Abstract: A desalination plant for treating a sea water or brackish water feed is provided. The desalination plant includes a first treatment section to effectively remove scaling species, the first treatment section including nanofiltration section, the nanofiltration section including at least two stages and at least two passes; and a reverse osmosis section that operates at high recovery to produce a purified permeate stream and a selectively NaCl salt-enriched reject stream as a saline output.

Abstract: The present invention discloses a desalination plant that operates with a sea water or brackish water feed and produces a concentrated and selectively improved salt reject stream and a pure water permeate stream from a first treatment section that is arranged to produce primarily water at high recovery using membrane desalination processes. The reject stream from the first treatment line has a component distribution that is substantially reduced in native di- and polyvalent scaling ions, essentially depleted of sulfate, has substantially higher total dissolved solids than a traditional sea water reverse osmosis reject, yet is suitable for thermal treatment processes. The system may be enhanced by monovalent salt components. The unit may be integrated with a second treatment section, in which the first reject stream is further concentrated, purified, and processed to produce a high purity salt product.