A comprehensive review of recent advances in membrane innovations for efficient heavy metal removal from mine effluents

The growing global challenge of water scarcity, intensified by industrialization and population growth has heightened the need for effective wastewater management in industries, including the mining sector. Mining operations discharge substantial volumes of wastewater laden with toxic metal such as copper, iron, cobalt, lead and mercury which poses significant environmental as well as human health risk. Efficient wastewater treatment is crucial to mitigate these effects. While technological advancements have improved mine effluents treatment, there remains a need for advanced methods that enable not only removal of the toxic metals but also recovery of resources such as valuable metals and water. Due to its high efficiency, selectivity and low environmental footprint, membrane technology has gained attention especially in the treatment of various mine effluent. Though fouling is a major challenge in its implementation. The review gives an updated overview on the membrane technology in mining effluent treatment, examining the performance of various membranes (pressure driven membrane, thermal and concentration) in removal of metals and recycle of valuable resources from mine effluents such Acid Mine Drainage (AMD) and other mine effluents. It also examines innovative approaches such as pre-treatment processes, hybrid membrane system as well as the use nanocomposites polymeric membrane. Furthermore, the recent advances in membrane modification techniques such as chemical vapour deposition, sol-gel process, lithography, Atomic layer deposition, layer by layer and electrospinning have been discussed. Studies show that >95 % separation efficiency,> 85 % water recovery and >90 % metal recovery for hybrid membrane processes and chemical precipitation. The recovered metals show high purity of >99 %. Studies indicate that standalone membrane system have limitations in recovery of metals but hybrid systems (membrane coupled with other complementary methods) can achieve better results. This review identifies future direction for advancing membrane technology in sustainable mine wastewater management for improved environmental as well as mine operations.