Key factors affecting performance of biogas latrines in urban informal areas: Case of Kampala and Nairobi, East Africa

Large scale application of biogas latrine technology in developing countries faces technical, socioeconomic and financial  challenges. As a result, harnessing its full potential has not been realized. This study examined variables describing the design, construction, operation and maintenance of nineteen biogas latrines in  relation to their performance in Kampala and Nairobi, based on survey and field observations. Pre-tested questionnaires were administered to users, owners and construction  technicians/masons of the biogas latrines. Field observations were also undertaken to assess physical conditions of the biogas latrines. Principal component analysis was then used to establish correlation between variables of design, construction, operation and maintenance in relation to the performance of biogas latrines in terms of burning hours in a day. The design types of all the studied biogas latrine digesters were found to be of fixed dome. Co-digestion of human excreta and cow dung increased the number of biogas burning hours in a day from 0.5 to 1.1. The findings also show that the performance of the biogas latrines was influenced by six of the variables examined describing construction, operation and maintenance: skills of masons, use of standards in construction, training of users on operation and maintenance aspects, number of users/owners and their motivation for installation of biogas plants and physical conditions of the biogas latrines. This  implies that the use of skilled masons,  comprehensive training of users on operation and maintenance aspects and use of cosubstrates are key variables for optimal performance of biogas latrines. Key words : Biogas latrines, Kampala, Nairobi, performance.