Salinity exchange between seawater/brackish water and domestic wastewater through electrodialysis for potable water

Two-thirds of the world’s population has limited access to potable water. As we continue to use up our freshwater resources, new and improved techniques for potable water production are warranted. Here, we present a general concept called “salinity exchange” that transfers salts from seawater or brackish water to treated wastewater until their salinity values approximately switch, thus producing wastewater with an increased salinity for discharge and desalinated seawater as the potable water source. We have demonstrated this process using electrodialysis. Salinity exchange has been successfully achieved between influents of different salinities under various operating conditions. Laboratory-scale salinity exchange electrodialysis (SEE) systems can produce high-quality desalinated water at ∼1 mL/min with an energy consumption less than 1 kWh/m3. SEE has also been operated using real water, and the challenges of its implementation at a larger scale are evaluated.