Spatial and Temporal Patterns of PFAS Occurrence at a Wastewater Beneficial Reuse Site in Central Pennsylvania
Open Access
- Author:
- Mroczko, Olivia
- Graduate Program:
- Agricultural and Biological Engineering (MS)
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- November 03, 2023
- Committee Members:
- Heather Elise Preisendanz, Thesis Advisor/Co-Advisor
Herschel A. Elliott, Committee Member
Tamie Veith, Committee Member
Patrick Joseph Drohan, Committee Member
Suat Irmak, Program Head/Chair - Keywords:
- PFAS
contaminants of emerging concern
Living Filter
international policy
PFOS
PFOA - Abstract:
- Per- and polyfluoroalkyl substances (PFAS) is a collective name for a growing range of synthetic fluorinated compounds that have been produced to enhance both consumer and industrial products since the 1940s. Due to their chemical composition, PFAS do not easily degrade and can persist in the environment, negatively impacting ecosystem and human health. With recent advances in analytical technology, the fate and transport of PFAS in the environment is becoming better understood, as are the risks they pose to human and environmental health. Because PFAS persist in treated wastewater, reusing wastewater effluent as an irrigation source can inadvertently introduce PFAS into agroecosystems. The Pennsylvania State University has been spray-irrigating all of its treated wastewater at a site known as the “Living Filter” since the early 1980s. The site contains ~250 ha of mixed use agricultural and forested land and 13 monitoring wells. To understand the effects of this long-term irrigation on the occurrence and the spatial and temporal patterns of PFAS at the site, groundwater water samples were collected bimonthly from October 2019 to February 2021 from the wastewater influent and effluent and from each of the groundwater monitoring wells, with all samples analyzed for 20 PFAS compounds. Additionally, crop tissue samples were collected at the time of harvest for corn silage and fescue to determine the potential impacts of spray-irrigation activities on PFAS occurrence in the crops harvested as livestock feed. To better understand potential human health impacts of PFAS occurrence at the Living Filter site, aqueous PFAS concentrations were compared to national and international drinking water policies, including throughout the United Kingdom, to determine if the long-term spray irrigation activities associated with beneficial reuse are significant enough to warrant human-health related concerns under different policy regimes. Data from the monitoring wells demonstrated that of the 20 analyzed PFAS compounds, 10 PFAS compounds were found to be present in the ground water. Concentrations of total measured PFAS ranged from below the detection limit to 155 ng/L, with concentrations increasing in the direction of groundwater flow. PFOA and PFOS across the Living Filter were detected at concentrations above the drinking water standards proposed by US Environmental Protection Agency (USEPA) at 10 of the 13 monitoring wells and above the Pennsylvania Department of Environmental Protection’s drinking water standards in 7 wells. However, all but 3 of the 13 wells met UK policy standards. Because the Living Filter is operated to maintain groundwater concentrations below the USEPA’s primary drinking water standard of nitrate of 10 mg NO3-N/L (USEPA, 2009), strict regulations for PFAS in potable water could limit the long- term feasibility of beneficial reuse of treated wastewater. However, these wells do not serve as supply wells for potable water and therefore do not pose a direct risk to human health. Research results provide insight into potential impacts of beneficial reuse of treated wastewater on groundwater and crop tissue quality. Crop tissue was also found to contain detectable levels of PFAS, with short chain compounds being the largest contributor (>84%). These results were used to estimate the amount of PFAS ingested by dairy cattle through their feed, which was found to range from 2.46 – 7.67 mg/animal/yr. These results suggest that beneficial reuse of wastewater effluent can impact groundwater and feed quality; however, the results to livestock and human health are not yet fully understood. Without these beneficial reuse programs, the treated wastewater would be discharged to surface water. Therefore, additional research is needed to better understand the risks and benefits associated with beneficial reuse programs as they relate to PFAS fate and transport in agroecosystems.