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About UNEP
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United Nations Environment Programme
Division of Technology, Industry and Economics
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Newsletter and Technical Publications
<International Source Book On Environmentally Sound Technologies
for Wastewater and Stormwater Management>

1.3.2 Small-scale and community-scale technologies

Aerated lagoon

In Lagos Island, an aerated lagoon was constructed in 1969 to treat night soil wastes. The site now known as the night soil treatment plant is currently being used by the local government as a fish pond. There is however a plan to rehabilitate it and re-convert it into a treatment plant.

Septic tanks

Table 1.14 presents a regional picture of the distribution of on-site sewage disposal technologies, including VIP toilets, in use.

Table 1.14: Access to onsite sanitation facilities in selected countries

Pit toilets

Composting latrine

The composting system is one of the alternative sanitation systems. Implicit to compost latrine technology is the notion of a dry (waterless) on-site system that accepts human excreta which gradually breaks down to produce a compost material that is safe for handling and disposal. It is recent in South Africa, having come into existence only since 1993. During the short period, its evaluation showed that Enviro Loo latrines performed adequately and were accepted by users as a satisfactory alternative to communal chemical toilets. Safety, privacy and accessibility are preferred aspects of the system (Scott, 1998). In particular:

  • no adverse health impact was recorded among the users; and

  • no sludge removal is required, though pumping out of storm water and grey water may be necessary.

  • the technology as practised in South Africa acts more like a prolonged process of dehydration rather than a composting latrine. Further treatment of the waste material is therefore advocated by evaluation, once removed from the latrine container.

The most unfavourable aspect is that it does not flush!

Double-vault VIP latrine

Botswana’s Ministry of Local Government and Lands, together with the Building Research Establishment in the UK has developed a double-vault ventilated pit latrine for use in squatter areas and site and service schemes. The VIP has been used in urban areas in Botswana since 1978. About 10,000 units have been built in Botswana since 1978.
It consists of a shallow pit divided into two vaults, each having an effective volume of 1.5m3. In stable soil, the pit is not lined. The covers are made of precast concrete and are removable. Emptying can be done manually or mechanically in a 3-4 year cycle. It is actually a cross between the double-vault compost latrine and the pit latrine. Like the compost latrine, it has the advantage of being permanent.

Reid’s Odourless Earth Closet (ROEC)

ROEC is a type of improved pit latrine developed in South Africa and patented in 1944 (du McPherson, 1994). The pit is 1m x 2m and at least 3m deep. It is covered with a concrete slab fitted with a 75mm diameter vent pipe.

Concrete slab to keep out flies

Water and sanitation present serious problem in Mozambique. Only 12% of the dwellings in Mozambique are directly supplied with drinking water. Water is mainly supplied by public fountains. In urban environments, more than 70% of homes can obtain water from a communal network (public fountains), others rely on rivers, ponds, wells and tank trucks. A rigorous latrine construction campaign multiplied the number of latrines in Mozambique from 60,000 to 1.2 million. In 1984, 72% of urban dwellings were equipped, 93% in Maputo. Problems include instability of the soils, high water table, and the failure of the covers which were to keep out insects.

The squatting slab is the heart of any pit latrine, and the drophole is a very important feature of the squatting slab. It is therefore understandable that the government of Mozambique adopted a standard model of latrine cover obtained by research in place of the former wooden covers. It is 1.5 m in diameter and made of reinforced concrete, circular and slightly conical, and can easily be managed by one person. Its shape corresponds exactly to that of the pit and provides a better cover than a simple slab. The pit is raised up if the water table is high; it is built on breeze-block if the soil is unusually unstable. The local authorities through the Directorate of Construction and Town Planning of Maputo set up cooperatives in order to produce the model.

Members of the cooperative were elected by local authorities (the Facilitator Groups) affected. This coordinating committee (Inter-Cooperative Management Committee) carries out many functions that used to be performed by the government. Annual production of latrine covers was 18,000 in 1986, from cooperatives and workshops. Produced at a cost of Mt 500 (US$12), the present need is 2,500,000 in urban and peri-urban areas. The number of cooperatives and production centres continues to increase, and the project has been replicated in other towns with a total annual production of more than 10million (Brandberg, 1985).

The project is largely dependent on international aid . It is also overly dependent upon support of government policy which could compromise its long term viability. The population must be more involved in the decisions to give the organizations greater autonomy.


1The contact institution is Mazingira Institute, P.O. Box 14550 Nairobi, Kenya.
Tel: 254-2-443219
Fax: 254-2-44 46 43.

 

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