Abstract: A ships' ballast water treatment agent is obtained by blending phosphate and sodium hydroxide into a hypochlorite solution and has pH of 10 to 13. A blending amount of phosphate is preferably such that a weight ratio of effective chlorine to phosphate acid (PO4) (effective chlorine:phosphate acid) is 30:1 to 2:1. A ships' ballast water treatment agent as such has excellent performance in killing bacteria and microorganisms, such as plankton, included in ships' ballast water and has stability and an anticorrosion property.

Abstract: A ships' ballast water treatment agent is obtained by blending phosphate and sodium hydroxide into a hypochlorite solution and has pH of 10 to 13. A blending amount of phosphate is preferably such that a weight ratio of effective chlorine to phosphate acid (PO4) (effective chlorine:phosphate acid) is 30:1 to 2:1. A ships' ballast water treatment agent as such has excellent performance in killing bacteria and microorganisms, such as plankton, included in ships' ballast water and has stability and an anticorrosion property.

Abstract: A method for treatment with a reverse osmosis membrane to reduce decrease in flux that occurs even under the conditions that water supplied to a reverse osmosis membrane treatment apparatus contains only a trace amount of iron and that the formation of scales of substances such as calcium and silica is prohibited. A method for performing a treatment with a reverse osmosis membrane to treat raw water containing iron at 1000 ?g/L or less as total iron with a reverse osmosis membrane, including a step of adding a compound having a sulfo group to the raw water.

Abstract: A process for preventing formation of scale which comprises adding, into a water system in which ozone is used for disinfection, a polymeric scale inhibitor having a high molecular weight which gives an average molecular weight within an optimum range for preventing formation of scale after the polymeric scale inhibitor is decomposed with ozone. In accordance with the process, the polymeric scale inhibitor having an average molecular weight within the optimum range for preventing formation of scale is present in the water system in which ozone is used for disinfection and formation of scale is effectively prevented.

Abstract: A process for preventing formation of scale which comprises adding, into a water system in which ozone is used for disinfection, a polymeric scale inhibitor having a high molecular weight which gives an average molecular weight within an optimum range for preventing formation of scale after the polymeric scale inhibitor is decomposed with ozone.

Abstract: A water-treating agent comprising a ternary copolymer of conjugated dienesulfonic acid/(meth)acrylic acid/2-hydroxyethyl (meth)acrylate, or a ternary copolymer of conjugated dienesulfonic acid/(meth)acrylic acid/(meth)acrylamido-2-methylalkanesulfonic acid ternary copolymer, is effective against scaling and fouling in water systems and a method for treating water with the water-treating agent. When combined with a corrosion inhibitor, the water-treating agent exhibits an excellent anti corrosion effect.

Abstract: A water-treating agent comprising a ternary copolymer of conjugated dienesulfonic acid/(meth)acrylic acid/2-hydroxyethyl (meth)acrylate, or a ternary copolymer of conjugated dienesulfonic acid/(meth)acrylic acid/(meth)acrylamido-2-methylalkanesulfonic acid ternary copolymer, is effective against scaling and fouling in water systems and a method for treating water with the water-treating agent. When combined with a corrosion inhibitor, the water-treating agent exhibits an excellent anti corrosion effect.