Kurita Water Industries Ltd.

Naohiro Nagai

Kouichi Tanaka

Akira Morita

Yutaka Yoneda

Masato Nakano

Yuki Sano

Takao Tsuneki

Takahiko Uchida

Kazuhiko Tsunoda

Takanori Yoshino

Hideo Otaka

Akira Iimura

Ikuko Chiba

The invention provides a bactericidal/algicidal method including adding an oxidant-based bactericidal/algicidal agent and a stabilizer therefor to a target water system, characterized in that the amount of combined chlorine or the stabilizer in the water system is controlled by generating free residual chlorine in the water system, and a bactericidal/algicidal method including adding an oxidant-based bactericidal/algicidal agent and a stabilizer therefor to a target water system, characterized in that the amount of the oxidant-based bactericidal/algicidal agent added is controlled so that the concentration of total residual chlorine in the water system falls within a predetermined range, and the amount of combined chlorine or the stabilizer is controlled so that the concentration of free residual chlorine in the water system falls within a predetermined range. An object of the present invention is to provide a bactericidal/algicidal method including adding an oxidant-based bactericidal/algicidal agent and a stabilizer therefor to a target water system for bactericidal/algicidal treatment, wherein the amount of combined chlorine or the stabilizer is controlled, and the amount of the oxidant-based bactericidal/algicidal agent added is controlled, which method realizes effective utilization of the stabilizer, to thereby reduce the amount of the stabilizer employed and to reduce COD and the amount of nitrogen derived from the stabilizer, and which method does not require a special control apparatus for in-line mixing as described above.

Bactericidal/algicidal method

A method for treating a cooling water system comprises adding, in a cooling water system having calcium hardness of 250 mg/L or less as CaCO, a treatment agent containing a (meth)acrylic acid-based copolymer. The (meth)acrylic acid-based copolymer comprises a structural unit (a) derived from a (meth)acrylic acid-based monomer (A) represented by the following general formula (1) and a structural unit (b) derived from a specific (meth)allyl ether-based monomer (B) represented by the following general formula (2), a content of the structural unit (b) is 1 to 15 mol % relative to 100 mol % of structural units derived from all the monomers, a weight average molecular weight of the (meth)acrylic acid-based copolymer is 7,000 to 28,000, and at least one of the main chain terminals of the (meth)acrylic acid-based copolymer is a sulfonic acid group or a salt thereof.

Method for processing cooling water system

A composition for preventing formation of slime which comprises a chlorine-based oxidizing agent, a sulfamic acid compound, one of an anionic polymer or a phosphonic acid compound and a process for preventing formation of slime which comprises adding the composition to a water system are disclosed. Troubles caused by slime in cooling water systems, heat-storage water systems, water systems in manufacturing processes of paper and pulp, water systems for collecting dusts and scrubber water systems can be effectively prevented with the composition in a small amount.

Composition for preventing of slime and method for preventing slime

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Tokyo, Japan

Naohiro Nagai