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IMPROVED RURAL SANITATION CONCEPTS By Dhanesh Gunatilleke SPECIALIST (SEWARAGE DESIGNS) NWSDB 1 st April 2014 1.

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Presentation on theme: "IMPROVED RURAL SANITATION CONCEPTS By Dhanesh Gunatilleke SPECIALIST (SEWARAGE DESIGNS) NWSDB 1 st April 2014 1."— Presentation transcript:

1 IMPROVED RURAL SANITATION CONCEPTS By Dhanesh Gunatilleke SPECIALIST (SEWARAGE DESIGNS) NWSDB 1 st April

2 2 1Why wastewater treatment? 2Policy on Wastewater Separation 3Types of sanitation systems 4Design of onsite sanitation systems in compliance to SLS 745 Part II:2009 5Further Treatment Options Presentation Outline 2

3 1 WHY WASTEWATER TREATMENT ? Protect the environment from;  high loads of suspended solids & organic matter  eutrophication & groundwater pollution  Substantial load of hazadous and non biodegradable compounds  Serious contamination with microorganisms …in order to establish/maintain healthy environment for flora & fauna allow mankind to use water resources for different purposes prevent transmission of waterborne diseases/improve public health 3

4 4

5 Definition of Safe Sanitation Ref: water supply and sanitation collaborative council Collection, Transport, Treatment & Disposal or reuse of human excreta, domestic wastewater and solid waste, and associated hygiene promotion 5

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10 Pollution from human beings  g BOD/person/day  g N/person/day  g P/person/day  Virus  Medical residues 10

11 Eutrophication & it’s impacts  Increase in rate of supply of organic matter to an ecosystem resulting nutrient built up (N, P)  Massive algae growth, anaerobic conditions, oxygen depletion  Changers in the structure and functioning of the lake and marine ecosystem  Reduction in biodiversity, fish and shellfish harvesting  Increase risk of poisoning by algal toxins 11

12 DO Sag Curve Wastewater DO sat Distance (Km) 7.83mg/l at 28 0 C 12

13 Health Problems  In some areas in the developing world, % of human illness is related to water and water pollution  Discharge of wastewater represents the greatest risk for pollution of potable water 13

14 Ref: A.J. Arcivala 14

15 Ref: A.J. Arcivala 15

16 Ref: Metcalf & Eddy

17 2. Wastewater Separation Rainwater Rainwater Harvesting/Surface Drainage System Separate them in concentrated form in separate plumbing system Restaurants Grease Interceptor Onsite/Sewerage Reticulation System WW of Domestic Nature

18  X-Ray Processing AgCl+NaOH AgO  Dental Wastewater (Amalgam) Ag, Pb, Sn  Radioactive Iodine Treatment Mutagenic  Full Blood Count Test (Cn)  Blood Urea Test  Total Protein Test  Albumin Test  Liver Functional Test  Cholesterol Test  Sugar Test  Skin Preparation (Salicylic, Benzoic Acid, yellow parafin)  Bottle Washing (Antibiotics)  Molecular Biology Research (Ethidium Bromide Mutagenic)  Formalin (preservative for biological specimens)

19 CONCEPT FOR HOSPITAL Retention (As per CEA/AEA Recommendation) Collection to Containers in concentrated form with separate plumbing system

20 Hazardous WW Disposal-Preconditioning

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22 22

23 23

24 24 Ref: National Institute of Minamata Disease

25 25 Ref: National Institute of Minamata Disease

26 26 Ref: National Institute of Minamata Disease

27 3. Types of Sanitation Systems On site sanitation systems (>90%) –Septic tank associated effluent disposal systems Off Site Sanitation Systems (>2.5%) –Wastewater collection, treatment & Disposal Decentralized System 27

28 PRODUCTION PRE TREATMENT DISPOSAL EVAPOTRANSPIRATION WATER TABLE PURIFICATION GROUND WATER SOIL ABSORBTION SEPTIC TANK GREASE TRAP Drainage field Unsaturated Zone Saturated Zone Schematic cross-section through a conventional septic tank soil disposal system for on-site disposal and treatment of domestic liquid waste How it Works 28

29 29 Onsite Sanitation Systems SIMPLE PIT LATRINE Manual 1:Latrine Construction Technical Manual Series on Rural Water Supply & Sanitation NORAD-Helvetas Sri Lanka 29

