METHOD FOR OBTAINING PURE WATER FROM HIGH-CONDUCTIVITY WATER BY REVERSE OSMOSIS METHOD

摘要

PURPOSE:To produce pure water from high-conductivity water by returning a part or the whole of the permeated water of the 2nd and succeeding reverse osmosis module to the previous stage to maintain the conductivity of the pure water within the limit when the conductivity of the produced pure water exceeds a presribed level. CONSTITUTION:The high conductivity water 1 in a raw water tank 11 is pressurized by a high-pressure pump A and is supplied to the 1st stage of a reverse osmosis module 12, by which the water is treated. The modules are arranged into a Christmas tree type in which the concd. water 2 is supplied to the 2nd stage of a reverse osmosis module 13. The concd. water 4 in the 2nd stage is disccarded or subjected to a solidifying treatment. The permeated water 3 from the 1st stage of the module and the permeated water 5 from the 2nd stage of the module are joined to form pure water 6 which is recovered and reused. The conductivity of the pure water is constantly monitored by a conductivity meter 14 and when the conductivity exceeds the predetermined level, a valve 15 is partly or fully shut to return a part or the whole of the permeated water of the 2nd stage into the tank 11.