Author(s)

Benjamin K. Kogo¹, Elijah K. Biamah², Philip K. Langat³

¹Environment Department, Norken International Limited, Nairobi, Kenya.
²Department of Environmental and Bio-Systems Engineering, University of Nairobi, Nairobi, Kenya.
³School of Environmental and Rural Science, University of New England, Armidale, Australia.

This study is aimed at evaluating alternative designs of waste stabilization ponds (WSPs) and constructed wetlands (CWs) for Kaputiei Housing Estate consisting of 2000 low cost housing units in Kenya. The entire analysis was carried out by simulating the effectiveness and purification efficiencies of WSPs and CWs in terms of Biological Oxygen Demand (BOD) reduction and faecal coliform (FC) removal under different scenarios of water treatment systems that included Re-sizing of the initial sewage treatment system, optimizing the design of the initial system and design of hybrid system for the estate. The graphic comparison of the simulated parameters under different scenarios showed that a hybrid design that combines both the WSPs and CWS provides an effluent BOD of 20 mg/l and 195 FC per 100 ml that meets the standard effluent discharge that is acceptable for unrestricted crop irrigation and thus will be reused in the housing estate for kitchen gardening and agroforestry.

Wastewater, Waste Stabilization Ponds, Constructed Wetlands, BOD, Faecal Coliforms, Purification

Kogo, B. , Biamah, E. and Langat, P. (2017) Optimized Design of a Hybrid Biological Sewage Treatment System for Domestic Wastewater Supply. Journal of Geoscience and Environment Protection, 5, 14-29. doi: 10.4236/gep.2017.55002.