal
surfacesofsewers

agglomerates.
WEFsPretreatmentofIndustrialWastes,Manualof
PracticeFD3definesgreaseas:fats,oils,waxes,and
soapsaccordingtotheireffectonwastewater
collectionandtreatmentsystemsandtheirphysical
(semisolid)forms.
FOG:generaltermforfats,oil,andgrease.

blockages
greaselogs
Greasealsoaccumulatesdue

tocoolinganddilutionof
surfactants,thatallows
greasetoseparateandcollect
onpipesandwetwells
foulingofcontrols
preventproperoperationof

pumps
TDEC FlemingTrainingCenter

TDEC FlemingTrainingCenter

CharacteristicsofOil&Grease

Fats,OilandGreaseLimits

Greaseblockagesmayleadtosewagebackupat

WhensettingFOGlimits,citiesmustconsider:
protectionofCSandWWTP
practicalityofmonitoringandenforcement
costandmanpowerneededforenforcement

servicelateralsormanholes.
Seweragencyisresponsibleforanydamagethat

occurs.
Ifthedamageresultsinaviolationofapermitissued

byTDECDWR,enforcementactionagainstthesewer
agencyispossible.
TDEC FlemingTrainingCenter

TDEC FlemingTrainingCenter

10

NumericalLimits

NumericalLimits

Mostcommonlyusedlimitis100mg/L.

EPAsuggestedinfluenttobiologicaltreatment

SomecitiesspecifydifferentFOGlimitsforFOGfrom

containlessthan50mg/LofFOGandthatdilutionin
CSwouldreduceany100mg/Ldischargesto
acceptablelevelsfortheWWTP.
Useofnumericallimitsallowuniformregulationof
localrestaurants.
FOGanalysisissomewhatcostlyandsome
restaurantsresistpayingforsampling.

differentsources.
Limitsmayvarydueto:
numberofwetwells
sewertype,slope,andflow
sewerO&M
historyofgreaserelatedclogs

TDEC FlemingTrainingCenter

11

Fats, Oil and Grease

TDEC FlemingTrainingCenter

12

111

Section 7

TDEC - Fleming Training Center

NumericalLimits

BestManagementPractices
(BMP)

Instead,mayusetemperaturelimitforgreasetrap

EffectivetoolincontrollingFOGwithoutrequiring

effluent.
Greasetrapsarenoteffectiveiftemperatureistoo
high(85F).
Numericaltemperaturelimitscanaidinapplyingand
enforcinglimits.
Caneasilybemonitored.
Cannotguaranteegreasetrapisproperlymaintained
andoperated.
TDEC FlemingTrainingCenter

extensivemonitoring
drywipingpots,pans,anddishware
discontinueuseofgarbagegrinders
routinecleaningofgreasetraps
retaincopiesofgreasetraphaulermanifests
placeoilrecyclecontainerinconvenientlocation

13

TDEC FlemingTrainingCenter

NumericalLimitsvs.BMP

Sampling

Citiesmayconsidersurchargingrestaurantsforhigh

Collectasgrabsamples

strengthBODandsuspendedsolids.
WhethernumericallimitsorBMPsareused,authority
fortheFOGprogramisbasedonthelocalseweruse
ordinance.
Shouldnotconflictwithlocalbuildingcodes,
plumbingcodes,andhealthdepartmentregulations.

Speciallycleaned1Lwidemouthglasscontainer

TDEC FlemingTrainingCenter

14

PreservewithHClorH2SO4topH<2
Refrigerateat6Corlessupto28days
Sampleatpeakflowstodetermineadequacyof

equipment
Forsurchargepurposes,sampleataverageflow

15

TDEC FlemingTrainingCenter

Sampling

Analysis

Frequencydependsontheneedfordata

NewEPAapprovedFOGmethodisMethod1664

16

Performsurchargemonitoringmonthly
Whenschedulingcompliancemonitoringconsider:
staffavailability
costofsampling
compliancehistoryofthefacility
Maybescheduledorunannounced

TDEC FlemingTrainingCenter

112

Useshexaneinsteadoffreon
MorelaborintensivethanMethod413.1
Averagepriceforanalysisissimilar

17

Fats, Oil and Grease

TDEC FlemingTrainingCenter

18

TDEC - Fleming Training Center

Section 7

PreventingGreaseFrom
EnteringSewers

ZeroDischargeofFOG
Scrapefoodintosolidwaste

Themosteconomicalandprudentmethodisproper

container

pretreatmentofwastestreamstoreduceoreliminate
grease.

Scrapecookwarebefore

washing

Sincewastestreamsvary,considerseveraloptions.

Nogarbagegrinders
Trainrestaurantmanagers

andemployeesindisposalof
cookingoilinrecycling
containers
TDEC FlemingTrainingCenter

19

GreaseRemovalDevices

TDEC FlemingTrainingCenter

20

GreaseInterceptor

Mustremoveemulsifiedand

freefloatingFOG
Threetypes:
passiveundersinkdevices
largeoutsidepassivedevices
mechanicaldevices

TDEC FlemingTrainingCenter

21

TDEC FlemingTrainingCenter

PreventingGreasefrom
EnteringSewers

UseofAdditivesbyFacilities

Remember,multiplesourcesofFOGinrestaurant

ShouldberegulatedbytheControlAuthority.

kitchens

22

Solvents,caustics,andacidsdissolveFOG,butcan

harmWWTPanditsworkers.
Commercial/residentialsourcesofFOG:
foodmanufacturersandprocessors
foodproviders
normalcookingandcleaninginhomes

TDEC FlemingTrainingCenter

EnzymesanddetergentsdissolveFOG,butthis

reactionisoftenreversible.Thisbenefitsthe
restaurant,butcausesaccumulationindownstream
areas.
Bacteriaconsumegreasemustuseproper
microorganisms;oftenmoreeffectiveinCS.
23

Fats, Oil and Grease

TDEC FlemingTrainingCenter

24

113

Section 7

TDEC - Fleming Training Center

GreaseSeparationDevices

CriteriatoEnsureSeparation

Greasetraporinterceptorconsistsofenclosed

Time:retentiontimetoallowemulsifiedgreaseand

chamber,designedtoseparateandretainoiland
greasefromwastewater.
Fatsandgreaseshavelowerspecificgravitythan
waterandrisetosurface.
Wastewaterpassesthroughtosewer.
Periodiccleaningneededtoremoveaccumulated
greaseandsettledsolids,restoringseparationvolume.

TDEC FlemingTrainingCenter

oiltoseparateandfloat.
Temperature:adequatevolumetoallowwastewaterto

cool,allowingFOGtoseparate.
Turbulence:duringhighdischargerates,ensuresolids

andgreasearenotkeptinsuspension.

25

TDEC FlemingTrainingCenter

PassiveSeparationDevices

PassiveSeparationDevices

SmallPointofUseInterceptors:
installednearwastewatersource
fabricatedsteel
sizedbystoragecapacityandflow

PrecastInGroundTraps:
concretewithmin.2compartments
manholeforcleaning/inspection
min.2hrsdetentiontimeatdesignflow,modifiedbya
loadingfactor
inspectandcleanregularly
samplingportsininletandoutletpiping

TDEC FlemingTrainingCenter

27

TDEC FlemingTrainingCenter

AutomaticSeparationDevices

AutomaticSeparationDevices

Trapandremovefreefloatinggreaseandoils(and

Heataccumulatedgreaseto115130Fsoitmeltsand

sometimesaccumulatedsolids)

26

28

canbedippedorskimmedofftoaseparatestorage
container.

Stainlesssteelenclosure,internalbaffles,removable
Typicallynotlocatedafterdishwasherssince

solidsseparatorscreen,greaselevelsensingprobe,
electricheaterelement,andskimmerordipper.

TDEC FlemingTrainingCenter

114

detentiontimesareinadequatetobreakhot,
detergentladengreaseandwateremulsions.

29

Fats, Oil and Grease

TDEC FlemingTrainingCenter

30

TDEC - Fleming Training Center

Section 7

DisposalOptions:Pumping

DisposalOptions:Recycling

UltimatedisposalofFOGisimportantpartofaFOG

Encouragefacilitymanagersstresswastecookingoil

controlprogram.
Trapsshouldgenerallybepumpedwhengreaseand
solidscombinedmeasure30%ofthedepthofthe
tank.
TDECrecommendspumpingtheentirecontentsof
thetrap,followedbycleaningwithascraper.Tees,
bafflesandbottomaretheninspected.

TDEC FlemingTrainingCenter

beplacedonlyinrecyclecontainer
Uses:dustsuppressant,manufacturinglubricant,and

binderforpesticidesandfertilizerstohelpthemstick
toplantswhensprayedonfields.

31

TDEC FlemingTrainingCenter

DisposalOptions:Land
Application

Education

Tolandfill,mustpasspaintfiltertest.

ToensureyourFOGcontrolprogramissuccessful,

32

youmusteducate:

Mostgreasetrapwastecontainsfreewater,somust

publicofficials

thereforebedewatered:
addabsorbent(sawdust,straw,etc.)

restaurantsandotherfacilities

mechanicaldryingordryingbed

recyclers

mechanicaldewatering(JEAusesgravitydrainingand

public(civicandenvironmentalgroups,scouts,local

media,etc.)

vacuumfiltrationwithpolymer)

TDEC FlemingTrainingCenter

33

TDEC FlemingTrainingCenter

34

InformationSources
OregonAssociationofCleanWaterAgenciesFOG

BMPManual
www.oracwa.org/pages/intro.htm

NorthCarolinaPollutionPrevention
www.p2pays.org/food/index.htm
TownofCary,NC
http://townofcary.org/grease/
TDEC FlemingTrainingCenter

