When
Location
Harvill 107
Seminar Format
Available in-person and via Zoom webinar. Contact the department to subscribe to the email list (zoom link provided in announcement).
Abstract
Much of the carpet manufacturing in the United States is concentrated in the headwaters of the Alabama river system near the city of Dalton, Georgia. At least 23 million kilograms of PFAS-based polymers were used by facilities in Dalton to treat carpets for repellency characteristics from 1996 until the phase-out of PFAS for carpet treatment in 2019. Previous sampling of surface water upstream and downstream of Dalton indicated a significant source of PFAS to the river. The largest increase in surface water PFAS concentrations is in the vicinity of the 9,600-acre land application system (LAS) used by the publicly owned wastewater treatment plants (WTPs) in Dalton. The LAS applies wastewater from Dalton Utilities’ WTPs to the land surface via spray application. Concentrations of PFOA (~1,700 ng/L) and PFOS (~5,000 ng/L) in streams draining the LAS appear to represent some of the highest concentrations reported for surface waters.
PFAS in wastewater currently applied at the LAS accounts for <5% of the annual PFAS discharging to surface water from streams draining the LAS. In addition, it has been more than a decade since 8+ chain PFAS have been used widely in carpet facilities. As a result, the persistence of these compounds in the surface water flowing from the LAS cannot be attributed to ongoing releases. Studies of PFAS-based polymers have shown degradation of the polymer with half-lives ranging from 10 to 112 years. Degradation is a two-step process: (1) cleavage of fluorinated side-chains from the polymer backbone and (2) degradation of the detached PFAS. The multi-step process and long-degradation rates of the PFAS-based polymers likely accounts for the continuing releases of PFAS observed emanating from the LAS. The results of this study provide indirect evidence of the slow degradation of PFAS-based polymers as a continuing source of PFAS in the environment.
Bio
Erica DiFilippo is an Associate and Senior Geochemist with S.S. Papadopulos & Associates. She has extensive experience in contaminant hydrology and organic geochemistry. Previously, she was a postdoctoral research associate at the USGS in Reston, VA working on in-situ measurement of DDT. She is also an alumna of the Hydrology PhD program at the University of Arizona. She is also a board member of the NGWA’s Scientists and Engineers Section Board and was the recipient of the 2021 NGWA Keith Anderson Award, acknowledging her outstanding contribution to the NGWA in the Scientists and Engineers Section.
Erica DiFilippo Email | Website | Google Scholar