Sulfate precipitation treatment for NOM-rich ion exchange brines

Ion exchange (IEX) resins can remove natural organic matter (NOM) from drinking water sources. However, the IEX system produces a waste brine rich of sodium, chloride, NOM and sulfate. The treatment aims to recover clean solution sodium that be reused regenerate resin. Previous research showed ceramic nanofiltration partially removes brine, but sulfate removal requires additional treatment. Sulfate by chemical precipitation was previously studied either on brines with low concentrations or salts. current work focussed NOM-rich dosing (1) BaCl2, resulting in barite (BaSO4), (2) CaCl2, Ca(OH)2 NaAlO2, calcium and, subsequently, ettringite (Ca6Al2(SO4)3(OH)12). Additionally, effect SO42− studied. Modelling batch experiments were conducted synthetic within typical ion strength range 0.1 1 M. With doses 2.2 g BaCl2 per initial sulfate, BaSO4 removed more than 83 percent final below 0.4 g/L even presence NOM. inhibited ettringite. 1.3 0.5–0.7 0.4–0.6 NaAlO2 between 8 95 brines, 0.8 2 g/L. As reference, NOM-free required 0.2–0.7 0.1–0.6 for 89 99 removal, 0.2 inhibition might attributed covering crystal sites molecules, coagulation aluminium.