Concentration system for water containing organic solvents, and method for concentrating water containing organic solvents.

Abstract

This invention provides a concentration system that can concentrate organic solvents to a higher concentration using the reverse osmosis membrane method. [Solution] A concentration system for organic solvent-containing water, comprising: a first reverse osmosis membrane apparatus for concentrating a liquid to be treated, which is organic solvent-containing water, to obtain a first concentrated liquid; and a second reverse osmosis membrane apparatus for further concentrating the first concentrated liquid to obtain a second concentrated liquid, wherein the rejection rate of the reverse osmosis membrane of the second reverse osmosis membrane apparatus is lower than the rejection rate of the reverse osmosis membrane of the first reverse osmosis membrane apparatus, and the difference between the osmotic pressure of the supply side liquid and the permeate side liquid in the second reverse osmosis membrane apparatus is lower than the operating pressure of the concentration system.

Claims

1. A first reverse osmosis membrane apparatus that concentrates the liquid to be treated, which is water containing an organic solvent, to obtain a first concentrated liquid, A system for concentrating water containing an organic solvent, comprising: a second reverse osmosis membrane apparatus for further concentrating the first concentrated solution to obtain a second concentrated solution; The rejection rate of the reverse osmosis membrane in the second reverse osmosis membrane apparatus is lower than the rejection rate of the reverse osmosis membrane in the first reverse osmosis membrane apparatus. A concentration system in which the difference between the osmotic pressure of the supply liquid and the osmotic pressure of the permeate liquid in the second reverse osmosis membrane apparatus is lower than the operating pressure of the concentration system.

2. The concentration system according to claim 1, wherein the concentration of the organic solvent in the second concentrated liquid is 11% by mass or more and 40% by mass or less.

3. The concentration system according to claim 1, wherein the concentration of the organic solvent in the liquid to be treated is 10% by mass or less.

4. The concentration system according to claim 1 or 2, wherein the reverse osmosis membrane of the first reverse osmosis membrane apparatus has a rejection rate of the organic solvent of 70% or more and 98% or less.

5. The concentration system according to claim 1 or 2, wherein the organic solvent is an aprotic polar solvent.

6. The concentration system according to claim 5, wherein the organic solvent is one or more selected from the group consisting of N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl sulfoxide, acetone, 2-butanone, tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, acetonitrile, ethyl acetate, dichloromethane, propylene carbonate, and hexamethylphosphate triamide.

7. The concentration system according to claim 1 or 2, further comprising a distillation apparatus.

8. The liquid to be treated, which is water containing an organic solvent, is concentrated using a first reverse osmosis membrane apparatus to obtain a first concentrated liquid. A method for concentrating water containing an organic solvent, comprising concentrating the first concentrated solution using a second reverse osmosis membrane apparatus to obtain a second concentrated solution, The rejection rate of the reverse osmosis membrane in the first reverse osmosis membrane apparatus is higher than the rejection rate of the reverse osmosis membrane in the second reverse osmosis membrane apparatus. A concentration method wherein the difference between the osmotic pressure of the feed solution and the osmotic pressure of the permeate in the second reverse osmosis membrane apparatus is lower than the operating pressure in the concentration method.

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