A study on the desalination process for high-concentration Na2SO4 using pilot-scale bipolar membrane electrodialysis

The production of battery cathode materials via wet processes in the lithium battery industry generates a substantial amount of Na₂SO₄ wastewater, necessitating treatments to meet regulatory discharge standards. Bipolar membrane electrodialysis (BPED) offers an effective method to convert Na₂SO₄ wastewater into valuable acid and base products. While a number of laboratory-scale studies have explored efficiency of BPED systems, there is a scarcity of research on pilot-scale BPED applications for Na₂SO₄ wastewater treatment. To assess industrial feasibility, a pilot-scale BPED system was systematically evaluated. In this study, the process exhibited energy consumption of 1.3 kWh/kg‐Na₂SO₄ and 0.9 kWh/kg‐Na₂SO₄ at 750 A/m2 and 550 A/m2, respectively. The H₂SO₄ and NaOH produced achieved purities of 96.1% and 99.6%, respectively. An economic analysis based on the treatment of 10,000 tons/year of a 20 wt% Na₂SO₄ solution estimated the capital expenditure (CAPEX) and operating expenditure (OPEX) at $22.2/ton-Na₂SO₄ and $229.2/ton-Na₂SO₄, respectively. These findings underscore cost-effectiveness and potential environmental advantages of upscaling the BPED process for industrial Na2SO4 wastewater treatment applications.