Methane production potential from anaerobic digestion of plant biomass residues and food waste as substrates

This research aimed to evaluate the production of biogas from anaerobic digestion (AD) using swine manure inoculum associated with different substrates: food scraps (FW), grass clippings (GR), and lentils (DW). The digestion of FW alone and co-digestion (co-AD) of FW with GR or DW were studied with biomass after pretreatment by drying. The evaluation of the methane production potential was performed in a bench-scale experiment using the biochemical methane potential (BMP) test in batch mode. The inoculum-to-substrate ratio used was 1:2. After 54 days of incubation, the IN + FW condition presented the highest accumulated methane production, reaching 369.71 NmLCH4 g VS−1, also the maximum methane content in the biogas (76%). The FW co-AD condition with FD was the best among the biomass treatments, it accumulated 347.24 NmLCH4 g VS−1 of methane, and its biogas content reached a maximum percentage of 70%. The Gompertz kinetic model was satisfied in all treatments. The maximum methane generation estimated by fitting the model curves was similar to the methane production verified in the experiment. Statistical analyses indicated that the co-AD of the FW with the pre-treated DW (IN:FW + DD) or not (IN:FW + FD) showed no significant difference in methane production. Furthermore, the pre-treated GR substrate (IN:FW + DG) did not increase the methane production efficiency, as well as the condition without pretreatment of GR (IN:FW + FG).