Interfacial Electron Transfer Powers Synergistic Fenton-like Oxidation and Enhanced Microbial Metabolism for E2–3S Estrogenic Risk Mitigation

Abstract

Conjugated estrogens like 17β-estradiol-3-sulfate (E2–3S) are ubiquitous in wastewater and pose latent ecological risks due to their potential conversion into endocrine disruptors. To address the limited removal efficiency of biological treatment and the energy dependence of advanced oxidation processes, we developed a novel biomaterial-coupled system (P.CE2S–Fe–Zn@NC) to mitigate the estrogenic risks of E2–3S by integrating microbial metabolism with advanced oxidation via interfacial electron transfer. The system achieved a 92.4% reduction in estrogenic activity, significantly outperforming standalone biological (80.2%) and catalytic treatments (38.6%). Mechanistic investigations revealed that the Fe–Zn@NC catalyst established a surface microelectric field that facilitated interfacial electron transfer from bacteria to the catalyst. This electron flux drove a self-sustained Fenton-like reaction, effectively activating bacteria-secreted H2O2 into •OH for oxidative transformation. Concurrently, gene transcriptional changes occurred in the functional bacteria within the coupled system, where the upregulation of respiratory energy metabolism and extracellular electron-transfer genes sustained energy-intensive catabolic processes, specifically desulfation and steroid ring cleavage of E2–3S, as evidenced by upregulated steroid catabolic genes. By synergistically coupling material-driven oxidation with microbe-mediated metabolism, this system reduced the estrogenic activity of the effluent. This study provides a transformative paradigm for bridging microbial bioenergetics with material catalysis, offering a sustainable strategy for remediating latent estrogenic contaminants.