Biogas potential of organic municipal solid waste: a multi-municipal assessment in Southern Brazil

Anaerobic digestion of the organic fraction of municipal solid waste (OFMSW) is a promising strategy for sustainable waste management and renewable energy generation in small municipalities. This study evaluated the biochemical methane potential (BMP) and biogas yield of OFMSW from five municipalities in southern Brazil sharing a regional landfill. Composite samples were analyzed for total solids, volatile solids, and soluble chemical oxygen demand (sCOD), and elemental composition including trace metals. BMP tests were conducted under mesophilic conditions (39 °C) using a substrate-to-inoculum ratio ≤0.5 (VS basis) following VDI 4630 guidelines. Under mesophilic conditions, biogas yields ranged from 519 to 733 m³ t−1 VS, and methane yields from 296 to 445 m³ t−1 VS, with sCOD correlating with energy potential. Elemental analysis revealed that molybdenum presence coincided with higher methane yields, while elevated iron and tungsten concentrations were observed in lower-performing samples. Heavy metal concentrations (Pb, Cd, Cr, Hg and As) exceeded regulatory limits for agricultural digestate application. Estimated regional biogas production reached 2,212 m³ day−1, supporting decentralized anaerobic digestion systems in rural contexts. These findings demonstrate the technical feasibility of biogas recovery from OFMSW and provide data to inform localized waste-to-energy initiatives.