Facebook Twitter Pinterest Share. Description Half of the world's people live in urban areas, and roughly a third of these live in desperate poverty without access to basic amenities. Taking on the themes of UN-HABITAT's Water and Sanitation in the World's Cities , this new volume focuses on the deficiencies in the provision of water and sanitation where most of the populations of the developing world live: in towns and small cities. Drawing on extensive unpublished research and 15 commissioned papers from experts involved in designing and implementing innovative projects around the world, this is the first major study of the problems facing the smaller urban centres that are recognized to be of enormous importance by governments, international agencies, NGOs and service providers.
Tackling these problems is a crucial part of development and of good governance, and critical to meeting the Millennium Development Goals. The volume will be essential reading for all professionals and researchers in the relevant fields and a valuable resource for teachers and students of urban development. Search all titles Search all collections. Your Account Logout. By Un-Habitat. Edition 1st Edition.
First Published Simplifed sewerage has recently been developed in South Africa Brocklehurst, ; Anon. Community-based sewerage schemes have been developed in Indonesia Foley et al. While not designed precisely ac- cording to the principles of Brazilian simplifed sewerage, these have been nonetheless very successful.
Application to STLV Simplifed sewerage has been implemented in a variety of locations in Brazil, from small villages, through medium-sized cities, to low-income periurban areas in major cities. This, together with its replication in other countries, including low-income areas with low water consumption, show that it is clearly applicable to STLV, provided of course that it is locally affordable and cheaper than other house- hold-level options.
National sewerage design codes Hydraulic theory and visual observation both indicate that small wastewater fows fow better in small diameter sewers. Yet many national sewerage design codes specify a minimum sewer diameter greater than mm in the mistaken belief that larger is ipso facto better, whereas in fact small fows fow better in small sewers. Such codes need to be altered to take into account present practice in simplifed sewerage; otherwise local design engineers will be forced to continue to develop very conservative, and hence expensive, solutions for the poor in STLV.
In STLV the best option for wastewater treatment is generally waste stabilization ponds as these are especially effective in removing or destroying faecal pathogens.
Meeting Development Goals in Small Urban Centres
Full details are given in Mara , Settled sewerage Settled sewerage also called solids-free sewerage; in the United States small-diameter gravity sewer- age, and in Australia septic tank effuent drainage is a sewer system that conveys only septic tank effuents. As these effuents are solids-free the sewer is designed differently from conventional and simplifed sewers which convey all the wastewater solids. Each house or a small group of neighbouring houses has a septic tank which discharges into the settled sewer.
The minimum sewer diameter is 75 mm and the sewer gradient closely follows the ground slope, with the fow in the sewer alternating as necessary between open channel fow and pressure fow. Settled sewerage is best applied in areas already served by septic tanks. Thus it is unlikely to be ap- plicable to poor and very poor households in STLV, for which simplifed sewerage is generally a better and cheaper alternative.
Meeting Development Goals in Small Urban Centres
It was frst feld-tested in the low-income areas of Rocas and Santos Reis in Natal, the state capital, in the early s. CAERNs development of simplifed sewerage in Natal was partially funded by the World Bank Me- dium-sized Cities project, which also saw the implementation of condominial sewerage in the city of Petrolina in the state of Pernambuco. This led to the produc- tion of the Brazilian national design manual for simplifed sewerage Guimares, and the formation of the ABES Low-cost Sanitation Committee , which in turn led to the adoption of a minimum sewer diameter of mm in the revision of the Brazilian national sewerage design code ABNT, previously it was mm.
A further key feature in the development of simplifed sewerage design in Brazil was the realisation by the late Brazilian sanitary engineer Eugnio Macedo that the sewer gradient should be based on the initial design fow and the sewer diameter on the fnal design fow; this is an important consideration incorporated into the Brazilian national sewer- age design code as in low-income areas the latter may be up to fve times the former.
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The hydraulic design basis was changed from a minimum self-cleansing velocity of 0. CAESB, the water and sewerage company of Brasilia and the Federal District, started implementing simplifed sewerage in poor areas in and now it considers simplifed sewerage as its standard solution for rich and poor areas alike see Figures 3.
CAESB now has over 1, km of condominial sewers in operation the largest example of simplifed sewerage in the world. Simplifed sewerage has now been successfully adopted into mainstream Brazilian sanitary engineer- ing. The reasons for this success have been: the ease of dissemination of innovative technologies at the biennial ABES Congresses which are attended by all the state water and sewerage companies, the relatively small number of leading Brazilian sanitary engineers who have been committed to, and have been excellent advocates of, the technology, and the keen interest shown in the technology since its beginning by the World Bank and UNDP which has acted within Brazil to give the system a seal of international approval.
Details are given in Brandberg and at www. They have also been used in low-density low-income urban areas in Botswana van Nostrand and Wilson, The vent pipe effectively controls odours and fies.
There are single-pit and alternating twin-pit versions; design details are given in Mara a, They are applicable in low-density STLV, provided that they are cheaper than simplifed sewerage emptying costs must be included in this cost comparison. Pour-fush toilets On-site pour-fush toilet systems comprise the toilet itself, with its integral water-seal, a discharge pipe and either a single leach pit or alternating twin leach pits the toilet bowl or squat pan can be and is used in other situations for example, simplifed and settled sewerage.
