The World of Activated Sludge
The World of Activated Sludge
The World of Activated Sludge
Suspended-Growth mechanisms 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.
BACTERIA
Composition:- C60H87O23N12P Characteristic:Ability to flocculate to form floc and their separation from the liquid phase for complete stabilization.
2.
Biosynthesis
COHNS + O2 + BACTERIA C5H7NO2 (New Cells)
GROWTH OF BACTERIA -
GROWTH OF BACTERIA -
They begin to form a thick outer slime layer. As they bump into each other, they stick together.
At first they form small clumps then masses large enough to settle Autoagglutination process
FILAMENTOUS BACTERIA
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 removal
2.
Predominate over the bacteria when:1. 2. 3. 4. 5. Low Dissolve Oxygen Low pH Low Nutrients F/M ratio not stable High level of Oil & Grease
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PROTOZOA
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 More sensitive to toxic organic compound
Examples:1. 2. 3.
PROTOZOA -
AMOEBAE
When abundant present in Activated sludge:Plant start-up. 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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PROTOZOA -
STALKED CILIATE
Stalk
Bacterial population and dissolved oxygen concentration of the treatment process are high A mature floc structure has developed They indicate a stable wastewater environment & a healthy activated sludge
Examples:-
PROTOZOA -
CRAWLING CILIATES
Characteristic:They are free forms, inhabit the surface of sludge flocs or biofilm
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
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METAZOA -
ROTIFER
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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BAD smell
Big & Compact Floc? Small & Pin Floc Condiction? Dispersed Growth?
Foaming ?!!!
High COD & TSS of Discharge water
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Protozoa?
Filaments?
Rotifer?
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Secondary Clarifier
Final Discharged
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Booth L220
i-Chem Solution Sdn Bhd
20, Jalan TPP 6/8, Taman Perindustrian Puchong, 47100 Puchong, Selangor, Malaysia.
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