Simultaneous synergistic effects of graphite addition and co-digestion of food waste and cow manure: Biogas production and microbial community.

•The graphite and co-digestion contributed to improving biogas production.•Illumina high-throughput sequencing was applied to analyze microbial communities.•The shift of archaeal structure indicate the metabolic pathway changed via graphite.•Clostridium and Methanosaeta were likely the major group responsible for DIET.•SEM images showed an extensive colonization and EPS in biofilm structure.