Enhancing Anaerobic Digestion of Food Waste by Combining Carriers and Microaeration: Performance and Potential Mechanisms

Enhancing the anaerobic digestion (AD) of organic wastes has been a widely discussed topic. This study aims to enhance AD performance by combining microaeration with conductive or nonconductive carriers, using food waste as the substrate. The use of carriers alone enhanced methane production, and microaeration further improved performance. The conductive carrier showed significant enhancement with microaeration, achieving a daily methane yield of 478 +/- 11.3 mL CH4/g VS, which was 1.1 and 1.3 times higher than that of the nonconductive carrier and the control digester, respectively. Furthermore, the study explored various aspects, including oxidative stress, antioxidant capacity, and microbial community structure during digestion. The results demonstrated that combining microaeration with a conductive carrier improved hydrolytic-acidification efficiency and promoted direct interspecies electron transfer among syntrophic microorganisms. Methanogenic archaea aggregated on the carrier surface and formed consortia with facultative anaerobes, thereby mitigating oxidative stress effects on cells and enhancing total methane production. Moreover, metabolomics analysis showed that combining conductive carriers with microaeration enhanced ATP transport across the bacterial membrane, accelerated nutrient conversion, and caused significant changes in metabolites and intermediates related to glycerophospholipids, amino acids, and signal transduction pathways.