Use of chelating agents in water desalination

Abstract From the Canadian patent

Abstract, Processes for the desalination of saline water especially seawater, which contains hardness ions (e.g. Ca2+ and Mg2+) and transition metal corrosion ions e.g. Fe3+), and in which an organic polymer antiscalant (e.g. a low molecular weight maleic acidacrylamide-styrene terpolymer) is being used to control alkaline earth hardness, have been improved by adding a chelating agent to the saline water before or at the same time as, adding the antiscalant. Typical chelating agents which can be used are citric acid, gluconic acid and hydroxyethylidenediphosphonic acid.