| abstract |
Membrane separation treatment is performed on the feed water of a first RO membrane separator in the presence of a chlorosulfamate oxidant, and the concentrated water of the first RO membrane separator is membrane-separated by a second RO membrane separator. In the treatment, the membrane degradation of the second RO membrane separation device due to the oxidizing agent concentrated in the concentrated water of the first RO membrane separation device is prevented, and the sterilization / growth suppression effect of microorganisms is effectively exhibited. Prevent membrane contamination. A reducing agent is added to the feed water of a second RO membrane separation device so that the oxidation-reduction potential of water introduced into the second reverse osmosis membrane separation device becomes 200 to 600 mV. The reducing agent is added in an appropriate addition amount to the feed water of the second RO membrane separation device 10 so that the necessary amount of the oxidant concentrated in the concentrated water of the first RO membrane separation device 5 remains. By reducing the part, film deterioration due to the oxidizing agent can be prevented and film contamination can be prevented. [Selection] Figure 1 |