Wastewater Treatment Plants as Major Sources of Atmospheric PFAS and Microplastics

AIDAN MCCLURE, Kanchana Chandrakanthan, Paul Westerhoff, Matthew Fraser, Pierre Herckes, Arizona State University

     Abstract Number: 460
     Working Group: Chemicals of Emerging Concern in Aerosol: Sources, Transformations, and Impacts

Abstract
Per and Polyfluoroalkyl Substances, or PFAS, are emerging pollutants of concern, both due to their nature as “Forever Chemicals” and their severe health effects at trace levels. Recently, the US EPA passed legislation to limit certain PFAS, such as perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), to 4 parts per trillion in drinking water. Drinking water plants largely rely on natural water sources, meaning that the chain of PFAS pollution must be broken in order for safe levels of PFAS to be achievable. Atmospheric emissions are the least understood process by which PFAS transport into the environment, owing to the difficulty of sampling, measurement, and source attribution. One important mechanism by which PFAS enter the atmosphere is sea spray, as recent studies have demonstrated. Analogous to sea spray, air bubbles bursting at the surface of aeration basins at wastewater treatment plants (WWTP) have the potential to emit large amounts of PFAS, along with other pollutants, to their surroundings. Of these other pollutants, microplastics are of particular concern, due to their ubiquity and potential to adsorb chemicals of concern, including PFAS, further complicating their transport.

Here, we present results from a study quantifying the emissions of PFAS and microplastics from aeration basins at a WWTP. Samples were collected daily using a high volume polyurethane foam (PUF) air sampler over two weeks at a WWTP, with particle phase PFAS and microplastics being collected on a frontal quartz fiber filter and gas phase PFAS being collected on XAD-4 impregnated PUF foams. PFAS were detected in all phases and all samples at concentrations substantially higher than in ambient air. Microplastics were found in all collected samples, ranging from 3.4 to 5.2 microplastics/m^3, which is an order of magnitude higher than in urban ambient air.