PFAS removal from drinking water and semiconductor wastewater by microbubble foam fractionation

Efficient separation of per- and polyfluoroalkyl substances (PFAS) from complex water matrices remains challenging because treatment performance depends on both PFAS concentration and matrix composition. This study evaluated microbubble foam fractionation (FF) in simulated waters, drinking water source waters, and real semiconductor wastewater, with and without coagulant addition. In simulated wastewater, adding 2000 mg/L NH₄Cl enhanced PFAS removal, consistent with an ionic-strength contribution. Within 20 min, FF removed 91-98% of PFOA, PFOS, and PFHxS and approximately 91% of PFBS from a natural source water with individual PFAS concentrations of 2-19 μg/L. Removal was lower in a second source water containing 0.4-1.2 μg/L PFAS but improved with coagulant addition. In semiconductor wastewater containing 0.1-0.6 μg/L PFAS, removal reached 94-99% for PFOA, PFOS, and PFHxS and approximately 90% for PFBS. These contrasting results highlight the importance of water matrix composition in enabling effective separation at low PFAS concentrations. To explore potential downstream treatment, UV/sulfite reduction was separately evaluated using a model concentrate containing 20 mg/L total PFAS. Complete parent-compound removal was achieved for PFOA, PFOS, and PFHxS within approximately 30 min, 110 min, and 7 h, respectively, whereas PFBS removal reached approximately 63% after 8 h. These findings support matrix-specific application of microbubble FF as a PFAS concentration pretreatment and provide a basis for developing multistage FF coupled with downstream UV/sulfite treatment.