An Integrated Perspective for Urban Water Management 59
Box 2.11
Wastewater as a Source of Energy: Naivasha, Kenya A lavatory, wastewater treatment, and biogas generation facility started operation in 2008 adjacent to the Naivasha Bus Park in Naivasha (a small town 90 kilometers northwest of Nairobi). It consists of five toilet cubicles, two showers, and one urinal with the wastewater from the facility being treated and used for biogas and water generation. The biogas generation project (including the water kiosk) is operated by the Water Services Trust Fund and had a total investment cost of approximately US$50,000. The facility served about 300 visitors per day in 2009 and provides biogas for cooking for a nearby kiosk. The facility is managed by the local water service provider, who contracted a local community-based organization to operate the toilet on a pay-per-use basis. Figure B2.11.1 Lavatory and Wastewater Treatment Plant with Installed Biogas Generation Facility in Naivasha, Kenya
Source: Rieck and Onyango, 2010.
To generate energy from the wastewater, a biogas plant with a capacity of 54 cubic meters was constructed to anaerobically pretreat the wastewater from the toilets, showers, and wash basins, lowering the organic pollution load. Treated effluent is discharged to an existing public sewer and the accumulated sludge is removed once a year and can be used as a fertilizer. The biogas is piped (through 1.5 centimeter galvanized iron pipe) to a nearby café where it is used for cooking. A water trap chamber is installed next to the biogas plant to collect condensed water in the pipe. Source: Rieck and Onyango, 2010.