2023 Agenda

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PFAS and the Law - Regulatory and Technical Drivers

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Treatment Train Approach to Address PFAS Impacts in Groundwater at a Fire-Training Facility in Wisconsin

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Technologies for effective treatment of ultra-short chain PFAS

Much of the published work to date has been on treating per- and polyfluoroalkyl substances (PFAS) compounds having 4 or more carbons. The performance of the treatment systems varies significantly when comparing ultra-short chain PFAS (C=2-3) to the longer chains (C>=4). The objective of this study was to develop a system for effective treatment of PFAS, including ultra-short chains, and demonstrate the capability through pilot testing. The treatment system included a combination of ultrafiltration, reverse osmosis, granular activated carbon, and regenerable ion exchange media. The streams tested in the pilot system included groundwater, stormwater, and process wastewater to determine the effects of varying levels of non-PFAS constituents in the water. The results of the pilot study showed that the proposed configuration of treatment technologies can remove PFAS to below analytical limits of detection with starting concentrations in the parts per million range.

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Understanding the Transformation of PFAS Under Reductive and Oxidative Treatment

The list of PFAS pollutants is expanding rapidly. PFAS pollutants have various chain lengths and end functional groups. These structural features substantially impact the molecular reactivity under reductive and oxidative treatment. The efficacy and efficiency of PFAS degradation systems also depend on solution chemistry, such as pH and the source of reducing/oxidizing species. This presentation will summarize our recent findings from treating over 60 legacy and emerging PFAS structures. The structure-reactivity relationship and system performance improvement will benefit the design of remediation systems for most PFAS pollutants.

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Hydrothermal Alkaline Treatment: From Proof-of-Concept to Commerical Product

MIn 2019, Dr. Timothy Strathmann’s research group at the Colorado School of Mines discovered that highly alkaline, hydrothermal conditions could be used to destroy and mineralize perfluorooctanesulfonic acid (PFOS), one of the most recalcitrant and widespread PFAS compounds. Now, in 2023, hydrothermal alkaline treatment (HALT) is being deployed by Dr. Brian Pinkard’s team at Aquagga, Inc. for PFAS destruction applications at a commercial scale.
In the years between, a collaborative research partnership was formed, understanding of the underlying science and applications of HALT have been expanded, the technology was patented and licensed, and funding for technology development and scale-up was secured. In this talk, Dr. Strathmann and Dr. Pinkard will discuss the four-year collaborative journey which has taken the HALT technology from proof-of-concept to commercial product.

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Analytical and Process-Oriented Advances in Exhaust Emissions Testing for Thermal Treatment of PFAS During GAC Reactivation

Thermal treatment during granular activated carbon (GAC) reactivation typically entails high temperature reactions followed by off-gas treatment. Spent GAC is heated in furnaces (or hearths) devoid of oxygen using steam as a selective oxidant. Reactivated GAC is recycled back to facilities for continued use. During reactivation, PFAS adsorbed to spent GAC is either volatilized or pyrolyzed. Volatilized PFAS is destroyed in a Thermal Oxidizer as a secondary treatment step. Acid gases, such as Hydrogen Fluoride (HF), are removed by means of a chemical scrubber. Although thermal reactivation of GAC is widely used, few studies exist regarding the destruction and removal of PFAS breakdown products in the exhaust. The objective of this research was to quantitively evaluate the degree of removal and destruction of PFAS evolved from GAC in various process steps of thermal reactivation. State-of-the-art solid, liquid, and gas-train analytics—including Method 1633, Total Organofluorine Combustion Ion Chromatography (TOF-CIC) and TOF Extractable Organofluorine (TOF-EOF), OTM-45, Modified Method 0010, Method 0026A, and Whole Air Emissions Samples with Evacuated Canisters—were utilized to assess PFAS removal and destruction within GAC reactivation steps, with particular emphasis on assessing the presence and significance of Products of Incomplete Destruction PIDs).

