Peracetic Acid-Based Oxidation for Ultrafiltration during Natural Water Treatment: Significant Performance Enhancement and Novel Prediction Based on PARAFAC-EEMs Coupling Hydrophilicity Characteristic

Abstract

In this study, peracetic acid (PAA) preoxidation based on Fe(II) and UV activation was proposed to mitigate the membrane fouling caused by natural organic matters (NOM) in surface water. Owing to the dual effect of oxidation and coagulation, Fe(II)/UV/PAA preoxidation was an efficient alternative strategy prior to the ultrafiltration (UF) process, with a significantly improved membrane flux by 2.35 times and a remarkably lessened reversible fouling and irreversible fouling resistance by 95.6% and 95.7%, respectively. The degradation effect of naproxen (NAP) exhibited that the oxidation capacities followed the sequence of Fe(II)/UV/PAA > UV/PAA > Fe(II)/PAA > Fe(II)/UV. Among them, the UV/PAA system with stronger oxidative capacity exerted superior removal of organics and irreversible fouling than the Fe(II)/PAA system. For the first time, the PARAFAC-EEMs method was employed to monitor the degradation effect of oxidation on hydrophilic/hydrophobic (HPI/HPO) parts in NOM components and their influence on membrane fouling. It was found that R–C• produced by the UV/PAA process preferentially degraded C1HPI, C2HPI, and C3N-HPO components, and the recalcitrant foulants that caused irreversible fouling in the Fe(II)/UV/PAA system were small hydrophobic proteins. Moreover, the novel prediction of membrane fouling revealed that C1HPI had a higher correlation with irreversible membrane fouling than C1N-HPO. There was a certain correlation between the irreversible fouling resistance and tyrosine-like proteins and a poor correlation with humics. Hence, the PARAFAC-EEMs method has a great potential for rapid detection and prediction of membrane fouling caused by the HPI/HPO parts of different fluorescent NOM components.