sludge management and sludge digesters
TRANSCRIPT
Unit‐ IIIENV ENGG – IIENV. ENGG. II
Prof S S JAHAGIRDARBE (CIVIL), ME(ENV.)PhD(persuing)g
NK Orchid college of Engg. and Tech. , Solapur
A] SLUDGE TREATMENTThickening DigestionDigestionConditioningDewateringDryingDryingDisposal (Incineration)
1. ThickningReduces moisture content of sludgeTh t f thi k iThree types of thickening
1. Gravity thickening1. Gravity thickening2. Air floatation3. Centrifugation
Gravity ThickeningThickening
2. DigestionAerobic or anaerobic decompositionof sludgeof sludgeCan be sent to mechanical filters orsand beds
3. ConditioningConditioning improves the drainability of digested sludge.Methods adopted –
1. Elutriation (involves passage of air to ( p gseparate particles)
2. Chemical conditioning (addition of g (coagulants)
3. Freezing etc.3 g
4. DewateringPurpose is to reduce volume of sludge andincrease concentrations of biosolids.increase concentrations of biosolids.Dewatering can be achieved on sand dryingb dbeds.
Sludge drying beds
5. Heat dryingReduces water contentT C Temp @ 350oC Process carried out in kilnProcess carried out in kiln.Dried sludge used as soil gconditioner
Heat drying unit
6. IncinerationCombustion of sludgeTemp @ 650oC to 750oC Residual ash is send to landfills
IncineratorIncinerator
B] Anaerobic DigestionConsists of decomposition of sludge from settling tankssludge from settling tanks.Two types of digestersTwo types of digesters
i] Standard rate or conventionalIi] High rate digester
The process of digestion The process has now been described by the following four steps: g pHydrolysis: large polymers are broken d b down by enzymes. Fermentation: Acidogenic fermentations are most important, acetate is the main end product. Volatile acetate is the main end product. Volatile fatty acids are also produced along with carbon dio ide and h drogen carbon dioxide and hydrogen.
Acetogenesis: Breakdown of Acetogenesis: Breakdown of volatile acids to acetate and hydrogen.
Methanogenesis: Acetate Methanogenesis: Acetate, formaldehyde, hydrogen and carbon dioxide are converted to
th d t methane and water.
Cross section of digester
Anaerobic Anaerobic digesters
A bi Anaerobic digester
Stratification in conventional digesterStratification in conventional digester
T t f di tTwo types of digesters
Two stage ‐ high rate digesterTwo stage ‐ high rate digester
Sludge drying Sludge drying beds
Sludge drying beds
C] DISPOSAL OF DIGESTED SLUDGESpreading on farm landDumping ( in abandoned quarries)Dumping ( in abandoned quarries)Land filling ( Sanitary)Sl d l iSludge lagooningCompostingp gDisposing in Inland water bodies or Sea Sea.
Disposal on l dland‐1
Disposal on l dland‐2
Disposal in ffarms
Disposal into the sea
Sludge L iLagooning
Sludge lagoons
What is sludge digestion? Explain anaerobic digestion. (Nov 2010, 8 marks)Write short note onWrite short note on1. Anaerobic digestion process. (Nov 2009, 6 marks)2. Sludge drying beds (May 2008, 6 marks)
Explain different methods of sludge disposal. (May 2009, 8 marks)E l i l bi di i h k h (M 2008 6Explain low rate anaerobic digester with a neat sketch. (May 2008, 6 marks)Enumerate the methods of sludge dewatering. Explain any one in detail.
(May 2008, 6 marks)Describe anaerobic sludge digester with neat sketch. Also explain various stages ofDescribe anaerobic sludge digester with neat sketch. Also explain various stages of anaerobic digestion of sludge. (May 2008, 8 marks)St t bj ti f l d t t t E t th th d f l d di lState objectives of sludge treatment. Enumerate the methods of sludge disposal.
(May 2007,5 marks )