Electropolarization-Promoted Membrane Fouling Mitigation in Treating Actual Chemical Secondary Effluent: Underlying...

Electrically conductive membranes (ECMs) offer a promising approach for advanced wastewater treatment as they can mitigate membrane fouling by an in situ electroregulation strategy. However, current studies have mainly focused on synthetic wastewater at a laboratory scale, which cannot fully reflect the complexity of real wastewater matrices and provide reliable guidance for practical implementation. Here, we developed a highly conductive carbon nanotube-composited polyvinylidene fluoride (CNT-PVDF) ECM to systematically investigate its antifouling performance for the advanced treatment of actual chemical secondary effluent in an engineering demonstration. The CNT-PVDF ECM with negative electropolarization exhibited improved antifouling performance, extending the backwashing interval to twice that under OCP and approximately 12 times that of the commercial PVDF membrane. In situ electrochemical experiments revealed that negative-potential electropolarization modulated interfacial pH and surface electron density, thereby enhancing electrostatic repulsion and mitigating foulant attachment. Quantitative analysis indicated that local interfacial alkalization accounted for ∼38% of the total reduction in filtration resistance, identifying an important antifouling contribution alongside the conventional electrostatic repulsion associated with potential-induced membrane charge modulation. Moreover, the engineering feasibility of this strategy was further validated in a 300 m3 day-1 demonstration-scale treatment system. During the 120-day operation, the CNT-PVDF ECM maintained sustained antifouling performance even under a prolonged backwashing interval of 5 h. These findings reveal a previously underappreciated role of interfacial alkalization in electroregulation-promoted fouling mitigation and provide engineering guidance for the practical application of ECMs in real wastewater treatment.