Abstract: A method for treating ship ballast water in which aquatic organisms in the ship ballast water are exterminated by adding hydrogen peroxide or a compound producing hydrogen peroxide in an amount such that a hydrogen peroxide concentration comes to be 10 to 500 mg/L to the ship ballast water, and then providing physical means for causing shear strength and/or cavitation to the ship ballast water.

Abstract: A method for treating ship ballast water in which aquatic organisms in the ship ballast water are exterminated by adding hydrogen peroxide or a compound producing hydrogen peroxide in an amount such that a hydrogen peroxide concentration comes to be 10 to 500 mg/L to the ship ballast water, and then providing physical means for causing shear strength and/or cavitation to the ship ballast water.

Abstract: A method for treating ship ballast water in which organisms viable in the ship ballast water are exterminated by adding to the ship ballast water hydrogen peroxide or a compound producing hydrogen peroxide in an amount such that a hydrogen peroxide concentration comes to be 10 to 500 mg/L and at least one type selected from a ferrous ion or a compound supplying ferrous ion in an amount such that a ferrous ion concentration comes to be 0.1 to 400 mg/L, catalase in an amount such that a concentration of catalase comes to be 0.5 to 2,500 unit/L and iodine or a compound supplying iodine amount such that an iodine concentration comes to be 0.1 to 100 mg/L.

Abstract: A method for treating ship ballast water in which organisms viable in the ship ballast water are exterminated by adding to the ship ballast water hydrogen peroxide or a compound producing hydrogen peroxide in an amount such that a hydrogen peroxide concentration comes to be 10 to 500 mg/L and at least one type selected from a ferrous ion or a compound supplying ferrous ion in an amount such that a ferrous ion concentration comes to be 0.1 to 400 mg/L, catalase in an amount such that a concentration of catalase comes to be 0.5 to 2,500 unit/L and iodine or a compound supplying iodine amount such that an iodine concentration comes to be 0.1 to 100 mg/L.

Abstract: A method for preventing obstruction in aluminum brass pipes in a water flow path, including the steps of continuously supplying iron ions or an iron ion supply compound to water in the water flow path in such a manner that a concentration of iron ions in the water is 0.005 to 0.05 mg/liter, and supplying hydrogen peroxide or a hydrogen peroxide supply compound for a period of time sufficient for preventing adhesion of organisms to the aluminum brass pipes but not impeditive to formation of corrosion-resistant coating inside the pipes, in such a manner that a concentration of hydrogen peroxide in the water is 0.1 to 1.5 mg/liter, whereby corrosion of aluminum brass pipes and adhesion of organisms to the pipes are prevented.

Abstract: A preventive agent against adhesion of a marine organism comprising: at least one amine compound represented by the following formula (I): ##STR1## , wherein R is a C.sub.8-22 saturated or unsaturated aliphatic hydrocarbon group, R.sup.1 is hydrogen atom, aminopropyl, a C.sub.1-22 saturated aliphatic hydrocarbon or C.sub.2-22 unsaturated aliphatic hydrocarbon group, R.sup.2 is aminopropyl, a C.sub.1-8 saturated aliphatic hydrocarbon or C.sub.2-8 unsaturated aliphatic hydrocarbon group, provided that R.sup.1 is hydrogen atom or aminopropyl group when R.sup.2 is represents aminopropyl group, or a salt thereof; and at least one N-alkyl polyamine compound represented by the following formula (II):R--?NH(CH.sub.2).sub.3 !.sub.n --NH.sub.2 (II), wherein R is a C.sub.8-22 saturated or unsaturated aliphatic hydrocarbon group and n is an integer from 2 to 4, or a salt thereof in an amount of 0.1 to 9 parts by weight to one part by weight of the compound (I).