Self-supported cathode based microbial electro-Fenton for water disinfection: The synergistic inactivation mechanism of biological and electrochemical oxidation

Abstract

The microbial electro-Fenton (MEF) system integrates bioelectrochemistry with Fenton oxidation for wastewater treatment. In this system, microbial oxidation of organic matter at the anode generates electrons that are transferred to the cathode, promoting the in-situ production of H₂O₂. The reactive species formed during the cathodic electrochemical reactions effectively degrade refractory organic pollutants in wastewater. However, research on the disinfection capabilities of this system is notably lacking with challenges including low H₂O₂ yield and ineffective cycling of Fe²⁺ and Fe³⁺. To address these limitations, a self-supported embedded composite electrode was designed as the MEF cathode, which enhanced electron transfer throughout the system. At an applied voltage of 0.4 V, a 4.0-Log reduction of E. coli was achieved within 2 h, with an energy consumption of 0.06 kWh/m³, significantly lower than traditional electrochemical disinfection. The stable adsorption sites on the composite electrode promoted the sustained production of H₂O₂ through oxygen reduction. Results demonstrated that elevated levels of ·OH induced the leakage of intracellular substances, which ultimately triggered bacterial inactivation. Furthermore, the anodic microbial community revealed that the growth of Firmicutes phylum accelerated electron transfer and cathodic oxidation, boosting the disinfection efficacy of MEF system. Thus, this technology shows great potential for simultaneous organic contaminants treatment at the anode and disinfection at the cathode, offering a low energy consumption, high-efficiency method for reducing pollution risks.