Recovery and purification of monovalent salt contaminated with divalent salt

Abstract

A method and system for improving the quality and quantity of a soluble salt recovered from the supernatant produced when concentrated solutions are mixed to precipitate an insoluble salt are disclosed. Liquid residual, or supernatant, contains salt that is reusable in the regeneration solution of ion removal devices such as ion exchange or electrodialysis metathesis (EDM). The disclosed embodiments include a method for concentration and purification of salt. NaCl is recovered in a truly Zero Discharge Desalination (i.e., ZDD) process. The ZDD process utilizes reverse osmosis (RO) or nanofiltration (NF) for the primary desalination of groundwater that has high concentration of CaSO4 and utilizes EDM to separately remove calcium and sulfate ions from the RO or NF concentrate so that water recovery can be improved. The recovered NaCl is reused in the EDM.

Dependencies are inferred from the claim text.