| 摘要 |
PROBLEM TO BE SOLVED: To treat concentrated water at low costs in a process for producing pure water by a method in which the alkaline concentrated water discharged from a reverse osmosis apparatus is directly, or after being treated further by a reverse osmosis membrane, neutralized by the acid regeneration drainage of a cation exchange resin column and the exhaust gas of a degasifier. SOLUTION: Raw water, after being passed through an H-type cation exchange resin column 1 to remove scale components such as calcium ions, is supplied to a degasifier 2 to remove carbonate ions and others. The treated water, after being added with an alkali agent to adjust its pH at 9.2 or above, is passed through a reverse osmosis membrane apparatus 3 to be treated. The filtrate is supplied to a deionization column 4 to obtain pure water. Alkaline concentrated water discharged from the apparatus 3 is supplied to a packed column 5 and contacted countercurrentwise with the acid regeneration drainage of the column 1 and the exhaust gas of the degasifier 2 to be neutralized. In this way, the concentrated water is neutralized economically by using acidic substances generated subordinately in a system.
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