A feasibility study of industrial wastewater recovery using electrodialysis reversal

A wastewater reclamation and reuse "mini-plant" was established at the site of China Steel Corporation (CSC) wastewater treatment plant. The purpose of the mini-plant is to demonstrate the technical and economical feasibility of electrodialysis reversal (EDR) process. The mini-plant includes a sand filtration unit and an EDR unit which has a daily treatment capacity of 350 CMD. Raw wastewater had an averaged conductivity of 3860 mu S/cm, pH between 7.7 and 8.3, and COD between 30 and 70 mg/L. When the EDR unit operates at a 75% of water reclamation rate, 92% of desalination rate, 98% of chlorine ion removal, 80% of sulfate removal, 99% of calcium ion removal, and 51% of COD removal rate can be achieved. The water quality of product stream is 305 mu S/cm for conductivity, 13 mg/L for chlorine ion, 86 mg/L for sulfate, 1.4 mg/L for calcium ion, and of 20 mg/L for COD concentration. Operation cost of the EDR mini-plant was also estimated in this project. The electricity required for electrodes power supply and pumping is 0.85 kW h per cubic meter of treated water. Total operation cost including electricity fee and chemical cost is about $0.146 per cubic meter of treated water.