Sanitation 21 planning framework - IWA

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Sanitation 21Some technical options for components of the sanitation systemNon-networked and nonconventionalNetworkednetworkedToilets • Dry toilets• Water closet (various types)• Dry urine diversion toilets• Pour flush slabs• Waterless urinalsTable4Collection • Fossa Alterna• Oil drums and containers• Vaults and Chambers• Collectors/ secondary sewersTransportation • Cartage systems• MAPET and Vacutug systems• Settled sewerage (smalldiameter)Treatment/ reuses• Co-composting• Dehydration• Planted soil filter• Anaerobic digestionDisposal/ re-use • re-use of wastes in gardens,urban agriculture or sale toagricultural market• Main sewers• Sewerage pumping stations• Baffled reactor• Upflow anaerobic filter• Upward flow anaerobic sludge blanket reactor• Facultative and maturation waste stabilisation ponds• Constructed wetlands• Duckweed ponds and other aquatic plant systems *• Disposal to downstream areas• Some reuse of sludge* These last two are not strictly ‘conventional’ but are definitely only appropriate for use with networked systemsand identify the optimal solution for a givensituation at a given time.Further challenges and constraints arise from whatmight be considered more ‘conventional’ technicalconsiderations – including ground and groundwaterconditions, availability of water, social practices,and the need to handle grey water and stormwater.3.8 Making use of some Generic systemsTo avoid the need to consider every permutationof technical components even where these are notrealistic, various publications and organisationshave developed generic urban sanitation system‘types’ which can be used to simplify the planningprocess. To assist with the discussion here we areadopting this approach and have identified eightgeneralised system types. These are summarisedbelow and in Table 5.ON-SITE DRY SYSTEMSDry systems are appropriate where water is notrequired for anal cleansing. A simple or double pitlatrine is used, with urine infiltrating away throughthe bottom and sides of the pit. Excreta are storedfor a period during which treatment occurs andthe material can subsequently be re-used as asoil conditioner. The level of treatment will varyand some latrines use composting technologyincluding the addition of materials such as ash ororganic matter which improve the quality of theend product. Particularly in urban areas, wastesfrom simple latrines may be collected (using handcarts or similar) and transported to a location in theneighbourhood or ward for decentralised treatment,often using composting technologies.An advanced form of dry sanitation uses a speciallydesigned latrine pan to separate urine and faeces.Urine is then available for use as a fertiliser, whiles– 20 –
Sanitation 21Sanitation Systems TypologyTable5SYSTEMGeneral DescriptionTechnical optionsToilet Grey water Stormwater1AOn-site dryDry latrineshygienisation andre-use of excreta ingardens.Twin pits or ,composting toiletInfiltration, onsitereuse or dischargeinto drainsOnsite reuse,infiltration ordischarge intodrains1BOn site dry with(semi-) centralisedtreatmentDry latrines, collection& treatment offaecal sludge atneighbourhood or citylevel before reuse inagricultureSimple pit latrinesInfiltration ordischarge intodrainsInfiltration ordischarge intodrains1COn site dry with urinediversionHH latrine with urineseparation. Onsitereuse of urinein garden. Faecesdehydrated on-site.Possible reuse onsite orfurther downstreamUrine separatinglatrines, cocompostingtoilets,twin pitsTreatmentand reuse athousehold level(eg constructedwetland)Infiltration ordischarge intodrains2AOn site semi wet(pour-flush)Latrine system at hhlevel with infiltration ofliquid wastes, emptyingof faecal sludgewhen full (additionalhygienisation?) andreuse in garden ordisposalTwin pit pour flushor similarInfiltration, onsitereuse or dischargeinto drainsInfiltration, onsitereuse or dischargeinto drains2BOn site wet with(semi) centralisedtreatmentAs 2A with faecalsludge evacuationsystem, transportand treatment onneighbourhood orcentralised level beforereuse in agricultureTwin pit pour flushor similar mayhave septic tank orABRMixed withblackwater andtreated on hh orneighbourhoodlevel, infiltrated orreused in gardenand agricultureOn-site use orinfiltration as in1A; discharge intodrains, possiblereuse in agriculture3AWaterborne with(pre) treatment and(semi) centralizedtreatmentToilet with on-site pretreatmentlinked tosmall bore seweragesystem.Pour flush or flushtoilet with septictank/ vault orsimilarMixed withblackwater andtransported fortreatmentDischarge intodrainage.3BWaterborne with(semi) centralizedtreatmentSame as 3A howeverwithout pretreatmenton hh level and usessimplified sewersPour flush or flushtoiletOn-site use orinfiltration as in 1A;or else dischargeinto drains forevacuation anddischarge insurface water orreuse in agricultureOn-site use orinfiltration as in 1A;or else dischargeinto drains forevacuation anddischarge insurface water orreuse in agriculture3CWaterborne withcentralized treatmentFlush toilets andconventional combinedsewersFlush toiletMixed with blackwater in the sewerMixed withblackwater– possibility ofstorm-overflow anddischarge to waterbodies.– 21 –
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Sanitation 21 planning framework - IWA

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