REGENERATIVE DEMINERALIZER APPARATUS

A regenerative demineralizer apparatus (201) comprises a cathode (8) and an anode (9); one or more water-splitting ion exchange membrane (1), having a cation exchange surface (1 a) in one surface and an anion exchange surface (1 b) in the other surface, and being laminated between the cathode and the anode so that the anion exchange surface faces the anode and the cation exchange surface faces the cathode; and a casing (7) for housing the cathode, the anode and one or more water-splitting ion exchange membrane, wherein the casing includes a first inlet (10) and a first outlet (11) serving as an inlet and an outlet of water for treatment, respectively, and a second inlet (12) and a second outlet (13) serving as an inlet and an outlet of water for regeneration, respectively, and wherein differential pressure of the water for treatment between the first inlet and the first outlet is larger than differential pressure of the water for regeneration between the second inlet and the second outlet at a flow rate identical with the flow rate of the water for treatment.