Different regulation strategies of anaerobic digestion by AC/CaO2 and Fe3O4/CaO2: Reactive oxygen species induction, methanogenic performance, and microbial response

This study examined the combination of activated carbon and magnetite with calcium peroxide in enhancing the anaerobic digestion (AD) performance of food waste (FW). The individual mechanisms of these two approaches were also clarified. The results indicated that AC/CaO 2 achieved the highest specific methane yield of 434.4 mL/g VS, followed by Fe 3 O 4 /CaO 2 (416.9 mL/g VS). Both were significantly higher than other groups (control, AC, Fe 3 O 4 , and CaO 2 were 330.1, 341.4, 342.8, and 373.2 mL/g VS, respectively). Additionally, compared to Fe 3 O 4 /CaO 2 , AC/CaO 2 further increased reactive oxygen species (ROS), thereby enhancing the hydrolytic acidification process. Simultaneously, the higher ROS levels of Fe 3 O 4 /CaO 2 and AC/CaO 2 promoted the formation of microbial aggregates and established a more robust enzymatic defense system and unique damage repair strategy. The research comparatively analyzed the synergistic mechanism of iron-based and carbon-based conductive materials with CaO 2 , providing new perspectives for optimizing the AD of FW.