Reverse osmosis membrane for water purificn. - is flushed free of deposits by applying pressurised raw water with very short intervals

摘要

In reverse osmosis treatment for water purificn. wherein deposits precipitates, clogging material, etc. are periodically removed from the semi-permeable membrane by flushing with raw soln.; the intervals between flushing periods are so short and/or the flushing stream strength is so great that outside the flushing periods there is n6 appreciable amt. of concentrate to be removed, as compared wtih permeate in the form of purified water, the flushing periods may for example last 2-15 seconds within a cycle of up to 15 minutes. In a specific example 0.1 litres of raw soln. are applied within 3 seconds every 2 1/2 minutes. An electronically controlled solenoid valve may apply flushing soln. at intervals controlled by a multi-vibrator. USE/ADVANTAGE - Esp. for domestic water supply. With no separate cleaning operation involved, membrane life is considerably lengthened.