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Supercritical Water Oxidation Destruction of Spent Filtration Media Generated During Remediation of PFAS-Contaminated Groundwater

On March 14, 2023, the US EPA (EPA) proposed the first-ever national drinking water standard for six per- and polyfluoroalkyl substances (PFAS). Compliance with these drinking water standards will lead to the deployment of hundreds, if not thousands, of PFAS remediation systems in the US over the next few decades. Treatment systems deploying filtration media generate PFAS-laden spent media will require further treatment to destroy the PFAS so it is not rereleased into the environment. Supercritical water oxidation (SCWO) is commercially available technology capable of mineralizing spent AIX and GAC and destroying PFAS. This presentation will examine the application of SCWO on spent GAC and AIX samples from three real-world PFAS remediation systems. It will include a discussion of the sources of the GAC and AIX, the SCWO technology used, and the results.

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Over Four Years of Using Regenerable Resin for PFAS Removal: Lessons Learned

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STAR and STARx: A Smoldering Solution to PFAS from Pilot to Field Scale Applications

Smoldering is a self-sustaining, flameless form of combustion that can reach the temperatures required for destruction of per- and polyfluoroalkyl substances (PFAS) with the use of a supplementary fuel. A study was conducted in partnership with the US Department of Defense (DoD) Strategic Environmental Research Program (SERDP) to evaluate the application of ex situ smoldering to treat PFAS-impacted soils and media with the use of low concentrations of granular activated carbon (GAC) as a supplementary fuel. This presentation will provide a summary of results at both laboratory and field scales, including a detailed understanding of the fluorine mass balance. An update on additional work in progress, including both ex situ and in situ smoldering pilot tests in collaboration with the US Air Force and DoD Environmental Security Technology Certification Program (ESCTP) will also be presented.

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Validation of Supercritical Water Oxidation to Destroy Perfluoroalkyl Acids

Hydrothermal destruction, specifically super critical water oxidation (SCWO), may be a viable option for mineralization of per- and polyfluoroalkyl substances (PFAS). Super critical conditions for water occur at pressures greater than 22 mega Pascals and can achieve temperatures as high as 650 degrees Celsius. At this extreme condition, concurrent unimolecular decomposition and bimolecular thermal oxidation of PFAS is believed to occur. A field-scale demonstration of SCWO was performed on a 1,000-fold dilution of aqueous film-forming foam (AFFF) concentrate. Performance data was collected from the aqueous and gaseous discharge. Gaseous discharge sampling was performed using isokinetic sampling from stack emissions and USEPA OTM-45 in one of the first field-scale implementations of this method. The destruction removal efficiency for perfluorooctane sulfonic acid (PFOS), the PFAS with the highest concentration in the subject AFFF, was 99.9999%. A fluoride mass balance was attempted and a discussion of comparative energy usage is presented.

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Full-Scale Operation of SCWO to Treat PFAS from Industrial Wastewater, Landfill Leachate and AFFF

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AVANTech PFAS Powder Ion Exchange (APPIX) Technology Development

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Insight Into the Next Chapter of PFAS Management: Residuals Treatment and Disposal

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Multi-Stage Counter Current Foam Fractionation Process for Removal of PFAS from Waste Derived Leachates: A Case Study

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Future-Proof Your Choice of PFAS Treatment with PFAS Selective Ion Exchange

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A Comprehensive Evaluation of Sorbent Media Performance, Sustainability, and Regenerability to Optimize PFAS Remediation

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Thermal Remediation Near Complex Infrastructure

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UV/SGM: A Scalable PFAS Destruction Technology

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Molecular Basis and Evolutionary Origin of 1-Nitronaphthalene Catabolism in Sphingobium sp. Strain JS3065

