115: Integrated bioelectrochemical valorization of food waste leachate for generating renewable hydrogen and biopolymers

Abstract: Food waste represents a major component of the organic fraction of municipal solid waste and accounts for 10% of global greenhouse-gas emissions, highlighting the urgent need for management and valorization strategies. Conventional approaches such as landfilling, composting, and incineration face environmental or energetic constraints, prompting increased attention to anaerobic digestion (AD) as a route for biomass conversion and energy recovery. To further enhance AD-based valorization, bioelectrochemical systems, including microbial electrolysis cells (MECs) and microbial electrosynthesis (MES) platforms, are increasingly explored to recover electrons as energy carriers and carbon as value-added materials. However, although AD-MEC and AD-MES have been validated independently, their concurrent assessment within a single framework remains scarce; such co-evaluation is critical for developing unified strategies that coordinate electron and carbon fluxes between liquid and gaseous phases for simultaneous energy recovery and carbon valorization. Here, we demonstrate an integrated approach based on acidogenic fermentation of food waste leachate (FWL), a municipal biomass residue stream, enabling parallel evaluation of MEC and MES within one system to bridge this gap. Fermentation of FWL yielded a liquor enriched in soluble organics and a CO2 off-gas; the former powered hydrogen evolution in the MEC as organics were depleted, while the latter supported CO2 reduction and polyhydroxybutyrate (PHB) accumulation in cultures of Rhodobacter sphaeroides. By co-producing an energy carrier (H2) and a carbon-storing bioproduct (PHB) from the same food-waste-derived feedstock, this integrated framework supports bioenergy-oriented valorization of municipal biomass residues and provides a proof-of-concept for coordinated MEC-MES operation under a shared upstream fermentation platform. Funding: This work was supported by the National Research Foundation (NRF) through the project of Consolidated e-Biorefinery of lignocellulosic biomass (RS-2022NR067354) and the Consolidator Grant Type 2 (Global Research Program; RS-2024-00337717) funded by the Korean government.