IMPROVED RURAL SANITATION CONCEPTS By Dhanesh Gunatilleke SPECIALIST

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

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

1 WHY WASTEWATER TREATMENT ? Protect the environment from; Øhigh loads of suspended solids & organic matter Øeutrophication & groundwater pollution ØSubstantial load of hazadous and non biodegradable compounds ØSerious contamination with microorganisms …in order to ü establish/maintain healthy environment for flora & fauna üallow mankind to use water resources for different purposes üprevent transmission of waterborne diseases/improve public health 3

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

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Pollution from human beings v 45 -60 g BOD/person/day v 8 - 14 g N/person/day v 0. 6 -2. 5 g P/person/day v. Virus v. Medical residues 10

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

DO Sag Curve Wastewater 7. 83 mg/l at 280 C DOsat Distance (Km) 12

Health Problems §In some areas in the developing world, 75 80% of human illness is related to water and water pollution §Discharge of wastewater represents the greatest risk for pollution of potable water 13

Ref: A. J. Arcivala 14

Ref: A. J. Arcivala 15

Ref: Metcalf & Eddy

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

v X-Ray Processing Ag. Cl+Na. OH Ag. O v Dental Wastewater (Amalgam) Ag, Pb, Sn v Radioactive Iodine Treatment Mutagenic Ø Ø Ø Ø Ø 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) Ø Formalin (preservative for biological specimens)

CONCEPT FOR HOSPITAL To the Existing Surface Drainage System Storm Water/ Rain Water Kitchen WW Grease Trap Other WW of Domestic Nature Effluent from Radiation Treatment (Iodine) • X- Ray Processing (Dark Room) • Dental WW • Laboratory WW Retention (As per CEA/AEA Recommendation) Existing Oxidation Ditch & Settling tank will be converted to a Floting wetland Collection to Containers in concentrated form with separate plumbing system Sewerage System Pumping Station Rat/ Mora WWTP Disposal as Hazadous Wastewater (Geo. Cycle)

Hazardous WW Disposal-Preconditioning

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Ref: National Institute of Minamata Disease 24

Ref: National Institute of Minamata Disease 25

Ref: National Institute of Minamata Disease 26

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

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

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

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

On Site Sanitation WATER SEAL POUR – FLUSH LATRINE (Off-set Pit Type) NWSDB through ADB 3 rd Project Puttalam 10, 112 Kegalle 11, 634 Kalutara 8, 745 Hambantota 12, 675 Monaragala 23, 128 Total 81, 333 164, 000 Manual 1: Latrine Construction Technical Manual Series on Rural Water Supply & Sanitation NORAD-Helvetas Sri Lanka 31

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

ECOSAN-BANGALIDESH/TAMIL NADU 33

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

GREAZE INTERCEPTOR 35

Service Stations ü Primary treatment by Grease Interceptors ü Subsequent Pre treatment by v. Coagulation v. Flocculation v. Sedimentation Disposal of Oil ØAs furnace oil Muthugala Service Station- Kurunegala 36

Nippon Steel Cor. 37

Frazer Thomas-NZ 38

Frazer Thomas-NZ 39

BIO TOILET-JAPAN 40

Problems in on site systems? • Faulty design & construction of septic tanks ØInadequate water depth for solid separation ØFailure in construction/water tightness • Faulty design of soakage arrangements ØSeasonal high ground water table ØPresence of non favorable soils ØPresence of shallow rock ØProne for flooding ØOverloading 41

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

Inspection port 150 mm INLET 750 mm minimum (internal dimension) SEPTIC TANK To further treatment Access openings 500 mm min. PLAN Vent pipe dia. 25 mm min. Access openings 500 mm min. Inspection port 150 mm Dia. 100 mm min. Free board 200 mm min. INLET Opening 25 mm min. 50 mm min. Liquid level Min. 20% of liquid depth Dia. 100 mm min. To further treatmen 300 mm min. t Partition Opening 100 mm min. First compartment approx. 2/3 length Second compartment approx. 1/3 length Total length between 2 – 4 times width SECTION Ref: SLS 745 Part II 43

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

DESIGN CRITERIA The Design and Construction of Septic Tank and Associated Effluent Disposal Systems (SLS 745 Part I : 2004) Design for All Wastewater No of members in a family = 5 Per capita Water Consumption = 140 liters/person/day Per Capita Wastewater Flow = 140 * 0. 8 liters/person/day = 112 Average daily WW flow Q = 112 * 5 Q = 0. 56 m 3/day Assume initial BOD = 200 mg/l Assume reduction in BOD = 55% Minimum depth of septic tank = 1 m Minimum width of Septic Tank = 0. 75 m Length to Width Ratio = 2 to 4 Septic Tank 45

SEPTIC TANK DESIGN FOR 5 PERSONS (DE-SLUDG PERIOD 5 YEARS) 1. 1) Volume required for settling, Vs (All Waste) Time required for settling V s = ts. Q ts = (1. 5 -0. 3 log Q) 1. 58 = days Should be > 0. 2 d OK Vs 0. 88 = m 3 1. 2) Volume required for sludge digestion Vd (All Waste) Vd = qs. Td. P Volume of fresh sludge person qs = 0. 001 Time required for sludge digestion td = 33 Population equivalent for all wastewater p = Q(m 3/day) / 0. 2(m 3/p/day) = 2. 8 = 0. 092 td =1853 T-1. 25 Vd m 3/day days (for all wastewater) (for an ambient Temperature of 20 0 C) m 3 46