There are 41,000 chemicals in commerce in the US and new compounds are invented regularly. When synthetic organic compounds enter the biosphere bacteria often evolve catabolic pathways by recruitment of genes from existing pathways for degradation of natural organic compounds. Such plasticity and the resulting metabolic diversity ensure destruction of most simple xenobiotic compounds. Usually it is possible to speculate on the origins of the genes, but the mechanisms of their recruitment are less obvious. Nitroaromatic compounds are often biodegraded by pathways encoded by patchwork assembly of genes beginning with a dioxygenase clearly recruited from an archetypal naphthalene catabolic pathway. Biodegradation of monoaromatic nitro compounds is well understood, but biodegradation of polycyclic nitro compounds has not been reported. Here, isolation of bacteria able to degrade 1-nitronaphthalene provided the basis for in situ bioremediation of a nitronaphthalene contaminated site. Subsequent investigation of the molecular basis for nitronaphthalene revealed that the nitronaphthalene catabolic pathway is the likely progenitor of the widely studied nitroarene dioxygenases involved in degradation of monoaromatic nitro compounds. The findings shed light on the biochemical processes involved in the microbial degradation of globally important nitrated polycyclic aromatic hydrocarbons, and also provide an evolutionary paradigm for how bacteria respond to introduction of novel xenobiotic compounds with minimal alteration of preexisting pathways for natural organic compounds.

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Establishing an Integrated Analytical Platform for Microplastics Exposure Monitoring in Humans

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Microbial Chain Elongation: A More Efficient Process for Promoting and Sustaining In Situ Bioremediation of Chlorinated Solvents

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Microplastic Removal in Stormwater Control Measures: Known Unknowns and Ways Forward

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Smoldering Hydrocarbons, Waste Products, Contaminated Soils, and Recalcitrant Compounds at Scale

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Field Sampling and Treatability Studies to Support Monitored Natural Attenuation as a Remediation Strategy for CCR-Impacted Groundwater

Laboratory treatability studies and field sample collections are commonly used for proof-of-concept and/or derivation of site-specific remediation design parameters. These methods have been used to develop groundwater remedial options for a wide variety of contaminants including those found at coal combustion residual (CCR), industrial groundwater and former mine sites that are primarily impacted by metals or other inorganic species. An important consideration in groundwater remedy selection is the suitability of monitored natural attenuation (MNA) as a remedy component or as a stand-alone passive remedy. Part of evaluating whether MNA is an appropriate remedial technology at a metals contaminated site, such as those found at CCR sites, involves the demonstration of the type(s) and longevity of ongoing natural attenuation processes, including the capacity of an aquifer to attenuate site-specific constituents. This requires the characterization of groundwater and/or aquifer solids geochemistry as well as subsequent column and/or leachability testing. This presentation will focus on the use of (i) a suite of field sample collection tools and data analysis approaches and (ii) microcosm and column treatability testing to evaluate groundwater treatment options for redox sensitive metals such as arsenic (As) and chromium (Cr), including enhanced and natural attenuation options.

In one demonstration, a comprehensive laboratory program was developed and performed based upon the USEPA’s tiered approach to identify the natural attenuation processes, rates, attenuation capacities, and longevity. The program included a detailed evaluation of the aqueous geochemistry, aquifer matrix minerology and chemical composition, As speciation, adsorption and desorption reactions, and stability of the immobilized constituents. The laboratory results, along with a detailed conceptual site model, were used to develop a hydrogeochemical site model that described the fate of dissolved As downgradient of a CCR impoundment. In another demonstration, a fifteen column study was constructed with materials from four aquifer sources to test different commercial zero valent iron (ZVI) amended dosages and electron donor sources for the treatment of Cr(VI) and chlorinated volatile organic compounds (cVOCs). The multi-column study determined that both ZVI and electron donor amendments were able to effectively treat Cr(VI) and cVOCs and the results will be used to optimize the remedial design in the field.