30 30 VENTILATED IMPROVED PIT LATRINE Manual 1:Latrine Construction Technical Manual Series on Rural Water Supply & Sanitation NORAD-Helvetas Sri Lanka 30

31 31 On Site Sanitation WATER SEAL POUR – FLUSH LATRINE (Off-set Pit Type) NWSDB through ADB 3 rd Project Puttalam10,112 Kegalle11,634 Kalutara8,745 Hambantota12,675 Monaragala23,128 Total81,333 Total164,000 Manual 1:Latrine Construction Technical Manual Series on Rural Water Supply & Sanitation NORAD-Helvetas Sri Lanka 31

32 32 DRY COMPOST LATRINES  Environmentally friendly  Designed to keep the faeces separate from the urine and water used for anal cleansing  Is usually an elevated construction  Urine/water drained into an evaporative plant bed or a cultivation plot  To eliminate bad odour and nuisance from flies a handful of ash, lime or soil has to be sprayed into the pit Manual 1:Latrine Construction Technical Manual Series on Rural Water Supply & Sanitation NORAD-Helvetas Sri Lanka NWSDBAbout 100 NGO’sAbout

33 33 ECOSAN-BANGALIDESH/TAMIL NADU 33

34 34 Onsite Sanitation Systems SEPTIC TANK / SOKAGE PITS/SOKAGE TRENCES Manual 1:Latrine Construction Technical Manual Series on Rural Water Supply & Sanitation NORAD-Helvetas Sri Lanka 34

35 GREAZE INTERCEPTOR 35

36 Service Stations Primary treatment by Grease Interceptors Subsequent Pre treatment by  Coagulation  Flocculation  Sedimentation Muthugala Service Station- Kurunegala 36 Disposal of Oil  As furnace oil

37 37 Nippon Steel Cor.

38 38 Frazer Thomas-NZ 38

39 39 Frazer Thomas-NZ 39

40 40 BIO TOILET-JAPAN 40

41 41 Problems in on site systems? Faulty design & construction of septic tanks  Inadequate water depth for solid separation  Failure in construction/water tightness Faulty design of soakage arrangements  Seasonal high ground water table  Presence of non favorable soils  Presence of shallow rock  Prone for flooding  Overloading 41

42 42 4. Treatment Options SLS 745:Part I: 2004 Part I- Small systems disposing to ground SLS 745:Part II: 2009 Part II- Systems Disposing To Surface, Systems For On-site Effluent Reuse And Larger Systems Disposing To Ground 42

43 43 SEPTIC TANK Ref: SLS745 Part II 43

44 44 SEPTIC TANKS Design Requirements SLS 745:Part I: 2004 SLS 745:Part II: 2009 Main functions Free board Vent pipe & cowl Access Commissioning Desludging 44

45 45 2 to 4=Length to Width Ratio 0.75m=Minimum width of Septic Tank 1m=Minimum depth of septic tank 55%=Assume reduction in BOD mg/l200=Assume initial BOD Septic Tank m 3 /day0.56=Q 112 * 5=QAverage daily WW flow 112= liters/person/day140 * 0.8=Per Capita Wastewater Flow liters/person/day140=Per capita Water Consumption 5=No of members in a family Design for All Wastewater The Design and Construction of Septic Tank and Associated Effluent Disposal Systems (SLS 745 Part I : 2004) DESIGN CRITERIA 45

46 46 t d =1853T -1.25

47 47

48 48 De-sludging Interval (Years)25 No of Occupants /House ST Volume (m) ST Height (m) ST Width (m) ST Length (m) Length / Width Surface Area (m 2 ) SIZING OF SEPTIC TANKS 48

49 49 Sludge Judge Sludge judge 49

50 SOKAGE PITS Soakage pits Soak septic tank effluent Effluent get treated before reaching GW Applicability –GWT below 2.5m (seasonal fluctuation) –Soil percolation rate between 25mm/h to 125mm/h Location –At least 18m away from nearest well/drinking water source –At least 5m away from the nearest building 50

51 SOKAGE PIT Ref: SLS745 Part II 51

52 Minimum Distance Between Soakage Pits Ref :table 2,SLS 745 part 2 Average daily flow (m3/d) Minimum distance between soakage pits (m) <

