Process for preventing the formation of CaSO4 deposits on the semipermeable membrane used in reverse osmosis

摘要

It is known that when reverse osmosis (RO) is employed to remove a large part of the salt content of untreated water, the used membrane is plugged after a certain time by depositing salts. The majority of the deposit is composed of CaSO4 which can no longer be dissolved in the solution concentrated by RO. In the present case, the formation of these salts is prevented by removing the sulphate ions from the as yet unconcentrated untreated water with the aid of a weakly basic specific anion exchanger, the Cl ions of which replace the SO4 ions.