| 摘要 |
PROBLEM TO BE SOLVED: To provide a pure water producing apparatus capable of saving power in the operation of a pressure pump.SOLUTION: In a pure water producing apparatus 1, when a ratio of the flow rate of concentrated water W3 and W5 to the flow rate of permeated water W2 and W4 separated by reverse osmosis membrane modules 11 and 12 is defined as a circulation ratio in the reverse osmosis membrane modules 11 and 12, at least one of the flow rate of supply water W1, the flow rate of permeated water W2 and W4 and the flow rate of concentrated water W3 and W5 is set so that a ratio R2/R1 of a circulation ratio R2 in the reverse osmosis membrane module 12 at the final stage of a plurality of reverse osmosis membrane modules to a circulation ratio R1 in the reverse osmosis membrane module 11 at the forefront stage of a plurality of reverse osmosis membrane modules is in the range of 0.08≤R2/R1≤0.12. |
