2022 Agenda

Due to the strong carbon-fluorine bonds, per and polyfluoroalkyl substances (PFAS) are highly resistant to biological and chemical degradation, particularly perfluoroalkyl acids (PFAAs). Since options for treatment are limited due to the recalcitrance of PFAAs, ex situ treatment with granular activated carbon (GAC) is common with thermal treatment processes used for destruction. As a result, management of PFAS sites is often very costly, and some of the PFAAs may break through GAC canisters more quickly than PFOA and PFOS, raising some concerns. Research efforts for treatment technologies have included treatment for in situ groundwater, ex situ groundwater, investigation-derived waste, and wastewater. Current research efforts aim to understand the degradation processes better and develop new remediation technologies to treat PFAS. The science and technologies surrounding the environmental characterization and remediation of PFAS are constantly developing. This session includes an evaluation of thermal treatment for impacted soil and the conditions for safe incineration from waste streams, a case study of a passive in situ remediation method for PFAS in water, and a demonstration of foam fractionation for removal of PFAS from source zones.

Learning Objectives

1. Identify thermal decomposition processes.
2. Identify site conditions where passive in situ remedies may be viable for the treatment of mobile, persistent compounds (e.g., PFAS, 1,4-dioxane) in groundwater and surface water.
3. Describe foam fractionation and how it harnesses the power of bubbles to remove PFAS.
4. Discuss some considerations for scaling up the process to treat large volumes of PFAS-laden soil piles.

The session will discuss the latest insights linked to measuring various PFAS, either relying on active or passive sampling. While grab sampling has been the standard approach to site characterization, recent developments in passive sampling implies that some of these samplers are now ready to be used in the field. No matter the sampling approach, a more complete characterization of PFAS in the environment has emerged with suspect screening, and non-target approaches, aided by instrument and workflow improvements.

Learning Objectives

1. Discuss why a diffusion-based passive sampler is a good candidate for quantification of dissolved PFAS due to the characteristics of PFAS compounds.
2. Compare and contrast passive sampler results to those obtained from traditional grab sampling.
3. Explore how these analytical tools compare and work together to provide a more comprehensive picture of PFAS contamination.
4. Explain a non-target analysis for PFAS compounds and how it is helping to further the understanding of PFAS in the environment.

Environmental forensics is the application of scientific techniques to identify the source and historical reconstruction of contamination releases to develop defensible scientific and legal conclusions. Given the widespread use of PFAS-containing materials and the growing litigation over their presence in the environment, there is a clear and immediate need for PFAS source attribution. This session focuses on the evolving field of PFAS forensics, including the evaluation of new approaches such as machine learning techniques and converging lines of evidence used to differentiate PFAS sources.

Learning Objectives

1. Recognize the types of challenges that arise in applying forensic techniques to PFAS sites.
2. Explain the types of methods that could be involved in PFAS source tracking.
3. Express why pattern recognition is necessary for recognizing PFAS sources from composition in environmental samples.
4. Summarize some of the pitfalls that might arise from machine learning methods.

This session wil review the issues of evaluating the toxicity of PFAS and implications this has on regulations. It is becoming increasingly clear that PFAS are ubiquitous within the environment. Furthermore, fluorinated chemistry function was primarily focused on product retardant and water proofing, these functions carryover to environmental impacts which has resulted in legacy contaminants and significant environmental persistence. With this in mind, short-term ecotoxicity experiments are of limited value when assessing PFAS impacts to aquatic receptors. This session includes a study evaluating the reproducibility of findings from a previous investigation of multigenerational PFOS exposure in zebrafish which reported effects at exposure levels nearly two orders of magnitude lower for the species than observed in other published studies. In addition, a review of a full-life cycle test (~300 days) with fathead minnow exposed to PFOS and PFOS mixtures is presented to provide critical data for regulatory agencies.

Learning Objectives

1. Describe mechanisms for accumulation of PFAS in birds.
2. Examine the distribution of different PFAS classes in birds.
3. Identify the types of differences that there are in PFAS accumulation in inter-species.
4. Discuss some of the ecotoxicological effects of long-term PFOS and PFOS mixture exposure to the fathead minnow.