Ceramic nanofiltration-based treatment of NOM-rich ion exchange brine

Abstract

Natural organic matter (NOM) in drinking water sources causes several problems in water consumption and distribution, and decreases the efficiency of water treatment steps. Ion exchange (IEX) with anion resin can be used to remove NOM in combination with or as an alternative to other techniques, such as coagulation and activated carbon. IEX resins require periodic regeneration with an electrolyte solution that is usually made of sodium chloride. A crucial problem of IEX for NOM removal is related to waste management of the regenerant electrolyte. The regenerant solution is reused several times before disposal, which increases the concentrations of NOM and anions like sulfate. The resulting spent IEX brine is a pollutant and is expensive to dispose, which hampers full-scale applications. In this research, we proposed a spent IEX brine treatment that is based on ceramic nanofiltration. Ceramic membranes have potential advantages over polymeric membranes, such as higher fluxes and lower fouling characteristics. The treatment aims to recover a permeate of a reusable IEX regeneration salt solution, which is typically sodium chloride, by removing NOM and other anions from the spent IEX brine. Also, concentrated NOM could be used in agriculture and industry, due to the presence of humic substances.