Effects of cation exchange membrane properties on the separation of salt from high-salt organic wastewater by electrodialysis

Abstract

High-salt organic wastewaters have attracted an increasing attention in recent decades. The separation of salt from high-salt organic wastewater is helpful to improve the efficiency of biological treatment. One possible separation method is through electrodialysis (ED), given the high selectivity and anti-fouling properties of ion exchange membrane. In this paper several cation exchange membranes (CEMs) with different properties were fabricated and applied in ED stack to desalt landfill leachate. The effects of CEMs properties on the ED separation performances were studied by the correlation analysis and linear regression. The results demonstrated that ion exchange capacity and surface hydrophilicity of CEMs were strongly correlated with the salt flux of ED, the correlation coefficient were 0.71 and −0.69, respectively. While the zeta-potential and crosslinking degree of CEMs significantly affected the rejection of organic matters by ED with the correlation coefficient of 0.72 and −0.71, respectively. Reducing the zeta-potential of CEMs and increasing the cross-linking degree of CEMs could improve the salt-organic separation ability of ED, and the separation factor reached 40.16, which was more than 2 times higher than that of commercial ED. The results provided reference for the preparation or modification of CEMs for salt-organic separation, and demonstrate the possibility of desalting high-salt organic wastewater by ED technology.