Sandra Dworatzek, (Ontario) will present a paper authored by Brent Pautler, “Development of an Equilibrium Passive Sampler for Monitoring PFAS,” and Sarah Cronk (Tennessee) will present “Optimization of PFAS treatment by In Situ Stabilization” at RemTec & Emerging Contaminants Summit at the Westin Westminster in Westminster, Colorado on October 4-6, 2022.

Sandra is a Principal Scientist with more than 25 years of experience in bioremediation of chlorinated solvents, petroleum hydrocarbons, emerging contaminants and other recalcitrant compounds. She has specific technical experience in the design of laboratory treatability studies, the scale up of growth of aerobic and anaerobic microbial cultures for bioaugmentation laboratory and field pilot tests, and evaluation of aerobic and anaerobic bioremediation, zero valent iron and chemical oxidation technologies in the laboratory. She currently provides senior technical oversight of laboratory treatability studies and the development and scaleup of new bioaugmentation cultures, including novel cultures for BTEX compounds under anaerobic conditions and aerobic 1,4-dioxane bioremediation. Sandra currently is the industry lead on a Genome Canada funded project for the commercialization of anaerobic BTEX degrading cultures.

Sarah Cronk is an Engineer-in-Training and lab supervisor based in Knoxville, Tennessee, has over 7 years of experience in environmental chemistry, geochemistry, and plant biology; environmental engineering; and lab managing. She works on client-funded investigation of biomethane generation from paper pulp residues, TAC-funded investigation of fluoride and sulfate reduction of metals-impacted mine water using biotreatability columns, and client-funded investigation of cobalt, arsenic, and molybdenum leaching from CCR materials under several chemical and biological treatments.

The RemTEC & Emerging Contaminants Summit delivers a truly unique platform focused on advancing the environmental science and remediation industry. It is the place where you can hear essential sources of information on technology, application and policy affecting contaminated site restoration field from the world’s leading experts within the academic, regulatory and environmental-consulting communities.

By daring to be different and distinctively focusing on the quality – not quantity – of topics, session chairs, presenters and posters, they have created the most advanced forum where knowledge sharing and innovative thought leadership come together and pave the way to progress.

Presentation Information

PFASsive™: An Equilibrium Passive Sampler for PFAS in Sediment Pore Water and Surface Water!
Presenter: Sandra Dworatzek, SiREM
Date/Time: Tuesday, October 4 from 3:55 p.m. – 4:25 p.m.
Sandra Dworatzek’s co-authors are Alexander Sweett, Faten Salim, Michael Healey, and Jeff Roberts, SiREM; Blessing Medon and Anh Pham, University of Waterloo; Florent Risacher, Lisa D’Agostino, Jason Conder, and Rachel Zajac-Fay, Geosyntec Consultants; Patricia McIsaac, Andrew Patterson, and Robert Mitzel, Eurofins Environment Testing America.
Abstract:
Per-and Polyfluoroalkyl Substances (PFAS) have emerged as a concern at many sites due to the use of aqueous film-forming foam (AFFF), containing high amounts of PFAS by volume. This historical use of AFFF in emergency response and firefighter training has resulted in the release of PFAS into groundwater, sediment, porewater, and surface water. As PFAS are persistent, bioaccumulate in living organisms, and have demonstrated toxicity in laboratory animals, there is a critical need to understand migration pathways and bioavailability of PFAS to ensure proper delineation and risk characterization. Although there are established sampling techniques available to analyze PFAS concentrations in sediment, porewater, and surface water, these techniques capture the total concentration, which may result in an overestimation of risk to human and ecological receptors. Therefore, a technique, tool, and/or technology that can assess bioavailability and risk of PFAS in the environment is required.

Traditional sampling methods for sediment, porewater, and surface water quantify total concentrations of chemicals present in that media by physical extraction. The use of total concentrations in risk assessments may result in an overestimation of risk, as only the bioavailable fraction of the chemical can bioaccumulate into organism tissues, resulting in exposures to human and ecological receptors. Although biota and tissue samples could be collected to assess this risk, these methods are time-consuming and costly. Passive sampling is a popular approach used by practitioners and regulators to assess bioavailability and risk through the dissolved phase of contaminants such as metals, persistent organic pollutants (i.e., PCBs, PAHs and pesticides), nutrients, pharmaceuticals, and others. Since PFAS are emerging contaminants, only very recently have researchers started investigating methods to measure the dissolved phase using passive samplers. Passive samplers traditionally used for hydrophobic organics are not amenable for PFAS; however, given their partially water-soluble nature and the ability of the commercial analytical laboratories to detect trace amounts of PFAS in water, a diffusion-based passive sampler is a good candidate for quantification of PFAS in groundwater, porewater and surface water. When deployed, analytes dissolved in the water or sediment equilibrate with the water in the sampler through the semi-permeable membrane. Through a series of bench-scale and field experiments it has been shown that a diffusive sampler is an effective passive sampler for PFAS.

This presentation will highlight both targeted (70 compounds) and non-targeted (LC-QTOF) results from in situ field testing of a passive sampler for sediment porewater and surface water, and compare these results to those obtained from traditional grab sampling, addressing the need to assess the bioavailability of PFAS and provide a better basis for assessing the risk associated with its presence. Technical analytical chemistry advancements will also be presented to further expand the capabilities of characterization of these emerging contaminants.

Poster Presentation: Optimization of PFAS treatment by In Situ Stabilization
Presenter: Sarah Cronk, SiREM
Sarah Cronk’s co-authors are Jacques Smith and Kyra Williams, SiREM.
Abstract:
Per-and Polyfluoroalkyl Substances (PFAS) release and migration into soil and sediment at contaminated sites can be widespread and pervasive enough to rule out traditional excavation and disposal strategies. Other viable PFAS treatment options are scarce and cost prohibitive. In situ stabilization (ISS) is a proven technology to immobilize contaminants in soils and sediments and have been used widely for a range of contaminants. Recent studies indicate promise for certain binders to solidify PFAS in soil and sediment. By containing PFAS-contaminated soil or sediment within a low-porosity matrix, ISS may offer short and long-term protectiveness to the surrounding environment.

ISS is accomplished by mixing contaminated soils with binders, such as Portland cement, to produce a monolithic material, thereby decreasing the mobility and toxicity of contaminants. While ISS has a demonstrated track record at hundreds of sites, it has not been used widely for PFAS sites. Laboratory treatability testing for ISS is key prior to moving to the field to understand the optimal binder and dose to be used in the site-specific material.  These findings can then be used to design the field program with confidence.

This presentation will review the latest developments of ISS and Deep Mixing Method (DMM) as applied to PFAS-contaminated soils and sediments. PFAS-containing soils from several sites were amended with different ratios of cement, slag, and bentonite. These mixtures were monitored and characterized for both physical and chemical transformations over time to determine stability of the material as well as their performance in leach testing. Results from these investigations have highlighted several properties (e.g. texture, water content, bulk density, and porosity) that may determine a fixed ratio of cement, slag, and bentonite to yield greater PFAS immobility in impacted soils.

More Information

About the event: RemTec and Emerging Contaminants Summit
About Geosyntec: Geosyntec Consultants
For consultation regarding PFAS, contact Sandra at SDworatzek@siremlab.com, or Sarah at SCronk@siremlab.com.
Learn more about Brent: Brent G. Pautler | LinkedIn
Learn more about Sarah: S. Sarah Cronk | LinkedIn