3 research outputs found
The role of NOM fouling for the retention of estradiol and ibuprofen during ultrafiltration
The impact of membrane fouling by natural organic matter (NOM) on the behavior of
micropollutants during ultrafiltration (UF) was investigated. Batch experiments with radioactively
labeled estradiol and ibuprofen in the presence of NOM model compounds (alginate, Nordic aquatic
and Aldrich humic acid) were performed using a hydrophilic and a hydrophobic membrane. The results
indicate that the impact of the NOM fractions studied on micropollutant retention correlated with the
fouling mechanism of the individual NOM fractions. NOM substances of high molecular weight such
as alginate and Aldrich HA that foul the membrane by pore blocking and cake/gel formation had a
greater impact than the Nordic aquatic humic acid of lower molecular weight. The effect of cake
formation was attributed partly to micropollutant-NOM partitioning and subsequent NOM retention
and partly to the effect of the fouling layer itself acting as a kind of second membrane. Fouling by
NOM cake/gel formation led to a significantly increased retention of estradiol, whereas the impact of
fouling on ibuprofen retention was negligible due to significantly lower Log Koc values of ibuprofen
compared to estradiol. Moreover, NOM adsorption on the membrane can lower the adsorption of
hydrophobic micropollutants. Membrane adsorption of estradiol was in the order of mg/m2 and was
largely reversible with caustic solutions. The results of this study may prove useful for predicting the
mass flow of micropollutants in UF applications