Patent ID: 8123958

Claim:
A method for treating ship ballast water in which aquatic organisms in the ship ballast water are exterminated, said method comprising: 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 in the ship ballast water, providing a physical means comprising at least two slit plates having a plurality of slit-like through holes defined by opening portions and closed portions of the slit plates, the at least two slit plates disposed in a traversal cross sectional direction of a water channel of the ship ballast water such that the opening portions of the at least two slit plates are not arranged in a straight line relative to a flowing direction of the ship ballast water in the water channel and the closed portions of the at least two slit plates are not arranged in a straight line relative to the flowing direction of the ship ballast water in the water channel, and wherein the opening portions of the at least two slit plates are located in parallel with the direction of longitudinal axes of the slit-like through holes, and then causing the ship ballast water to pass through said physical means, thereby causing shear strength and cavitation to the ship ballast water.