Membrane filtration technologies for sustainable industrial wastewater treatment: a review of heavy metal removal.

Industrial wastewater is generated by industries such as manufacturing, food processing, pharmaceuticals, textiles, and mining. Nevertheless, the wastewater generated from this process contains varying levels of heavy metals that are detrimental to both the environment and living organisms. However, it also offers opportunities for selectively retrieving valuable metals, which can enhance the economic feasibility and sustainability of the treatment process. There are several types of wastewater treatment methods, such as chemical precipitation, adsorption, coagulation, flocculation, and ion exchange. These conventional treatment methods have demonstrated promising results, but they have some drawbacks, including the generation of significant amounts of sludge, lower removal efficiencies, limited effectiveness at low metal concentrations, and sensitivity to pH variations. Latest technologies such as nanotechnology, electrochemical coagulation, and membrane filtration offer notable advantages, including higher removal efficiencies, enhanced energy performance, and increased selectivity for specific contaminants. Among these, membrane filtration stands out for its dual function, efficiently removing heavy metals while concentrating them into a smaller volume. This reduces the need for chemicals and sludge handling, thus facilitating cost-effective recovery through secondary processes such as electrowinning or crystallization. Metals such as copper (Cu), zinc (Zn), nickel (Ni), and silver (Ag) have been successfully recovered using membrane filtration technologies, particularly from electroplating and mining effluents. This review highlights recent advancements in membrane-based technologies for industrial wastewater treatment, emphasizing their role in metal recovery, fouling mitigation strategies, and their potential to reduce treatment costs and environmental impact.