Fe-Mn Impregnated Biochars for Efficient Hydrogen Production by Thermophilic Clostridiales Consortium Through Promoting Extracellular Electron Transfer and the Abundances of Hydrogenogen

In this research, a thermophilic Clostridiales consortium was enriched with pretreated sugarcane bagasse (PSCB). Then the effects of Fe-Mn impregnated biochars on hydrogen production by consortium with co-wastes were studied. The hydrogen production was 63.57 mmol/L at a 5:5 ratio of PSCB and food waste. Moreover, the Fe-Mn impregnated biochars (Fe.Mn.SB) could further get a yield of 75.84 mmol H2 /L and a hydrogenase activity of 946.63 mL/g-cell protein.h, with a shorter lag phase (1.54 h). Microbial community analysis demonstrated that Fe.Mn.SB could considerably increase the relative abundances of hydrogenogen, such as Thermosinus and Anaerocolumna. Electrochemical analysis implied Fe.Mn.SB promoted a higher reducing power and released more electroactive shuttle - cytochrome c, which was conducive to extracellular electron transfer (an 18.39% increasement of power density in microbial fuel cell). PICRUSt analysis indicated Fe.Mn.SB boosted substrate degradation and carbon metabolism. Carbon flow analysis indicated that Fe.Mn.SB group could enhance hydrogen producing pathways and suppress hydrogen consuming pathways. The present work established a feasible process for hydrogen production by dark fermentation and revealed the enhanced mechanism of Fe-Mn impregnated biochars to biohydrogen.