Research Progress of Bio-electro-Fenton System and Its Application in Wastewater Treatment

The bio-electro-Fenton (BEF) system integrates bioelectrochemistry with Fenton advanced oxidation technology. It can achieve self-sustained electricity generation via anaerobic microbial metabolism and construct an efficient advanced oxidation system relying on in-situ hydrogen peroxide production at the cathode. This system effectively addresses the limitation of conventional biological methods that struggle to treat refractory and highly toxic organic wastewater, thus holding promising application prospects in water pollution remediation. This paper systematically reviews the core reaction mechanisms of BEF systems, elaborates the microbial electrogenic oxidation mechanism at the bioanode as well as the oxygen reduction and Fenton catalytic oxidation mechanisms at the cathode, and summarizes recent research advances in modification and optimization of anode and cathode electrode materials. Emphasis is placed on analyzing the effects of carbon-based modification, nanocomposites and biochar-based electrode materials in boosting electron transfer efficiency and enhancing electricity generation performance and hydrogen peroxide production efficiency. Meanwhile, this paper compares and evaluates the merits and demerits of homogeneous iron-based catalysis and supported heterogeneous catalytic systems. It points out that traditional homogeneous catalysis suffers from narrow applicable pH range, high reagent consumption and high risk of secondary pollution. In contrast, supported heterogeneous catalysts have become a research hotspot for BEF catalytic materials owing to their advantages including stable active sites, low metal leaching, recyclability and strong adaptability under neutral conditions. At present, BEF technology still faces challenges such as easy electrode passivation, weak anti-interference capacity in complex water matrices, high material fabrication cost, and ambiguous interfacial mechanisms underlying multi-mechanism coupling. Future research should further develop long-term stable, low-cost functional electrodes and composite catalytic materials, deeply uncover the synergistic mechanisms among microbial metabolism, electron transfer and Fenton catalysis, and promote the transformation of bio-electro-Fenton technology from fundamental laboratory research to large-scale engineering applications for practical wastewater treatment.