| 摘要 |
PROBLEM TO BE SOLVED: To economically remove an organic pollutant in sewage for a short time by efficiently forming hydroxyl radicals from supplied ozone by changing the irradiation quantity of ultraviolet rays. SOLUTION: In sewage treatment irradiating water to be treated with ultraviolet rays under the contact with ozone, an oxidation-reduction potential value is set to a constant range by controlling an ultraviolet irradiation condition. It is desirable to control the ultraviolet irradiation condition so that the oxidation-reduction potential value becomes 75-95% of that shown in an ultraviolet non-irradiation state under the contact with ozone. Further, it is desirable to control the ultraviolet irradiation condition so that the oxidation-reduction potential value becomes 85-90%. By this method, the amount of hydroxyl radicals obtained by a change in the dissolved ozone in water to be treated can be optimally controlled.
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