Abstract: A urea treatment method in which hypobromite ions are generated by adding a chlorine-based oxidizer and a bromide salt to to-be-treated water containing urea so as to break down the urea in the to-be-treated water and obtain treated water, the method including: a) determining the free residual bromine concentration and the free residual chlorine concentration in the treated water; and b) controlling the added amount of the chlorine-based oxidizer and the bromide salt on the basis of the free residual bromine concentration and the free residual chlorine concentration. The device includes a bromide salt adding means, a chlorine-based oxidizer adding means, a urea decomposition tank, a residual chlorine meter, and a control device for controlling the added amount of the chlorine-based oxidizer by the chlorine-based oxidizer adding means on the basis of the method.

Abstract: An apparatus for producing pure water has: biological treatment means for biological treatment of water to be treated that contains an organic material; means for adding hypohalogous acid that is positioned downstream of biological treatment means and that adds hypohalogous acid to the water to be treated after the biological treatment is carried out; and ultraviolet ray radiating apparatus that is positioned downstream of means for adding hypohalogous acid and that radiates ultraviolet rays to the water to be treated to which the hypohalogous acid has been added.

Abstract: A water treatment apparatus that can remove persistent organic materials more efficiently is provided. Water treatment apparatus has hypohalogenous acid addition means that adds hypohalogenous acid to water to be treated that contains organic materials; and ultraviolet ray radiating apparatus that is positioned downstream of hypohalogenous acid addition means and that radiates ultraviolet rays to the water to be treated to which the hypohalogenous acid has been added.