Natural organic matter removal and flux decline with charged ultrafiltration and nanofiltration membranes

Ultrafiltration (UF) has become one of the best alternatives replacing conventional drinking water treatment technologies because of increasing stringent regulations for drinking water quality. However, UF is not very effective to remove natural organic matter (NOM) due to the comparatively larger pore size compared with the size of NOM. Membrane fouling is another factor which restricts its widespread application. In this study, the effect of charge modification of regenerated cellulose (RC) membrane was investigated by discussing NOM removal and flux decline with neutral and negatively charged version of RC membranes. Effects of the hydrophilicity/hydrophobicity of membrane and NOM on the flux decline with charged UF membranes were also investigated. Further, the performance of charge modified UF membrane and nanofiltration (NF) membrane on NOM removal and flux decline was compared. Results indicated that the appropriate charge modification on the neutral RC membrane could be an effective way for better removal of NOM and reduction of the membrane fouling due to the electrostatic interaction with the combination effect of membrane pore size. Charge modified RC membrane could be potentially used to replace NF membrane on the aspect of NOM removal.

► Charge modified membrane increases NOM removal rate and decreases the flux decline.
► Larger amount of charge on the membrane decreases the flux decline more.
► Charged UF could be potentially used to replace NF on the aspect of NOM removal.