The Fate of PFAS in Biosolids and Biosolid Amended Compost from Two Wastewater Treatment Plants in Utah (Student Poster #35)

Abstract Description: Through the everyday use of household products per and poly fluoroalkyl substances(PFAS) enter wastewater treatment plants. Current conventional wastewater treatment technology does not provide effective removal of these substances, resulting in wastewater effluent and biosolids that are impacted by PFAS. This study compares two wastewater treatment plants, a mechanical plant with magnetite addition that composts biosolids and a membrane bioreactor plant that land applies dried biosolids to support feed crop production.
PFAS transport and accumulation are influenced by their functional groups and the length of their fluoroalkyl chains. During the wastewater treatment process long chain precursor PFAS are transformed to more mobile short chain PFAS. In addition, composting lowers the partition coefficient (Kd) of PFAS through decomposition of organic material, increasing their leachability. Compost amendments like protein and organic matter can increase the Kd and consequently reduce leaching potential by providing additional adsorption sites for PFAS. This study seeks to determine the presence and quantify the concentration of PFAS in the biosolids generated in these two systems, and to determine the fate of PFAS in various compost or air-drying processes used by the plants. In addition, a range of compost amendments will be evaluated in terms of their effectiveness in immobilizing PFAS, making biosolids and biosolids amended compost safe for agricultural and personal home garden use.
Results of laboratory and field studies will be summarized along with implications of the results for the safe processing, distribution, and use of municipal biosolids generated in the peri-urban communities that utilize these wastewater treatment plants.