Increased population growth and concurrent decrease in fresh water supply are propelling societies globally to produce potable and industrial water supply from impaired sources including treated municipal wastewater. As part of their groundwater replenishment system, Orange County Water District (OCWD) in California treats municipal wastewater with total dissolved solids (TDS) 0f 600 mg/L prior to pumping it into recharge basins and sea water intrusion barriers. For high recovery, reverse osmosis or RO is used and the process is, as expected, energy intensive. Our work has led to a hybrid ion exchange (HIX) process that is capable of using carbon dioxide as the primary driver to desalinate municipal wastewater with simultaneous phosphate recovery. The process utilizes unique acid-base chemistry of CO2 where it can serve both as an acid and a base. Hybrid ion exchange resins are uniquely designed to overcome intra-particle diffusion resistance and recover phosphate. From a sustainability viewpoint, the process does not produce any secondary waste and consumes miniscule energy compared to RO processes.

Physics and chemistry of carbon dioxide as the driver for low-energy desalination and decontamination of impaired wastewater

255th National Meeting (2018)

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