Investigation of possible strategies and solutions to improve the operation of DAWASAs stabilization ponds in Dar es Salaam, Tanzania

Abstract: The waste stabilization ponds in Dar es Salaam, Tanzania, do not operate properly. The purpose of this study was therefore to investigate the current state of DAWASAs stabilization ponds and explore different strategies that can be used to improve the wastewater treatment efficiency by the ponds. This was done through an extensive literature review, root-cause analysis and a stakeholder interview. Data obtained through the stakeholder interview indicated inadequate levels of BOD, TSS, COD and colour in the effluent discharged from ponds in Mikocheni, Kurasini and Mabibo. Discussed strategies of improvement were both technical and non-technical. Among the technical strategies were coverage of the anaerobic ponds, recirculation of effluent as well as effluent polishing methods. Non-technical improvements were maintenance and construction of fences and surveillance of the ponds, increased monitoring of the process within the ponds as well as re-evaluating desludging routines. It was concluded that the non-technical approaches would be a preferable option to begin with, since the variation among the samples does not provide a strong argument for investing in a more expensive technical approach.