Municipal solid waste (MSW) management in Mbeya City, Tanzania, is currently characterized by unsorted collection, open dumping, and minimal energy recovery, contributing to serious environmental and public health concerns. This study addressed the urgent need for sustainable waste treatment solutions by proposing the design of a centralized anaerobic digestion (CAD) system tailored to the city’s organic waste profile. The main objectives were to quantify the biodegradable waste stream, estimate biogas production potential, and develop a technically and economically feasible CAD system. A ten-day sampling campaign revealed an average generation of 45,000 kg/day of organic waste, predominantly food scraps with high moisture content (65–78%), suitable for biogas production. The proposed CAD system was designed to process 6 m³/day of substrate, generating 1,080 m³/day of biogas, equivalent to 2.16 MWh of electricity and 23,760 MJ of heat per day. Thermal system design ensured energy self-sufficiency under thermophilic conditions (55°C), supported by heat recovery efficiencies of 80%. Environmental analysis projected annual greenhouse gas reductions of 16,948.95 tons CO₂-equivalent and 60% diversion of organic waste from landfills. Economic evaluation revealed a capital cost of $320,000, a payback period of 2.8 years, and an internal rate of return (IRR) of 25.1%. The study concludes that a CAD facility, integrated with improved waste segregation and supported by public-private partnerships, offers a viable pathway to circular economy practices in Mbeya City. Policy support, technical training, and community engagement are essential for successful implementation and replication in similar urban contexts.
Keywords: Centralized Anaerobic Digestion; Municipal Solid Waste Management; Biogas Energy Recovery; Thermophilic Digestion Systems; Sustainable Urban Waste Solutions
