Method, apparatus and system for desalinating saltwater

A method of reducing salinity of a product in a stack comprising:

• (a) flowing a product feed through a first product chamber in the stack, the first product chamber having a first anion exchange membrane on one side of and in ionic communication with the first product chamber and a first cation exchange membrane on another side of and in ionic communication with the first product chamber;
• (b) flowing a concentrate feed through a first concentrate chamber in the stack in ionic communication with the first anion exchange membrane;
• (c) flowing the concentrate feed through a second concentrate chamber in the stack in ionic communication with the first cation exchange membrane;
• (d) flowing an electrolyte through a first and second electrolyte chamber in the stack, the first electrolyte chamber bounded on one side by and in ionic communication with a first stack end cation exchange membrane and on another side by and in electrical communication with a first electrode, the second electrolyte chamber bounded on one side by and in ionic communication with a second stack end cation exchange membrane and on another side by and in electrical communication with a second electrode;
• (e) flowing a rinse solution through a first and second rinse chamber in the stack, the first rinse chamber bounded on one side by and in ionic communication with a first stack end anion exchange membrane and on another side by and in ionic communication with the first stack end cation exchange membrane, the second rinse chamber bounded on one side by and in ionic communication with a second stack end anion exchange membrane and on another side by and in ionic communication with the second stack end cation exchange membrane;
• and
• (f) applying a voltage across the stack to force anions and cations respectively across the first anion and exchange membrane and the first cation exchange membrane from the product feed to the concentrate feed, thereby producing a product output with a reduced salinity relative to the product feed and a concentrate output with an increased salinity relative to the concentrate feed,
• wherein the rinse solution consists of a conductive non-scaling aqueous salt to minimize transfer of scaling cations from the rinse solution to the electrolyte.