Abstract: 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.

Abstract: 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 CaCO3, 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.

Abstract: A method for treating a cooling water system includes adding a (meth)acrylic acid-based copolymer to a cooling water system having a part where the calcium hardness of the cooling water is 150 to 300 mg/L and the flow rate of the cooling water is 0.3 to 0.5 m/s, wherein the (meth)acrylic acid-based copolymer has a structural unit (a) derived from a specific (meth)acrylic acid-based monomer (A) and a structural unit (b) derived from a specific (meth)allyl ether-based monomer (B), the content of the structural unit (b) is 15% by mole to 20% by mole relative to 100% by mole of the structural units derived from all the monomers, the weight-average molecular weight of the (meth)acrylic acid-based copolymer is 10,000 to 30,000, and at least one of the main chain terminal groups of the (meth)acrylic acid-based copolymer is a sulfonic acid group or a salt thereof.

Abstract: 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 CaCO3, 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.

Abstract: 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.

Abstract: Cooling water (circulating back water) which is raised its temperature by a refrigerator 12 is sprayed from a spraying device 2 of a cooling tower, and is collected in a pit 4. The cooling water in the pit 4 is circulated via a circulation pump (10), a circulation forward pipe (11) and a circulation return pipe through the refrigerator 12. Make-up water is supplied from a make-up water line 9 at a rate corresponding to an evaporation loss, windage loss W and a blowdown water amount B from a blowdown valve 8 of a blowdown line 7 of the cooling tower 1. A load of the cooling tower is calculated based on a temperature difference between the circulating forward water and the circulating back water, and a feeding rate of a treating agent from a feeding device 14 is controlled based on the load.

Abstract: 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.

Abstract: 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.