REVERSE OSMOSIS MEMBRANE SEPARATION DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a reverse osmosis membrane separation device which can keep flow rate of permeate water to a target flow rate value even when a water permeability coefficient of an RO membrane module rapidly changes.SOLUTION: A reverse osmosis membrane separation device includes: a reverse osmosis membrane module 5; flow rate detecting means 6 for detecting flow rate of permeate water W2 to output a detected flow rate value corresponding to the flow rate; a supply water line L1 for supplying supply water W1 to the reverse osmosis membrane module 5; a pressure pump 2 driven at rotation speed corresponding to an input drive frequency and to pressure feed the supply water W1 which passes through the supply water line L1 to the reverse osmosis membrane module 5; an inverter 3 for outputting a drive frequency corresponding to an input frequency designation signal to the pressure pump 2; and a control unit 10 for calculating a drive frequency of the pressure pump 2 by velocity type digital PID algorithm, such that a detected flow rate value output from the flow rate detecting means 6 becomes a predetermined target flow rate value to output a frequency designation signal corresponding to a calculation value of the drive frequency to the inverter 3.