Constructed Wetlands: Potential for their Use in Treatment of Grey Water in Kenya.

Abstract

Constructed wetlands are cost-effective, nature oriented alternatives for wastewater treatment that have gained acceptance worldwide. For Kenyan small communities in particular, constructed wetlands offer opportunities for wastewater reuse and resource recovery as well as improvements in local environmental health conditions. These communities generally lack conventional centralized waste water treatment systems. This thesis aims to identify peri- urban and rural areas suitable for the establishment of CW for their use in treatment of grey water in Kenya. Further, it identifies the most suitable constructed wetland type and suggests suitable emergent wetland plants for use in Kenya. Literature research and digital mapping are the proceedings of this thesis. The literature explores case studies and journals investigating constructed wetlands, emergent wetland plants and grey water reuse. Digital mapping on the other hand uses GIS data to delineate areas suitable for constructed wetland establishment in Kenya. This study reveals that large areas in Kenya are suitable for constructed wetland establishment are mostly located around the fertile agricultural areas where most of Kenya‘s population lives. Taking into account the tropical climate of Kenya which is characterized by high temperatures and conducive weather all year round, sub surface flow systems have been identified as the constructed wetlands of choice. Six emergents of the species Typha, Phragmites and Poaceae have been identified as showing high biomass productivity and versatility in utilization options, thus a high potential for waste water treatment At present due to lack of awareness and funding constructed wetlands are not widely used in Kenya especially in small communities. There is a need for further investigation of suitable wetland plants and also raising awareness and financial support for constructed wetland establishment.