| 摘要 |
PROBLEM TO BE SOLVED: To provide a fresh water generating method using reverse osmotic separation by which the generating cost of fresh water from sea water is reduced and besides, a stable operation is enabled for a long period. SOLUTION: In this fresh water generating method from sea water, at least two reverse osmosis membrane module units 2, 4 containing reverse osmosis membrane elements provided in connection in series are used, and sea water is fed to the reverse osmosis membrane module unit 2 and also concentrated sea water obtained from the reverse osmosis membrane module unit 2 at the preceding stage is fed to the reverse osmosis membrane module unit 4 at the succeeding stage, and then permeated water is obtained from respective stages. In this case, sea water is treated in such a way that in every reverse osmosis membrane element, a membrane surface flow rate of the feeding sea water is controlled at >=0.03 m/s and also a permeated water quantity per 1 m2 reverse osmosis membrane is in a range of 0.07-1.2 m3/d.
|