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Fate of Per and Poly Fluoroalkyl Substances (PFAS) During Thermal Remediation

Recent laboratory work conducted by TerraTherm, the University of Texas, and Kruger, provide important insights into the destruction and removal mechanisms of PFAS during thermal treatment, by effectively tracking and closing the mass balance on the fluorine associated with the PFAS. These results indicate that target PFAS undergo 30 to 45% mineralization in the soil at 350-400°C, with the remainder being removed in the vapor stream as non-target PFAS and/or PFAA precursors. Standard target PFAS in the vapor stream were below nanogram reporting limits. Closing the fluorine mass balance provides a basis for designing effective treatment strategies and methods for both the soil and produced vapor stream and ensures that target PFAS and associated non-target PFAS are effective destroyed and/or captured. For example, the vapor stream from the thermally treated soil can then be passed through sorbents (e.g., granular activated carbon) or other treatment technologies to remove remaining polyfluorinated substances. Using this approach, very little of the standard target PFAS mass is produced in the vapor and liquid discharge streams and 100% of the fluorine mass can be accounted for. This presentation will present the results of the laboratory work and the approach that would be used for high-temperature thermal remediation of PFAS impacted soil, including project examples from similar applications.

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Source Area Bioremediation in Fractured Bedrock with Karst Features Revisited as Sustainable and Resilient Remediation

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Delivering Micro-scale Zero-Valent Iron and Bioremediation Amendments using Hydraulic Fracturing for Lasting Semi-Passive Treatment of Low-Permeability Zones

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The Role of Total Organic Fluorine Measurements as a Screening Tool for PFAS

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PFAS Fate and Transport Considerations

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Synergistic Defluorination and Mineralization of PFAS

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Advancements in Analytical Techniques to Demonstrate Successful Mineralization of PFAS

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Advancements in Analytical Techniques to Demonstrate Successful Mineralization of PFAS

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Using REMChlor-MD to Evaluate PFAS Fate and Transport While Incorporating Matrix Diffusion and Precursor Transformation

There has been extensive research on modeling per- and polyfluoroalkyl substance (PFAS) transport in the vadose zone. However, there has been much less research on modeling PFAS fate and transport in the saturated zone, particularly regarding matrix diffusion. Building on previous work, this study presents a novel application of a publicly available fate and transport model (REMChlor-MD) for simulating PFAS plume migration, including transformation of precursors to PFAA end-products, and forecasting the future outcomes of active and passive PFAS plume remediation strategies. Results of this modeling study will be presented, including comparisons against field data from a former AFFF site, potential future plume migration, impact of matrix diffusion, and contribution of precursor transformation to the persistence of PFAS plumes.

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Evaluation of Injectable Amendments for In Situ Treatment of PFAS-Impacted Groundwater

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Analyzing PFAS in Wastewater Treatment Plants: Analytical Challenges, and Statistical Insights into Spatial-Temporal Variability, and Potential Precursor Transformation

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PFAS Groundwater Transport Toolkit

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Low-Temperature Persulfate Activation by Powdered Activated Carbon for Simultaneous Destruction of Perfluorinated Carboxylic Acids and 1, 4-Dioxane

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Suggestions on Using Lysimeters to Determine the Potential of PFAS to Leach from Soil to Groundwater

The use of suction lysimeters at AFFF release areas has been proposed to collect porewater samples for determining the mass flux of PFAS to groundwater. In addition, lysimeter data are being proposed to establish surface soil cleanup values that are protective of groundwater. EPA technical staff reviewed work plans and investigation results involving lysimeters and provided suggestions to improve the utility and reduce the variability of results. Overall, EPA technical staff view suction lysimeter samples as not reproducible because the volume of soil that the sample represents depends on soil-water content which is spatially and temporally variable. Consequently, lysimeters are appropriate for qualitative comparisons of mass flux to groundwater. This presentation will cover our understanding of lysimeters and suggestions for using them in a weight of evidence approach when developing site-specific PFAS cleanup levels that are protective of groundwater.

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Analyzing PFAS in Wastewater Treatment Plants: Analytical Challenges, and Statistical Insights into Spatial-Temporal Variability, and Potential Precursor Transformation

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In Situ Thermal Treatment of PFAS in Vadose Zone Soils

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Vertebrae™ Segmented Horizontal Wells to Monitor PFAS Mass Flux/Discharge

The purpose of this project is to field-validate the Vertebrae™ segmented nested horizontal well system (Vertebrae well system) or VWS) for long-term monitoring of contaminant mass flux/discharge over time. Three 8-port well VWSs were installed at Grayling Army Airfield (Grayling MI): shallow and deep systems along a transect across plume perpendicular to groundwater flow, and one “longsect” system along the axis of the plume in the direction of groundwater flow. Flux measurement methods specific to the VWS were developed and demonstrated through field testing and method comparisons. Multiple groundwater flux estimation methods were successfully adapted to the Vertebrae system and appear to yield reasonable and consistent darcy flux values.The VWSs approach is novel and advantageous because multiple closely spaced measuring points across a transect can be easily installed from a single boring (reducing costs) and contaminant zones that may have been previously inaccessible via vertical boreholes can be characterized.

