Environmental awareness, community health and the need for clean water have been the impetus for developing countries to address the problem of inadequate wastewater treatment in both urban and rural communities. Tenwek Hospital is located in the Rift Valley Region of Kenya and serves a community of approximately 600,000 households with their 300-bed facility that is the largest rural hospital in East Africa. This facility supports and administers, in addition to the residential patients, a Community Health Program whereby satellite and mobile health care is provided to nearby communities, a School of Nursing and a Physician Residence Program training nationals alongside American and European physicians.
In 2000, the Kenyan Department of Natural Resources and Environment required the hospital to modernize its antiquated septic tank system that was used for sewage treatment from the hospital and adjoining staff housing. This system was in danger of polluting the Nyangores River that supplies hundreds of communities downstream who rely on the river for untreated drinking water.
The project, accomplishing this directive from the government, had the following scope:
The treatment technology that was chosen for the WWTP was the WesTech Aerator, an activated sludge technology using a “paddle wheel” design as the mechanism for introducing air into the mixed liquor. This process only required two 1.5 HP motors to turn the connecting chains to the paddles and a motor control board, thus, making it one of the simplest and most energy-efficient processes on the market. Disinfection was provided from a drip liquid chlorine tank followed by an in-ground discharge to a constructed sand bed that ultimately discharged to the river.
The sewer system was constructed using PVC pipe, brick manholes with primarily hand tools for trenching and excavation.