WATER TREATMENT METHOD AND APPARATUS USING OZONE

摘要

PROBLEM TO BE SOLVED: To suppress the formation of bromic acid by monitoring the concn. of dissolved ozone remaining in a contact tank wherein gas to be treated comes into contact with ozone gas to control the injection amt. of ozone so that the concn. of ozone becomes a range capable of reducing trihalomethane forming capacity and not forming bromic acid. SOLUTION: Three dissolved ozone concn. measuring devices 8 are arranged in the respective contact tanks 2 of a horizontal flow type countercurrent three- stage ozone contact basin for a large-scale water purification plant and the signals of the measuring devices 8 are operationally processed by a control device 9 to control the ozone generation amt. of an ozone generator 3. Herein, the injection amt. of ozone is controlled so that the concn. of ozone becomes a range capable of reducing trihalomethane forming capacity (THMFP) and not forming bromic acid. By this constitution, the formation of bromic acid being a harmful ozone disinfecting byproduct is suppressed and THMFP is sufficiently reduced to enable the injection control of ozone and the safety of treated water can be kept and ensured.