1. 3) Volume required for sludge storage Vst (All Waste) Vst = r. p. n Volume of digested sludge person per year for all wastewater r = 0. 04 Desludging interval>1 n = 5 Vst = 0. 56 m 3 Volume required for scum storage = 0. 5 Vst 1. 5)Total Volume required for septic tank = Vs+Vd+1. 5*Vst m 3 = 1. 81 m 3/year 1. 4) Volume required for scum storage V m 3 ( 1 m 3 < V < 12 m 3 ) m ( Minimum Depth 1 m) Take Depth, H = 1 Then, Surface Area A = 1. 81 Assume width, W = 0. 75 m Then Length L = 2. 42 m L/W = 3. 23 m 2 ( 2<L/W<4 ) Hence ok Assume rate of BOD removal in septic tank = BOD of effluent = 55% 90 47 mg/l

SIZING OF SEPTIC TANKS De-sludging Interval (Years) No of Occupants /House 2 5 5 7 10 ST Volume (m) 1. 31 1. 80 2. 52 1. 81 2. 51 3. 53 ST Height (m) 1. 00 1. 20 ST Width (m) 0. 75 0. 80 0. 75 0. 90 1. 00 ST Length (m) 1. 75 2. 40 2. 63 2. 42 2. 78 2. 94 Length / Width 2. 33 3. 20 3. 28 3. 23 3. 09 2. 94 Surface Area (m 2) 1. 31 1. 80 2. 10 1. 81 2. 51 2. 94 48

Sludge judge Sludge Judge 49

SOKAGE PITS Soakage pits • Soak septic tank effluent • Effluent get treated before reaching GW Applicability – GWT below 2. 5 m (seasonal fluctuation) – Soil percolation rate between 25 mm/h to 125 mm/h Location – At least 18 m away from nearest well/drinking water source – At least 5 m away from the nearest building 50

SOKAGE PIT 900 mm < Length < 3000 mm 900 mm Dia. < < 3000 mm Inlet pipe PLAN (SQUARE TYPE) PLAN (CIRCULAR TYPE) Length < 3000 mm Width > 900 mm Ref: SLS 745 Part II Inlet pipe PLAN (RECTANGULAR TYPE) Impermeable cover 300 mm min. Inlet pipe Between 900 mm & 3000 mm Ground level dia. 100 mm min. Minimum 1000 mm Impermeable liner / wall Open jointed brick / cement block Minimum 2. 5 m 1. 2 m Minimum GWT (Seasonal high ) SECTION 51

Minimum Distance Between Soakage Pits Ref : table 2, SLS 745 part 2 Average daily flow (m 3/d) Minimum distance between soakage pits (m) <2 10 2 -5 15 5 -10 20 10 -30 36 52

Specific Effective Areas for Soakage Pits Ref : table 3, SLS 745 part 2 Percolation Rate Specific Effective Area mm/hr (m 2 / m 3 per day) 25 34 50 17 75 11 100 8. 4 125 6. 6 53

Minimum depth to groundwater table from bottom of soakage pit Ref : table 4, SLS 745 part 2 Percolation rate Minimum depth to GWT (m) (mm/hr. ) 25 -50 1. 2 50 -75 1. 8 75 -100 2. 4 100 -125 3. 0 54

SEEPAGE BED The maximum bed length shall be 20 m. SLS 745 Part II: 2009 55

SEEPAGE TRENCH SLS 745 Part II: 2009 56

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) 25 50 50 25 75 17 100 12. 5 125 10 150 8. 3 175 7. 1 200 6. 25 225 5. 6 250 5. 0 57

Minimum, maximum and typical dimensions of seepage beds Ref : table 6, SLS 745 part 2 Bed dimension Typical Range (mm) Width 1000 -6000 Depth of 300 -600 aggregate Depth of topsoil 100 -150 Spacing between beds (sidewall to sidewall) Maximum (mm) Minimum (mm) 6000 600 1000 300 N/A 1000 58

Typical dimensions of seepage trenches Ref : table 7, SLS 745 part 2 Trench dimension Typical Range (mm) Width 300 -600 Depth of 300 -600 aggregate Depth of topsoil 100 -150 Spacing between 1000 -2000 beds (sidewall to sidewall) Maximum (mm) Minimum (mm) 600 300 N/A 1000 59

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

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

Frazer Thomas-NZ 62

Frazer Thomas-NZ 63

Further Treatment §In compliance to Disposal Standards Inland Water Body Sea Outfall Re Use For Non Potable Uses ØBOD ØCOD ØSS ØN, P ØFaecal Coliform 64

ANAEROBIC FILTERS SLS 745 Part II: 2009 65

Ø The minimum design HRT shall be 0. 6 days and the maximum shall be 1. 5 days. Ø Surface loading rate (m/d) = Average daily flow (m 3/d) Plan area of filter (m 2) Ø SLR ≤ 2. 8 Ø Total volume of void space in the bed > 35 per cent Volume of the bed Ø 0. 6 m < h > 1. 8 m Ø invert of the outlet shall be at least 50 mm below the invert of the inlet 66

WETLANDS • FREE WATER SURFACE WETLANDS 67

WETLANDS • SUBSURFACE WETLANDS 68

Typical Wetland Plants 69

Cattails Kok mota 70

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

Free Floating Aquatic Plants Floating Treatment Wetlands 72

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

3. Floating Wetlands 1. Duckweed 2. Salvinia 74

Natural Floating Wetlands cont. . . 3. Water lettuce Common Features ØSelf buoyant root structure ØUncontrolled rapid growth ØCutoff sunlight 75

Natural Floating Wetlands cont. . 4. Eichhornia crassipes 76

Floating Wetlands 77

Removal glycol from de-icing water at Heathrow Airport 78

JHOKASOU (private sewage treatment system)

Jhokasou 80

Anaerobic contact aeration type

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

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

contact aeration type

(3) Separate aeration type

(4) Total aeration type

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