Co-valorization\nof Food Waste and CO<sub>2</sub> to\nProduce Volatile Fatty Acids Using Liter-Scale Tubular Microbial Electrosynthesis\nCells

This study presents the simultaneous\nconversion of food\nwaste and\nCO<sub>2</sub> into volatile fatty acids (VFAs) using a 6 L tubular\nmicrobial electrosynthesis cell (MES). The MES reactor uses a bioanode\nto convert food waste into current and CO<sub>2</sub>, while on the\ncathode, H<sub>2</sub> is produced and subsequently consumed by cathode\nmicrobes for the conversion of CO<sub>2</sub> to VFAs. The study reveals\nthat system performance is impacted by organic loading, applied voltage,\nand flow rate, and optimal operational conditions achieve a VFA titer\nof 1763 mg/L with the Coulombic efficiency (CE) exceeding 90% at the\nanode, highlighting efficient electron recovery from food waste. Resistance\nanalysis indicates that the cathode contributed most to system resistance,\nwhile microbial community analysis shows a synergy between fermentative\nand electroactive bacteria in the anode and dominant acetogens in\nthe cathode, facilitating efficient electron recovery and VFA synthesis,\nrespectively. The research underscores the tubular MES’s potential\nfor sustainable food waste treatment and CO<sub>2</sub> valorization\ninto valuable VFAs, contributing to waste management and greenhouse\ngas mitigation strategies.