Mechanistic insights into the potential applicability of a sulfate-based advanced oxidation process for the control of transparent exopolymer particles in membrane-based desalination

Transparent exopolymer particles (TEPs), often massively produced from algal blooms, are considered one of the most difficult foulants in membrane-based desalination processes and contribute significantly to membrane biofouling. This study explored the potential application of a UV-activated peroxymonosulfate (UV/PMS) system for the mineralization of TEP using alginate as a model. The effects of salinity in the form of chloride ions on the removal of organics were investigated, and the reaction mechanisms were postulated. In addition, the scavenging effect of the co-presence of cations and anions with chloride ions was examined. The results indicated that 100% TEP mineralization could be achieved in freshwater when a PMS concentration above 0.25 mM was added. However, the presence of chloride retarded the removal efficiency by approximately 25%, with more severe retardation observed in the presence of chloride with bromide. This was ascribed to the generation of less reactive and more selective halogen species. Furthermore, approximately 44% organic mineralization was observed when this system was applied to seawater, implying its feasibility as a pretreatment unit in membrane-based desalination.