Performance of nanofiltration membrane in rejecting trace organic compounds: Experiment and model prediction

This study aimed to investigate the rejection ratios for 40 trace organic compounds (TOrCs) by the Desal HL nanofiltration (NF) membrane and to assess the applicability of the DSPM&DE model in predicting the rejection performance. Steady state rejection ratios were considered. A higher water flux normally led to a higher rejection ratio. At a filtration flux of 6.59 x 10(-6) m/s, the NF membrane could effectively reject most of the TOrCs (>80%), except for a few that included acyclovir, caffeine, carbamazepine, chloramphenicol, metronidazole, nandrolone, oxytetracycline, sodium nifurstyrenate and trenbolone. Most poorly rejected TOrCs had a molecular weight lower than 275 Da. Steric hindrance effect was the primary mechanism that contributed to the rejection of TOrCs by the NF membrane. The rejection ratio for methylparaben decreased when the water flux increased. The DSPM&DE model was successful in predicting the rejection ratios for acyclovir, caffeine and ranitidine, which all have relatively low molecular weight and are hydrophilic. The model generally over-predicted the rejection ratios for the remaining TOrCs. The over-prediction could not be explained by high hydrophobicity only. Lack of consideration of the TOrC-membrane interactions on the partitioning of TOrCs to the membrane material was probably the primary reason for over-prediction by the model. (C) 2015 Elsevier B.V. All rights reserved.