Constructed Wetlands in Tanzania

South Initiatives 2011 VLIR UOS University Development Cooperation

Rob Van Deun - Mia Van Dyck
Katholieke Hogeschool Kempen, Department Agro- and Biotechnology

dr. Karoli Njau
The Nelson Mandela African Institute of Science and Technology (NM-AIST), Arusha
University of Dar Es Salaam

2011 - 2013

Apart from the natural scarcity of freshwater in Tanzania, the quality of the available freshwater is also deteriorating due to pollution, hence intensifying the shortage. Liquid wastes such as untreated sewage or industrial waste are the major sources of pollutants in Tanzania. Municipal sewage and industrial wastewaters containing readily biodegradable organic matter, inorganic and organic chemicals, toxic substances and disease causing agents are frequently discharged into aquatic environments without treatment. This unregulated practice results in contamination of water that is then unsuitable for human consumption, land irrigation, fish production or recreation.  Poorly served informal settlements are becoming more abundant in urban areas. The possible expansion of sanitation related problems will have tremendous impact to the welfare and health of people.

Technological solutions such as the development of improved latrines, design of decentralized ecological engineering systems have been tried for more than two decades, but the situation is not getting better. These technologies promise significant benefits in terms of public health and economic productivity but the implementation has been minimal. Low cost and sustainable wastewater treatment strategies are critically needed.

Former research has shown that, given the actual sanitation chains in Tanzania, constructed wetlands can be an interesting solution for two specific problems: the effluent of malfunctioning central wastewater treatment systems (usually Waste Stabilization Ponds) and the effluent of septic tanks installed near institutional buildings (schools, hospitals, governmental buildings,...). These sanitation service chains are typical for approximately 20% of the discharge points in Tanzania. But these discharge points are responsible for far more than 20% of the total amount of wastewater discharged in surface waters since they use water driven systems.
Constructed Wetlands