Application of UF, NF and ED in natural organic matter removal from ion-exchange spent regenerant brine

The objective of the study was to compare the efficiency of pressure and electrically driven membrane processes in the treatment of brines containing high concentrations of NOM. In the pressure driven processes 6 ultrafiltration and 2 nanofiltration Nadir polymeric membranes were tested. Electrodialysis was performed using Neosepta AMX and CMX ion-exchange membranes. Experiments were carried out on a model solution containing 12% NaCl and 1 g of humic substances per liter. Electrodialytic treatment of spent regenerant brought an almost 100% recovery of NaCl when the feed to receiver volume ratio amounted to 5:3. The retention of NOM particles reached 91%. The increase of volume ratio up to 5:5 resulted in the decrease of salt recovery to 79%. In the same time organic macromolecules separation increased to 97%. UF and NF membranes were very effective in NOM separation from spent regenerant. The reduction of color reached 88% for UF membranes and 99% for NF ones. Pressure membrane filtration only slightly influenced the NaCl concentration in the permeate.