| 摘要 |
PROBLEM TO BE SOLVED: To rapidly control CT values in a reaction tank to suppress the generation of bromic acid in water to be treated to a reference level or less by operating dissolved ozone decomposing devices, when the sum total of CT values exceeds a preset range, to decompose dissolved ozone in water flowing in one of contact tanks and residence tanks. SOLUTION: Water to be treated is introduced into an ozone contact tank 2 from an introducing port 1 and also gaseous ozone from an ozonizer 3 is introduced into it through a diffuser 4 to perform ozone contact and mixing in three stages. A signal from a dissolved ozone monitor 8 is sent to a computing element 10, and based on its signal, dissolved ozone decomposing devices 9a-9d are controlled. And in CT value control, the computing element 10 is used, for example, when the sum total exceeds the set value, a dissolved ozone decomposing device 9c is operated. When the dissolved ozone is decomposed, oxidizing effect of ozone is reduced. With the function of the computing element 10 expanded, the ozone decomposing device 9 is properly operated while increasing the injected quantity of ozone, both effects of maximum ozone oxidation and bromic acid formation suppression are obtained.
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