Electrodialysis and hybrid membrane systems for sustainable removal and recovery of toxic metal ions from water and industrial effluents: A systematic review

The release of toxic metal ions from industrial effluents poses environmental and public health risks because of their non-biodegradability and bioaccumulation potential. Conventional treatment methods such as chemical precipitation, coagulation–flocculation, adsorption, ion exchange, and electrocoagulation often have low selectivity, generate secondary waste, and offer limited options for metal recovery; therefore, efficient, sustainable solutions are needed. Electrodialysis (ED) and hybrid membrane systems have emerged as promising alternatives, providing electrically assisted, selective ion separation that requires fewer chemicals and improved potential for metal recovery. This systematic review critically evaluates recent developments in ED and hybrid membrane technologies for the sustainable removal and recovery of toxic metal ions from water and industrial effluents. Following the PRISMA guidelines, the search for peer-reviewed literature was conducted across Scopus, Web of Science, ScienceDirect, Google Scholar, and PubMed databases, employing standardized Boolean search strategies, filtered for relevance and methodological robustness. Comparison analysis focused on system configuration, membrane material, performance metrics, and sustainability measures. Findings reveal significant progress in ion selectivity, energy efficiency, and recovery efficiency through advanced ion-exchange membranes, electro-deionization, and hybrid-electrodeionization-based systems integrated with adsorption, electrochemical oxidation, and nanofiltration. However, challenges such as membrane fouling, high energy consumption, and limited scalability remain unresolved. ED systems and hybrid membrane systems represent a transformative route for sustainable metal ion recovery. Further innovation in membrane materials, hybrid process integration, and pilot-scale validation is vital to achieving industrial-scale implementation.