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.  Phyto-remdiation systems  Pond systems  Constructed wet lands

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

10. Aerobic processes TypeCommon NameUse Suspended Growth Activated-Sludge process (es) Aerated Lagoons Aerobic digestion Membrane bioreactors Carbonaceous BOD removal, nitrification Stabilization, carbonaceous BOD removal Attached growthTrickling Filters Rotating biological contactors Packed bed reactors Carbonaceous BOD removal, nitrification -do- Hybrid (Combined) suspended and attached Growth processes Trickling filters/ activated sludge Carbonaceous BOD removal, nitrification

11. Anoxic processes TypeCommon NameUse Suspend ed Growth Suspended- growth denitrification Denitrification Attached growth Attached-growth denitrification Denitrification

12. Anaerobic processes TypeCommon NameUse Suspend ed Growth Anaerobic contact processes Anaerobic digestion Carbonaceous BOD removal Stabilization, solids destruction, pathogen kill Attached growth Anaerobic packed and fluidized bed Carbonaceous BOD removal, waste stabilization denitrification Sludge blanket Upflow anaerobic sludge blanket Carbonaceous BOD removal, especially High-strength Waste HybridUpflow sludge blanket/attached growth Carbonaceous BOD removal

13. Combined aerobic, anoxic, and anaerobic processes TypeCommon NameUse Suspen ded Growth Single- or multistage processes, Various proprietary processes Carbonaceous BOD removal, nitrification, denitrification, and phosphorus removal HybridSingle- or multistage processes with packing for attached growth Carbonaceous BOD removal, nitrification, denitrification, and phosphorus removal

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 TypeCommon NameUse Aerobic lagoons Carbonaceous BOD removal Maturation (tertiary) lagoons Carbonaceous BOD removal, nitrification Facultative lagoons Carbonaceous BOD removal Anaerobic lagoons Carbonaceous BOD removal, waste stabilization.

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 PollutionBiomass + breakdown products (Sludge) Aerobic (with oxygen)Anaerobic (without oxygen) Microorganisms

25. Proteins nitrate- N ammonia-N N2 gas autotrophic- aerobic heterotrophic- anaerobic nitrification denitrification Nitrogen removal  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. Constructed wetlands: Different types Vertical subsurface flow Floating Macrophyt es system

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 1.Wastewater flow rate 2.Organic loading rate 3.Rate of diffusivity of food and oxygen into the biofilm. 4.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

51. Membrane Bioreactors Employ biological reactor and membrane filtration as a unified system for the secondary treatment of wastewater Membranes perform the separation of the final effluent from the biomass through filtration Filtration takes place by the application of a pressure gradient

52. Process Basics SS Deni Nitri SS SCT discharge conventional technology membrane technology NDN effluent UF not Sec. Clarif.

53. Process Basics membrane water suction dis. solids sludge floc viruses bacteria kinet. energy

54. Re-circulation Feed SS Submerged MBR System Cleaning chemicals Module Back pulse BP Tank effluent Permeate ZeeWeed Aeration aeration

55. Assessment of MBR Technology Advantages –High effluent quality –No sludge settling problems –Reduced volume requirements Disadvantages –Membrane fouling –Increased operational costs

56. Space Requirement Many Compact Units are available

57. For Sustainability 1. Promote Anaerobic treatment technologies for energy generation  Less energy intensive  Can generate alternate energy  So far not very successful due to the lack of information about the process Demonstration plants Operational guidelines Training in design, maintenance and operation

58. 2. Develop Wastewater reuse and recycle systems after adequate treatment  Wastewater is not a problem, but a resource  Treat the waste according to the beneficial use Agricultural - Preserve as much nutrients as possible, kill the pathogens (low cost technologies) Industrial – Higher degree of treatment- (bio membrane processes) Domestic – Flushing toilets, gardening etc… Groundwater Recharge- needs high end treatment if the GW table is high, otherwise the soil will act as a treatment unit.. Base flows in Rivers – Needs treatment based on the carrying capacity of the existing river, water body

60. Wastewater reuse applications Wastewater reuse categoriesIssues/ constraints Agricultural irrigation crop irrigation Commercial nurseries Surface and groundwater contamination Marketability of crops and public acceptance Landscape irrigation Parks, School yards, Freeway medians, Golf courses, Cemeteries Green belts, Residential Effect of water quality, particularly salts, on soils and crops Public health concerns related to pathogens Use area control including buffer zone may result in high user costs Industrial recycling and reuse Cooling water Boiler feed Processes water Heavy construction Constituents in reclaimed water related to scaling, corrosion, biological growth, and fouling Public health concerns, particularly aerosol transmission of pathogens in cooling water Cross connection of potable and reclaimed water Groundwater recharge Groundwater replenishment Saltwater intrusion control Subsidence control Possible Contamination of groundwater aquifer used as a source of potable water Organic chemicals in reclaimed water and their toxicological effects Total dissolved solids, nitrates, and pathogens in reclaimed water

61. Wastewater reuse applications Wastewater reuse categoriesIssues/ constraints Recreational/environmental uses Lakes and ponds Marsh enhancement Stream-flow augmentation Fisheries, Snowmaking Health concerns related to presence of bacteria and viruses Eutrophication due to nitrogen and phosphorus in receiving water Toxicity to aquatic life Nonpotable urban uses Fire protection Air conditioning Toilet flushing Public health concerns about pathogens transmitted by aerosols Effect of water quality on scaling, corrosion, biological growth, and fouling Cross connection of potable and reclaimed water lines Potable reuse Blending in water supply reservoirs Pipe-to-pipe water supply Constituents in reclaimed water, especially trace organic chemicals and their toxicological effects Aesthetics and public acceptance Health concerns about pathogens transmission, particularly enteric viruses

62. Selection of Treatment Technologies Life cycle analysis of wastewater treatment systems The treatment system should be Economically viable, Environmentally Friendly, and Sustainable. Many times these factors are not being considered. Develop guidelines for life cycle analyses of wastewater treatment systems. Pros and cons of the systems Eg: Energy consumption, Residual pollution left over, Environmental degradation, contribution to global warming etc..