| 摘要 |
PROBLEM TO BE SOLVED: To provide a reverse osmosis membrane separation device capable of suppressing scale and fouling in an RO membrane without the usage of chemicals.SOLUTION: A reverse osmosis membrane separation device includes a reverse osmosis membrane module 5; a flow rate detecting means 6 of permeate water W2; a pressure pump 2; an inverter 3; drain valves 11-13; a flow rate control part 10 for outputting a drive frequency to the inverter 3 so that the flow rate of the permeate water W2 is at a target flow rate value; a target flow rate value control part 10 for setting a first target flow rate value when the state that an EC (electric conductivity) of concentrated water W3 is equal to or lower than a set value or more than the set value does not continue for the prescribed time, and setting a second target flow rate value smaller than the first target flow rate value when the state that the EC of the concentrated water 3 exceeds the set value continues for the prescribed time or more; and a discharge flow rate value control part 10 for controlling the drain valves 11-13 so that the concentrated water W3 is at a first discharge flow rate value when the first target flow rate value is set, and controlling the drain valves 11-13 so that the concentrated water W3 is at a second discharge flow rate value equal to the first discharge flow rate value when the second target flow rate value is set. |
