PROBLEM TO BE SOLVED: To provide a treatment method of an open circulating cooling water system, by which Legionella bacteria can be surely sterilized, the multiplication thereof can be suppressed, the number of the Legionella bacteria in cooling water can be kept at a non-detection level over a long period of time, and drug resistant bacteria and algae and fungi and the like having drug resistance are hardly proliferated.SOLUTION: On cooling water of an open circulating cooling water system, treatment by a halogen oxide is performed at least one hour in every 24 hours, and treatment by a water-soluble cationic polymer obtained by the reaction of dimethylamine and epichlorohydrin is performed at least once in every 30 days.COPYRIGHT: (C)2014,JPO&INPIT【課題】レジオネラ属菌を確実に殺菌し、その増殖を抑制して、冷却水中のレジオネラ属菌数を長期間不検出レベルに維持することができ、しかも、薬剤耐性菌や薬剤耐性を持った藻類、真菌類等が繁殖しにくい開放循環冷却水系の処理方法を提供する。【解決手段】開放循環冷却水系の冷却水に対して、ハロゲン系酸化物による処理を24時間に1時間以上行い、かつ、ジメチルアミンとエピクロロヒドリンとの反応によって得られる水溶性陽イオン重合体による処理を30日間に1回以上行う。【選択図】なし
