4961851 Self-cleaning reverse osmosis liquid treatment system, method and dual configuration check valve therefor

Abstract

A self-cleaning reverse osmosis liquid treatment system, method of cleaning a reverse osmosis membrane, and a dual configuration flow check valve for inlet and outlet heads of such a system. The system includes at least two membrane vessels each having at least one reverse osmosis membrane contained therein. One vessel processes intake liquid such as sea water, ground water or other fluids or juices into product liquid in the normal way, having a waste liquid discharge, while the other vessel simultaneously undergoes cleansing. Product liquid discharging from the vessel processing the product liquid is redirected at lower pressure back through an additional inlet in the inlet head having one check valve in its normally closed configuration positioned in the inlet head of the vessel being cleansed. Another check valve in a normally opened configuration in the outlet head of the vessel being cleansed cooperatively acts with the normally closed check valve in the inlet head to allow all liquid as product liquid to exit the cleansing vessel to a storage tank for later use. The flow of product liquid through the membrane being cleaned is at low pressure so that very little further reverse osmosis activity occurs in the membrane being cleansed and descaled. The check valves act in unison to close upon the introduction of intake liquid into the vessel at higher pressure to activate the cleansed membrane then ready for reuse.