The use of chitosan and pressure-driven membrane processes to remove natural organic matter from regenerative brine recovery

The research on the removal of natural organic matter (NOM) from post-regeneration brine solution, that is, a mixture of NaCl and natural organic substances (fulvic and humic acids) generated during regeneration of MIEX® resin used in the treatment of surface and synthetic water via ion-exchange process is discussed. Different chitosan modifications (powdered chitosan, chitosan-based coagulant and chitosan balls) and pressure-driven membrane processes (ultrafiltration [UF] and nanofiltration, [NF]) were used. A number of treatment process arrangements, such as chitosan-based coagulation and sorption, single-stage membrane processes (UF and NF) and integrated membrane systems (UF+NF) were tested. The research showed the efficient removal of NOM by means of chitosan coagulation at the dose 0.6 g/L and pH = 6, for which 44% decrease of dissolved organic carbon (DOC) concentration was obtained. The high efficiency of post-regeneration brine solution treatment was reached using integrated system of chitosan coagulation and NF. For this system 97% removal of DOC accompanied with the highest, among all investigated systems, relative permeate flux 0.65 was obtained.