Abstract: A urea treatment apparatus for treating urea in a water to be treated includes a first reaction tank in which urea in the water to be treated is treated; a first addition means connected to the first reaction tank or to a first piping connected to the first reaction tank and supplying the water to be treated to the first reaction tank, for adding a bromide salt and a chlorine-based oxidation agent to the water to be treated; a second reaction tank in which a residual urea in a first treated water treated by the first reaction tank is treated, a second addition means connected to the second reaction tank or to a second piping connected to the second reaction tank and supplying the first treated water to the second reaction tank, for adding a chlorine-based oxidation agent or a mineral acid to the first treated water.

Abstract: A method for purifying a non-aqueous solvent includes: pretreating by passing a non-aqueous solvent for dehydration treatment through a packed bed of an ion exchange resin that is not yet subjected to dehydration treatment, to remove water in the ion exchange resin; and purifying by passing a non-aqueous solvent to be purified through the packed bed of the ion exchange resin from which water is removed during the pretreating, to purify the non-aqueous solvent to be purified, in which the harmonic-mean particle size of the ion exchange resin is 0.20 to 0.50 mm. According to the present application, a method for purifying a non-aqueous solvent can be provided, the method includes pretreating by removing water in a water-containing ion exchange resin by passing therethrough a non-aqueous solvent for dehydration treatment, in which the amount of the non-aqueous solvent for dehydration treatment used during the pretreating is small.

Abstract: A method for purifying an organic solvent has a first treatment of bringing an organic solvent to be treated into contact with an H-type cation exchanger, and a second treatment of bringing a treated liquid from the first treatment into contact with an anion exchanger and an H-type strongly acidic cation exchanger. According to the present application, the provided method and an apparatus for purifying an organic solvent remove metal impurities of both metal species of monovalent and polyvalent metals in the organic solvent.