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Underestimation of Per- and Polyfluoroalkyl Substances in Biosolids: Precursor Transformation During Conventional Treatment
Citation:
Thompson, J., N. Robey, T. Tolaymat, J. Bowden, H. Solo-Gabriele, AND T. Townsend. Underestimation of Per- and Polyfluoroalkyl Substances in Biosolids: Precursor Transformation During Conventional Treatment. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 57(9):3825-3832, (2023). https://doi.org/10.1021/acs.est.2c06189
Impact/Purpose:
Wastewater treatment plants generate a solid waste known as biosolids. The most common management option for biosolids is to beneficially reuse them as an agricultural amendment but because of the risk of pathogen exposure, many regulatory bodies require a certain level of pathogen reduction before the biosolids can be reused. Per- and polyfluoroalkyl substances (PFAS) have been well documented in biosolids but there is limited information available on how biosolids treatment processes will impact PFAS. Furthermore, quantification of PFAS has focused on perfluoroalkyl acids (PFAAs) which are a small fraction of thousands PFAS that are known to exist. The objective of this study was to quantify 92 PFAS in biosolids collected from eight biosolids treatment facilities before and after four pathogen treatment applications: heat treatment, composting, lime treatment, and anaerobic digestion. Overall, total PFAS concentrations before and after treatment were dominated by PFAA-precursor species, which differs from historic data that found PFAAs, primarily PFOS, dominated total PFAS concentrations. Furthermore, treatment options such as heat treatment and composting changed the ratio of PFAA-precursors to PFAAs indicating a transformation of PFAS during treatment. This study finds that PFAA-precursors are likely underrepresented by other studies and make up a larger percentage of the total PFAS concentration in biosolids than previously estimated.
Description:
Wastewater treatment plants generate a solid waste known as biosolids. The most common management option for biosolids is to beneficially reuse them as an agricultural amendment but because of the risk of pathogen exposure, many regulatory bodies require a certain level of pathogen reduction before the biosolids can be reused. Per- and polyfluoroalkyl substances (PFAS) have been well documented in biosolids but there is limited information available on how biosolids treatment processes will impact PFAS. Furthermore, quantification of PFAS has focused on perfluoroalkyl acids (PFAAs) which are a small fraction of thousands PFAS that are known to exist. The objective of this study was to quantify 92 PFAS in biosolids collected from eight biosolids treatment facilities before and after four pathogen treatment applications: heat treatment, composting, lime treatment, and anaerobic digestion. Overall, total PFAS concentrations before and after treatment were dominated by PFAA-precursor species, which differs from historic data that found PFAAs, primarily PFOS, dominated total PFAS concentrations. Furthermore, treatment options such as heat treatment and composting changed the ratio of PFAA-precursors to PFAAs indicating a transformation of PFAS during treatment. This study finds that PFAA-precursors are likely underrepresented by other studies and make up a larger percentage of the total PFAS concentration in biosolids than previously estimated.
URLs/Downloads:
DOI: Underestimation of Per- and Polyfluoroalkyl Substances in Biosolids: Precursor Transformation During Conventional Treatment
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