Pre-fermentation and filtration pretreatments enhance hydrogen production from food waste through microbial electrolysis

Abstract

Bioavailable organic-rich food waste (FW) is a promising feedstock for renewable hydrogen production. However, its highly suspended and complex nature presents substantial challenges for producing high-purity hydrogen in dual-chamber microbial electrolysis cells (MECs). This study examined the effects of pretreating FW through pre-fermentation and/or filtration on its microbial electrolysis. Both methods enhanced the exoelectrogenic utilization of FW, with pre-fermentation being especially effective by conditioning substrate composition, while filtration alone was less advantageous due to associated energy loss. The MECs fed with prefermented FW exhibited significantly higher performances, achieving the highest hydrogen yield of 1,029 mL/g chemical oxygen demand fed (39.1 % increase over raw FW) when pre-fermentation was followed by filtration. Bioanodes across all MECs were dominated by exoelectrogenic bacteria, mainly Geobacter and Desulfovibrio, with significantly greater abundance observed with pre-fermentation. These findings highlight the value of pretreatment, particularly pre-fermentation, and warrant further optimization research to maximize FW conversion into hydrogen.