Conductive fillers accelerate electrical-stimulation biodegradation of refractory dissolved organic matter in...

Refractory dissolved organic matter (RDOM) is a primary bottleneck in landfill leachate treatment, as it induces membrane fouling and inhibits microbial activity. Electrical stimulation has been shown to accelerate RDOM biodegradation following leachate pretreatment. However, electron transfer limitations often hinder the efficiency of electrically stimulated microbes. Herein, a conductive filler (PVA-SA-FeCl₃) was developed by crosslinking polyvinyl alcohol (PVA) and sodium alginate (SA) with FeCl₃ doping to enhance RDOM biodegradation. The synergistic coupling of electrical stimulation and conductive filler significantly improved chemical oxygen demand removal (66%) compared to conventional biological treatment (40%). The PVA-SA-FeCl₃ filler effectively diminished electron transfer resistance within the electrically stimulated microbial system, while its porous architecture promoted the formation of biofilms. Consistently, molecular characterization of RDOM confirmed that conductive fillers potentiated microbial electro-stimulation, thereby promoting the degradation of refractory lignin/CRAM-like in the leachate. Further analysis confirmed augmented microbial electron transfer capacity and extracellular polymeric substance production, thereby accelerating electron shuttling between microbes and pollutants. Additionally, microbial activity and community stability were enhanced, with the selective enrichment of taxa functional in refractory organic matter degradation. This study provides a promising strategy for landfill leachate treatment.