Advancing sustainable treatment of sodium sulfate (Na2SO4)-containing wastewater: Recent advances in electrochemical technologies

With the rapid expansion of the electric vehicle market, the demand for lithium-ion batteries (LIBs) has surged, leading to a significant increase in sodium sulfate (Na 2 SO 4 )-containing wastewater generated during LIB manufacturing and recycling processes. Beyond the LIB industry, substantial Na 2 SO 4 discharges also originate from mining, textiles, and chemical manufacturing, raising serious environmental concerns. The widespread release of Na 2 SO 4 into aquatic ecosystems can lead to elevated salinity levels and pose ecological risks. Conventional treatment methods—such as evaporation, reverse osmosis, and biological or chemical processes—often suffer from high costs, intensive energy requirements, and the potential for secondary pollution. Recently, electrochemical technologies, particularly electrodialysis (ED) including bipolar membrane electrodialysis (BMED), have emerged as promising alternatives. These systems not only remove Na 2 SO 4 effectively but also enable the simultaneous recovery of valuable products such as sulfuric acid and sodium hydroxide. This comprehensive review highlights recent advances in electrochemical approaches for treating Na 2 SO 4 –containing wastewater, with a primary focus on ED and BMED systems. It systematically examines the influence of key operational parameters—such as applied voltage, feed concentration, current density, volume ratio, flow rate, and membrane type—on treatment performance, energy efficiency, and economic feasibility. Overall, this review provides a comprehensive overview of process mechanisms and the trade-offs, emphasizing the potential of ED-based technologies as scalable and sustainable solutions for the valorization of Na 2 SO 4 -laden wastewater. • Na 2 SO 4 is widely found in wastewater from batteries, mining, and pharmaceuticals. • High Na 2 SO 4 levels raise salinity and hinder biological and chemical treatments. • Conventional Na 2 SO 4 removal methods are costly and consume large amounts of energy. • Electrochemical technologies show great potential for Na 2 SO 4 treatment. • This review evaluates ED-based technology for Na 2 SO 4 wastewater treatment.