A study on near zero liquid discharge approach for the treatment of reverse osmosis membrane concentrate by electrodialysis.

A lab-scale electrodialysis (ED) which consisted of 11 pieces of cation-exchange membranes and 10 pieces of anion-exchange membranes was used to treat concentrated brine of Reverse osmosis (RO) membrane. The effect of operating parameters such as applied voltage, flowrate, and operating mode was investigated to measure the performance of a lab-scale ED. Three different voltages (5, 10, and 15 V) and flowrates (20, 30, and 40 L/h) were applied in order to optimize the operating conditions of the ED system. The maximum TDS removal efficiencies were 85%, 97%, and 98% for 5, 10, and 15 V, respectively. It was concluded that the desalination efficiencies were almost the same at flowrates values of 20, 30 and 40 L/h. The TDS concentration of the treated brine in the concentrate compartment rises to the highest value of 25,400 mg/L with desalination rate of 92.5% after five cycle operation. Moreover, the desalinated brine can be used as fresh water.