Mechanism of Biochar for Enhancing Volatile Fatty Acids Production during Anaerobic Fermentation of Food Waste

• • Biochar addition at 1 g/L increased total VFAs concentration to 2150 mg/L, a 30.2% improvement over the control (1651 mg/L), demonstrating a direct yield enhancement in a 7-day fermentation. • • The biochar-amended system maintained pH stability, preventing excessive acidification, which is critical for sustaining acidogenic microbial activity and avoiding process inhibition. • • Biochar's porous structure adsorbed soluble ions, leading to lower electrical conductivity compared to the control, indicating a modified ionic environment that may favor microbial metabolism. • • Microbial community analysis showed that biochar enriched key acidogenic genera (Defluviitoga and norank_f__Family_XI) while reducing Streptococcus abundance, optimizing the microbial consortium for VFAs production.