Biochar derived from straw regulate anaerobic digestion: Insights into the roles of vegetative organs

Biochar derived from straw has been proven as an alternative additive in anaerobic digestion for enhancing methane production performance from bio-wastes, however, the specific functions and mechanisms of biochar derived from different vegetative organs of straw in anaerobic digestion remain unclear. The biochar (CSBC) derived from corn stems showed superior physicochemical properties than that derived from corn roots and leaves. Specifically, the volatile carbon content of CSBC was 62.7 %, the carbon/nitrogen ratio was 78.73, and the aperture was 11.0 nm. These properties promoted the enrichment of functional microorganisms and improved electron transfer performance. The surface functional groups and large aperture of this biochar provided excellent attachment sites for microorganisms. The Methanobacterium increased by 39.4 % and 68.6 % in the group with CSBC addition compared to that with the biochar derived from corn leaves and corn roots, respectively. Moreover, CSBC significantly improved the activities of key enzymes, accelerated the metabolic reactions, and optimized the substrate conversion pathways. Therefore, the highest methane yield was obtained in the group with CSBC, with the increase ratio of 24.1 % than that of control. This study emphasized the essential roles of biochar that derived from different vegetative organs in anaerobic digestion and offered valuable insights into organic waste valorization.