| 摘要 |
PROBLEM TO BE SOLVED: To provide a desalting device for operating an electric deionizing device stably for a long period with suppressed maintenance cost, and stably manufacturing high purity of treated water, as the desalting device using the electric deionizing device. SOLUTION: In the desalting device where a membrane type turbidity- removing device, a reverse osmosis membrane treating device, a sodium type strong acidic cation exchange resin device and an electric deionizing device are arranged along a flow path in order, an alkali chemical addition means with which pH of water fed to the electric deionizing device is adjusted to >=7.5 and <=11.0, or an alkali chemical addition means to adjust pH of a circulation system of concentrated water in the electric deionizing device to >=9.0, is installed in a circulation flow path of concentrated water in the electric deionizing device. By addition of the alkali chemical, the number of bacteria in concentrated water of the electric deionizing device can be brought close to 0 pieces/ml, thus the problem of operational unbalance due to decrease in the flow rate of a concentrated room due to bacteria and the problem of lowering in the quality of treated water caused by this unbalance are dissolved, and water quality stabilized for a long period is obtained. |
