Experimental study on concentrating the simulated salt water with electrodialysis

The demand of comprehensive utilization of sea water and the requirement of environment protection promote the development of technologies to concentrate salt water. The electrodialysis has been applied extensively to salt water concentration. The electrodialysis process is strongly affected by the membrane characteristics and the operating conditions. To investigate the performance of electrodialysis in concentrating salt water, the intermittent circulating electrodialysis experiments were carried out with a NaCl solution of 70 g·L-1, oriented to the target that concentration higher than 150 gNaCl·L-1· while energy cost less than 120 kWh·(tNaCl)-1. The influence of solution flow rate, flow-rate ratio, temperature, and voltage on energy cost and concentrating ratio were examined. Experimental results show that the influence of concentrated solution flow rate and temperature on energy cost and concentrate ratio is ignorable, while the influence of the voltage and the flow-rate ratio is significant. The optimal membrane performance was obtained under a condition of 250 L·h-1, 2:3, 19 V and 30℃.