Efficient hydrogen production from sugarcane bagasse and food waste by thermophilic clostridiales consortium and Fe–Mn impregnated biochars

In this research, a thermophilic Clostridiales consortium was enriched with pretreated sugarcane bagasse (PSCB). Then the hydrogen production of Clostridiales consortium through dark fermentation had been greatly improved through two-step strengthening. Firstly, food waste was added to optimize C/N ratio of substrate to 10.47. Secondly, Fe–Mn impregnated biochars (Fe·Mn·SB) were supplemented to the co-substrate fermentation system to further improve hydrogen production. Overall, the hydrogen production (1.71 mL H2/mL-culture) and yield (586.19 mL H2/g-carbohydrate) of Clostridiales were increased by 113.75% and 32.48% compared with that of fermentation from single PSCB, respectively. The mechanism of Fe·Mn·SB promoting hydrogen production was further elucidated. Microbial community analysis demonstrated that Fe·Mn·SB could increase the relative abundances of dominant hydrogenogen and stabilize community structure. PICRUSt analysis indicated Fe·Mn·SB boosted substrate degradation and carbon metabolism. Electrochemical analysis implied Fe·Mn·SB promoted reducing power and release of cytochrome c, stimulating extracellular electron transfer (an 18.39% increase in power density). Carbon metabolism analysis indicated that Fe·Mn·SB enhanced hydrogen-producing pathways and suppressed hydrogen-consuming pathways. The present work established a feasible process for hydrogen production by Clostridiales consortium fermentation from co-substrate, deepened the understanding of metal-modified biochars improving hydrogen production, and provided references for future research.