Sustainability of DEWATS (Tanzania)

Decentralized Wastewater Treatment Systems (DEWATS) are increasingly being recognized by decision makers and city developers across the world as another layer of option for sanitation service delivery, particularly in densely populated low- income areas. DEWATS have been piloted in a few areas of Dar es Salaam to test their treatment feasibility potential. This study assessed the DEWATS sustainability in unplanned settlements of Mlalakuwa and Mburahati in Dar es Salaam. The study employed several data collection methods including, physical observation, a questionnaire, key informants’ interview, and fecal sludge samples lab analysis. Some data analysis tools used included multi-criteria decision- making by using the Analytic Hierarchy Process (AHP) tool, Statistical Package for the Social Sciences (SPSS), and Sanitation Sustainability Index (SSI). The study has revealed that DEWATS performance for pH and temperature complied with Tanzania Bureau of Standards (TBS). The study concluded that, the DEWATS system had an SSI value of 70%, indicating its sustainability. However, the study identified several areas for improvement, including increasing flexibility and adaptability, improving durability and lifetime, reducing complexity, increasing material recovery and reuse, lowering capital costs, reducing operation and maintenance costs, and minimizing the risk of infection to the immediate environment. The Ministry of Water should promote the use of DEWATS for wastewater solutions. Awareness campaigns should be undertaken to promote the use of DEWATS.