Texas Tech University
Jennifer Guelfo, Ph.D., is an Assistant Professor in Civil, Environmental, and Construction Engineering at Texas Tech University. She joined Texas Tech University in 2018 following a postdoctoral appointment in the Brown University School of Engineering. Dr. Guelfo has a BA in Geology from the College of Charleston, a MS in Environmental Science & Engineering from the Colorado School of Mines (CSM), and a PhD in Hydrologic Science and Engineering, also at CSM. For the past ten years, her research has focused primarily on occurrence, fate, transport, and remediation of emerging organic contaminants, such as per- and polyfluoroalkyl substances (PFASs), in impacted drinking water, soil, and groundwater. In addition to academia, she also has a combination of consulting and industry experience, and she uses this background to engage in activities that can inform policy and bridge gaps between research and practice.
Enhanced PFAS Recovery from Impacted Soil Using Oxidative Pre-Treatment
Marzieh Shojaei (firstname.lastname@example.org), Michelle Crimi (email@example.com) (Clarkson University, Potsdam, NY, USA), and Jennifer Guelfo (Jennifer.Guelfo@ttu.edu) (Texas Tech University, Lubbock, TX, USA)
Tens to hundreds of per- and polyfluoroalkyl substances (PFAS) may occur at AFFF-impacted sites, including anionic perfluoroalkyl acids (PFAAs), and anionic, cationic, and zwitterionic polyfluoroalkyl substances, which have the potential to transform into PFAA endpoints. This poses challenges for remediation techniques, particularly those that rely on pump and treat technologies. Whereas recovery of PFAAs and other relatively more mobile, anionic PFAS may be relatively easy, slower recovery of stronger sorbing (in most soils), zwitterionic and cationic PFAS may lead to complicating factors such as extended remediation times and rebound in aqueous PFAS concentrations. Further, precursors not recovered during pump and treat efforts may continue to transform to PFAAs over time. Remediation techniques, such as in situ persulfate oxidation and biosparging, are incapable of completely degrading total PFAS under ambient conditions. However, persulfate oxidation may degrade a fraction of PFCAs, and persulfate oxidation and biosparging both have potential to facilitate transformation of precursors to PFAA endpoints. This would convert a complex mixture of PFAS, some of which are less mobile, to a relatively more mobile, recoverable, and simple mixture of PFAAs. The objective of this study was to determine if persulfate oxidation and biosparging can lead to increased recovery of total PFAS in AFFF-impacted soils. Two types of batch experiments were used to evaluate these techniques. First, heat-activated persulfate was applied in batch reactors containing a slurry of AFFF-impacted soil and deionized water. Following oxidation, batch reactors were subjected to a 14-day desorption experiment. Total PFAS recovery in soil and water was evaluated immediately following oxidation and over the 14-day desorption period. Second, separate batch reactors were prepared using the same AFFF-impacted soil and deionized water and connected to an oxygen sparging manifold. Aqueous phase recovery of total PFAS was measured over 40+ days, and soil was analyzed at the mid-point and completion of the experiment. All results were compared to recovery in control experiments in which no treatment was applied. Soil and water were analyzed using a combination of targeted, liquid chromatography (LC) mass spectrometry techniques, total oxidizable precursors, and suspect screening using high resolution mass spectrometry (HRMS) methods. Following persulfate oxidation, total PFAS composition showed the expected shift to a higher fraction of PFAAs, although oxidation did not achieve 100% precursor transformation. Batch experiments containing persulfate yielded higher total PFAS recovery (85%) in the aqueous phase when compared to controls (58%) at the end of the 14-day period. Biosparging experiments showed higher concentrations of PFAAs in sparged reactors vs. controls, but data analysis for total PFAS is ongoing. These results suggest that in situ remediation methods have promise for application as PFAS flushing techniques and also have implications for sites where prior remediation has been conducted to address other classes of contaminants.