Improving methane production from hydrogenogenic effluent with magnetic leaf biochar

Magnetic biochar is a potential economical additive for anaerobic digestion. To better understand the possible role of magnetic biochar on methanization performance, the effect of magnetic biochar on anaerobic digestion process and its enhancement mechanism were explored. The performance of magnetic biochar on methane production from hydrogenogenic effluent was better than that of raw biochar. The final methane production with magnetic biochar addition was 53.28% and 70.92% higher than that of raw biochar addition and the control, respectively. The modified Gompertz equation showed that the addition of magnetic biochar increased the maximum methane production potential and maximum methane production rate by 77.72% and 71.57%, respectively. Magnetic biochar improved the cell biomass and promoted the utilization efficiency of acetate and butyrate. Raw biochar stimulated the secretion of microbial extracellular cytochromes, while magnetic biochar significantly increased the relative abundance of the pilA gene in conductive pili. The addition of magnetic biochar enriched syntrophic partners Syntrophomonas and Methanosarcina and enhanced the hydrogenotrophic methanogenesis pathway. In this study, the addition of magnetic biochar resulted in higher methane production of hydrogenogenic effluent, which improved the energy conversion efficiency of waste biomass. This study also provided new insights into the underlying mechanism by which magnetic biochar enhanced anaerobic digestion performance. Graphical abstract