35

Fats, Oil and Grease

115

Section 7

TDEC - Fleming Training Center

EXAMPLE FOG ORDINANCE

ORDINANCE NO. _______
AN ORDINANCE TO REGULATE ANIMAL AND VEGETABLE FATS, OILS AND
GREASE AS WELL AS SOIL/SAND AND LINT TRAPS AND INTERCEPTORS.
BE IT ENACTED BY THE ________________________________ OF THE
CITY OF ________________________________, TENNESSEE, THAT: [Or
whatever introductory provision, if any, is required by the citys
charter.]
Section 1. Purpose. The purpose of this ordinance is to
control discharges into the public sewerage collection system and
treatment plant that interfere with the operations or the system,
cause blockage and plugging of pipelines, interfere with normal
operation of pumps and their controls and contribute waste of a
strength or form that is beyond the treatment capability of the
treatment plant.
Section 2. Fat, Oil, and Grease (FOG),waste food, and sand
interceptors. FOG, waste food and sand interceptors shall be
installed when, in the opinion of the Superintendent, they are
necessary for the proper handling of liquid wastes containing Fats,
Oils, and Grease, ground food waste, sand, soil, and solids, or other
harmful ingredients in excessive amounts which impact the wastewater
collection system. Such interceptors shall not be required for
single family residences, but may be required on multiple family
residences. All interceptors shall be of a type and capacity
approved by the Superintendent, and shall be located as to be readily
and easily accessible for cleaning and inspection.
Section 3. Definitions. In the interpretation and application
of this chapter the following words and phrases shall have the
indicated meanings:
(1) Interceptor. A devise designed and installed to separate
and retain for removal, by automatic or manual means, deleterious,
hazardous or undesirable matter from normal wastes, while permitting
normal sewage or waste to discharge into the drainage system by
gravity.
(2) Grease Trap. An interceptor whose rated flow exceeds 50
g.p.m. and is located outside the building.
(3) Grease Interceptor. An interceptor whose rated flow is
50 g.p.m. or less and is typically located inside the building.
Section 4. Fat, Oil, Grease, and Food Waste. (1) New
construction and renovation. Upon construction or renovation, all
restaurants, cafeterias, hotels, motels, hospitals, nursing homes,
schools, grocery stores, prisons, jails, churches, camps, caterers,
manufacturing plants and any other sewer users who discharge
applicable waste shall submit a FOG and food waste control plan that
will effectively control the discharge of FOG and food waste.
(2) Existing structures. All existing restaurants, cafeterias,
hotels, motels, hospitals, nursing homes, schools, grocery stores,
116

Fats, Oil and Grease

TDEC - Fleming Training Center

Section 7

prisons, jails, churches, camps, caterers, manufacturing plants and

any other sewer users who discharge applicable waste shall be
required to submit a plan for control of FOG and food waste, if and
when the Superintendent determines that FOG and food waste are
causing excessive loading, plugging, damage or operational problems
to structures or equipment in the public sewer system.
(3) Implementation of plan. After approval of the FOG Plan by
the Superintendent the sewer user must: implement the plan within a
reasonable amount of time; service and maintain the equipment in
order to prevent adverse impact upon the sewer collection system and
treatment facility. If in the opinion of the Superintendent the user
continues to impact the collection system and treatment plant,
additional pretreatment measures may be required.
Section 5. Sand, soil, and oil interceptors. All car washes,
truck washes, garages, service stations and other sources of sand,
soil, and oil shall install effective sand, soil, and oil
interceptors. These interceptors will be sized to effectively remove
sand, soil, and oil at the expected flow rates. These interceptors
will be cleaned on a regular basis to prevent impact upon the
wastewater collection and treatment system. Owners whose
interceptors are deemed to be ineffective by the Superintendent may
be asked to change the cleaning frequency or to increase the size of
the interceptors. Owners or operators of washing facilities will
prevent the inflow of rainwater into the sanitary sewers.
Section 6.
Laundries. Commercial laundries shall be equipped
with an interceptor with a wire basket or similar device, removable
for cleaning, that prevents passage into the sewer system of solids
inch or larger in size such as ,strings, rags, buttons, or other
solids detrimental to the system.
Section 7.Control equipment. The equipment or facilities
installed to control FOG, food waste, sand and soil, must be designed
in accordance with Southern Plumbing Code and Tennessee Department of
Environment and Conservation engineering standards or applicable city
guidelines. Underground equipment shall be tightly sealed to prevent
inflow of rainwater and easily accessible to allow regular
maintenance. Control equipment shall be maintained by the owner or
operator of the facility so as to prevent a stoppage of the public
sewer, and the accumulation of FOG in the lines, pump stations and
treatment plant. If the City is required to clean out the public
sewer lines as a result of a stoppage resulting from poorly
maintained control equipment, or lack there of, the owner or operator
shall be required to refund the labor, equipment, materials and
overhead costs to the City. Nothing in this section shall be
construed to prohibit or restrict any other remedy the City has under
this ordinance, or state or federal law.
The City retains the right to inspect and approve installation
of the control equipment.
Section 8.
Solvents Prohibited. The use of degreasing or
line cleaning products containing petroleum based solvents is
prohibited.

Fats, Oil and Grease

117

Section 7

TDEC - Fleming Training Center

Section 9.Enforcement and penalties.

Any person who violates
this ordinance shall be guilty of a civil violation punishable under
and according to the general penalty provision of the Citys
municipal code of ordinances. Each days violation of this ordinance
shall be considered a separate offense.
Section 10.
Alteration of Control Methods. The city through
the Superintendent reserves the right to request additional control
measures if measures taken are shown to be insufficient to protect
sewer collection system and treatment plant from interference due to
the discharge of fats, oils, and grease, sand/soil, or lint.
Section 11.
Each section, subsection, paragraph sentence, and
clause of this ordinance, is declared to be separable and severable.
Section 12.
[Ordinance publication requirements or other
formalities, upon which the legality of the ordinance depends, may be
stated here.]
Passed first reading: _______________________________
Passed second reading: _____________________________
______________________________________
(Mayor)
______________________________________
(Recorder)

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Section 7

Town of Cary
Sewer Use Ordinance Fats, Oils, and Grease Control
Adopted by Town Council: December 10, 1998
Modified by Town Council: August 10, 2006
Sec. 36-183. Fat, oil, and grease control
(a) Scope and purpose. The objective of this section is to aid in preventing the introduction and accumulation of fats,
oils, and greases into the municipal wastewater system which will or tend to cause or contribute to sanitary sewer
blockages and obstructions. Food Service Establishments and other industrial or commercial establishments
generating wastewater containing fats, oils or greases are subject to this section. This section regulates such
users by requiring that grease interceptors and other approved strategies be installed, implemented, and
maintained in accordance with the provisions hereof.
(b) Definitions. The definitions contained in Section 36-172 and the following terms, when used in this section, shall
apply.
Action Level means the concentration based numeric value that the Grease interceptor effluent, at the devices outlet
tee and prior to mixing with any other waste water from the contributing establishments property, are expected to
achieve on a consistent or stipulated basis.
Common interceptor means one or more interceptors receiving FOG laden wastewater from more than on
establishment. Common interceptors may be located at shopping centers, malls, entertainment complexes, sporting
arenas, hotels, multi-tenant flex spaces, mixed use spaces, and other sites where multiple establishments are
connected to a single grease interceptor. The owner of the property on which the common grease interceptor is
located shall be primarily responsible for the maintenance, upkeep, and repair of the common interceptor.
Fats, oils, and greases means organic polar compounds derived from animal and/or plant sources that contain
multiple carbon chain triglyceride molecules. These substances are detectable and measurable using analytical test
procedures established in 40 CFR 136, as may be amended from time to time. All are sometimes referred to herein as
"grease" or "greases." or FOG.
Food Service Establishments or FSE means those establishments primarily engaged in activities of preparing,
serving, or otherwise making available for consumption foodstuffs and that use one or more of the following
preparation activities: Cooking by frying (all methods), baking (all methods), grilling, sauting, rotisserie cooking,
broiling (all methods), boiling blanching, roasting, toasting, or poaching, and infrared heating, searing, barbecuing,
and any other food preparation or serving activity that produces a consumable food product in or on a receptacle
requiring washing to be reused.
FOG enforcement response plan means the document and written plan and procedures by which the director
implements an enforcement strategy applicable to the FOG control and management program established herein.
The plan applies to FOG program violations and matters of program noncompliance. Stipulated penalties for specific
and programmatic infractions are addressed in the plan and set forth in the Towns annual budget ordinance. The
director shall make site and case specific determinations of program non-conformance in accordance with this
Division 2.
Grease trap or interceptor means a device for separating waterborne greases and grease complexes from wastewater
and retaining such greases and grease complexes prior to the wastewater exiting the trap and entering the sanitary
sewer collection and treatment system. Grease traps also serve to collect solids that settle, generated by and from
activities that subject Users to this section, prior to the water exiting the trap and entering the sanitary sewer collection
and treatment system. Grease traps and interceptors are sometimes referred to herein as "grease interceptors."
Minimum design capability means the design features of a grease interceptor and its ability or volume required to
effectively intercept and retain greases and settled solids from grease-laden wastewaters discharged to the public
sanitary sewer.
Noncooking establishments means those establishments primarily engaged in the preparation of precooked foodstuffs
that do not include any form of cooking: but that may produce a consumable food product in or on a receptacle
requiring washing to be reused.
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Town
of Cary
Sewer Use Ordinance Fats, Oils, and Grease Control

TDEC - Fleming Training Center

On-site grease interceptor treatment (sometimes Onsite Treatment) means mechanisms or procedures utilized by a
User to treat grease interceptor contents on the Users site, followed by the reintroduction of such treated wastewater
back into the interceptor. On-site grease interceptor treatment may only be accomplished by a User if the User or the
Users contract service provider is permitted by the NC Division of Waste Management as a septage management
firm or service provider.
Program Acknowledgement Certificate means program confirmation documentation issued by the Director. The User
is required to keep Program Acknowledgement Certificate on premises and produce it upon request of Town of Cary.
Service provider means any third party not in the employment of the User that performs maintenance, repair, and
other services on a Users grease interceptor at the Users directive.
User is as defined in Section 36-172 for the purpose of this Section. Users include property owners who provide
common interceptors for one or more independent establishments, including tenants.
(c)

Grease interceptor installation, maintenance, recordkeeping, and grease removal.

(1) Grease interceptors shall be installed and maintained at the Users expense, when a User operators a
food service establishment. Grease interceptors may be required in noncooking or cold dairy and frozen
foodstuffs establishments and other industrial or commercial establishments when the establishment
generates wastewater containing fat or grease and the director determines an interceptor is necessary to
prevent contribution or accumulation of grease to the sanitary sewer collection and treatment system.
Upon notification by the Director or designee that the User is subject to the terms of an enforcement
action, as stipulated in the FOG Enforcement Response Plan, said user shall not allow wastewater
discharge concentration from subject grease interceptor to exceed an establishment action level of 200
milligrams per liter, expressed as Hexane Extractable Material. All grease interceptors shall be of a type,
design, and capacity approved by the director and shall be readily and easily accessible for maintenance
and repair, including cleaning and for town inspection. All grease interceptors shall be serviced and
emptied of accumulated waste content as required in order to maintain minimum design capability or
effective volume of the grease interceptor, but not less often than every sixty (60) days or as permitted in
a valid program modification. Users who are required to pass wastewater through a grease interceptor
shall:
a. Provide for a minimum hydraulic retention time of 24 minutes at actual peak flow between the
influent and effluent baffles, with twenty-five percent (25%) of the total volume of the grease
interceptor being allowed for any food-derived solids to settle or accumulate and floatable greasederived materials to rise and accumulate, identified hereafter as a solids blanket and grease cap
respectively."
b. Remove any accumulated grease cap and solids blanket as required, but at intervals of not longer
than sixty (60) days at the user's expense, or in accordance with a valid program modification or
other directors requirements. Grease interceptors shall be kept free of inorganic solid materials,
such as grit, rocks, gravel, sand, eating utensils, cigarettes, shells, towels, rags, etc., which could
settle into this solids blanket and thereby reduce the effective volume of the grease interceptor.
c. If the User performs on-site grease interceptor treatment pursuant to a modification granted under
36-183(g)(5) below, User shall
1. Prior to commencement of Onsite Treatment obtain written approval by and from the
Director of all processes utilized in said Onsite Treatment.
2. If any pumped wastes or other materials removed from the grease interceptor are treated
in any fashion on-site and reintroduced back into the grease interceptor as an activity of
and after such on-site treatment, the user shall meet the criteria contained in (c)(1)(c)(3)
below.

