This PFI: AIR Technology Translation project focuses on translating ion exchange fundamentals to fill the gap in brackish water desalination through a Reversible Ion Exchange-Membrane (RIX-M) process. The translated technology has the following unique features: increased product water recovery due to reduction in scaling from sulfate and carbonate salts of calcium on the surface of Reverse Osmosis (RO) membranes without requiring addition of any anti-scaling chemicals. Threats of barium sulfate scaling and consequent fouling of membranes, wherever present, may also be avoided.
The project accomplishes this goal by integrating a self-regenerated ion exchange system along with the RO process. An appropriately designed mixed bed of anion exchange resins significantly reduce sulfate concentration at the membrane inlet, thus avoiding sulfate precipitation. The reject of the RO membrane process is used to regenerate the anion exchange resins without needing addition of external chemicals.
The potential economic impact is expected to be a significant reduction in operating expenses of the desalination plants due to elimination of anti-scaling chemicals. The partnership engages an ion exchange resin manufacturer and an engineering firm to move into the growing brackish water desalination market space globally through validation of the technology under representative conditions. From a business viewpoint, the innovation can also be retrofitted for existing RO plants, thus expanding the market for the proposed technology.
From a broader perspective, the proposed work will also lay the basis for an in-land desalination technology which does not create a reject stream containing environmentally objectionable anti-scaling chemicals requiring post treatment. With higher product water recovery, the reject brine will be smaller in volume, thus reducing the land requirement for disposal. The scientific approach envisioned through fundamentals of ion exchange may also be transplanted in multi-stage evaporative desalination systems to avoid scaling and consequent reduction in heat transfer efficiency of evaporators.
