Bioelectrochemical enhancement of waste valorization: synergistic power generation, metal stabilization, and resistome dynamics in electro-stimulated composting system

Abstract

The integration of microbial electrochemical systems with organic solid wastes treatment offers a groundbreaking strategy for sustainable resource recovery. Nevertheless, the underlying biological mechanism remains unclear, limiting its practical application. Here, a two-phase microbial desalination cell (TPMDC) was constructed using dewatered sludge (DS) and kitchen waste (KW) or corn straw as co-composting substrate. We investigated the mediating role of substrate-driven microbial succession in energy harvesting, metal stabilization, and the antibiotics resistance gene (ARG) dynamics using metagenomics. Results demonstrated that TPMDC DS + KW achieved a maximum power density of 1.910 ± 0.009 W/m3, peck voltage of 0.893 ± 0.005 V, and highest organic matter removal rate of 31.13 %. Notably, we demonstrated substrate-dependent metal stabilization that simultaneously enhanced Zn bioavailability (agriculturally beneficial) and immobilizes >90 % toxic Cu/Cr. Metagenomic analysis identified 74 ARGs types (relative abundance: 2.44–3.08 %) and Mesorhizobium could be considered as a keystone ARG suppressor due to its significant negative correlations with multiple ARG subtypes. Additionally, we established a mechanistical link between electro-stimulation and upregulated TCA cycle genes (EC:6.2.1.1/6.2.1.16), directly coupling microbial metabolism to electron flux. These findings establish a robust scientific foundation for optimizing bio-electrochemical co-composting systems and advance circular economy implementation.