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Town
of Cary
Sewer Use Ordinance Fats, Oils, and Grease Control
3.

Section 7

Attain and adhere to the criteria listed below:

a.
b.

c.

d.

e.

After 30 minutes of settling time, not more than 3.0 ml/L of settlable solids, as
measured in a 1 liter Imhoff cone shall be allowed, and;
Within and not more than 24 hours after onsite grease interceptor servicing,
not more than 2 (inches) of settlable solids and/or grease shall be allowed to
have accumulated therein as a result of said operations.
Service vehicles and equipment used in onsite Grease interceptor servicing
shall be registered with the Public Works and Utilities Department, and as
required by the North Carolina Division of Waste Management.
When servicing Grease interceptors service vehicles and equipment shall
have onboard, at all times, a certificate of approval for the operations and
methods used, issued by the Director.
Any tanks, tankage, or vessel(s) associated with a modification shall be
empty upon arrival at the initial FSE user site for which this modification is
intended to be applied.

d. Operate and maintain the grease interceptor to achieve and consistently maintain any applicable
grease action level . "Consistent" shall mean any wastewater sample taken from such grease
interceptor must meet the terms of numerical limit attainment described in subsection (c)(1). If a
User documents that conditions exist (space constraints) on their establishment site that limit the
ability to locate a grease interceptor on the exterior of the establishment, the User may request an
interior location for the interceptor. Such request shall contain the following information:
1. Location of town sewer main and easement in relation to available exterior space outside
building.
2. Existing plumbing layout at or in a site.
3. A Statement of Understanding, signed by the User or authorized agent, acknowledging and
accepting conditions Director may place on permitting an identified interior location.
Conditions may include requirements to use alternative mechanisms, devices, procedures,
or operations relative to an interior location.
4. Such other information as may be required by the Director.
e. The use of biological or other additives as a grease degradation or conditioning agent is permissible
only upon prior written approval of the director. Any User using biological or other additives shall
maintain the trap or interceptor in such a manner that attainment of any grease wastewater, action
level, solids blanket or grease cap criteria, goal or directive, as measured from the grease
interceptor outlet or interior, is consistently achieved.
f. The use of automatic grease removal systems is permissible only upon prior written approval of the
director, the lead plumbing inspector of the town, and the Wake County Department of
Environmental Services or the US Department of Agriculture. Any user using a grease interceptor
located on the interior of the site shall be subject to any operational requirements set forth by the
North Carolina Division of Waste Management. Any User using this equipment shall operate the
system in such a manner that attainment of the grease wastewater discharge limit, as measured
from the unit's outlet, is consistently achieved as required by the Director.
g. The director may make determinations of grease interceptor adequacy need, design,
appropriateness, application, location, modification(s), and conditional usage based on review of all
relevant information regarding grease interceptor performance, facility site and building plan review
by all regulatory reviewing agencies and may require repairs to, or modification or replacement of
grease interceptors.

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Section 7
Town
of Cary
Sewer Use Ordinance Fats, Oils, and Grease Control
(2)

TDEC - Fleming Training Center

The user shall maintain a written record of grease interceptor maintenance for three years. All such
records will be available for inspection by the town at all times. These records shall include:
a.
b.
c.
d.
e.
f.
g.
h.
i.
j.
k.
l.

FSE name and physical location

Date of grease interceptor service
Time of grease interceptor service
Name of grease interceptor service company
Name and signature of grease interceptor service company agent performing said service
Established service frequency and type of service: full pumpout, partial pumpout, on-site
treatment (type of nature of operations)
Number and size of each grease interceptor serviced at FSE location
Approximated amount, per best professional judgement of contract service provider, of
grease and solids removed from each grease interceptor
Total volume of waste removed from each grease interceptor
Destination of removed wastes, food solids, and wastewater disposal
Signature and date of FSE personnel confirming service completion
Such other information as required by Director

(3)

No nongrease-laden sources are allowed to be connected to sewer lines intended for grease interceptor
service.

(4)

Access manholes shall have an installed diameter of 24 inches, a maximum weight of 50 pounds, and
shall be provided over each chamber, interior baffle wall, and each sanitary tee. The access
penetrations, commonly referred to as risers into the grease interceptor shall also be, at a minimum,
24 inches in diameter. The access manholes shall extend at least to finished grade and be designed
and maintained to prevent water inflow or infiltration. The manholes shall also have readily removable
covers to facilitate inspection, grease removal, and wastewater sampling activities.

(5)

A User may request a modification to the following requirements of this ordinance. Such request for a
modification shall be in writing and shall provide the information set forth below.
(a)

The users grease interceptor pumping frequency. The Director may modify the 60 day grease
interceptor pump out frequency when the User provides data, and performance criteria
relative to the overall effectiveness of a proposed alternate and such can be substantiated by
the Director. Proposed alternatives may include: grease interceptor pumping or maintenance
matters, bioremediation as a complement to Grease interceptor maintenance, Grease
interceptor selection and sizing criteria, onsite grease interceptor maintenance, and
specialized ware washing procedures

(b)

Grease interceptor maintenance and service procedures. The Director may modify the
method(s) or procedure(s) utilized service a grease interceptor when the User provides data,
and performance criteria relatie to the overall effectiveness of a proposed alternate method or
procedure and such can be substantiated by the Director. If a modification to maintenance
and service procedures is permitted it shall be a conditional discharged permit approval.

(c)

Any modification must be approved by the Director in written form before implementation by
the User or the users designated service provider. The User shall pay modification fees as
set forth in the Budget Ordinance Fee Schedule.

Sec. 36-184. Severability.

If any provision, paragraph, word, section or article of this division is invalidated by any court of competent jurisdiction,
the remaining provisions, paragraphs, words, sections, and chapters shall not be affected and shall continue in full
force and effect.
Sec. 36-185. Conflict.
All other ordinances and parts of other ordinances inconsistent or conflicting with any part of this division are hereby
repealed to the extent of such inconsistency or conflict.

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Section 7

Hamilton County Water & Wastewater Treatment Authority

FOOD SERVICE ESTABLISHMENT GREASE CONTROL INSPECTION FOR M
Inspection Date :

Facility Name :
Facility Representative : Mr./Ms.

Title :
Owner/Regional Manager Name :

Phone :

Mail Address ;

Facility Address :

(if different )

Sewer Plat ID :

Sewer Map ID :

1000
2 . Interceptor Size (gallons) _500 _750
3000
Two interceptors in series Other

1 . Grease Interceptor? _Yes _ No

(For #1, if "NO" then go to #14)

Yes

(inspector can see the

No Unknow n

6 . Effluent T attached &in good condition : _Yes

No

1500 _2000

4. Estimated Grease Layer Depth :

3 . Manhole Access to interceptor : 1 _2 _3 _4

5 . Effluent T visible?

GPS ID :

T)

8. Bacteria / Enzymens used :

7 . Grease Interceptor Hauler Used :

Yes _N o

9 . Product Name :

1.1 . Complete Contents Pumped?

10. Frequency Interceptor Cleaned?

12 . Records of Maintenance/Cleaning Available?

No

Yes

Yes

No

13 . Last date cleaned :

Grease Tra p

15 . Location : _Under sink trap Floor trap Outside "floor" trap

No
14 . Grease Trap? _Yes
(For #14, if "NO" then go to #20)

_5 gpm/10 lb
16. Grease Trap flow-through rating / grease capacity Estimate :
_ Other :
_20 gpm/40 lb _35 gpm/70 lb _50 gpm/100 lb

10 gpm/ 20 lb

18 . Maintenance/Cleaning Records :

17. Frequency Trap is cleaned :

19 . Grease Trap comments/location disposed

15 gpm/ 30 l b
Yes _ N o

of waste :

BMPs & outside conditons, other than grease interceptor or tra p

Yes

20 . Best Management Practices Implemented

22. Cleanout Covers missing or damaged? _Yes

No

21 . Grease Recycle Bin

No (# Cleanout covers missing :

Yes

damaged :

No
)

(Facility needs to repair missing or damaged cleanout covers immediatley )

23. FOG impact at dumpster or around recycle bin?

Yes

No (if Yes, give explanation below )

Evidence of Grease in Manhole (

24. DOWNSTREAM MANHOLE :

slight moderate -heavy )

Comments :
25. SAMPLE POINT Access?

Yes

26. Sample point ID : _ Interceptor EffluentT

27. Picture ID :

//

Effluent pH :

Effluent Temp :

No

_Downstream MH

of Interceptor

Cleanout

_ of downstream MH

Sample drop bo x

other :

Visual inspection results, comments :

Inspector Name :

Signature :

Facility Representative Signature :

Fats, Oil and Grease

Inspection form

copy

provided to facility? _ Yes

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Section 7

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Fats, Oil and Grease

Section 8
Biosolids

125

Section 8

TDEC - Fleming Training Center

Sludge Types and Characteristics

Primary sludge is defined as all suspended solids that are

Sludge Thickening, Digestion,

and Dewatering

removed from the wastestream and that are not a by-product

of biological removal of organic matter.
Secondary sludge is from new bacterial cells that are
produced as the bacteria feed on and degrade organic matter

- or Now What Do We Do With It?

