Electrochemical desalination system

A method for separating a solvent from a salt dissolved in the solvent, comprising:

• providing an electrodialysis apparatus comprising:
• a first reservoir comprising a first input and a first output, wherein the salt dissolved in the solvent in the first reservoir is reduced below a threshold concentration during an operation mode;
• a second reservoir comprising a second input and a second output, wherein the salt dissolved in the solvent in the second reservoir increases in concentration during the operation mode;
• a first electrode contacting a first aqueous solution of a first redox-active electrolyte material and configured to have a first reversible redox reaction with the first redox-active electrolyte material, and the first redox-active electrolyte material accepts a salt ion of the salt from the solvent in the first reservoir;
• a second electrode contacting a second aqueous solution of a second redox-active electrolyte material and configured to have a second reversible redox reaction with the second redox-active electrolyte material, and drive a salt ion of the salt from the second redox-active electrolyte material into the solvent in the second reservoir, wherein at least one of the first and second redox-active electrolyte materials comprises a ferrocene derivative that is chemically stable in oxidized and reduced forms to reaction with oxygen gas;
• a first type of membrane disposed between the first and second reservoirs;
• a second type of membrane, different from the first type, disposed between the first electrode and the first reservoir and disposed between the second electrode and the second reservoir;
• transporting solvent having a first concentration of dissolved salt into the first and second reservoirs;
• operating the electrodialysis apparatus to generate a first stream having a second concentration of the dissolved salt that is lower than the first concentration of the dissolved salt and to generate a second stream having a third concentration of the dissolved salt that is higher than the first concentration of the dissolved salt;
• and
• transporting the first stream through a switching unit to a further desalination system to generate a further stream having a final concentration of the dissolved salt that is lower than second concentration of the dissolved salt, wherein the further desalination system uses a solvent treatment process different from the electrodialysis apparatus.