| 摘要 |
PROBLEM TO BE SOLVED: To suppress fouling of a separation membrane to be supplied to a membrane separation technique. SOLUTION: A pump P1 injects a chlorine-based chemical solution stored in a washing chemical solution tank 14 into filtrate discharged from a membrane treating unit 12 for obtaining washing water supplied for washing the separation membrane of the treating unit 12 being a membrane separation means filtering raw water introduced from natural water systems, e.g., rivers. The pump P1 injects the chemical solution to the filtrate at an injection rate of hypochlorite based on the turbidity of the raw water in the membrane washing process of the membrane treating unit 12. In the injection process of the chemical solution, the turbidity of the raw water is recommended to be used as a control factor for feed-forward controlling the injection rate of the chemical solution, and also residual chlorine concentration in washing drain of the treating unit 12 is recommended to be used as a control factor for feed-back controlling the injection rate of the chemical solution. Electrical conductivity of raw water can be used as the control factor for feed-forward controlling in place of the turbidity of the raw water. COPYRIGHT: (C)2008,JPO&INPIT
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