Usually these bacterial cells are removed in the secondary

clarifier to maintain the proper balance between food and

microorganisms (F/M)

TDEC - Fleming Training Center

Sludge Types and Characteristics

Primary Sludge

Secondary Sludge

Coarse and fibrous

More flocculant, less

Higher density than water

fibrous
Specific gravity close to
water
75-80% volatile (organic)
matter
20-25% nonvolatile
(inorganic) matter

40-80% volatile (organic)

solids
20-60% nonvolatile

(inorganic) solids

TDEC - Fleming Training Center

Primary Sludge Production

The quantity of primary sludge generated depends on:
Influent wastewater flow
Concentration of influent settleable suspended solids
Efficiency of the primary sedimentation basin

TDEC - Fleming Training Center

TDEC - Fleming Training Center

Secondary Sludge Production

Secondary Sludge Production

The quantity of secondary sludge generated depends on:

General rule of thumb that operators may use to estimate

Influent flow to the biological or secondary system

Influent organic load to the biological system
Efficiency of the biological system in removing organic matter
Growth rate of the bacteria in the system, which is highly dependent
on:

secondary sludge production is that for every pound of

organic matter (soluble 5-day BOD) used by the bacterial
cells, approximately 0.30 0.70 pounds of new bacterial
cells are produced and have to be taken out of the system

Temperature
Nutrient balances
Amount of oxygen supplied to the system
Ratio between the amount of food supplied (BOD)
Mass quantity of biological cells developed within the system
Detention time
and other factors

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Biosolids

TDEC - Fleming Training Center

TDEC - Fleming Training Center

Section 8

Sludge Thickening, Digestion,

and Dewatering
Thickening

Dewatering

Gravity

Centrifuge

Floatation

Plate and frame

Gravity belt

Belt filter press

Stabilization
Anaerobic digestion

Sludge Thickening

Vacuum filter

Main component of sludge is water

~90% or more before treatment

Drying beds

Aerobic digestion

TDEC - Fleming Training Center

Thickening

Thickening

Settled solids removed from the bottom of the primary

The advantages normally associated with sludge thickening

clarifier (primary sludge) and settled biological solids

removed from the bottom of secondary clarifiers (secondary
sludge) contain large volumes of water

include:

Primary sludge 95-97% water

For every pound of primary solids, there are 20-30 pounds of water

Construction cost savings for new digestion facilities due to

For every pound of secondary solids, approximately 50-150

A reduction in digester heating requirements because less water

Improved digester performance due to a smaller volume of

sludge
smaller sludge volumes treated

pounds of water are incorporated in the sludge mass

TDEC - Fleming Training Center

has to be heated

TDEC - Fleming Training Center

10

TDEC - Fleming Training Center

DRIVE
ASSEMBLY

Gravity Thickening

EFFLUENT
WEIR

Most effective on primary sludge

DISTRIBUTION
ASSEMBLY

Detention time is around 24 hours

SCUM
BAFFLE

WATER LEVEL

Thickening tank looks like a primary circular clarifier

SCUM
COLLECTION

Monitored for blanket depth and sludge concentration

INFLUENT LINE

Affected by temperature of sludge

PICKETS
SCUM
DISCHARGE

Increased temperature will increase biological activity and gas

production
Separates solids into three zones
Clear supernatant
Sedimentation zone

SLUDGE
RAKE

Thickening zone
11

SLUDGE
HOPPER

TDEC - Fleming Training Center

12

Biosolids

SLUDGE
WITHDRAWAL

TDEC - Fleming Training Center

GRAVITY THICKENER

127

Section 8

TDEC - Fleming Training Center

Gravity Thickening

Factors Affecting Gravity

Thickeners

Dilute sludge is fed into center well

Type of sludge

Sludge rake provides for movement of the settled (thickening) sludge.

Age of the feed sludge

As the rake slowly rotates, the settled solids are moved to the center of the

Sludge temperature

tank where they are deposited in a sludge hopper.

The vertical steel members (pickets) that are usually mounted on the

Sludge blanket depth

sludge rake assembly provide for gentle stirring or flocculation of the

settled sludge as the rake rotates

Solids and hydraulic detention times

This gentle stirring action serves 2 purposes

Solids and hydraulic loadings

Trapped gasses in the sludge are released to prevent rising of the solids
Also, stirring prevents accumulation of a large volume of solids (scum)

floating on the thickener surface

Supernatant is returned to primary clarifier or plant headworks

Thickened sludge is pumped to digester or dewatered

13

TDEC - Fleming Training Center

14

Factors Affecting Gravity

Thickeners

Factors Affecting Gravity

Thickeners

Secondary sludges are not as well suited for gravity

If sufficient oxygen is not

available in the aeration basin or

nutrient imbalances are present,
filamentous organisms may
grow in the aeration basin
The predominance of these
organisms will decrease the
settleability of activated sludge
and it will not settle as readily in
the secondary clarifiers or
compact to its highest degree in
gravity thickeners
Greater compaction can be
achieved by the addition of
chemicals

thickening as primary sludge

Secondary sludges contain large quantities of bound water
that makes the sludge less dense than primary sludge solids
Biological solids are composed of approximately 85-90% water

by weight within the cell mass

The water contained within the cell wall is referred to as

bound water
The fact that biological solids contain large volumes of cell

water and are often smaller or finer than primary sludge solids
makes them harder to separate by gravity concentration
15

TDEC - Fleming Training Center

TDEC - Fleming Training Center

16

TDEC - Fleming Training Center

Factors Affecting Gravity

Thickeners

Gravity Thickening

As the temperature of the sludge (primary or secondary)

Normal operating procedures:

Monitoring of the influent, effluent and concentrated sludge streams

increases, the rate of biological activity is increased and the

sludge tends to gasify and rise at a faster rate
During summertime (warm weather) operation, the settled
sludge has to be removed at a faster rate from the thickener
than during wintertime operations.

should be done at least once per shift and should include collection of
samples for later laboratory analysis
Water at the surface should be relatively clear and free from solids
and gas bubbles
The sludge blanket is usually kept around 5-8 feet
The speed of the sludge collectors should be fast enough to allow the
settled solids to move toward the sludge collection sump
On occasion, sludge in primary sedimentation tanks and gravity

thickeners can become very thick and resistant to pumping.

If this happens, a hole (coning) can develop in the blanket and liquid

from above the blanket can be pulled through the pump

17

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18

Biosolids

TDEC - Fleming Training Center

TDEC - Fleming Training Center

Section 8

SLUDGE
REMOVAL
MECHANISM

Flotation Thickener
Treats waste activated sludge
Often with added polymers

FLOATED
SLUDGE
DISCHARGE

Dissolved-air flotation (DAF)

Small amount of recycled water is aerated under pressure

RECYCLE FEED

Air bubbles attach to the solids and carry them to the surface

POLYMER FEED

The Float Cake is skimmed off the surface

Cake is 2 4% solids without polymer fed, or 3 5% solids

19

BOTTOM
SLUDGE
COLLECTOR

TDEC - Fleming Training Center

20

TDEC - Fleming Training Center

Factors Affecting DAF

The objective of flotation thickening is to separate solids from the

Primary sludges are generally heavier than excess biological

sludges and are not as easy to treat by flotation concentration

Gritty or heavy primary sludge particles will settle and be

Dispersed air flotation where bubbles are generated by mixers or

deposited on the floor of the flotation unit and provisions

should be made to remove these settled solids
Sludge age usually does not affect flotation performance as
drastically as it affects gravity concentrators.

diffused aerators

Biological flotation where gases formed by biological activity are used

to float solids

Dissolved air (vacuum) flotation where water is aerated at

atmospheric pressure and released under a vacuum

Dissolved air (pressure) flotation where air is put into solution under

A relatively old sludge has a natural tendency to float due to

pressure and released at atmospheric pressure

gasification and this natural buoyancy will have little or no

negative effect on the operation of flotation thickeners

Flotation by dissolved air (pressure) is the most commonly used

procedure for wastewater sludges

TDEC - Fleming Training Center

22

Troubleshooting DAF
Operational Problem
1. Solids carry over with
effluent but good float
(thickened sludge)
concentration

Possible Cause
1. Float blanket too thick

2. Good Effluent quality but

2. Float blanket too thin
float thin (dilute
3a. Air to Solids Raito (A/S)
is low
3b. Pressure too low or too
high
3. Poor effluent quality and 3c. Recycle pump
inoperative
thin (dilute) float
3d. Rearation pump
inoperative
3e. Chemical addition
inadequate
3f. Loading excessive
23

INFLUENT
DISTRIBUTION
BOX

Flotation Thickener
liquid phase in an upward direction by attaching air bubbles to
particles of suspended solids

21

SLUDGE FEED

RECYCLE
FLOW

with polymer fed

Primary sludges are not easier to treat than biological sludges
in a DAF

TDEC - Fleming Training Center

Check or Monitor

Gravity Belt Thickener

Possible Solution

1a.Flight Speed

1a. Increase flight speed

1b. Solids loading

1b. Lower flow rate to unit; if

possible

2a. Flight speed

2b. Solids loading
3a(1) Air rate
(2) Compressor
3b. Pressure gauge

Very effective sludge

thickening alternative for

secondary sludges
Sludge to be thickened is
preconditioned (usually with a
polymer) then applied to the
gravity belt thickener where
free water drains through
small openings in the belt and
is collected in a trough below
the belt.

2a. Decrease flight speed

2b. Increase flow rate; if
possible
3a(1) Increase air input
(2) Repair or turn on
compressor
3b. Open or close valve

3c. Pressure gauge and pump 3 c. Turn on recycle pump.

3d. Pump pressure

TDEC - Fleming Training Center

3d. Turn on rearation pump

3e. Chemical system

3e. Increase chemical dosage

3f. Loading rates

3f. Lower flow rate

24

Biosolids

TDEC - Fleming Training Center

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Section 8

TDEC - Fleming Training Center

Gravity Belt Thickener

Gravity Belt Thickener

Belts are available in a variety of materials (nylon, polypropylene)

The belt speed can be varied from approximately 2-10 ft/min

each with various porosities

The speed at which the belt should be operated depends on the

As the porosity increases, the resistance to flow decreases and larger

sludge flow rate to the belt and the concentration of the influent
sludge
As the belt speed is increased, the rate of belt area contacting the
influent sludge also increases and allows for greater volumes of
water to drain, belt washout will cause a reduction in the
thickened sludge concentration.

volumes of water are able to be drained

If the porosity is too large, sludge solids may pass through the belt and
result in poor filtrate quality
If the porosity is too low, the belt may bind or plug, which will
produce frequent washouts
Washout occurs when a large quantity of free water is unable to be released

in the drainage zone and it travels to the discharge end where it is carried out
with the thickened sludge.

As the concentration of influent sludge increases, less water is

associated with the sludge mass and reduced belt speed can be used.

With proper operating conditions, secondary sludges can be

thickened from concentrations of 0.3-0.6% suspended solids to

concentrations of 4-6% suspended solids

25

The ideal operating belt speed is the slowest the operator can

maintain without washing out the belt.

