Purifying anion exchange resin regeneration effluent using polyamide nanofiltration membrane

Abstract

The objective of this study was to investigate the effect of feed concentration (40–100 g/l at four levels), transmembrane pressure (1.0–2.0 MPa at five levels) and temperature (30–50 °C at three levels) on the recovery of usable brine obtained from waste brine by using polyamide tubular nanofiltration membrane in order to save on both salt and water consumption for ion-exchange regeneration process. A 77% reduction in salt consumption, a 90% reduction in water consumption and removal value of greater than 99% for colorants were achieved. The rejection of sodium chloride was found to be 15% to 37%, which was the highest rejection value obtained at 40 g/l, 2.0MPa and 30 °C. The rejection of sodium chloride declined with increase in the feed concentration and temperature, whereas increasing the transmembrane pressure led to an increase in sodium chloride rejection. The permeate flux was found to be stable during the whole nanofiltration process; however it was decreased by increasing the feed concentration and increased with increase in temperature and pressure.