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AssigneeKurita Water Industries Ltd.
InventorsYasuharu MINATO, Yuki NOMURA, Kouya ABE
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A pure-water production apparatus includes a retention tank retaining water to be treated, and water-flow piping, the water-flow piping being provided with, in the following order, a liquid-sending pump, a second reverse osmosis membrane for which the permeation flux per 1 MPa of effective pressure is 0.8 m3/(m2·day) or greater, a first reverse osmosis membrane for which the permeation flux per 1 MPa of effective pressure is 2.0 m3/(m2·day) or greater, and an ion exchange device. An NaOH aqueous solution addition section is connected at a stage preceding the first reverse osmosis membrane, it being possible for the amount of NaOH aqueous solution added to be controlled by a control mechanism in accordance with the flow rate of the water-flow piping and the pH of the water to be treated, such that water to be treated by the first reverse osmosis membrane reaches a prescribed pH.
A multi-stage reverse osmosis membrane treatment system, in which two or more stages of reverse osmosis membranes are arranged in series, wherein at least one of the two or more stages of reverse osmosis membranes is a first reverse osmosis membrane having a pure water or permeated water flux of 2.0 m3/(m2·day) or more at 1 MPa of membrane surface effective pressure and a water temperature of 25° C., and pH of water to be treated by the first reverse osmosis membrane is adjusted to an alkaline side for treatment.
Dependencies are inferred from the claim text.