Feasibility of enhancing hydrogen production from cornstalk hydrolysate anaerobic fermentation by RCPH-biochar

This study presents a novel approach based on addition of biochar generated from residue of cornstalk left after pretreatment and hydrolysis (RCPH-biochar) to improve hydrogen production from cornstalk hydrolysate. RCPH-biochar at concentration of 15 g L^-1 substantially enhanced hydrogen generation during batch tests, with the highest cumulative hydrogen volume (3990 mL L^-1) being 1.7 times that without RCPH-biochar. Then, continuous hydrogen production performance demonstrated that RCPH-biochar was capable of retaining biomass in the reactor, at 6 h hydraulic retention time, hydrogen production rate (22.8 mmol H₂ L^-1 h^-1) was tripled compared to the control, meanwhile, glucose and xylose utilization reached to 82.3% and 54.6%, respectively. Overall material balance indicates continuous hydrogen production with RCPH-biochar enabled 63.4% higher cornstalk transfer to H₂ and 53.3% more cornstalk utilization. The findings reported is a closed-loop process and is economically and environmentally attractive, which might support comprehensive cornstalk utilization with less energy input in the future.