CENTER OF EXCELLENCE IN URBAN DEVELOPMENT (DECENTRALIZED WASTEWATER MANAGEMENT &

1. CENTER OF EXCELLENCE IN URBAN DEVELOPMENT (DECENTRALIZED WASTEWATER MANAGEMENT & PUBLIC PRIVATE PARTNERSHIPS) Department of Civil Engineering IIT Madras, Chennai

2. DECENTRALIZED WASTEWATER MANAGEMENT

3. CURRENT STATUS IN INDIA The wastewater generation increased from 7,000 mld in 1978-79 to 17,000 mld in 1994-95 in Class I cities. 39% of wastewater was treated in the year 1978-79. But, in the year 2003, only 26% of wastewater generated in cities was treated 27 cities have only primary treatment facilities

4. The mode of disposal is: indirectly into the rivers/ lakes/ ponds/ creeks in 118 cities; on to the agriculture land in 63cities directly into rivers in 41 cities. in 44 cities, it is discharged both into rivers and on agriculture land. In many of the coastal cities, the wastewater finds its way into estuaries, creeks, bays etc. (Around 25% of total wastewater)

5. PARADIGM SHIFT IN RECENT PAST • In the past, wastewater was a “problem” • Now, it is considered as a “resource” • Example: • “Newater” scheme in Singapore • Treated domestic wastewater for Industrial use • “Zero Discharge” norm for major industries • “Recycled water” for domestic use • Treated wastewater for groundwater recharge & irrigation Zero Discharge

6. ISSUES TO BE ADDRESSED • To develop tailor made treatment processes for various situations • Wastewater treatment, reuse and recycle • Life cycle analysis of wastewater treatment systems.

7. How can we solve the problem.. • Develop “Tailor Made” wastewater treatment processes for various situations • Decentralized, economically viable and environmental friendly technologies • Pond systems • Constructed wet lands • Phyto-remdiation systems • Biofiltration and sand filters • Septic Tanks • Biomembrane processes • Biotowers • Selection of the systems depends on soil and groundwater conditions and availability of land

8. Pond systems • Phyto-remdiation systems • Constructed wet lands

9. Biofiltration and sand filters • Septic Tanks • Biomembrane processes

10. Aerobic processes

11. Anoxic processes

12. Anaerobic processes

13. Combined aerobic, anoxic, and anaerobic processes

14. Ponds and Lagoons Sewage Contains • Pathogens or disease-causing organisms • Water, with only 0.06 percent of the dissolved and suspended solid material. • Suspended particles present in untreated sewage ranges from 100 to 350 mg/l. • Pathogens or disease ranges from 100 to 350 mg/l. • Sewage also contains nutrients (such as ammonia and phosphorus), contains nutrients (such as ammonia and phosphorus), • Ammonia can range from 12 to 50 mg/l and phosphorus can range from 6 to 20 mg/l in untreated sewage.

15. Lagoon processes

17. Lagoons • Like most natural environments, conditions inside facultative lagoons are always changing. • Lagoons experience cycles due to variations in the weather, the composition of the wastewater, and other factors. • In general, the wastewater in facultative lagoons naturally settles into three fairly distinct layers or zones. • Different conditions exists in each zone, and wastewater treatment takes place in all three

18. Lagoons… • The top layer in a facultative lagoon is called the aerobic zone, because the majority of oxygen is present there. • How deep the aerobic How deep the aerobic zone is depends on loading, climate, amount of sunlight and wind, and how much algae is in the water. • The wastewater in this part of the lagoon receives oxygen from air, from algae, and from the agitation of the water surface (from wind and rain, for example). • This zone also serves as a barrier for example). This zone also serves as a barrier for the odors from gases produced by the treatment processes occurring in the lower layers.

19. Preliminary treatment • Things like rags, sand, gravel and larger pieces of organic matter must be removed before it enters the Treatment System.

20. Aerial View of a Lagoon System

21. Advantages and Disadvantages Advantages • Inexpensive and Reliable system in tropical countries • Min operation and maintenance • No energy requirement Disadvantages • Requirement of large area • Odor and rodent problem • Effluent with high total BOD

22. Constructed Wetlands

23. Removal Mechanisms Wetland treatment: Organic matter, TSS, N, P, pathogens • Removal mechanism: • Biological: • microbial degradation • plant uptake • Physico- chemical: • adsorption • sedimentation • precipitation

24. Organic Matters • Sugars, Proteins, lipids; • Toilet wastes, cleaning, food wastes Microorganisms Pollution Biomass + breakdown products (Sludge) Aerobic (with oxygen) Anaerobic (without oxygen)

25. Nitrogen removal Proteins ammonia-N nitrification autotrophic- aerobic nitrate- N denitrification heterotrophic- anaerobic N2 gas • Plant uptake • Ammonia volatilization • Storage in detritus and sediment

26. Phosphorous removal Phosphorous adsorption:clay-humus complex Phosphorous precipitation:iron, aluminum, calcium Problems:saturation and clogging Plant uptake

27. Pathogens • Sedimentation / filtration • Natural die-off • Excretion of antibiotics from roots of macrophytes

28. Plants The role of the plants: • The root system increases the surface available to bacterial colonisation; • Transfer oxygen to provide an aerobic/oxidized environment, oxygen leakage from the roots( limited); • Nutrient assimilation (N and P) (limited); • Maintain hydraulic pathways in the substrate; • Plant litter provides substrate to the microorganisms; • Accumulated liter serves as thermal insulation; • Aesthetics of the wastewater treatment plant.

29. Plants • A wide variety of aquatic plants can be used. • Selecting plants: • Native plants; • Active vegetative colonizers; • Considerable biomass, stem densities; • Sometimes a combination of species.

30. Wastewater treatment Primary treatment : Septic tank :lower the total organic loading, and separate the solids from the liquid Secondary treatment: Constructed wetland:convert the dissolved or suspended material into a useful form separated from the water

31. Vertical subsurface flow Floating Macrophytes system Constructed wetlands: Different types

32. Aerobic Suspended Growth Systems(s32)

33. Process Description The aerobic conversion of the organic matter occurs in three steps: • Oxidation • COHNS + O2 + BACTERIA  CO2 + NH3 + END PRODUCTS+ ENERGY (Organic matter) • Synthesis of new cells • COHNS + O2+ BACTERIA + ENERGY  C5H7NO2 (new cells ) • Endogenous respiration • C5H7NO2 + 5O2  5 CO2+ NH3+ 2H2O + ENERGY

34. Pathways for the breakdown of organic matter

35. Extended Aeration System External substrate is completely removed. Auto oxidation (internal substrate is used) Net growth = 0

36. Advantages • Sludge production minimal • Stabilized sludge  No digesters are required • Nutrient requirement minimal

37. Disadvantages • High power requirement • Large volume of aeration tank • Suitable for small communities

38. Oxidation ditch – Pasveer Ditch

40. Attached Growth systems • Aerobic • Trickling filters • Rotating biological contactors • Anaerobic • Anaerobic filters • Denitrification systems

41. System biology - Heterogeneous microbes

42. Rate of organic matter removal • Wastewater flow rate • Organic loading rate • Rate of diffusivity of food and oxygen into the biofilm. • Temperature

43. Trickling Filters T.F  Reactor in which randomly packed solids forms provide surface for microbial growth. - system for wastewater distribution Specific surface area and porosity Specific surface area: The amount of surface area of the media that is available for bio film growth

50. RBCs