Effects of co-digestion of food waste, corn straw and chicken manure in two-stage anaerobic digestion on trace element bioavailability and microbial community composition

Co-digestion is known to effectively alleviate trace elements (TEs) deficiency in mono-substrates; however, the bioavailability of TEs is crucial for the stability of anaerobic digestion. Therefore, this study investigated the effects of co-digestion of food waste (FW), corn straw (CS) and chicken manure (CM) in two-stage anaerobic digestion on TEs bioavailability and microbial community composition. Various VSFW:(VSCS:VSCM) ratios of 8:2, 7:3, 4:6, and 2:8 were evaluated in two-stage (group A, B, C, D) anaerobic digestion in which the VSCS:VSCM ratio was fixed at 3:1. Results showed that the highest hydrogen production of 106 mL/g VS and methane production co-efficiency of 125.3% was obtained in group A. Group A has a high close range of easily bioavailable TEs (32-64%) compared to other groups, especially the mono-substrate, where almost all TEs ranged between 10 and 36%. The increased relative abundance of the obligate hydrogenotrophic methanogens reflected a positive two-stage methane co-digestion efficiency.