Electrodialysis is a separation technology utilizing electrophoresis of ionic substances in solutions and the selective permeability of ion exchange membranes to separate ionic substances in aqueous solution, enabling efficient desalination, concentration, refining and recovery. There are two types of ion exchange membranes. Cation exchange membrane selectively allows cation permeation and anion exchange membrane selectively allows anion permeation. In an electrodialyzer, a large number of these membranes are arranged alternately between two electrodes and direct current is applied to separate ions in solution (Figure 3).