METHOD FOR CONTROLLING SUPPLY OF OZONE GAS

摘要

PROBLEM TO BE SOLVED: To provide a method for controlling the supply of ozone gas, in water treatment utilizing ozone oxidation and membrane filtration capable of realizing stable water treatment by a necessary minimum injection amount of ozone without lowering filtering capacity. SOLUTION: In a water treatment method wherein water to be treated is subjected to ozone treatment and membrane filtering treatment successively and a filter membrane is backwashed at every predetermined membrane filtering treatment time (one cycle) and washed with air at every predetermined number of cycles, the concentration of residual ozone in water to be subjected to membrane filtering treatment before the completion of membrane filtering treatment of one cycle is measured and, on the basis of a difference between this measured value and a predetermined residual ozone concentration target value and the number of membrane filtering cycles after air washing, the increase/decrease magnification (%) of the concentration of supplied ozone gas in the next cycle of one cycle is preset and the concentration of the supplied ozone gas of the next cycle is controlled to a value calculated by multiplying the concentration of the supplied ozone gas before the completion of membrane filtering treatment of one cycle by the increase/decrease magnification (%).