Assessing the Sustainability of Decentralized Wastewater Treatment Systems in Rwanda

Kigali city, the capital of Rwanda, relies on decentralized, on-site, wastewater systems due to the absence of central sewerage systems and the limited finances to construct sustainable sanitation infrastructures. However, the city has increasingly shown failures in managing these on-site systems either at individual or collective levels. This study aims at assessing the sustainability of the operated collective public semicentralized sewage systems in Kigali city. To fully cover the sustainability assessment of such collective systems, the methods used were field observation, questionnaires, interviews, and laboratory tests. The study also reviewed the influence of national ruling sanitation legal instruments in addressing development, operation and management of such decentralized wastewater systems. The results showed that the sustainability levels of these systems were low in the technical, socioeconomic status, institutional, and legal dimensions. While the sustainability level was fair for the environmental quality. In conclusion, the research highlighted that the improved sanitation coverage does not mean coverage in terms of sewerage connection proportions for wastewater collection as these connections do not imply safe and sustainable treatment before being discharged into the environment.