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<International Source Book On Environmentally Sound Technologies
for Wastewater and Stormwater Management>

1.5 Disposal (Topic e)

Only 5% of the inhabitants of Lagos Metropolis, Nigeria are connected to water-borne system and associated sewerage treatment plants. The plants do not treat the sewage to acceptable standards, and are poorly maintained and operated. Open storm water drains are common and in many cases act as open sewers, particularly for the conveyance of sullage water.

Most industrial wastewater was being discharged directly into water courses/bodies without any form of treatment. Major stormwater drains are not maintained. Both secondary and tertiary drains are also poorly maintained, hence they fail to alleviate flooding. The bulk of wastewater is being discharged directly and untreated into water courses or the Lagos Lagoon.

The Niger Delta is one of the worldís largest wetlands, encompassing over 20,000km2. The Niger Delta is relatively highly populated and urbanised, and has serious problems not only with industrial and oil pollution, but with inadequate domestic waste management. No municipal sewage treatment plants operate in the Niger Delta. Households, commercial establishments and industries discharge wastes directly into open drains. Many of the drains are unlined, blocked with solid wastes, or broken. Untreated urban wastewater is transported via sewage systems or drains emptying organic matter, including nutrients into receiving waters.

In Port Harcourt (the Niger Delta, Nigeria), dissolved oxygen levels in some rivers are very low and no longer able to support even herbivorous fish. High density areas of the city also have elevated levels of total solids, chloride and turbidity. Urban wastewater also contains industrial effluents, and household pesticides released into common drainage or sewerage systems. Water supplies are often degraded from the practice of laying water pipes in open drains or near soakaway pits, and constructing shallow wells near poorly maintained drains. Consequently, health risks associated with sewage contaminated water are highly significant and affect a large proportion of the urban population in the region, since there are no sewage treatment facilities. Plans are afoot to remedy the anomalous situation in this oil producing region.
The average wastewater flow for Lagos metropolis is only 115 l/c/d (compared to Cairo where it is 310 litres/day). In 1995 the total wastewater emptied into Lagos Lagoon was 811,300 m3 per day, of which domestic wastewater accounted for 54%. The volume of wastewater generated is expected to increase to 1,663,090 m3 per day by 2010 (Harrington, 1996).


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