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Gravity Belt Thickener Troubleshooting

Gravity Belt Thickener Troubleshooting

The most frequent problem encountered with gravity belt

If the polymer dose is too low, the solids will not flocculate and free

water will not be released from the sludge mass

thickeners is washing out

If the polymer dose is adequate, evidenced by large floc particles and

free water, increase the belt speed so as to provide more belt surface
area for drainage
If the belt is already at its maximum setting, check the flow rate to the
belt and reduce it if the rate is higher than normal
If the polymer dose, belt speed and hydraulic loading are set properly
but washing out is still occurring, the problem may be related to binding
of the belt

Usually this problem is indicated by large volumes of water

carrying over with the thickened sludge

When this happens check
The polymer dosage
Hydraulic loading
Solids loading

Check the appearance of the belt as it leaves the washing chamber

If the belt appears to be dirtier than normal, increase the wash water rate,

Belt speed

turn off the polymer and feed pumps and allow the belt to be washed until it
is clean

Belt washing equipment

Belt binding often develops because of polymer overdosing

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CHEMICALLY
CONDITIONED
SLUDGE

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THICKENING
SLUDGE
PLOWS

Biosolids Stabilization (Digestion)

FILTRATE

TO STABILIZATION

BELT FILTRATE
AND WASH WATER
RECYCLE

Reduce volume
Stabilize organic matter
Eliminate pathogenic organisms

BELT WASH WATER

WASH WATER
BOOSTER PUMP
TO HEADWORKS

Gravity Belt Filter Thickener

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Section 8

Stabilization

General Overview

Converts the volatile (organic) or odor-causing portion of

the sludge solids to

Before digestion of 100

pounds of sludge: 75%
Volatile, 25% Fixed Solids

Non-odorous end products

Prevents the breeding of insects upon disposal
Reduces the number of pathogenic (disease-carrying) bacteria

50 Lbs of CH4, CO2, H2O

content
Improves the sludge dewaterability

75 Lbs VS

Can be done:
Anaerobically
Aerobically
Chemically

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After a 65% reduction in

Volatile Solids there is less
sludge remaining to process

25 Lbs VS
25 Lbs Fixed

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25 Lbs Fixed

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Anaerobic Digestion
The most widely used method of sludge stabilization is

anaerobic digestion in which decomposition of organic

matter is performed by microorganisms in the absence of
oxygen
Anaerobic digestion is complex biochemical process in which
several groups of anaerobic and facultative (survive with or
without oxygen) organisms break down organic matter.

Biosolids Stabilization
Anaerobic Digestion

In the first phase, facultative, acid-forming organisms convert

complex organic matter to volatile (organic) acids

In the second phase, anaerobic methane-forming organisms

convert the acids to odorless end products of methane gas and

carbon dioxide

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Anaerobic Digestion

Anaerobic Digestion

Anaerobic digesters are usually heated to maintain

2-phase process:
Acid formers - Facultative bacteria convert organic matter to volatile

temperatures of 94-97F (34-36 C).

If the temperature falls below this range or if the digestion
time falls below 15 days, the digester may become upset and
require close monitoring and attention

acids, CO2, and H2S

SAPROPHYTIC ORGANISMS
Methane producers - Anaerobic bacteria convert acids to CH4 and

CO2

The methane producers are not as abundant in raw wastewater as are the acid

formers.

The methane producers desire a pH range of 6.6 to 7.6 and will reproduce

only in that range.

28-40% carbon dioxide, 60-72% methane

Minimum methane for reuse is 62%

Sludge retention time is 30-60 days

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Psychrophilic Bacteria

Mesophilic Bacteria

The lowest range (in an unheated digester) utilizes

Organisms in the middle temperature range are called the

Psychrophilic (cold temperature loving) bacteria.

Mesophilic (medium temperature loving) bacteria

The psychrophilic upper range is around 68F (20C).

Thrive between about 68F (20C) and 113F (45C).

Digestion in this range requires from 50 to 180 days, depending

The optimum temperature range is 85F (30C) to 100F

upon the degree of treatment or solids reduction required.

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(38C), with temperatures being maintained at about 95F

(35C) in most anaerobic digesters.
Digestion at 95F may take from 5 to 50 days or more
(normally around 25 to 30 days), depending upon the required
degree of volatile solids reduction and adequacy of mixing.

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Thermophilic Bacteria

Changing Temperatures

Organisms in the third temperature range are called

You cant change temperature and expect a quick change in

Thermophilic (hot temperature loving) bacteria and they

thrive above 113 F (45C).
The optimum temperature range is considered 120 F (49C).
The time required for digestion in this range falls between 5
and 12 days, depending upon operational conditions and
degree of volatile solids reduction.

bacteria population and therefore a shorter digestion time

An excellent rule for digestion is never change the

temperature more than one degree a day to allow the

bacterial culture to become acclimated (adjust to the
temperature changes).

However, the problems of maintaining temperature, sensitivity of

the organisms to temperature change, and some reported

problems of poor solids - liquid separation are reasons why only a
few plants have actually been operated in the thermophilic range.
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Anaerobic Digestion

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Anaerobic Digestion Normal Ranges

Parameter

Normal Ranges

Sludge retention time

30 60 days (Heated)

Operating Temperature
Volatile Solids Loading

90 95 F (Heated)
0.04 0.1 lb VM/day/ft3

% Methane in gas

60 72%

% Carbon Dioxide in gas

28 40%

pH
Volatile acids: alkalinity ratio

6.8 7.2
0.1

Volatile solids reduction

40 60%

* For every 1 lb. of VM destroyed, 12-18 ft3 of gas is produced.

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Section 8

Anaerobic Digestion

Acid-Alkalinity Relationship

Volatile Acids to Alkalinity Ratio

Optimum
Stress
Deep Trouble
Failure

Ratio =

volatile acids concentration, mg/L

alkalinity concentration, mg/L

VA/Alk relationship is the key to successful digester operation

VA/ALK = .05 - 0.1

VA/ALK = 0.3 - 0.4
VA/ALK = 0.5 - 0.7
VA/ALK = 0.8 and above

Each treatment plant will have its own characteristic ratio for

Must monitor alkalinity

proper sludge digestion (generally less than 0.1)

Can be used to control operation of anaerobic digester

High buffer capacity exists when VA are low and the Alkalinity is high

Very sensitive indicator of process condition

(120 mg/L VA/2400 mg/L Alk)

One of the first indicators that the digester is going sour

When the VA/Alk ratio is 0.8 or higher, the pH of the digester will

begin to drop.

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Acid-Alkalinity Relationship

Anaerobic Digestion

When the VA/Alk ratio starts to increase

Mixing

Extend the mixing time of the digester contents

Puts microorganisms in contact with food

Control the heat more evenly

Controls pH, distributes buffering alkalinity

Decrease the raw sludge feed rates

Distributes heat throughout the tank

Decrease the digested sludge withdrawal rates from digesters

Mixing combined with heating speeds up the digestion rate

Pumping a thicker sludge to the digester can help prevent a

loss of alkalinity

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Anaerobic Digestion

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Anaerobic Digestion

Mechanical mixing is most common method

Anaerobic Digestion Sludge Parameters

Shaft-driven propeller extended down into sludge

Susceptible to wear
Cleaning and replacement necessary

< 4% Solids

Loss of alkalinity
Decreased Sludge retention time
Increased heating requirements
Decreased volatile acid/alkalinity ratio

4 8% Solids

Normal Operation

> 8% Solids

Poor mixing
Organic overloading
Decreased volatile acid/alkalinity ratio

Other methods
Propeller with draft tube
Bubble-gun type

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Anaerobic Digestion

Anaerobic Digestion

A digester can be compared with

Foaming

your own body.

Problems: odors, excess pressure on cover, plugs gas piping system

Both require food; but if fed too

Cause: Gas production at startup with insufficient solids separation

much will become upset.

Excess acid will upset both.

Prevention: Adequate mixing before foaming starts

Sour digester?
Lime
Lime is added at a 1:1 ratio, 1 lb of lime
for every 1 lb or volatile acid
Soda ash
Transfer alkalinity from secondary

digester to primary
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Neutralizing a Sour Digester

Neutralizing a Sour Digester

The recovery of a sour digester can be accelerated by

When neutralizing a digester, the prescribed dose must be

carefully calculated.

neutralizing the acids with a caustic material such as

anhydrous ammonia, soda ash, or lime, by transferring
alkalinity in the form of digested sludge from the secondary
digester.
Such neutralization reduces the volatile acid/alkalinity to a
level suitable from growth of the methane fermenters and
provides buffering material which will help maintain the
required volatile acid/alkalinity relationship and pH.
If digestion capacity and available recovery time are great
enough, it is probably preferable to simply reduce loading
while heating and mixing so that natural recovery occurs.
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Too little will be ineffective, and too much is both toxic and wasteful.

In considering dosage with lime, the small plant without laboratory

facilities could use a rough guide a dosage of about one pound of
lime added for every 1000 gallons of sludge to be treated.
You must realize that neutralizing a sour digester will only bring the
PH to a suitable level, it will not cure the cause of the upset.
Stuck Digester - A stuck digester does not decompose organic

matter properly.

The digester is characterized by low gas production, high VA/alk

relationship, and poor liquid-solids separation.

A digester in a stuck condition is sometimes called a sour or upset

digester.

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Gas Production
When methane fermentation starts and the methane content

reaches around 60%, the gas will be capable of burning.

