Concentration of solution by the reverse osmosis process.

摘要

An apparatus for concentrating a solution by reverse osmosis includes membrane modules comprising reverse osmosis membranes. The apparatus comprises a first concentrating assembly for concentrating the solution, and a second concentrating assembly for concentrating the solution which has been concentrated by the first concentrating assembly. The first concentrating assembly comprises at least one concentrating unit (10, 20) and is positioned upstream with respect to the direction in which the solution flows. The second concentrating assembly comprises at least one concentrating unit (30) and is positioned downstream with respect to said direction. The membrane module (19 29) of the concentrating unit (10, 20) of the first concentrating assembly comprises a tight reverse osmosis membrane with a higher rejection percentage, and the membrane module (39) of the concentrating unit (30) of the second concentrating assembly comprises a loose reverse osmosis membrane with a lower rejection percentage.