Methane production from the co-digestion of banana crop residues and the organic fraction of municipal solid waste: influence of steam explosion

Anaerobic digestion of residual biomass is of great interest due to its contribution to the circular economy and the reduction of greenhouse gas emissions. The biogas sector is focused on the identification of new feedstocks and the application of innovative technologies to improve biogas production and process efficiency. Colombia is one of the major banana producers and exporters worldwide, generating large amounts of agricultural waste. This study investigates the use of banana crop residues (BCR), specifically rachis (R) and pseudostem (P), and their co-digestion with the organic fraction of municipal solid waste (OFMSW) in the anaerobic digestion process. Due to their high lignocellulose content, BCR were pretreated by steam explosion (SE). R was pretreated at 180 and 200 °C for 10 min, while P was pretreated at 160 and 180 °C for 10 min. Biochemical methane potential (BMP) tests showed methane yields of 534.5, 363.3 and 202.2 L CH4 /kg VS (on a volatile solids (VS) basis) for OFMSW, raw P and raw R, respectively. SE pretreatment increased biodegradability and methane yield in co-digestion assays. SE at 180 ºC for P (P180) and R (R180) increased biodegradability by 25% in a mixture composed of OFMSW, P and R (70%, 20% and 2% on a VS basis, respectively). This mixture (OFMSW-P180-R180) exhibited the highest methane yield, with 457.5 L CH4 /kg VS , equivalent to 201.85 kWh e /t of wet biomass. The results demonstrate that SE pretreatment, when applied within an optimal severity window, enhances the synergistic co-digestion of lignocellulosic agricultural residues with urban organic waste. This integrated approach demonstrates promising potential as a technically viable strategy, under controlled laboratory BMP conditions, to improve methane production and supports the development of circular bioeconomy systems in regions with high availability of both waste streams. Nevertheless, the methane yields reported in this study correspond to laboratory-scale BMP assays under optimized batch conditions and should therefore be interpreted as maximum biomethane potentials rather than direct industrial-scale performance values.