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Tracking PFAS in an Island Environment

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Photoactivated Reductive Defluorination as a Mechanism for PFAS Destruction

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To Be or Not To Be a PFAS

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A Screening Model for Quantifying PFAS Leaching in the Vadose Zone and Mass Discharge to Groundwater

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Developing PFAS Source Remediation Priorities Using Predictive Groundwater Modeling

Adequately modeling PFAS movement in groundwater is problematic because of the large population of PFAS compounds, the transport properties unique to each PFAS, and the lack of well constrained literature values for transport properties. Ramboll calibrated site-specific distribution coefficients and groundwater source concentrations for PFOA, PFOS, PFNA, and longer chain PFAS compounds by fitting the model to several rounds of site groundwater monitoring data and data from an on-site treatment system. Predictive contaminant transport simulations were then run to simulate PFAS transport from the beginning of AFFF use to 30 years into the future as a baseline. This modeling approach was used to successfully prioritize source remediation at an AFFF site, and based on these PFAS modeling results, Ramboll was able to recommend potential future remedial actions that would be expected to have the greatest material impact on operating costs and timeframes of the treatment system.

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A Study of PFAS Analytical Methods Applied to Wastewater for the Purpose of Assessing Impacts to Surface and Drinking Water

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Understanding Sources, Measurement and Occurrence of Ultrashort PFAS

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Understanding Sources, Measurement and Occurrence of Ultrashort PFAS

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Field Testing of the Sentinel Passive Sampler for PFAS Measurement in Environmental Waters

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Developing Robots for Autonomous Characterization of Contaminated Soils

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Microbial Metagenomics to Estimate Field-based Biodegradation Rates: Examples of 1,4-Dioxane and Chlorinated Solvents Mixtures

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Combining Micro-Scale Zero-Valent Iron and Bioremediation to Treat Chlorinated Solvent Plumes

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Adaptive Sampling Algorithm for Rapid and Efficient Autonomous Screening of Soil Contaminant Distributions at Large Sites

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Adaptive Sampling Algorithm for Rapid and Efficient Autonomous Screening of Soil Contaminant Distributions at Large Sites

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Occurrence and Mitigation of 1,4-Dioxane in the Long Island Water Cycle

1,4-Dioxane is a probable human carcinogen and a widespread contaminant in Long Island water supplies, with some of the nation’s highest concentrations detected (up to 34 μg/L). Analysis of the Unregulated Contaminant Monitoring Rule 3 data from the USEPA revealed that 39 water districts/distribution areas in Long Island had detections of 1,4-dioxane greater than the EPA’s cancer risk guideline level of 0.35 μg/L. Furthermore, recent studies have confirmed the presence of very high levels of 1,4-dioxane in several household products and thus domestic wastewater could potentially serve as an important and ongoing source of 1,4-dioxane pollution in the environment. Due to its environmental persistence, conventional water and wastewater treatment processes are not effective in removing 1,4-dioxane. A combination of concentrated onsite wastewater treatment systems, sole-source aquifer, and elevated background 1,4-dioxane levels in groundwater, as observed in Long Island, NY, presents a unique challenge to prevent further contamination via wastewater discharges. This presentation will summarize recent works from our group: (i) a pilot-scale evaluation of different Advanced Oxidation Processes (AOP) technologies to treat 1,4-dioxane; (ii) the occurrence of 1,4-dioxane in septic systems confirming domestic wastewater as a source of 1,4-dioxane pollution in Long Island aquifer, and (iii) the performance of an innovative and alternative onsite wastewater system called the Nitrogen Removing Biofilters (NRBs) to remove 1,4-dioxane from domestic wastewater.

