waste water treatment
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Transcript of waste water treatment
- 1. By srishti rawat
2. Water that has been utilized in some capacity that negatively impacts the quality of water. Sewage is a subset of wastewater that is contaminated with feces or urines. 3. Residences (kitchen, bathroom) Rainfall, Highway drainage Industrial institution 4. Water (more than 95%) Pathogens (bacteria, viruses and parasitic worms) Non-pathogenic bacteria Organic particles(feces, hair, food, paper fiber, plant materials) Soluble organic (urea, protein, sugar ,drug) Inorganic particles (sand, grit, metals, ceramics etc.) Soluble inorganic (ammonia, hydrogen sulfide, thiosulfates etc.) Toxins (pesticides, poisons, herbicides etc.) 5. Delhi Jal Board is responsible for treatment and disposal of waste water through an efficient network of about 7000 Km of Sewage lines across Delhi. There are 36 SewageTreatment plants at 21 locations 6. S.No. SewageTreatment plants at Capacity(MGD- Million Gallons per Day) 1 Keshopur Phase I,II,III 72 MGD 2 Okhla Ph I,II,III,IV,V,VI 170 MGD 3 Kondli Ph I,II,III,IV 90 MGD 4 Rithla I,II 80 MGD 5 YamunaVihar I,II 20 MGD 6 Vasantkunj I,II 5MGD 7 Coronation Pillar I,II,III 40 MGD 8 Narela 10 MGD 9 Nilothi 40 MGD 10 Najafgargh 5 MGD 11 Papankalan 20 MGD 7. 12 Dr.Sen Nursing Home Nalla 2.2 MGD 13 Delhi Gate Nalla 2.2 MGD 14 Mehrauli 5 MGD 15 Rohini 15 MGD 16 Ghitorni 5MGD 17 Kapashera 5MGD 18 Commonwealth GamesVillage 1 MGD 19 Bakkarwala 0.66MGD 20 Molarbandh 0.66MGD 21 Timarpur Oxidation Pond 6 MGD Total 594.72 8. S. No Unsewered areas Total Sewerage provided 1. Unauthorized- Regularized 567 541 2. UrbanVillage 135 129 3. Resettlement colonies 44 44 4. RuralVillages 189 34 5. Unauthorized colonies 1639 100 9. process of removing contaminants from wastewater, both runoff and domestic and making it suitable to discharge back into the environment. Municipal wastewater treatment Industrial wastewater treatment 10. Physically a) Total solid (tested by boiling water) b) Odors c) Colors d) Turbidity Chemically a. Biological oxygen demand (BOD) b. Chemical oxygen demand (COD) 11. WastewaterTreatment Mechanical (Physical)Treatment a) Preliminary b) Primary Secondary (Biological)Treatment Tertiary (Chemical)Treatment SludgeTreatment 12. The objective of preliminary treatment is the removal of coarse solids and other large materials often found in raw wastewater. Removal of these materials is necessary to enhance the operation and maintenance of subsequent treatment unit. Coarse Screening Grit Removal 13. Removal of large non biodegradable and floating solids (e.g. rags, clothes, woods, plastics, papers etc.) 14. Grit particles which are smaller than the aperture of the coarse screen will pass through and may cause abrasive problems to pipes and pumps. In grit removal process, velocity is so controlled that grit may settle but most of the organics are retained in suspension. 15. Objective is the removal of settelable organic and inorganic solids by Sedimentation, and the removal of the material that will float (scum) by skimming. Around 25-50% of the incoming BODs, 50-70% of the total suspended solids and 65% of oil and grease are removed during primary treatment. 16. BiologicalTreatment Secondary treatment is designed to substantially degrade the biological content of the sewage which are derived from the human waste, food waste, soaps and detergents etc. Aerobic bacteria and protozoa consume biodegradable soluble organic contaminants (e.g. sugar, fats, short chain carbon molecules etc.) and binds much of the less soluble fractions into floc. 17. Secondary sedimentation Microorganisms must be separated from the treated water by sedimentation to produce clarified secondary effluent. Biological floc is settled out in secondary clarifier and the secondary sludge is then sent to sludge treatment unit. 18. Purpose is to provide a final treatment stage to further improve the effluent quality before it is discharged to the receiving environment. Nutrients removal Disinfection to reduce the number of microorganisms Chlorination Ultraviolet radiation Ozone Odor control 19. Wastewater may contain high level of nutrients (N or P compounds) which excessive release to environment may cause eutrophication. Overgrowth of weeds, algae, blue-green algae (cyanobacteria). DE oxygenation Toxins produced by some algae may contaminate drinking water supply. 20. Nitrification Biological oxidation of nitrogen from ammonia to nitrate. I. Ammonia to nitrite using Nitrosomonas II. Nitrite to Nitrate using Nitrobacter ssp. DE nitrification (anoxic condition) Nitrate is converted into nitrogen gas and released into air. 21. Biologically Using Polyphosphate Accumulating Organism (PAOs) The process is called Enhanced biological phosphorus removal. By chemical precipitation Using salts of irons (e.g. ferric chloride) or aluminium (e.g. alum) or lime. 22. Odor emitted by wastewater treatment are typically an indication of anaerobic or septic condition. Generally arises due to hydrogen sulfide. Controlled by adding iron salts or hydrogen peroxide or calcium nitrate. 23. This process describes the management and disposal of primary and secondary sludge. processes involved are Anaerobic digestion Composting De watering 24. Anaerobic bacteria acts on sludge and produces large amount of waste solids and biogas ( high concentration of methane). Methane can be used to generate electricity and run few pumps. Solid waste (containing water) is sent for composting. 25. An aerobic process that involves mixing of wastewater solids with sources of carbons such as sawdust, straw or woodchips. Aerobic bacteria digests both wastewater solids and carbon source and produce large amount of heat. Resultant solid is then sent for dewatering. 26. Water is removed from solid waste for volume reduction. Using drying beds Mechanically filtering often through cloth screens. Centrifugation. The sludge is now ready to be used off sites as fertilizers.