Pit emptying The pits of SanPlat and VIP latrines anf PF toilets require emptying when they are full; the faecal sludge is removed manually alternating twin-pit version only , or mechanically by high-powered vacuum tank- ers both versions Carroll, However, in practice pit emptying is not well planned: the vacuum tankers are not properly maintained and poor households are often disadvantaged as they are the last to be serviced Jones, This alone should militate against on-site sanitation systems in STLV.
Ecological sanitation toilets The basic philosophy of ecological sanitation EcoSan is to recycle all the nutrients in human excreta as each person excretes almost enough NPK to produce all the cereals he or she needs Drangert, A consequence of this is that the various streams of excreta and wastewater should not be mixed as they differ greatly in their volumes and nutrient loads. Thus yellow water urine , brown water faeces and toilet fush waters and grey water wastewater from sinks and showers or baths should be kept separate to facilitate nutrient and water treatment and reuse Otterpohl, , although in some EcoSan systems yellow water and brown water are combined to form black water.
EcoSan can be either on-site or off-site, and it can even be partially on-site and partially off-site. There are many EcoSan variants: some are high-tech and high-cost; others are low-tech and low-cost, and may or may not include urine diversion; on-site treatment options for brown waters include double-vault dehydrating and composting toilets, and anaerobic digestion possibly supplemented by domestic animal excreta and use of the resulting biogas for cooking as in some STLV in northern Vietnam. However, the cost data in Tables 3. Communal sanitation facilities In almost all STLV there are many very poor households which are unable to afford any kind of individual household-level sanitation, whether it be an on-site or off-site system.
In such areas, the only option is the construction of communal sanitation blocks of the type implemented in India by Sulabh Interna- tional Pathak, , ; Singh, ; www. The blocks provide toilet and washing facilities; soap is provided to all users. The blocks are maintained 24 hours per day by caretakers who are employed by Su- labh and live on the premises.
The caretakers also collect the user charges and the blocks are regularly inspected both by Sulabh and the local council United Nations, ; www. Sanitation selection algorithm Figure 3. Such reuse may be decentralized, centralized or intermittent, depend- ing on user preference, local feasibility and the type of sanitation technologies used. Decentralized reuse is reuse at household or local community level a housing estate, for example. It may also refer to grey water collection within a natural drain- age basin followed by treatment and reuse.
Intermittent reuse refers to on-site systems, including pit latrines, pour-fush toilets and septic tanks, which provide biosolids for agricultural or horticultural reuse only when they are desludged every few years. The symbols are to indicate cost and affordability , socio-cultural acceptability technical feasibility and environmental impact and reuse potential. The answers given by the algorithm are likely to be correct, but they are no substitute for engineering judgement and they must always be carefully checked in the local sociocultural and socio-economic situation.
Nonetheless the algorithm is a useful tool in sanitation programme and project planning as it prompts planners and engineers to answer questions that they might not generally consider asking. These include: A. Technical There is currently a general lack of knowledge amongst sector professionals, especially in Africa and Asia, of condominial water supplies and condominial i. Simplifed sewerage has not been promoted as vigorously and as effectively as, for example, ecological sanitation, yet it has to be known much more widely if the poor in STLV are to receive improved water supplies and sanitation.
Condominial water supplies and sewerage are both very close in theory and design to conventional piped water supplies and conventional sewerage, so that, once they are understood, they should be readily embraced by design engineers. Many, if not most, national water supply and sewerage design codes do not currently permit the adoption of condominial water supplies and sewerage.
Even in the case of India, where the national sewerage code at least mentions both simplifed and settled sewerage as shallow and small bore sewerage, respectively , so little detail is given that these options are in practice ignored both these technologies are covered in just 7 pages, whereas over pages are devoted to conventional sewerage Ministry of Urban Development, Yet there is plenty of money in the world see Feachem, National fnancial systems are not geared to support the poor see Basu, , for a review of the situation in India.
A notable exception is the Grameen Bank in Bangladesh and its replicates in other countries www. Varley discusses household credit for water supplies ans sanitation. Institutional STLV are, essentially by defnition, too small to be able to employ design engineers of their own and they are unable to judge whether any consultants they might engage are suffciently. Poor governance, combined with an absence of explicitly pro-poor policies, often excludes poor and very poor households from water supply and sanitation improvement projects.
The lack of planning at local level often means that one years budget allocation remains largely untouched until just before the end of the fnancial year, with the consequence that it is seldom spent wisely, and often not on pro-poor projects as these are commonly felt to be too diffcult to design and implement in a short time period.
National design codes need to be altered to permit their use however, code change is a lengthy business, even in industrialized countries; an initial frst step would be to permit their use for demonstrational purposes. Local research needs to be undertaken to develop condominial models best suited to local conditions for example, condominial yard-tap supplies or condominial standpipes, and operation and maintenance responsibilities for the in-condominium networks.
Socially and fnancially appropriate water and sewerage tariff structures need to be developed locally. Alternatively, several regional models could be developed, from which local design engineers and communities could select the one most suited to their needs. In all STLV sanitation programmes it should be ascertained whether condominial sewerage is cheaper than on-site systems i. If it is not, then on-site systems should be used.
Projeto de Redes Coletoras de Esgoto Sanitrio. Medmenham: Foundation for Water Research. Basu, P. A fnancial system for Indias poor. Economic and Political Weekly 40 37 , Brandberg, B. Brocklehurst, C.
Cairncross, S. Canelli, N.
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