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Optimization of a Combined Active and Passive In Situ Remediation Approach for High Concentration Metals in Groundwater

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Artificial Intelligence for Obstacle Avoidance and Autonomous Exploration by Robotic Platforms

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Establishing the Prevalence and Relative Rates of 1,4-Dioxane Biodegradation in Groundwater to Improve Remedy Evaluations

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A Multi-Class Machine Learning Approach to Source Identification for PFAS in Environmental Samples: Testing Against Unknown Samples

This presentation will discuss work carried out in collaboration with Brown and Caldwell involving a blinded test of a recently-developed multiclass method for source identification of PFAS in environmental samples. The method builds on previous work, but is adapted to provide probabilities of different source types, in addition to making an overall assessment of whether PFAS is likely of AFFF or non-AFFF origin. Methods permitting the use of data with different subsets of analyzed PFAS components allowed for the use of a training dataset of more than 13,000 samples from a highly diverse range of sites. A blinded test was conducted where Brown and Caldwell provided de-identified unknown sample data which were classified with the method. Results showed extremely strong performance of the method both in terms of its ability to identify the likely sources of unknown samples, and its ability to make more subtle distinctions between sample origin.

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Bioremediation of Chlorinated Solvents and 1,4-Dioxane in Low-Permeability Settings Using Fracture-Connected Wells

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Bioremediation of Chlorinated Solvents and 1,4-Dioxane in Low-Permeability Settings Using Fracture-Connected Wells

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Combined Remedy: Non-ZVI Chemical Reduction with Colloidal Carbon

Background Activated carbon (AC) sequestration of contaminants has become a go-to strategy for in situ remediation of petroleum sites for over 20 years. It is often combined with other amendments to add treatment components, e.g., biological or chemical oxidation. More recently, activated carbon has been applied to chlorinated solvent sites with chemical reduction additives that are based on zero valent iron (ZVI). In both cases there is an ongoing industry and regulatory debate as to which process dominates, sequestration or the treatment chemistries. Cascade, an industry provider of colloidal carbon chemistries, through our internal R&D program, has developed a patent pending “ColloidalChem +ISCR” technology that combines a novel chemical reduction using sodium dithionite with activated carbon that has distinct advantages for in situ treatment of PCE and TCE when compared with conventional approaches.
An exploratory laboratory research program was focused on coupling potential contaminant destruction reactions with the effective adsorption properties of activated carbon. These experiments were run from 7 to 14 days and generally focused on the destruction of 10 mg/L of either PCE or TCE in water. Reactions were monitored by GC/MS, and intermediates were quantified. Formation of ethene and ethane products were evaluated by GC/FID. This work has resulted in discovery of a new chemical remediation process whereby activated carbon surfaces facilitate chemical reduction of the carbon-chlorine bonds of VOCs such as chlorinated ethenes. This new chemistry allows enhancement of activated carbon treatment in many scenarios, including the in situ treatment of PCE and TCE with colloidal forms of activated carbon.
Results / Lessons Learned Thorough reactivity studies have provided unequivocal evidence of the destruction of PCE and TCE by sodium dithionite/AC mixtures with minimal generation of the toxic daughter products dichloroethene and vinyl chloride. Analysis of dissolved gases confirmed the formation of ethene and ethane in reaction mixtures. The mechanism of these reactions is under investigation, and early reactivity data coupled with carbon-free control experiments emphasize the importance of the activated carbon surface in these transformations. Compared with earlier literature reports of the use of dithionite for TCE remediation on mineral surfaces, this new carbon-based reaction is much faster and more reliable. Compared with conventional ISCR based on iron metal particles (ZVI), the use of the water-soluble dithionite provides a distinct injection application advantage where injection of solid metal particles is challenging. The potential of this new ISCR technology will be discussed, along with currently unanswered questions, ongoing topics of study, and plans for field implementation and commercialization.

