| 摘要 |
PROBLEM TO BE SOLVED: To provide an electro-deionizing apparatus capable of drastically enhancing a removing ratio of a weak electrolyte such as silica or boron and suitable for the primary pure system or recovery system of an ultrapure water making apparatus and a pure water making apparatus capable of obtaining treated water of high quality with a specific resistance value of 18.0 MΩ.cm or more by using this electro-deionizing apparatus. SOLUTION: In an electro-deionizing apparatus wherein a plurality of cation exchange membranes and a plurality of anion exchange membranes are arranged between a cathode and an anode to alternately form concentrating chambers and desalting chambers, and the desalting chambers are packed with an ion exchanger, an electro-deionizing apparatus 3A capable of obtaining treated water the pH of which is higher by >=1.0 than that of water to be treated when water to be treated with pH 8.5 or less is treated without adding an alkali chemical agent is provided. A pure water making apparatus is constituted by connecting a plurality of electro-deionizing apparatuses 3A, 3B so as to pass water to be treated through these apparatuses and, as the front stage electro-deionizing apparatus 3A, this electro-deionizing apparatus is used. |
