Research on Biohydrogen Production from different phase state of Corn stover Pre-treated with Alkali blackwater

Alkaline blackwater pretreatment of corn stover for fermentative hydrogen production was investigated. Systematic investigations were conducted to characterize the hydrogen production characteristics and microbial community differences of pretreated corn stover in the solid, liquid, and solid-liquid mixture stages. The results indicated that alkaline blackwater pretreatment synergistically disrupted the lignocellulosic structure. Compared with the untreated control, the extraction efficiencies of reducing sugars and soluble chemical oxygen demand (SCOD) were increased by 155.4% and 122.8%, respectively. X-ray diffraction (XRD) analysis revealed that the crystallinity index of corn stover increased from 0.44 to 0.50 after pretreatment. This increase was attributed to the removal of amorphous components (e.g., lignin and hemicellulose) and the improvement of fiber pore structure. This significantly enhanced substrate bioaccessibility. Additionally, among the three stage systems, the solid stage exhibited the optimal baseline hydrogen production performance (33 mL/g). After bioaugmentation with exogenous G1 bacteria, hydrogen production was enhanced in all stages. The most pronounced improvement was observed in the liquid stage (from 19.33 to 54 mL/g, representing a 179.4% increase rate). This improvement was closely associated with exogenous bacteria mitigating inhibitory effects and cooperating with indigenous bacteria to strengthen the butyrate-type hydrogen production pathway. Metabolite analysis demonstrated that the butyrate-type metabolic pathway was the dominant pathway across all systems. Furthermore, microbial community analysis indicated a positive correlation between the relative abundance of Clostridium sensu stricto and hydrogen production efficiency. These findings suggested that alkaline blackwater pretreatment combined with G1 bacterial bioaugmentation effectively promotes fermentative hydrogen production from corn stover. This highlights its potential as a reliable strategy for biohydrogen production from lignocellulosic biomass.