Enhanced anaerobic biodegradation of 17α-ethinylestradiol via a flow-through electrode

Removal of 17α‑ethinylestradiol (EE2) remains a major challenge of anaerobic wastewater treatment technologies. In this study, we proposed and demonstrated that integrating a flow-through electrode (FTE) into anaerobic system can effectively overcome this constraint. The electroactive biofilm formed on the FTE significantly enhanced the removal efficiency of EE2, increasing it from 60.1 % to 89.4 % during long‑term operation. This improvement was primarily attributed to intensified EE2 biodegradation, with pathways shifting toward enhanced deethylation and A-ring cleavage. Electroactive bacteria (Geobacter and Pseudomonas) and EE2‑degrading bacteria (Microbacterium and Methylobacterium) were substantially enriched, facilitating the development of an "internally-externally active" microbial structure. Metaproteomic analysis revealed upregulation of key degradation enzymes (e.g., CYPs), and molecular simulations further corroborated these findings by confirming strong binding affinity and dynamic stability between these enzymes and EE2 in the electroactive biofilm. Collectively, this study provides a practical and effective approach for enhancing EE2 removal in anaerobic wastewater treatment systems and expands the application scope of the flow-through electrodes.