Optimizing anaerobic digestion of corn straw via exogenous hydrogen permeation adjustments Post-Trichoderma viride pretreatment

Abstract

The recalcitrant lignocellulosic structure of corn straw poses significant challenges to its valorization through anaerobic digestion (AD), with hydrolysis remaining a key bottleneck. This study introduces a novel integrated approach combining pretreatment with hydrogen regulation to address hydrolytic and methanogenic limitations. Through Trichoderma viride pretreatment, leading to significant lignin degradation (74.06% reduction) and structural modification, substrate accessibility was significantly improved, resulting in a 136% increase in maximum methane production compared to untreated substrates. An advancement was achieved through orthogonal optimization (L₉(3⁴) design) of exogenous hydrogen supplementation, identifying 60 mL H₂ injection for 13 min thrice daily as optimal parameters. This staged hydrogenation strategy enhanced biogas upgrading efficiency via: (1) selective enrichment of hydrogenotrophic methanogens; (2) maintaining favorable H₂/CO₂ stoichiometry (approximately 4:1) for thermodynamic stability; (3) extending the active digestion phase by 80% (Extended from 5 to 9 days). Kinetic modeling, using a modified Gompertz equation (R² = 0.98–0.99), revealed parameters aligned with microbial shifts, with the maximum methane potential (\(G \text{max}\)) reaching 132.44 mL/g TS under optimized conditions. This study demonstrates a synergistic approach to enhance lignocellulosic AD, integrating Trichoderma pretreatment for improved hydrolysis with optimized hydrogen supplementation for enhanced and sustained methanogenesis, offering a promising pathway for enhanced renewable biogas production from agricultural waste.