STANDALONE SEWAGE SYSTEM IN DEVELOPING COUNTRIES

What is, and how do local engineers construct sewage systems in Africa.

In Nigeria and some other parts of Africa, the sewage system comprises of soak-away pit and septic tank. They are built together and then separated by a wall. This system is predominant in developing countries due to the absence of a centralised system. This independent system is usually funded and built by the household.

Septic tank are watertight chambers below ground level to receive excreta and flush water from flush toilets and other domestic sullage (collectively known as wastewater).

Soak-away tank is where the wastewater slowly drains into the soil. Soak-away can also be a drain field which disperse septic effluent (sewage without high concentration of solids) into the sub soil at the site. 

Generally, the base of a sewage system is about 12 feet. The insides of the septic tank have a cement mortar covering to make it water proof. While that of the soak-away usually have no mortar to allow the effluent escape easily into the soil. Solids lighter than water  (such as grease and oil) floats to the top forming a layer of scum. Solids heavier than water settle at the bottom forming a layer of sludge. This leaves the middle layer of partially clarified wastewater.

Leave a Comment