Optimal performance of electrodialysis process for the recovery of acid wastes in wastewater: Practicing circular economy in aluminum finishing industry

Abstract

This work aimed to apply electrodialysis (ED) for the recovery of diluted sulfuric acid (H2SO4) waste liquor generated at rinsing baths in the aluminum anodizing industry. A bench-scale ED process was used to recover acid and water from diluted waste acid liquors in the aluminum anodizing process. The optimal conditions and parameters defined in bench-scale studies were utilized to treat a real industrial acid solution. A bench-scale ED system was run continuously with a connected rinse water line of aluminum plating to concentrate diluted sulfuric acid for recovery. Industrial-scale studies confirmed that the produced concentrated acid and water solutions were of sufficient quality to be reused during the aluminum anodizing process. Besides, diluate characteristics allowed it to be reused as rinse water and reduced the effluent volume sent to the wastewater treatment plant by 90%. Electrodialysis treatment provided a near-zero pollutant discharge. Closed cycle water and acid usage loop were achieved for the aluminum galvanic process, which lessens the environmental and economic impacts of the process. Overall, electrodialysis presented a promising option for the aluminum industry.