Biosolids Stabilization

Methane production eventually should predominate,

generating a gas with 65-70% methane and 30-35% carbon

dioxide by volume.
Digester gas will burn when it contains 56% methane, but is
not usable as a fuel until the methane content approaches
62%.
When the gas produced is burnable, it may be used to heat
the digester as well as for powering engines and for providing
building heating.
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Section 8

Factors Affecting Aerobic Digestion

Aerobic Digestion

Sludge type

Extended aeration of wastewater

Wastes stabilized by long-term aeration of about 10-20 days
Check pH weekly and adjust if less than 6.5
Lower equipment costs than anaerobic (but higher energy costs)
Less noxious odors at DO 1 mg/L
Better on secondary sludge than primary sludge
Sludge has higher water content
By products: residual solids, CO2, H2O, SO4-, NO3-

Digestion time
Digestion temperature
Volatile solids loading
Quantity of air supplied
Dissolved oxygen (DO) concentrations within the digester
This is the most important water quality test for an aerobic

digester

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Aerobic Digestion

Aerobic Digestion

Widest application is with secondary sludges

When primary sludge is fed into an aerobic digester, food

Which are made primarily of biological cells that are produced

becomes available to the microorganisms

in activated sludge or trickling filter processes as a by-product

of degrading organic matter
In the absence of an external food source (no new food being
introduced), these microorganisms enter the endogenous or
death phase of their life cycle.
When no new food is available, the biomass begins to selfmetabolize (consume its own cellular material), which results in
a conversion of biomass to end products of carbon dioxide and
water; and a net decrease in the sludge mass

biomass will convert the food to end products of carbon dioxide and
water; and will function in the growth phase, the biomass will
reproduce, resulting in a net increase in the sludge mass
Aerobic digestion times are long enough to allow the food to be
depleted and the biomass to eventually enter the endogenous or death
phase
The main drawback to aerobically digested primary sludge is that
more air has to be supplied to maintain a desirable DO level because
the bacteria are more active when food is available

In the presence of an external food source (the primary sludge), the

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Chemical Stabilization
Sludges that are not biologically digested or thermally

stabilized can be made stable by the addition of large doses of

lime or chlorine to destroy pathogenic and nonpathogenic
organisms.
Chemical addition to sludge to prepare it for ultimate
disposal is not a common practice
Chemical addition is usually considered to be a temporary
stabilization process and finds application at overloaded
plants or at plants experiencing stabilization facility upsets
The main drawback to chemical stabilization is the cost
associated with the large quantities of chemical required.

Biosolids Stabilization
Chemical Stabilization

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Lime Stabilization

Lime Stabilization

Lime stabilization is accomplished by adding sufficient

Lim arrives from the supplier in powder form and cant be

quantities of lime to the sludge to raise the pH to 11.5 -12.0

Estimated dosages to achieve a pH of 11.5-12.0 are generally
200-220 pounds of lime per ton for primary sludge solids
The addition of lime adds to the overall quantity of solids that
must be ultimately disposed
The high pH of the stabilized solids may also reduce the
range of beneficial reuse opportunities

added directly to the sludge

The powdered lime must be made into a slurry with the

addition of water prior to blending with the sludge

The process of lime stabilization produces an unfavorable

environment and destroys pathogenic and nonpathogenic

bacteria
Studies have shown that >99% of the fecal coliforms and fecal

streptococci can be destroyed

If the pH is not adjusted to the 11.5-12.0 range, the goals of

stabilization will not be achieved.

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Chlorine Stabilization
Chlorine stabilization is accomplished by adding sufficient

quantities of gaseous chlorine to the sludge to kill pathogenic

and nonpathogenic organisms.
Estimated dosages to achieve disinfection are generally 100300 lbs chlorine/ton of sludge solids
Waste activated sludge (WAS) requires higher doses than
primary sludge
The addition of the large quantities of chlorine required for
stabilization will result in an acidic (pH less than 3.5) sludge
and neutralization with lime or caustic may be required prior
to dewatering due to the corrosive condition of the mixture.
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Sludge Dewatering

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Sludge Dewatering

Centrifuge

Dewatering reduces sludge moisture and volume to allow for

Used to thicken or dewater

more economical disposal

Types:

Sludge fed at constant rate

secondary sludges
into rotating horizontal
bowl
Solids separated from liquid
and compacted by
centrifugal force (1000
2000 rpm)

Centrifuge
Plate and Frame Press
Belt Press
Vacuum Filter
Drying Beds
Composting

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SOLIDS
DRYING

SOLIDS
SEPARATION

Section 8

Plate-and-Frame

SCREW CONVEYORS

Solids are pumped in batches

into spaces between plates

SLUDGE FEED

200 250 psi pressure applied

to squeeze out water

CENTRIFUGE FRAME

POLYMER FEED

SLUDGE CAKE
SLUDGE CAKE

At end of cycle (1.5 4

hours), plates are separated

and solid drops out onto
conveyor
Pressure filtration that forces
liquid through the filter media

CENTRATE
DISCHARGE

CENTRATE
SLUDGE

SCROLL CENTRIFUGE
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Plate-and-Frame

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Belt Filter Press

Low power use
Reliable
Continuous operation
Two long belts that travel over a series

of rollers

Sludge applied to free water zone

(much water will drain off here)

Solids then squeezed between a series

of rollers (and more water is removed)

Remaining solids are scraped from the

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belt

JVAP (US Filter) Chattanooga

Modified plate and frame that is vacuum assisted
Steam heated at 163.4F for 30 min
Entire
process takes about 4 hours
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Belts are washed and the process

repeats

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Belt Filter Press

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Vacuum Filter
Sludge pumped into a tank around a partially submerged

rotating drum
Drum rotates, vacuum collects solids on surface
Vacuum removes excess water
Vacuum is then released and solids are removed

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Vacuum Filter

Drying Bed
Simplest of all methods
Sludge deposited in layer on

sand bed or other surface

with drain
Dewatering occurs by
drainage and evaporation
Time required is affected by
climate, depth of solids, and
type of solids
Sometimes drying beds are
covered while others have
vacuum assisted drainage
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Cleanouts
At Grade

PLAN SECTION

Composting

Bedding
Underdrain

Composting results in the decomposition of organic matter

by the action of Thermophilic facultative aerobic

microorganisms to sanitary, nuisance-free, humus-like
material
Composting generally falls into three categories

Sludge Feed Line

From Digesters

Bedding Return Line to Head Works

Windrow
Most common method

Cleanout
At Grade

Static pile

CROSS SECTION

Mechanical

Sand Surface
Sludge Inlet
Bed Drain Lines

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Sand
Pea Gravel
Crushed Rock
Drain Line

Bed Detail

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Composting Windrow Operation

Composting Windrow Operation

Dewater sludge to the highest degree economically practical.

If stacks are turned too often, excessive heat will be released

and the temperature may drop to a point where it is

unfavorable for the thermophilic composting bacteria.
When pathogen destruction is a goal, temperature
measurements must be taken and recorded.
A well-operated windrow compost facility can dry sludge
from an initial moisture content of approximately 60% to a
moisture content of 30% in about 15-20 days to a final
moisture of 20% in approximately 20-30 days.
The most common problems that arise are anaerobic
conditions and reductions in compost temperatures.

Blend dewatered sludge with recycled compost or bulking agents

to produce a homogenous (evenly blended) mixture with a

moisture content of 45-65%.
Form the windrow piles and turn (aerate) once or twice daily for
the first 4-5 days after windrow formation.
Turn the piles approximately once every two days to once a week
to maintain the desired temp. (130-140F or 55-60C) until the
process is complete.
The temperature of the piles should be routinely monitored during

this period.

Load the compost onto trucks for disposal or recycle purposes.

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Section 8

Composting Safety

503 Regs

Large numbers of spores are

The 40 CFR part 503 Sludge Regulations was published in

released into the atmosphere during

certain composting operations
(compost screening, dumping and
mixing of compost, and wood chip
dumping).
To reduce the exposure to airborne
pathogens:

the Federal Register on February 19, 1993,and became

effective on March 22, 1993.
This regulation requires the generator of sludge to treat the
sludge to a certain degree before land applying of the sludge.
The 503 regulation requires the sludge to be monitored for
certain pollutants (metals)
disease causing organisms called pathogens
and Vector Attraction Reduction, which is the reduction of

Enclose the cabs of heavy equipment

Ventilate all enclosed areas properly
Provide dust masks to employees

Volatile organic solids to the degree where vectors (flies,

mosquitoes, and other disease -carrying organisms) are not
attracted to the sludge or biosolids once it is placed on the land.

working in dusty areas.

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503 Regs

503 Regs

Now that the 503 regulation is in effect, digesters will have

Class A alternatives produce a sludge that is virtually

to be efficiently operated to meet the parameters of the

regulation.
If the Sludge is prepared for land application or surface
disposal, it must comply with applicable pathogen reduction
requirements.
The part 503 regulation allows nine pathogen reduction
alternatives, which are divided into two distinct classes :

pathogen free.
Class B alternatives significantly reduce the pathogen level in

sludge.
Both Class A and B alternatives specify maximum levels of

fecal coliform allowed in the sludge.

Monitoring frequency for the pollutants, pathogen reduction

and vector reduction requirements are based on amount of

(dry weight tons) disposal per year.
Records of the results will be kept at the sludge wastewater
plant.

Class A
Class B

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503 Regs

Metals Limits

If your wastewater plant has a design influent flow rate equal

The sludge (Biosolids) applied

to land must meet the ceiling

concentrations for table
section 503.13 pollutants at a
minimum.
The Table 3 section 503.13
pollutant concentration limits
are the best limits to meet
because they are considered
exceptional quality required
no loading rate limits to the
land being applied to.

to or greater than 1 million gallons per day, or serves a

population of 10,000 or more, or Class I Sludge management
facilities (State of Tennessee Industrial Pretreatment
Program) you must report annually to the permitting
authority.
Annual reports cover information and data collected during
the calendar year (January 1 to December 31) and are due
February 19, every year and submitted to the permitting
authority, which is the EPA Regional 6 in Kansas Office for
Tennessee.
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Pathogen Requirements

Pathogen Requirements

Either Class A or Class B pathogen requirements and site

There are a total of 3 options to meet the Class B Reduction:

restrictions must be met before the biosolids (sludge) can be

land applied; the two classes differ depending on the level of
pathogen reduction that has been obtained.

Fecal Coliform Count

Processes to Significantly Reduce Pathogens
Processes to Significantly Reduce Pathogens Equivalent

Aerobic digesters with adequate detention times (40-60 days),

maintaining correct dissolved oxygen levels and feeding the

digesters correctly will usually be able to have to the sludge
tested for class B pathogens and meet it with satisfactory results
(less than 2 million colony - forming units per gram of total
solids - dry weight).

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Requirements in one of the following options

must be met for vector attraction reduction

Vector Attraction Reduction

Vector attraction reduction is to reduce the attraction of

Reduce the mass of volatile solids by a minimum of 38%

vectors (flies, mosquitoes, and other potential disease carrying organisms) to the biosolids or sludge.
1 of 10 options specified in part 503 to achieve vector
attraction reduction must be met when biosolids are applied
to land.

Demonstrate vector attraction reduction with additional

anaerobic digestion in a bench-scale unit

Meet a specific oxygen uptake rate for aerobically treated

biosolids
Use aerobic processes at greater than 40C (avg. temp 45C)

for 14 days or longer (during biosolids composting)

Add alkaline materials to raise the pH under specified

conditions

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Requirements in one of the following options

must be met for vector attraction reduction
Reduce the moisture content of biosolids that do not contain

unstabilized solids from other than primary treatment to at

least 75% solids
Reduce the moisture content of biosolids with unstabilized
solids to at least 90%
Inject biosolids beneath the soil surface within a specified
time, depending on the level of pathogen treatment
Incorporate biosolids applied to or placed on the land surface
within specified time periods after application to or
placement on the land surface
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Section 8

Sludge Digestion Math

Volatile Solids to the Digester, lbs/day
1. If 8,250 lbs/day of solids with a volatile solids content of 68% are sent to the
digester, how many lbs/day volatile solids are sent to the digester?

