From waste to fuel: Characterization, upgrading, and storage of biogas from a pilot-scale MSW digester

Abstract

Municipal solid waste (MSW) management presents persistent challenges in rapidly urbanizing regions of Sub-Saharan Africa. This study evaluates the technical feasibility and field performance of a pilot-scale “waste-to-fuel” system in Kimbiji, Tanzania. A 75:25 mix of food/vegetable waste and grasses/leaves was digested for nine weeks in a floating drum system, producing biogas with 65 ± 1 vol% CH₄, 33.3 ± 1 vol% CO₂, and 277 ± 1 ppm H₂S. Upgrading with rusted steel wool and Ca(OH)₂ increased methane to 82 ± 1 vol% and reduced H₂S to below 3 ppm, achieving 62% CO₂ and 99.3% H₂S removal. Calorimetric testing showed upgraded gas reached 303 W, surpassing both untreated biogas (79 W) and LPG (230 W). The system operated with locally available materials and solar-powered compression, demonstrating a low-cost, off-grid pathway for decentralized fuel storage in repurposed LPG cylinders. The results confirm the technical feasibility of integrating anaerobic digestion, upgrading, compression, and storage within a single waste-to-fuel chain using context-appropriate engineering solutions. The system provides a replicable pilot-scale model for sustainable waste valorization and decentralized energy supply in resource-constrained settings.