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Emerging contaminant research at the US EPA: PFAS and microplastics
Citation:
Potter, P. Emerging contaminant research at the US EPA: PFAS and microplastics. UC seminar, Cincinnati, OH, November 17, 2022.
Impact/Purpose:
PFAS contamination is widespread in our environment and may adversely impact human health. Thermal treatment is commonly used for both sewage sludge and GAC, which both typically contain PFAS. There is growing attention on non-targeted analysis of PFAS to properly assess the fate of these compounds during thermal treatment. A pilot-scale fluidized bed reactor was used to mimic both full-scale sewage sludge incineration and GAC reactivation. Gas-phase emissions were collected, along with solid and liquid residuals, and analyzed for products of incomplete combustion (PICs). These findings should influence future studies on thermal treatment of PFAS by assessing current thermal treatment conditions on the fate of these compounds. These methodologies may be useful to a variety of government and academic researchers investigating PFAS remediation. Plastics breakdown into micro- (< 5 mm) and nano-sized (<100 nm) particles when they undergo environmental exposure and aging. While these microplastics have been studied in many geographic regions, there are still many questions about their origins. This research used quantum cascade laser-based infrared imaging to identify and quantify microplastic contamination from freshwater and urban watershed systems. These findings should influence future studies on microplastics by identifying sources of microplastics in freshwater and urban watershed systems. These methodologies may be useful to a variety of government and academic researchers investigating microplastics.
Description:
Per- and polyfluoroalkyl substances (PFAS) are a group of man-made chemicals that have been in use since the 1940s in a wide array of consumer products. PFAS are persistent in the environment and bioaccumulate. Thermal treatment methods are currently applied to a variety of materials, including sewage sludge and granular activated carbon (GAC). There is a critical need to assess the efficacy of existing and emerging thermal treatment methods to completely destroy or mineralize PFAS. Currently, most assessments of thermal treatment methods use targeted PFAS quantification of a limited number of compounds. This targeted approach can overlook products of incomplete combustion (PICs). Non-targeted analysis (NTA) of PFAS is required to properly assess the efficacy of these thermal treatment methods and to determine the fate of these compounds in thermal treatment systems. A summary of current EPA research in this field will be presented. Microplastics (MPs) are another class of emerging contaminant that are particularly hazardous due to their high surface area to volume ratio that facilitates leaching of their inherent additives and allows them to be efficient vectors for toxic metals and persistent organic pollutants. There is a critical need for fast and efficient microplastic detection to track sources, transport routes, and fate in urban watersheds. Nanoplastics (NPs) are generally considered to be < 1000nm and potentially pose increased risk over MPs due to smaller size that facilitates increased environmental transport, biological uptake, and adsorption/leaching of co-contaminants. As most plastic pollution originates in urban environments, studies of urban watersheds with high population density and industrial activity are especially relevant. Current and future work to characterize microplastic occurrence, fate, and transport in the environment will be discussed.