Bioelectroactive Membranes for Heavy Metal Removal from Wastewater Remediation

Abstract: Heavy metal contamination in wastewater is a serious environmental and public-health problem because metals such as chromium, lead, cadmium, nickel, copper, mercury, arsenic, and zinc are toxic, persistent, and difficult to degrade. Conventional technologies such as chemical precipitation, coagulation-flocculation, ion exchange, and adsorption are useful, but they can suffer from incomplete removal, sludge generation, high chemical demand, fouling, or high operational cost. Membrane-based processes, including ultrafiltration, nanofiltration, reverse osmosis, micellar- enhanced ultrafiltration, and polymer-enhanced ultrafiltration, provide compact and efficient methods for heavy metal removal. In parallel, microbial fuel cells (MFCs) and related bioelectrochemical systems provide a pathway for simultaneous wastewater treatment and electricity generation. The membrane or separator in an MFC regulates proton and ion transport, separates anodic and cathodic reactions, limits oxygen diffusion, and influences power density, current density, coulombic efficiency, and chemical oxygen demand removal. This review discusses bioelectroactive membrane systems for heavy metal removal by integrating membrane separation principles with MFC-based treatment. The paper reviews heavy metal contamination, conventional treatment methods, membrane processes, MFC fundamentals, separator materials, ceramic and earthen membranes, electrode reactions, fouling, surface modification, performance indicators, limitations, and future perspectives. New schematic figures are included to illustrate water contaminant classification, membrane separation processes, MFC configurations, oxygen reduction reactions, enhanced ultrafiltration mechanisms, membrane fouling, and surface modification strategies.

Keywords: Bioelectroactive membrane; microbial fuel cell; heavy metals; wastewater treatment; proton exchange membrane; ceramic membrane; earthen membrane; nanofiltration; reverse osmosis; surface modification; membrane fouling.