Multivariate insights into enhanced biogas production in thermophilic dry anaerobic co-digestion of food waste with kitchen waste or garden waste: Process properties, microbial communities and metagenomic analyses.

• Co-digestion promoted biogas production and the maximum OLR tolerance. • Co-digestion reduced ammonia nitrogen inhibition and VFAs accumulation. • Co-digestion enriched key hydrolytic bacteria at high OLRs. • FW and KW co-digestion strengthened the methane metabolic pathway. • FW and GW co-digestion increased ABC transporters abundance. Multisubstrate synergetic anaerobic co-digestion can effectively overcome low efficiency of food waste (FW) mono-digestion. This study investigated the effect of supplementing FW with kitchen waste (KW) or garden waste (GW) on thermophilic dry anaerobic co-digestion. FW-KW and FW-GW co-digestion enhanced biogas production by 24.69 % and 44.96 % at organic loading rate (OLR) of 3 g VS L-1 d-1, and increased OLR tolerance from 3 to 4 g VS L-1 d-1 through mitigating ammonia nitrogen inhibition and volatile fatty acids accumulation. Co-digestion enriched the dominant hydrolytic bacteria Defluviitoga , resulting in an acceleration of substrate hydrolysis. FW-KW co-digestion improved biogas production by increasing gene abundance related to key enzymes in methanogenesis pathways and promoting the conversion of intermediate products into methane. FW-GW co-digestion enhanced biogas production by enriching ABC transporters-associated genes, leading to efficient substrate utilization. This study provides a promising approach for FW treatment with multivariate insights into thermophilic dry anaerobic co-digestion. [ABSTRACT FROM AUTHOR]