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Sewage treatment Disposal
- 2. CHARECTERISTICS OF WATER • Colour • Odour • Turbidity • Specific gravity • Temperature PHYSICAL • Total solids • Ph value • Chloride content • Toxic compound • Dissolved oxygen • Biochemical oxygen demand • Chemical oxygen demand • Total organic carbon • Theoretical oxygen demand CHEMICAL • Aerobic bacteria • Anaerobic bacteria • Facultative bacteria • Pathogenic bacteria • Non-pathogenic bacteria BIOLOGICAL
- 12. LIMITATIONS OF BOD TEST • BOD test measures only bio-degradable organic matter. • If the sample of sewage contains toxic wastes, it should be given pre-treatment before applying the BOD test. • It is essential to have a high concentration of active bacteria present in the sample of sewage. • The effects of nitrifying bacteria should be reducted or eliminated by pre-treatment. • The time required for the test is long. • For the BOD5 test, the 5-day period may not correspond to the point where soluble organic matter present has been used.
- 13. CHEMICAL OXYGEN DEMAND • The amount of oxygen is required for decomposing of organic matter in sewage by strong oxidising agent under acidic condition is called Chemical Oxygen Demand • COD test is used in waste water as well as water treatment plant • This test only takes 3 hours for process. • The agent of oxidising chemical is potassium dichromate • COD test is used for Industrial sewage
- 14. DIFFERENCE BETWEEN BOD • Oxygen required for the micro organism to carry out biological decomposition of organic matter in the sewage under aerobic condition at standard temperature • It takes 5 days to complete the process • The BOD test gives the amount of biologically active organic matter in sewage • Not useful to control treatment process • Used for domestic sewage only • It doesn’t determine the strength of sewage • Huge amount of Clean water is required to perform oxidation of organic matter • BOD < COD COD • COD may be designed as the oxygen required for the chemical oxygen decomposition of organic matters in the sewage by strong oxidising agent under acidic condition • The COD test make only 3hours time. • The COD test gives the total of biologically active as well as biologically inactive organic matter in the sewage • The test is useful in the control of treatment process • COD test it is necessary for the industrial sewage • It determine the strength of sewage • COD can be achieved by controlling the amount of chemical oxidising agents • COD Value is always greater than BOD value • COD > BOD
- 15. SEWAGE TREATMENT PLANT PRELIMINARY TREATMENT •Screen •Grit Chamber •Skimming Treatment Primary Treatment •Plain sedimentation •Sedimentation with coagulation SECONDARY TREATMENT • Aeration tank • Secondary sedimentation • Sludge digestion tank • Trickling filter • chlorination
- 16. PRELIMINARY – GRIT CHAMBER • Objectives Of Grit Chamber • To Protect Pump And Other Equipment Used Against Abrasion • To Reduce The Frequency Of Cleaning Of Sludge Digestors And Setting Tanks • To Reduce The Clogging Of Sludge Pipes
- 17. GRIT CHAMBER
- 18. GRIT CHAMBER • Grit is small or finer particles like, silt sand etc • Grit chamber is aimed to remove grit from waste water • If the grit is not removed it increases the wear and tear of mechanical equipment and also occupy space left for other substances • It creates disposal problem • It is long rectangular channel
- 19. GRIT CHAMBER-HORIZONTAL FLOW : • Maintain velocity of 0.3m/s • It will carry organic matter • It will allow heavy grit to settle down • Grit chamber is that the flow velocity should neither to slow nor too fast
- 20. SKIMMING TANK To remove oil and grease from surfaces of tank
- 21. TRICKLING FILTER
- 22. TRICKLING FILTER Coarse gravel (25-75mm) is used- Packed media Finer media not used because of tough cleaning process Around the gravel layers of micro- organism and organic matter is observed that layer is called SLIME Layer
- 23. • DEPTH OF SLIME LAYER : 0.1-0.2mm • Remaining part is anaerobic bacteria • As micro-organism grow thickness of slime layer increases • Process of shearing of slime layer/biological layer is called sloughing in order to avoid problems • Fly and odour nuisance occured
- 24. STANDARD TRICKLING FILTER • No provision of recirculation • Discharge cant be controlled • Operation troubles, fly and odour nuisance HIGH RATE TRICKLING FILTER • Recirculation is occurred • Discharge can be controlled • Operation trouble can be eliminated
- 25. TYPES OF TRICKLING FILTER • Low rate trickling filter • High rate trickling filter
- 26. ADVANTAGES • They are highly nitrified and stabilised • They can remove 80% of BOD • They are simple in operation • They are self cleaning • Moisture content sludge is 99% • Filter loading capacity is higher DISADVANTAGES • Head loss is more • It produce high foul smell • It requires larger area • Cost of construction is high • It cannot treat raw sewage • It needs primary sedimentation
- 27. SLUDGE DIGESTION TANK • It includes organisms, enzymes, decayed food. • The sludge digestion breaks the organic matter of the sludge into liquid and simple compound which are stable in nature A portion of solids converted into liquid and gases due to which volume of sludge is reduced by 60-75% The gases produced can be used as fuel and digested sludge has good fertilizing value Sludge digestion takes place in anaerobic condition Which form : 1. Acid fermentation 2. Methane fermentation
- 28. FACTORS AFFECTING SLUDGE DIGESTION • TEMPERATURE • pH value • Sludge seeding • Mixing
- 29. FINAL DISPOSAL OF SLUDGE • Spreading of farm land • Dumping • Land filling • Disposing in sea • incineration
- 30. OXIDATION POND • Oxidation pond or stabilization ponds • Relatively small shallow body • They are designed and construct to treat sewage and bio-degradable industrial waste • Such ponds are for detention periods • Treatment in a lagoon depends on condition such as sunlight,alage ,evaporation,percolation,sedimentation and oxidation
- 31. CLASSIFICATION OF STABILIZATION PONDS • Aerobic ponds • Faculative ponds • Anerobic ponds
- 32. OXIDATION POND ADVANTAGE • Lower initial cost • Lower operation cost • No skilled supervision DISADVANTAGE • Requires extensive land area • They create odour • Maintaining suspended solid is difficult
- 33. SEWAGE SICKNESS • When sewage is contionusly applied on the land the pores of soil is damaged • At that stage air cannot circulate through soil pores • Therefore aerobic condition is stopped • When anaerobic condition start foul smell generated • Gases like hydrogen sulphide,CO2 ,methane are produced • This is called sewage sickness
- 34. PREVENTION METHOD OF SEWAGE SICKNESS • Pretreatment of sewage • Choice of land • Giving rest to land • Under drainage of soil • Rotation of crops • Shallow depth
- 35. THANK YOU