Hydrothermal pretreatment of food waste enhances performance of anaerobic co-digestion with sludge

Food waste (FW) presents a significant opportunity for renewable energy production through anaerobic digestion (AD) when subjected to appropriate treatment. This study investigates the impact of thermal hydrolysis pretreatment (THP) on FW at varying temperature levels (90 °C, 120 °C, and 140 °C) prior to mesophilic anaerobic co-digestion with sewage sludge (SS). Results demonstrate enhanced FW hydrolysis at 120 °C, leading to a cumulative methane yield of 324.39 ± 4.5 mL/gVS_add, representing a 41.75% increase over untreated FW (228.83 ± 1.13 mL/gVS_add). Shifts in microbial communities, particularly Methanosarcina, Methanobactrium, and Methanobrevibacter, support efficient methanogenesis. Co-digestion of FW pretreated at 120 °C yields maximum energy production of 11.48 MJ/t, a 49.47% improvement compared to untreated processes. The economic analysis underscores the profitability of co-digestion with FW pretreated at 120 °C. These findings highlight the potential for enhanced methane production and energy conversion efficiency with hydrothermally pretreated FW and SS co-digestion.