Methods and Systems for Ion Separation and Recovery

A method for treating feed-, raw-, or wastewater, or other aqueous streams (“streams”) for select constituents while simultaneously recovering select desirable constituents from the streams, the method comprising:

• (i) providing a selective ion separation system (SISR) comprising a pair of electrodes, a catholyte compartment containing the cathode and aqueous electrolyte, an anolyte compartment containing the anode and aqueous electrolyte, and one or more multi-compartment cell “quartets,” in which each of the cell quartets includes:
• a first membrane (monovalent-selection cation exchange membrane or ion-specific cation exchange membrane), the first membrane being impermeable to a first aqueous ion and selectively permeable to a second aqueous ion,
• a second membrane (nonselective anion exchange membrane), the second membrane being selectively permeable to a third aqueous ion,
• a third membrane (monovalent-selection anion exchange membrane or ion-specific anion exchange membrane), the third membrane being selectively permeable to a fourth aqueous ion,
• a fourth membrane (bipolar ion exchange membrane), the fourth membrane being impermeable to ions in order to maintain a barrier between repeating units of membranes 1-3 when repeating units of the membrane quartets are utilized,
• at least four spacing frames, where each spacing frame comprises a structural element, a gasket, and a flow channel,
• wherein the membrane cell quartets are positioned between the catholyte and anolyte compartments, and the catholyte and anolyte compartments are each separated from the membrane quartet by means of a spacing frame and permselective cation exchange membrane;
• (ii) applying a voltage across said cathode and anode to transport select ions through compatible ion exchange membranes while flowing a feed-, raw-, or wastewater containing select undesirable constituents for treatment and/or select desirable constituents for recovery through the SISR system;
• (iii) using the membrane cell quartets and the applied voltage to produce at least four concentrated output streams, wherein each output stream comprises a higher level of the first aqueous ion, the second aqueous ion, the third aqueous ion, and the fourth first aqueous ion compared to the feed, raw, or wastewater.