Biochar-mediated enhancement of butanol and hydrogen co-production from food waste via ABE fermentation: Process optimization and economic assessment

Butanol production through acetone-butanol-ethanol (ABE) fermentation of food waste offers a sustainable solution for biofuel generation and waste management. However, challenges such as pH instability and low yields hinder its application. This study explores the role of biochar in enhancing ABE fermentation in food waste medium using Clostridium acetobutylicum CICC 8012, with a focus on process optimization and economic scalability. Comparative analysis revealed that biochar supplementation (3 g/L) accelerated the transition to the solventogenic phase, increasing butanol by 11% (from 13.4 to 14.8 g/L) and hydrogen production by 18% (from 404 mL to 476 mL). Initial pH and biochar dosage not only independently influenced hydrogen yield and butanol synthesis but also exhibited synergistic interaction effect. Response surface methodology (RSM) identified optimal conditions: initial pH 6.5, 1.74 g/L biochar, and 108.7 h fermentation time. Economic assessment of a simulated 625 ton/day plant showed a 3% cost reduction with biochar addition compared to the conventional ABE fermentation, driven by improved higher yields and operational efficiency. These results position biochar as a cost-effective catalyst for sustainable ABE fermentation, advancing circular bioeconomy strategies by converting low-value waste into high-value biofuels (butanol and hydrogen) while addressing industrial scalability challenges.