REVERSE OSMOSIS APPARATUS PROVIDED WITH AUTOMATIC REVERSE OSMOSIS MEMBRANE WASHING MECHANISM

PROBLEM TO BE SOLVED: To improve water quality of pure water, keep the water permeation capability of a reverse osmosis membrane, make washing with a chemical unnecessary or lessen the frequency of the washing, and suppress propagation of bacteria on membrane surface by preventing accumulation and precipitation of impurities of raw water on the reverse osmosis membrane surface in pure water production by reverse osmosis. SOLUTION: A recirculation loop 3 is formed by connecting a raw water load line 1 and a primary (concentrated water) line 2 and a line for returning pure water of a pure water (reverse osmosis-permeated water) tank and a water discharge line 4 are formed in the loop. A plurality of solenoid-controlled valves for flow adjustment are installed in each line and controlled interlockingly with the liquid surface level of the pure water tank to control the flow direction and the flow rate and thus concentrated water in the reverse osmosis membrane module by exchange with pure water returned and supplied to the recirculation loop 3 is discharged, the reverse osmosis membranes are washed by recirculation of pure water in the recirculation loop 3 at high flow rate, and water recirculated by returning and supplying pure water to the recirculation loop 3 is discharged.