53 Specific Effective Areas for Soakage Pits Ref :table 3,SLS 745 part 2 Percolation Rate mm/hr Specific Effective Area (m 2 / m 3 per day)

54 Minimum depth to groundwater table from bottom of soakage pit Ref :table 4,SLS 745 part 2 Percolation rate (mm/hr.) Minimum depth to GWT (m)

55 SEEPAGE BED The maximum bed length shall be 20 m. SLS 745 Part II:

56 SEEPAGE TRENCH SLS 745 Part II:

57 Specific effective areas for seepage beds and seepage trenches Ref :table 5, SLS 745 part 2 Percolation rate (mm/hr) Specific effective area (m 2 / m 3 per day)

58 Minimum, maximum and typical dimensions of seepage beds Ref :table 6, SLS 745 part 2 Bed dimensionTypical Range (mm) Maximum (mm) Minimum (mm) Width Depth of aggregate Depth of topsoil N/A100 Spacing between beds (sidewall to sidewall) -N/A

59 Typical dimensions of seepage trenches Ref :table 7, SLS 745 part 2 Trench dimensionTypical Range (mm) Maximum (mm) Minimum (mm) Width Depth of aggregate Depth of topsoil N/A100 Spacing between beds (sidewall to sidewall) N/A

60 MOUND SYSTEMS Cross-section of a mound system for slowly permeable soil on a sloping site (US EPA, 1980) ROCK STRATA OR IMPERMEABLE SOIL LAYER SLOPE PLOUGHED LAYER OF TOP SOIL ABSORBTION BED DISTRIBUTION LATERAL CAP 3 1 STRAW, HAY OR FABRIC FILL 60

61 MOUND SYSTEMS Cross-section of a mound system for a permeable soil with hight ground water or shallow creviced bed rock (US EPA, 1980) ROCK STRATA OR IMPERMEABLE SOIL LAYER PLOUGHED LAYER OF TOP SOIL ABSORBTION BED DISTRIBUTION LATERAL CAP 3 1 STRAW, HAY OR FABRIC FILL 61

62 Frazer Thomas-NZ 62

63 Frazer Thomas-NZ 63

64  In compliance to Disposal Standards Inland Water Body Sea Outfall Re Use For Non Potable Uses  BOD  COD  SS  N,P  Faecal Coliform Further Treatment 64

65 ANAEROBIC FILTERS SLS 745 Part II:

66  The minimum design HRT shall be 0.6 days and the maximum shall be 1.5 days.  Surface loading rate (m/d) = Average daily flow (m 3 /d) Plan area of filter (m 2 )  SLR ≤2.8  Total volume of void space in the bed > 35 per cent Volume of the bed  0.6m 1.8m  invert of the outlet shall be at least 50 mm below the invert of the inlet 66

67 WETLANDS FREE WATER SURFACE WETLANDS 67

68 WETLANDS SUBSURFACE WETLANDS 68

69 Typical Wetland Plants 69

70 Cattails 70 Kok mota

71 SUBSURFACE WETLAND RATMALANA TSUNAMI RESETTLEMENT HOUSING SCHEME AT FOOD STORES LAND 71

72 Free Floating Aquatic Plants Floating Treatment Wetlands 72

73 Floating Wetlands Biofilm covered roots Variable water depth Floating mat Leaf litter 73

74 3. Floating Wetlands 1. D uckweed 2.Salvinia 74

75 Natural Floating Wetlands cont Water lettuce Common Features  Self buoyant root structure  Uncontrolled rapid growth  Cutoff sunlight 75

76 Natural Floating Wetlands cont.. 4. Eichhornia crassipes 76

77 77 Floating Wetlands 77

78 Removal glycol from de-icing water at Heathrow Airport 78

79 JHOKASOU (private sewage treatment system)

80 80 Jhokasou

81 Anaerobic contact aeration type

82 Sludge Return Pipe Blue valve for aeration Yellow valve for air- release White or Grey valve for air-Lift Red valve for Back-washing

83 Sludge Return Equipment ( Air- Lift ) Disinfection Tank ( Disinfectant ) Sedimentation Tank Anaerobic contact aeration type

84 contact aeration type

85 (3) Separate aeration type

86 (4) Total aeration type

87 Sprinkling filter bed type sludge scum Filter media Filter media Exhaust pipe Sprinkling weir inflow effluent ← anaerobic tank → ← aerobic part →


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