2. A total of 3600 gpd of sludge is pumped to a digester. If the sludge has 5.7% solids
content with 71% volatile solids, how many lbs/day volatile solids are pumped to the
digester.

Digester Loading Rate, lbs VS added / day / ft3

3. What is the digester loading if a digester, 45 ft. diameter with a liquid level of 20 ft.,
receives 82,500 lbs/day of sludge with 5.8% solids and 69% volatile solids?

4. A digester, 40 ft. in diameter with a liquid level of 18 ft. receives 26,400 gpd of
sludge with 5.7% solids and 71% volatile solids. What is the digester loading in lbs
VS added/day/ft3?

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Volatile Acids / Alkalinity Ratio

5. The volatile acids concentration of the sludge in an anaerobic digester is 170 mg/L.
If the measured alkalinity is 2150 mg/L, what is the VA/Alkalinity ratio?

6. What is the VA/Alkalinity ratio if the volatile acids concentration of the sludge in an
anaerobic digester is 215 mg/L and the measured alkalinity is 1957 mg/L?

Percent Volatile Solids Reduction

7. The raw sludge to a digester has a volatile solids content of 69%. The digested
sludge volatile solids content is 53%. What is the percent volatile solids reduction?

8. The raw sludge to a digester has a volatile solids content of 72%. The digested
sludge volatile solids content is 51%. What is the percent volatile solids reduction?

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Volatile Solids Destroyed, lbs VS / day / ft3

9. A flow of 3750 gpd sludge is pumped to a 35,000 ft3 digester. The solids
concentration of the sludge is 6.3% with a volatile solids content of 68%. If the
volatile solids reduction during digestion is 54%, how many lbs/day volatile solids
are destroyed per ft3 of digester capacity?

10. A flow of 2165 gpd sludge is pumped to a 22,500 ft3 digester. The solids
concentration of the sludge is 4.5% with a volatile solids content of 72%. If the
volatile solids reduction during digestion is 45%, how many lbs/day volatile solids
are destroyed per ft3 of digester capacity?

Digester Gas Production, ft3 Gas Produced / lb. VS destroyed

11. The anaerobic digester at a treatment plant receives a total of 10,500 gpd of raw
sludge. This sludge has a solids content of 5.3% of which 64% is volatile. If the
digester yields a volatile solids reduction of 61%, and the average digester gas
production is 22,300 ft3, what is the daily gas production in ft3/lb VS destroyed
daily?

12. The anaerobic digester at a treatment plant receives a total of 11,400 gpd of raw
sludge. This sludge has a solids content of 5.4% of which 62% is volatile. If the
digester yields a volatile solids reduction of 58%, and the average digester gas
production is 25,850 ft3, what is the daily gas production in ft3/lb VS destroyed
daily?

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Digestion Time, days

13. An aerobic digester 40 ft. in diameter has a side water depth of 12 ft. The sludge
flow to the digester is 8200 gpd. Calculate the hydraulic detention time in days.

14. A 50 ft. aerobic digester has a side water depth of 10 ft. The sludge flow to the
digester is 9500 gpd. Calculate the detention time in days.

Oxygen Uptake Rate, mg/L/hr

15. Dissolved air concentrations are taken on an air-saturated sample of digested
aerobic sludge at one-minute intervals. Given the following results, calculate the
oxygen uptake, mg/L/hr.
Elapsed Time, Min
0
1
2
3
4
5

DO, mg/L
7.9
6.8
6.1
5.3
4.6
3.9

16. Dissolved air concentrations are taken on an air-saturated sample of digested

aerobic sludge at one-minute intervals. Given the following results, calculate the
oxygen uptake, mg/L/hr.
Elapsed Time, Min
0
1
2
3
4
5

144

DO, mg/L
6.9
5.8
5.0
4.3
3.7
2.9

Biosolids

TDEC - Fleming Training Center

Section 8

Answers
1. 5610 VS lbs/day
2. 1215 lbs/day
3. 0.10 lbs VS added/day/ft3
4. 0.39 lbs VS added/day/ft3
5. 0.08
6. 0.11
7. 49%
8. 59.5%
9. 0.021 lbs VS/day/ft3
10. 0.012 lbs VS/day/ft3
11. 12.3 ft3/lb VS destroyed
12. 14.0 ft3/lb VS destroyed
13. 13.7 days
14. 15.5 days
15. 44 mg/L/hr
16. 42 mg/L/hr

Biosolids

145

Section
7
TDEC - Fleming Training
Center

Section 8

146

Sludge Thickening, Digestion and Dewatering

Biosolids

Section
Section 7
8

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Sludge Thickening, Digestion and Dewatering

Biosolids

147

Section
7
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Center

Section 8

148

Sludge Thickening, Digestion and Dewatering

Biosolids

Section
Section 7
8

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Sludge Thickening, Digestion and Dewatering

Biosolids

149

Section 8

TDEC - Fleming Training Center

150

Biosolids

Section 9
Reclamation and Reuse

151

Section 9

TDEC - Fleming Training Center

TDEC - Fleming Training Center

Wastewater Reclamation and Reuse

2

Recycled
Water

or wastewater is used within a facility before it

is discharged to a treatment system

Reclamation
Operation

or process of changing the condition or

characteristics of water so that improved uses can be
achieved.

WASTEWATER
RECLAMATION AND REUSE

Reuse
Water

is discharged and then withdrawn by another

user

Advanced Wastewater Treatment

TDEC - Fleming Training Center

Wastewater Reclamation and Reuse

3

Water Reuse: Historical Perspective

4

Water agencies forced to seek new water sources

Water reuse common in many areas

Population growth
Contamination of surface or groundwater
Droughts
Uneven water distribution
In US, especially in arid and semi-arid areas
Mostly restricted to non-potable reuse, like irrigation

1912

San Francisco, CA

First small urban reuse

begins with the irrigation of
Golden Gate Park

1942

Baltimore, MD
(Bethlehem Steel)

Metals cooling and steel

processing

1960

Colorado Springs, CO

Landscape irrigation of
golf courses, cemeteries
and freeways

1984

Tokyo, Japan

Water recycling for toilet

flushing in 19 high-rise
buildings in congested
metropolitan area

1987

Monterey, CA

Agricultural irrigation for

food crops eaten uncooked
(celery, broccoli, lettuce,
cauliflower, etc.)

Other alternatives

Water conservation
More efficient use
Development of new water resource and management
TDEC - Fleming Training Center

TDEC - Fleming Training Center

Wastewater Reuse Categories

5

Agricultural Irrigation
6

Agricultural irrigation
Landscape irrigation
Industrial recycling and reuse
Groundwater recharge
Recreational and environmental uses
Non-potable urban uses
Potable reuse

Largest use in US
Uses:
Crop

Issues/Constraints:
Surface

and groundwater contamination if not

managed properly
Marketability of crops and public assistance

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152

irrigation
nurseries

Commercial

TDEC - Fleming Training Center

Reclamation and Reuse

TDEC - Fleming Training Center

Section 9

Landscape Irrigation

Industrial Recycling and Reuse

Uses:

Parks
School yards
Golf courses
Greenbelts
Cemeteries
Freeway medians
Residential

Cooling water
Process water
Boiler feed
Heavy construction

Issues/Constraints:

Uses:

Issues/Constraints:
Constituents in reclaimed water related to scaling, corrosion,
biological growth and fouling
Possible aerosol transmission or pathogens in cooling water
Cross-connection of potable and reclaimed water lines

Effect of water quality, particularly salts, on soils and crops

Public health concerns related to pathogens
Use area control including buffer zone may result in higher costs
TDEC - Fleming Training Center

TDEC - Fleming Training Center

Groundwater Recharge

Recreational and Environmental Uses

10

Uses:

Saltwater intrusion control

Subsidence control

Uses:
Development of lakes and ponds
Marsh enhancement
Stream flow augmentation
Fisheries
Snowmaking

Spreading basins

Groundwater replenishment

Direct injection

Issues/Constraints:
Possible contamination of groundwater aquifer used as
potable water source
Organic chemicals in reclaimed water and their
toxicological effects
Total dissolved solids, nitrates and pathogens

Issues/Constraints:
Health concerns about pathogens
Eutrophication due to nitrogen and phosphorus in receiving
water
Toxicity to aquatic life

TDEC - Fleming Training Center

TDEC - Fleming Training Center

Non-potable Urban Uses

Potable Reuse

11

12

Minimal use in US
Uses:

Fire protection
Air conditioning
Toilet flushing
Flushing of sanitary sewers

Blending

in water supply reservoirs

water supply

Pipe-to-pipe

Issues/Constraints:
Health concern over possible aerosol transmission of
pathogens
Effects of water quality on scaling, corrosion, biological
growth and fouling
Cross-connection of potable and reclaimed water lines

Minimal use in US
Uses:

Issues/Constraints:
Constituents

in reclaimed water (especially trace

organic chemicals and their toxicological effects)
Aesthetics and public acceptance
Health concerns about pathogen transmission

TDEC - Fleming Training Center

TDEC - Fleming Training Center

Reclamation and Reuse

153

Section 9

TDEC - Fleming Training Center

Effluent Disposal

Disposal by Dilution

13

14

Dilution

Stabilize waste
Protect public health
Meet discharge requirements

Lakes

Rivers
Streams

Treatment required prior to discharge:

Wastewater
Reclamation

Land

application
Underground disposal

Site specific
Most common method of effluent disposal
How does one evaluate the effect of a WWTPs
effluent upon the receiving stream?
Sample water in stream above and below the plants outfall
location
Perform a DO profile of the stream

TDEC - Fleming Training Center

TDEC - Fleming Training Center

Disposal by Dilution

Land Treatment Systems

15

16

Diffusers
Cascading outfalls

Increase

D.O.
chlorine
Remove sulfur dioxide

When high-quality effluent or even zero-discharge

is required, land treatment offers a means of
reclamation or ultimate disposal

Remove

Surface discharge

TDEC - Fleming Training Center

TDEC - Fleming Training Center

Land Treatment Systems

Hydrologic Cycle

17

18

Simulate natural pathways of treatment

Use soil, plants, and bacteria to treat and reclaim
wastewater
Treatment is provided by natural processes as
effluent moves through soil and plants
Some of wastewater is lost by evaporation and
transpiration
Remainder returns to hydrologic cycle through
surface runoff or percolation to groundwater

