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IIIINTRODUCTIONNTRODUCTIONNTRODUCTIONNTRODUCTIONOOOOFFFF AAAACTIVATEDCTIVATEDCTIVATEDCTIVATED SSSSLUDGELUDGELUDGELUDGE

� Biological Treatment Process:-

� Use of Microorganisms to break down the organic matter in

wastewater

Suspended-Growth mechanisms

Organic Matter CO2 + H2O + Energy + New BiomassO2

� Suspended-Growth mechanisms:-

� This process maintain a culture of organisms in suspension of

wastewater liquid, either by vigorously aerating the liquid or

by mechanical mixing.

� Aerobic Bacteria grow and form particles that clump together.

� These particles (flocs) are allowed to settle to the bottom of the

clarifier, leaving a relatively clear liquid free of organic material

and suspended solids after aeration process.2

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MicroorganismsMicroorganismsMicroorganismsMicroorganisms

inininin

Activated SludgeActivated SludgeActivated SludgeActivated Sludge

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Activated SludgeActivated SludgeActivated SludgeActivated Sludge

BBBBACTERIAACTERIAACTERIAACTERIA

� Composition:- C60H87O23N12P

� Characteristic:-� Ability to flocculate to form floc and their separation from the liquid phase for complete stabilization.

� Removal of organic matter from wastewater is carried out through 2 process:-

1. Biological Oxidation / Respiration1. Biological Oxidation / Respiration

2. Biosynthesis

� Examples:-� Zooglea, Bacillius spp. , Pseudomonas, Flavobacterium, Alcaligenes, Acinetobacter 5

COHNS + 02 + BACTERIA ���� CO2 + H2O + ENERGY + others

COHNS + O2 + BACTERIA ���� C5H7NO2 (New Cells)

GROWTH OF BACTERIA - HIGH LEVEL OF FOODHIGH LEVEL OF FOODHIGH LEVEL OF FOODHIGH LEVEL OF FOOD

� When abundance of food is

available

� Bacteria are grow, motile, &

extremely active

� They are multiply rapidly.

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� Bacteria will not flocculate and

settle as long as they are growing

at a lag phase.

� Biosynthesis (new cell)����;

Respiration (energy)����

� Activated Sludge with a

poor settling properties

� When low level of food is available

� The bacteria begin to conserve energy & become non-

motile form

� They begin to form a thick outer slime layer. As

they bump into each other, they stick together.

GROWTH OF BACTERIA - LOW LEVEL OF FOODLOW LEVEL OF FOODLOW LEVEL OF FOODLOW LEVEL OF FOOD

they bump into each other, they stick together.

� At first they form small clumps then masses large

enough to settle

� Autoagglutination process

� Biosynthesis (new cell)����;

Respiration (energy) ����

� Activated Sludge with a good settling properties7

FFFFILAMENTOUSILAMENTOUSILAMENTOUSILAMENTOUSBBBBACTERIAACTERIAACTERIAACTERIA

� Characteristic:-

� Filaments do not have the same flocculating characteristics

as the bacteria which do not compact to a readily settleable

mass.

� Roles:-1. BOD/COD removal1. BOD/COD removal

2. Add a backbone for strengthen purpose to the floc structure

� Examples of Filaments:-

� S. natans,

� Nocardia,

� Beggiatoa…

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When filaments abundant in

activated sludge:-� Foaming

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Predominate over the bacteria when:-1. Low Dissolve Oxygen

2. Low pH

3. Low Nutrients

4. F/M ratio not stable

5. High level of Oil & Grease

PPPPROTOZOAROTOZOAROTOZOAROTOZOA

� Roles:-

� Removing & digesting free-swimming dispersed bacteria

and other suspended particles. This improves the clarity of the effluent

� Biological Indicator of the activated sludge condition:-

� Strict Aerobes � Strict Aerobes

� More sensitive to toxic organic compound

� Examples:-

1. Ciliates (Opercularia, Carchesium polypinum …)

2. Amoebae (Arcella,Euglypha…)

3. Flagellates (Peranema… )

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PROTOZOA -AAAAMOEBAEMOEBAEMOEBAEMOEBAE� Food:-

� They feed on small organic particulates

� When abundant present in Activated sludge:-

� Plant start-up.

� A shock load of BOD / large amount of organic � A shock load of BOD / large amount of organic

particulates has entered the treatment system

� They move slowly & cannot compete with bacteria / protozoa for

food. Sudden increase in food allows them to compete & multiply

� They required less O2 & able to

compete with other protozoa

when the O2 is limited.

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� Food:-

� They feed on suspended bacteria, algae & smaller protozoa

� Stalked Ciliate dominance in the system when:-

� Bacterial population and dissolved oxygen concentration of the

treatment process are high

PROTOZOA -SSSSTALKEDTALKEDTALKEDTALKED CILIATECILIATECILIATECILIATE

Stalk

treatment process are high

� A mature floc structure has developed

� They indicate a stable wastewater environment & a healthy

activated sludge

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Examples:-1. Carchesium sp.

2. Suctorian

PROTOZOA -CRAWLING CILIATESCRAWLING CILIATESCRAWLING CILIATESCRAWLING CILIATES

� Food:-

� They feed on suspended bacteria, algae & smaller protozoa

� Characteristic:-

� They are free forms, inhabit the surface of sludge flocs or

biofilmbiofilm

� They dominance in the system when:-

� After most soluble nutrients have been removed which are

reflect a stable wastewater

environment & healthy

activated sludge

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METAZOA

� They are multicellular organisms & include all animals

except the protozoa

� Roles:-

� Feed on bacteria, bacteria floc, fungi, protozoa

& rotifer

Examples:-� Examples:-

� Nematode worms (Genus Aelosoma, Rhabditis)

� Rotifers

� Tartigrades (water bear)

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METAZOA -RRRROTIFEROTIFEROTIFEROTIFER

� Roles:-

� Feed on good, stabilized floc; They graze on the floc

structure and increase oxygen penetration

� As environmental indicator due to they are usually the first

to be affected by a toxic load.

� When abundant present in activated sludge:-

� Old sludge age with high MLSS

� Low F/M ratio

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EVALUATION OF ACTIVATED

SLUDGE

Bacteria Testing Report16

Lab TestingLab

Testing

Routine M

icroscopic

Examination

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Microscopic

Examination

Microscopic

Examination

Routine M

icroscopic

Examination

Big & Compact Floc?

Small & Pin Floc

Condiction?

Dispersed Growth?

Sludge Carry Over

BAD smell

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Foaming?!!!

High COD & High COD & TSS of

Discharge water

Protozoa?

Filaments?

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Rotifer?

Secondary

Clarifier

Secondary

Clarifier

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Final

Discharged

Final

Discharged

Booth L220

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Booth L220i-Chem Solution Sdn Bhd

20, Jalan TPP 6/8, Taman Perindustrian Puchong,47100 Puchong, Selangor, Malaysia.

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