Enzyme Pretreatment Enhancing Biogas Yield from Corn Stover: Feasibility, Optimization, and Mechanism Analysis

In this study, feasibility, optimization, and mechanisms of enzyme pretreatment to enhance anaerobic digestion of corn stover were investigated. Results showed that the enzyme pretreatment efficiently enhanced the biogas yield, and the optimal conditions of enzyme pretreatment were an enzyme load of 30 FPU/g, a pretreatment time of 24 h, and a solid content of 60 g/L. Under the optimal conditions, the cumulative biogas yield increased by 36.9%, which was mainly attributed to disruption of surface structure and degradation of noncrystalline cellulose in the enzyme-pretreated corn stover. The kinetic analysis indicated that enzyme pretreatment significantly enhanced the hydrolysis rate and biogas production rate to 0.15/d and 23.89 mL/gVS, and shortened the lag phase time to 1.2 d. Correlation analysis illustrated that the SCOD yield of 250–350 mg/g from corn stover after enzyme pretreatment was suitable for the further anaerobic digestion of corn stover.