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TDEC - Fleming Training Center

Reclamation and Reuse

TDEC - Fleming Training Center

Section 9

Land Application System

19

Land Application System

20

Treatment prior to application

Transmission to the land treatment site
Storage
Distribution over the site
Runoff recovery system
Crop systems

Evapotranspiration

Treated
Plant
Effluent

Storage
Reservoir

Land
Disposal
Site

Surface
Runoff

Percolation
TDEC - Fleming Training Center

TDEC - Fleming Training Center

Site Considerations
21

22

Control of ponding problems

Wastewater Reclamation:
Land Application

Percolation
Crop

Irrigation most
common:
Ridge

selection
tiles

and furrow

Drainage

Sprinklers

Install PVC laterals below ground

Potential odor release with spray systems
Routine inspection of equipment
Plan B in case system fails

Surface/drip

systems

Overland flow
Wastewater Treatment Plant &
Poplar Tree Reuse System;
Woodburn, Oregon

TDEC - Fleming Training Center

TDEC - Fleming Training Center

Irrigation

Irrigation

23

24

Method depends on crop

grown
Silage / hay
Parks / golf courses
Horticulture / timber / turf
grass

Water & nutrients enhance

plant growth for beneficial
use.
Water removed by:

Surface evaporation &

plant transpiration
Deep percolation to subsoil

Irrigation application of wastewater over relatively flat

area, usually by spray (sprinklers) or surface spreading
Water and nutrients are absorbed by plants and soil
In soil, organic matter is oxidized by bacteria

TDEC - Fleming Training Center

TDEC - Fleming Training Center

Reclamation and Reuse

155

Section 9

TDEC - Fleming Training Center

Irrigation

Irrigation - Spray Systems

25

26

Most common land treatment in US

Spray: fixed or moving
Surface spreading: controlled flooding or ridge &
furrow
Climate affects efficiency

Moving - center pivot

Minimum slope 2 3%

Maximum slope in TN:

If ground freezes, subsurface seepage is greatly reduced.

Therefore storage of treated wastewater may be necessary

Buried or on surface
Cultivated crops or woodlands

Fixed

Promotes lateral drainage and reduces ponding

Row crops
8%
Forage crops 15%
Forests
30 %

Ex: lawns, parks, golf courses, pastures, forests, fodder

crops (corn, alfalfa), fiber crops, cemeteries

TDEC - Fleming Training Center

TDEC - Fleming Training Center

Irrigation - Spray Systems

Irrigation Ridge & Furrow

27

28

Center pivot, moving

spray irrigation

Wastewater flows through furrows between rows of

crop
Wastewater slowly percolates into soil
Wastewater receives partial treatment before it is
absorbed by plants

Fixed spray
irrigation on risers

TDEC - Fleming Training Center

TDEC - Fleming Training Center

Irrigation Ridge & Furrow

Irrigation Removal Efficiencies

29

30

Irrigation ditch in foreground supplying

water to furrows

Parameter

% Removal

BOD

98

COD

80

Suspended Solids

98

Nitrogen
Phosphorus

85
95

Metals

95

Microorganisms

98

Gated pipe applying flow to furrows

TDEC - Fleming Training Center

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Reclamation and Reuse

TDEC - Fleming Training Center

Section 9

Irrigation Removal Efficiencies

31

Overland Flow
32

Under normal circumstances:

Water and nitrogen are absorbed by crops

Phosphorus and metals are adsorbed by soil particles
Bacteria is removed by filtration
Viruses are removed by adsorption

Nitrogen cycle

Secondary effluent contains ammonia, nitrate and organic

nitrogen
Ammonia and organic nitrogen are retained in soil by
adsorption and ion exchange, then oxidized to nitrate
Major removal mechanisms are ammonia volatilization, crop
uptake and denitrification

TDEC - Fleming Training Center

6-12 hours/day
5-7 days/week

2-4% slope
Slow surface flow treats
wastewater
Water removed by
evaporation &
percolation
Runoff collection

TDEC - Fleming Training Center

Overland Flow
33

Spray or surface
application

Overland Flow
34

Wastewater is applied intermittently at top of

terrace
Runoff collected at bottom (for further treatment)
Treatment occurs through direct contact with soil

TDEC - Fleming Training Center

TDEC - Fleming Training Center

Overland Flow
35

Distribution Methods
36

Low pressure sprays

psi
energy costs
Good wastewater distribution
Nozzles subject to plugging

Methods

Surface distribution
Generate

minimal aerosols
Higher energy costs
Hard to maintain uniform distribution
TDEC - Fleming Training Center

Limitations

Low energy costs

Minimize aerosols and wind drift
Small Buffer zones

Difficult to achieve uniform distribution

Moderate erosion potential

Gated Pipe

Same as General, plus:

Easy to clean
Easiest to balance hydraulically

Same as General, plus:

Potential for freezing and settling

Slotted or
Perforated
Pipe

Same as General

Same as Gated Pipe, plus:

Small openings clog
Most difficult to balance hydraulically

Bubbling
Orifices

Same as General, plus:

Not subject to freezing/settling
Only the orifice must be leveled

Same as General, plus:

Difficult to clean when clogged

Low-pressure
Sprays

Better distribution than surface methods

Less aerosols than sprinkler
Low energy costs

Nozzles subject to clogging

More aerosols and wind drift than
surface methods

Sprinklers

High energy costs

Most uniform distribution
TDEC - Fleming Training CenterAerosol and wind drift potential

<20
Low

Advantages

General

Large buffer zones

Reclamation and Reuse

157

Section 9

TDEC - Fleming Training Center

Suitable Grasses
Rooting
Characteristics

Method of
Establishment

Growing
Height
(cm)

Reed canary

Perennial

sod

seed

120-210

Tall fescue

Perennial

bunch

seed

90-120

Rye grass

Annual

sod

seed

60-90

Redtop

Perennial

sod

seed

60-90

KY bluegrass

Perennial

sod

seed

30-75

Orchard grass

Perennial

bunch

seed

15-60

Common
Bermuda

Perennial

sod

seed

30-45

Coastal
Bermuda

Perennial

sod

sprig

30-60

Dallis grass

Perennial

bunch

seed

60-120

Bahia

Perennial

sod

seed

60-120

Common Name

Warm Season

Cool Season Grass

37

Suitable Grasses

Perennial
or Annual

TDEC - Fleming Training Center

38

TDEC - Fleming Training Center

Suitable Grasses
39

40

Well established plant cover is essential for efficient

performance of overland flow
Primary purpose of plants is to facilitate treatment
of wastewater
Planting a mixture of different grasses usually gives
best results
Ryegrass used as a nurse crop; grows quickly until
other grasses are established

Overland Flow Removal

Efficiencies

Cool Season Grass plant from Spring through early

Summer or early Fall to late Fall
Warm Season Grass generally should be planted
from late Spring through early Fall
Planting time affected by expected rainfall, location,
climate, grass variety, etc
Amount of seed required to establish cover depends on:

Parameter

% Removal

BOD

92

Suspended Solids

92

Nitrogen

70-90

Phosphorus

40-80

Metals

Expected germination
Type of grass
Water availability
Time available for crop development

50

Treatment by oxidation and filtration

SS

removed by filtration through vegetative cover

oxidized by microorganisms in soil and on
vegetative debris
Nitrogen removal by denitrification and plant uptake
BOD

TDEC - Fleming Training Center

TDEC - Fleming Training Center

Rapid Infiltration

Rapid Infiltration

41

42

Primary objective is to recharge the groundwater

Wastewater is applied to spreading basins or
seepage basins and allowed to percolate through
the soil
No plants are used or desired

Top Picture of a
seepage basin in
Nevada
Bottom - Large volumes
of reclaimed water,
which have undergone
advanced secondary
treatment, are reused
through land-based
applications in a 40square-mile area near
Orlando, Florida.

TDEC - Fleming Training Center

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Reclamation and Reuse

TDEC - Fleming Training Center

Section 9

Rapid Infiltration

Land Treatment Limitations

43

44

Effluent is discharged into a basin with a porous

liner
No plants needed or desired
Primary objective is groundwater recharge
Not approved in Tennessee

Due

Sealing soil surface due to high SS in

final effluent

More common in clay soils

Three possible solutions:

to Karst topography cracks in limestone provide

direct route of infiltration to groundwater and therefore
no treatment achieved and groundwater may become
contaminated

Build up salts in soil

TDEC - Fleming Training Center

Remove SS from the effluent

Disk or plow field to break mats of
solids
Apply water intermittently and allow
surface mat to dry and crack

Salts are toxic to plants

Leach out the salts by applying fresh
water (not effluent)
Rip up the soil 4 5 ft deep to
encourage percolation

TDEC - Fleming Training Center

Land Treatment Limitations

Land Treatment Limitations

45

46

The severity of both soil sealing due to suspended solids

and salinity problems due to dissolved solids depends
on the type of soil in the disposal area.
These problems are more difficult to correct in clay soils
than in sandy soils.
Excessive nitrate ions can reach groundwater if
irrigation or rapid infiltration are overloaded or not
properly operated.

Rapid infiltration systems have no crops to remove nitrogen

so they must be operated in wet/dry cycles in order to first
nitrify the ammonium (dry) and then denitrify the nitrate
(wet) to form nitrogen gas (N2), which is released to the
atmosphere.

Excessive nitrate ions reach groundwater

Rain

can soak soil so that no treatment is achieved

not apply nitrate in excess of crops nitrogen uptake
ability
Excessive nitrate in groundwater can lead to
methylmoglobenemia (blue baby syndrome)
Do

Too

much nitrate consumed by child leads to nitrate in

stomach and intestines where nitrogen is absorbed into
bloodstream and it bonds to red blood cells preventing them
from carrying oxygen.
Baby becomes oxygen deprived, turns blue and suffocates

TDEC - Fleming Training Center

TDEC - Fleming Training Center

Monitoring Requirements
47

Area
Effluent and
groundwater or
seepage

Vegetation
Soils

Test
BOD
Fecal coliform
Total coliform
Flow
Nitrogen
Phosphorus
Suspended solids
pH
Total dissolved solids (TDS)
Boron
Chloride

Frequency
Two times per week
Weekly
Weekly
Continuous
Weekly
Weekly
Two times per week
Daily
Monthly
Monthly
Monthly

- - - variable depending on crop - - Conductivity

pH
Cation Exchange Capacity (CEC)

Two times per month

Two times per month
Two times per month

TDEC - Fleming Training Center

Reclamation and Reuse

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Section 9

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160

Reclamation and Reuse