Estimating Potential for Nonvolatile PFAS Removal in Aeration Basins via Near-Surface Aerosol Capture

Abstract

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) accumulation near the water surface was measured within a wastewater treatment plant (WWTP) aeration basin. Three different sampling methods targeted near-surface samples (centimeters below the water surface), surface microlayer samples (millimeters below the water surface), and PFAS flux meters (centimeters above the water surface to capture aerosols) were used to interrogate PFAS enrichment as a function of proximity to the water surface. Sampling of stable foams was also employed in this investigation. Results showed that, for long-chained PFAS, substantial PFAS enrichment occurred only within millimeters of the surface, in aerosols, and in foams. Deployed PFAS flux meters showed increasing capture with decreasing height above the wastewater surface and with increasing PFAS surface activity. Using a screening-level model to extrapolate results of the field test, substantial (64%–92%) removal of long-chained PFAS from the bulk wastewater could be attained if near-surface (within centimeters of the water surface) aerosol capture to prevent redeposition of the PFAS-rich aerosols into the bulk wastewater was extended to the entire aeration basin.