Can Heat-Activated Peroxymonosulfate Be Used as a Pretreatment to Mitigate Fouling for Membrane Distillation: Performance of Individual Organics?

Abstract

Heat-activated persulfate preoxidation was recently proposed as a potential approach to mitigate membrane fouling in membrane distillation (MD) for treating actual water. However, the possible mitigation mechanism involved has not yet been elucidated. In this study, we explored the relationship between membrane fouling and the pretreatment of natural organic matter (NOM) solutions with peroxymonosulfate (PMS). Individual humic acid (HA), bovine serum albumin (BSA), and sodium alginate (SA) contaminants were chosen as model NOM samples. The degradation efficiency of heat-activated PMS preoxidation was investigated. The removal rates of organic contaminants improved as the PMS dose and activation temperature of the feed increased. Specific flux (J/J0) measurements coupled with multiple characterizations were performed to assess the fouling behavior. The fouling data showed that when pretreatment was conducted without PMS, pure HA caused the most severe fouling, followed by pure BSA, whereas pure SA caused almost no membrane fouling. After PMS preoxidation, the oxidation products of the NOM unexpectedly caused more fouling, despite the reduction in the amount of the NOM. Further work is needed to evaluate fouling mitigation when working with complex streams.