| 摘要 |
PROBLEM TO BE SOLVED: To stabilize treated water by suppressing the variation in the ozone dissolved in the treated water. SOLUTION: The ozone concn. set value SV for a waste ozone concn. setting functional part is supplied to the plus end of a deviation part 22. The waste ozone concn. PV measured by a waste ozone densitometer is supplied to the minus end of the deviation part 22. The deviation between both ends is outputted from the deviation part 22, calculated by a PI control arithmetic part 23 and inputted to an ozonizer 24, and the ozone generating quantity is controlled in accordance with calculation output. The ozone gas from the ozonizer 24 is supplied to an ozone contact tank 25 and brought into contact with raw water in the tank 25 to treat the raw water, and the waste ozone concn. PV of the ozone gas not dissolved in the raw water and discharged measured by a densitometer 26 for waste ozone and supplied to the deviation part 22. Meanwhile, the ozone gas generated from an ozonizer 24 is measured by a generated ozone densitometer 27, and the generated ozone concn. is supplied to the waste ozone concn. setting functional part 21.
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