Effects of feed water temperature on irreversible fouling of ceramic ultrafiltration membranes

Temperature is known to influence the filtration performance of membrane systems through its direct impact on water viscosity. This research demonstrates that the changes in natural organic matter (NOM) fouling behavior with temperature are over and beyond simple viscosity changes in water. Constant flux experiments were performed in a tubular ceramic ultrafiltration (UF) system at 5, 20, and 35 degrees C. The unified membrane fouling index (UMFI) was used to identify NOM reversible and irreversible fouling mechanisms; while the modified UF fouling index (MFI-UF) was used to predict the fouling potential of NOM. The results showed that after correcting for viscosity to standard 20 degrees C compared to 5 degrees C, UMFI values were higher than expected and reflected the higher fouling irreversibility observed at the lower temperature. The lower water temperature resulted in an increase in NOM retention along with decrease in backwash and chemical cleaning effectiveness as determined by the UMFI and FEEM analyses. However, increased water temperature did not adversely impact existing backwash or chemical cleaning protocols. In addition, The MFI-UF exhibited the same trend as UMFI for establishing NOM fouling and retention, and therefore, the MFI-UF method is suitable for use as fouling predictor with ceramic membrane systems.