浓盐水极限浓缩时的电渗析过程水迁移现象研究

Water Transport Phenomena During Concentration of High-SalinityWastewater by Electrodialysis

基于实验室小试电渗析系统研究了高浓盐水极限浓缩情景下的水迁移现象,对比了4种商用离子交换膜在不同料液含盐量、电流密度、温度下的水迁移数。结果表明,其中“C膜”具有相对最低的水迁移数,平均为4.78,水迁移数随料液含盐量的下降而显著上升,但与电流密度无明显相关关系。降低温度可进一步降低水迁移数,但会使膜对电压上升。利用C膜对实际高浓盐水开展极限浓缩测试,电渗析系统可将原水中盐的质量分数由20%进一步浓缩至24.7%,在该过程中电迁移是水迁移的主要形式。

Water transport phenomena during the high-salinity electrodialysis(ED)process was investigated based on a lab-scale ED system.The water transport number of four commercial ion-exchange membranes was evaluated under different salinity,current density,and temperature.The ion exchange membrane C possesses the lowest water transport number,averaging 4.78.The water transport number increases significantly with the decrease of the salinity,but there was no significant correlation with the current density.The lowering temperature will furthermore reduce water transport number while increased the voltage of membrane pair.The concentration of high-salinity wastewater was tested in the ED system installed with C membranes,resulting in a final concentration of 24.7%from 20%.The water electro-osmotic transport is the dominant water transport way during the ED concentration process.