Feasibility of Resource Recovery from Operational Decentralised Wastewater Treatment Systems for Urban Sanitation Economy in Dar es Salaam, Tanzania

Abstract

This study explored whether it's possible to recover valuable resources from five operational Decentralised Wastewater Treatment Systems (DEWATS) in Dar es Salaam, Tanzania, to help build a stronger urban sanitation economy. We gathered data on biogas, biosolids, treated effluent, and household tariff revenues through laboratory analyses and interviews between December 2025 and April 2026, then ran a 20-year cost-benefit analysis using three discount rates. Two sites, Kigamboni-Tungi (131% OPEX cost coverage) and Tuangoma (115%), are already paying for themselves through resource recovery. However, across all sites, there’s still a combined annual revenue gap of 5,025 USD. Our findings show that better management, rather than new technology, is the key to success: benefit-cost ratios improved by 44–109% under more optimistic scenarios. The biggest challenges were institutional, not technical. For example, formalizing biosolid sales, adding disinfection to the effluent at three sites, and starting household tariffs at Mlalakuwa could help each site cover its costs with minimal additional investment. We encourage the Ministry of Water and Sanitation to recognize DEWATS as productive infrastructure in national water sector funding. Our study offers the first verified, multi-site financial dataset linking effluent quality, resource-recovery revenues, and lifecycle cost-benefit analysis for DEWATS in sub-Saharan Africa, providing practical evidence to inform sanitation-economy policy in low-income urban areas. To improve DEWATS sustainability, we recommend formalizing biosolid and effluent sales and investing in low-cost disinfection upgrades to unlock higher-value resource recovery. Strengthening CBWSO management capacity and incentives will further support long-term financial viability and effective operation.