Successfully reported this slideshow.
Your SlideShare is downloading. ×

SEWAGE TREATMENT PLANT.pptx

Ad
Ad
Ad
Ad
Ad
Ad
Ad
Ad
Ad
Ad
Ad
Loading in …3
×

Check these out next

1 of 28 Ad

More Related Content

Recently uploaded (20)

Advertisement

SEWAGE TREATMENT PLANT.pptx

  1. 1. SEWAGE TREATMENT PLANT PRESENTED BY DR.ATHIRA MENON MPH ,JIPMER
  2. 2. SEWAGE Sewage is waste water from a community, containing solid and liquid excreta, derived from houses, street and yard washings, factories and industries..(Park 25th ed) Dry Weather Flow:The average amount of sewage which flows through the sewerage system in 24 hours
  3. 3. Health aspects: a) unsightliness and unpleasant odours. b) breeding of flies and mosquitoes c) soil and water pollution d) contamination of food e) increase in the incidence of disease
  4. 4. Composition of Sewage a) 99.9% Water+ 0.1% solids (organic/inorganic in suspension/solution). b) 1g faeces: 1000 million E. coli 10-100 million faecal streptococci 1 to 10 million Cl. perfringens spores
  5. 5. Biological Oxygen Demand Chemical Oxygen Demand dissolved oxygen required by aerobic organisms to breakdown organic materials, during a specified period days, at a specified temperature. oxygen equivalent of that portion of organic matter in a sample which is susceptible to oxidation by strong chemical oxidizer Slow : five days required Fast: takes just two hours to complete 300 mg/L and above : "strong“ 100 mg/L: "weak" *COD and BOD can be indicated as mg/L or ppm (parts per million). Expression of strength of sewage
  6. 6. Suspended Solids : a) The amount of suspended solids in domestic sewage b) vary from 100 to 500 mg/L c) 100 mg/L, the sewage is said to be weak : if the amount is 500 mg/L the sewage is said to be strong.
  7. 7. Decomposition of organic matter In sewage, decomposition of organic matter takes place by 2 ways: 1. Aerobic: Most efficient method Require continuous supply of free dissolved oxygen Organic matter Bacteria, fungi & protozoa CO2, H2O, Ammonia, nitrates & sulphate 2. Anaerobic: Effective when sewage is highly concentrated with plenty of solids Slower Extremely complex mechanism Methane, ammonia, CO2 and H2
  8. 8. MODERN SEWAGE TREATMENT
  9. 9. Treatment divided into 2 stages: 1.Primary 2.Secondary screening and sedimentation Aerobic oxidation & Anaerobic digestion
  10. 10. PRIMARY TREATMENT 1 . SCREENING a) Sewage passed through a metal screen b) Vertical or inclined steel bars usually set 5 cm (2 in) apart c) Necessary to prevent clogging d) Fixed type and moving type. e) The screenings are removed from time to time and disposed off by trenching or burial.
  11. 11. 2 . GRIT CHAMBER a) Passed through grit chamber or detritus chamber. b) 10 to 20 metres in length c) Two important types of Grit Chambers (i) Horizontal rectangular flow (ii) Aerated Grit Chamber. d) Allow the settlement of grits sand, gravel and other heavy solid materials
  12. 12. e) The grit is removed periodically or continuously, and disposed off by plain dumping or trenching. f) Grit chamber i. prevents unnecessary abrasion and wear of mechanical equipment ii. grit deposition in pipelines and channels iii. accumulation of grit in anaerobic digesters and aeration basins.
  13. 13. 3 . Primary sedimentation a) flow very slowly at a velocity of 1- 2 feet per minute b) spends about 6-8 hours in the tank c) purification by sedimentation of suspended matter. d) 50-70% solids settle down e) reduction of 30 to 40 % of coliform organisms
  14. 14. g) sludge is removed mechanically h) Complex organic matter broken down to simpler soluble substances and ammonia. i) Fats and grease rise on the surface, Scum is removed
  15. 15. SECONDARY TREATMENT 1.Aeorobic Oxidation a) Trickling filter method b) Activated sludge process
  16. 16. a) TRICKLING FILTER METHOD
  17. 17. b) ACTIVATED SLUDGE PROCESS I. The heart, Aeration tank II. Effluent mixed with sludge from final settling tank (activated sludge) III. Activated sludge: effluent : 20-30% IV. Mixture in aeration chamber for 6-8 hrs. V. Aeration by Mechanical agitation or by compressed air from bottom (diffused aeration) VI. Organic matter CO2, nitrates and water
  18. 18. 2. Secondary sedimentation I. It is detained for 2-3 hours. II. 'Aerated sludge’ or activated sludge III. It is a valuable manure, if dehydrated. IV. Rest pumped into the sludge digestion tanks for treatment an disposal.
  19. 19. Sludge digestion I. One million gallons of sewage produces 15- 20 tons of sludge. II. methods of sludge disposal : a) Digestion: 1. incubated under favourable conditions of temperature and ph 2. anaerobic auto-digestion 3. complex solid water, CO2, methane and ammonia. 4. Takes 3-4 weeks to complete. 5. In-offensive, sticky and tarry mud, dry readily & form excellent manure
  20. 20. b) Sea disposal: By pumping into sea c) Land: composting with town refuse
  21. 21. Disposal of effluent 1. By dilution: Rivers and streams a) Diluting capacity depends on dissolved oxygen contents of receiving bodies. b) Effluent should not have more than 30 mg/l suspended solids and BOD should not exceeds 20 mg/l ( 8:1 dilution)----Royal commission of England 5th report. 2. Disposal on land: irrigation
  22. 22. S. No. Parameter Required Standards 1 pH 6.5-8.5 2 BOD(5th day) <10mg/l 3 COD <50mg/l 4 Suspended Solids <10mg/l 5 Ammonical Nitrogen <5mg/l 6 Total Nitrogen <5mg/l 7 Fecal Coliform <100 MPN/100 ml Treated Sewage Standards *CPCB
  23. 23. • There are 1,631 STPs (including proposed STPs) with a total capacity of 36,668MLD covering 35 States/UTs*. • Out of 1,631 STPs, 1,093 STPs are operational, 102 are Non-operational, 274 are under construction and 162 STPs are proposed for construction. • Sewage generation from urban centers estimated as 72,368 MLD. STPs in India
  24. 24. *CPCB
  25. 25. Estimated sewage generation for the State of Puducherry is 161 MLD and total treatment capacity (including proposed) is 59 MLD. STPs in Puducherry

×