Technical Guide to EcoSan Promotion

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Organic.dry.matter.(Kg).(Kg.ODM /m3) CR = Effective.digestor.volume.(m3) Table 3: The recommended maximum digester charge ratio Temperature of digestion( o C) Change ratio CR (Kg ODM/m 3 ) 25 3-Feb 35 4-Mar 45 5-Apr 55 6-May Biogas is a mixture of methane and carbon dioxide as described above. It has a density of 1.2 kg/ m 3 and a caloric value of 6 KWh/m 3 .The amount of biogas and its percentage of methane is basically depended on the type and composition of the fed substrate, the digester volume and the temperature. 4.3 Design Procedure of fixed dome biogas digesters The inflow is forced through the sludge which settles at the base of the tanks to come into contact with the biologically active bacteria. Baffled reactors have at least six chambers. The treatment capacity increases with the number of chambers. This system requires no electricity. The wastewater constituents are broken down anaerobically. The treatment capacity lies between 70 to 90% BOD decomposition. The space required for a baffled reactor for 8 persons is less than 5 m 2 . Calculating the size of the reactor is based on the maximum up-flow velocity of approximately 1.4 m/hr and retention time of the waste in the reactor of 40 hours. Step 1 Conduct baseline survey of the project area (public place, institution or informal settlement) • GPS mapping and levelling (location, topography & hydrogeology of the location, climate, rainfall, farming systems, soils) • Data collection (Populations, water use & availability, peak and average black, grey and brown water flows, daily solid faecal and other animal dung production, waste water quality, existing sanitation system, level of awareness on proper sanitation and hygiene, energy requirements 54
Technical Guide to EcoSan Promotion and existing sources of energy. • Site selection (close to gas use points, low ground water table, far from big trees and other buildings, etc). • Establishment of site layout plan with existing and proposed sanitation systems. Step 2 Conducting the necessary trainings for the beneficiaries • Basics of biogas technology • Use of biogas and slurry • Safety measures • Operation and maintenance • Monitoring and data collection during the operation Step 3 Choosing the design parameters for the anaerobic digestion process and doing the design work (See Annex 1) • Start by identifying the source(s) of wastewater constituents which includes grey water from the kitchen and bathrooms, urine and faeces • In parameters for design, determine the following: total population served by sanitation infrastructure; amount of urine produced; amount of water used in the kitchen, water used in hand and toilet washing, toilet flushing and finally amount of water used in laundering and showering. Determine daily sludge flow by computing the BOD reductions in urine, faecal matter, toilet flushing and showering. Biochemical oxygen demand (BOD) is the main evaluation parameter for the organic contamination of wastewater. BOD5(20) describes the oxygen required over 5 days at a temperature of 20 o C to oxidise the organic constituents of sewage. • Calculate the chemical oxygen demand (COD) fluxes; i.e. COD coming in and out of the system, and COD reduction. Chemical Oxygen demand (COD) is the amount of oxygen required to oxidise all of the oxidisable constituents including those which are not biologically degradable. Volatile Solids (VS) are presumed to be organic matter (proteins, carbohydrates and fats). • Calculate the volume of fixed dome digester by computing the volumes of liquid, gas, sludge and scum as shown in the formula and table 4 below: Effective.digestor.volume.(m 3 ) = Total.Organic.Dry.Matter(ODMkg) Digester.Discharge.Ratio(kgODM /m3)) 55
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Technical Guide to EcoSan Promotion
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Cataloguing-in-publication data Pub
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Preface The EcoSan Promotion Projec
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Acronyms ABR BC BDBR BOD COD DTS Ec
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3.3.2 Current design and costs of U
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List of figures Figure 1 : Average
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1.1 Global historical perspective t
Page 16 and 17: 1.3 The MDG sanitation targets Acco
Page 18 and 19: There are some 50 diseases, includi
Page 20 and 21: 1.6 Kenyan context of eco-sanitatio
Page 22 and 23: The most commonly used technologies
Page 24 and 25: The EU-GTZ-SIDA EcoSan Promotion pr
Page 26 and 27: Vision 2030 focuses on correcting K
Page 28 and 29: 2.1 The Philosophy of Ecological-sa
Page 30 and 31: The benefits of humanure is maximiz
Page 32 and 33: 2.4 Reaping maximum benefits from E
Page 34 and 35: Figure 4 : Ecosan water and nutrien
Page 36 and 37: 24 Figure 5 : Imparting knowledge o
Page 38 and 39: 2.8 Policy And Advocacy Issues On S
Page 40 and 41: Other very involved ministries are
Page 42 and 43: Sanitation coupled with hygienic ha
Page 44 and 45: Of these, 470 million live in Afric
Page 46 and 47: 3.1 Introduction A Urine Diverting
Page 48 and 49: The diverted urine that is loaded w
Page 50 and 51: Flush systems come in different des
Page 52 and 53: alternately with only one vault in
Page 54 and 55: Slab thickness of 80 mm is used to
Page 56 and 57: Steps Steps are direct in front of
Page 58 and 59: Figure 8: Modulated squatting pan i
Page 60 and 61: Although this is the cheapest optio
Page 62 and 63: Faeces should be applied and mixed
Page 64 and 65: 4.1 Introduction An Anaerobic Baffl
Page 68 and 69: Table 4: The charge ratio for vario
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Page 72 and 73: Anaerobic baffled reactor (ABR) con
Page 74 and 75: conditions. To produce acetic acid,
Page 76 and 77: 5.1 The Fossa Alterna 5.1.1 Introdu
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Page 80 and 81: Once working at full capacity it is
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Page 84 and 85: • Ensure that primary treatment i
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Page 88 and 89: 6.1 Introduction Many public instit
Page 90 and 91: 6.2 Case examples of schools using
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Page 114 and 115: 102 Annex 3 Drawings of 6m Anaerobi
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Annex 4 Sources of waste water cons
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Volume of liquid(VL) m 3 /d Is equa
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Length of each chamber m 1 Depth of
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