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Prediction of 35 Target PFAS in California Groundwater Using Multi-Label Semi-Supervised Machine Learning

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Prediction of 35 Target PFAS in California Groundwater Using Multi-Label Semi-Supervised Machine Learning

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A Candidate for the Next Potential Worldwide Emerging Contaminant: Short-Chained Chlorinated Paraffins

Short-chained chlorinated paraffins (SCCPs) are widely used in industry today and in the past. SCCPs are mobile in the environment and have been found worldwide, including far from industrial sources. There is a growing body of research documenting their toxicity, and there are potentially thousands of congeners with a wide range of physicochemical properties. This presentation introduces SCCPs with a summary of what they are, how they are used, where they have been found, and their toxicity.

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Direct Push Technology Injection of Solid Amendments for In-Situ Remediation: Best Practices Developed from Applications in Europe and North America

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Degradation of 1,4-Dioxane and CVOCs by Iron Impregnated Activated Carbon (CAT100)

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Investigation and Remediation of Strategy for a Fast-Moving 1,4-Dioxane Plume at a Military Site

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The Evolution of Two Remediation Methods: Combined In Situ Stabilization and In Situ Chemical Oxidation

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Reducing Time of Remediation at Clay and Fractured Rock Sites

Remediation in clay dominant and fractured bedrock environments is among the most challenging remediation site conditions recognized globally, commonly resulting in failed injections, excessive surfacing of injectate, minimal distribution, significant rebound post remediation, unidentified pockets of residual NAPL mass, and years to decades longer remediation timeframes. The primary limitation is diffusion and secondary permeability that is not interconnected through the zone. The objective of the approach is to achieve increased distribution through the target treatment zone such that the target contaminants can be reached and remediated. Results presented for multiple projects with different site conditions and with different injected media for chlorinated compounds and heavy metals. Injection propagation mechanics for hydraulics is also presented to highlight the benefits of the selected approach, (2) the use of proppants is presented to highlight the benefits of reusable proppant fractures, and (3) tilt metering survey presented to demonstrate successful radius of distribution.

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Reducing Time of Remediation at Clay and Fractured Rock Sites

Remediation in clay dominant and fractured bedrock environments is among the most challenging remediation site conditions recognized globally, commonly resulting in failed injections, excessive surfacing of injectate, minimal distribution, significant rebound post remediation, unidentified pockets of residual NAPL mass, and years to decades longer remediation timeframes. The primary limitation is diffusion and secondary permeability that is not interconnected through the zone. The objective of the approach is to achieve increased distribution through the target treatment zone such that the target contaminants can be reached and remediated. Results presented for multiple projects with different site conditions and with different injected media for chlorinated compounds and heavy metals. Injection propagation mechanics for hydraulics is also presented to highlight the benefits of the selected approach, (2) the use of proppants is presented to highlight the benefits of reusable proppant fractures, and (3) tilt metering survey presented to demonstrate successful radius of distribution.

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What Will it Take to Commercialize and Widely Adopt Destructive PFAS Technologies?

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Recent Advances in Understanding PFAS Bioaccumulation and Toxicity in Aquatic Ecosystems

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Biotransformation of Perfluoroalkyl Acids by Acidimicrobium sp. Strain A6, and Potential Applications for Remediation

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Chemical-Free Light-Driven Destruction of PFAS Using Non-Toxic Boron Nitride

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An Evaluation of PFAS Avian Tissue Distribution: Implications on Ecological Risk Assessments

Internal concentrations of chemicals have been used in ecological risk assessments as a measure of exposure in that it takes into account aspects of bioavailability, routes of exposure, assimilation, and metabolic capacity Tissue-based toxicity reference values (TRV) for birds, typically try to extrapolate surrogate toxicity data to a species of interest, but these extrapolations can be uncertain. This is especially true for perfluoroalkyl substances (PFAS) that with varying capacities, can partition into lipid as well as bind to proteins. As a result, PFAS tissue distribution can be species specific. To address this issue, a critical examination of tissue distribution data from avian studies was conducted that focused on species/tissue specific differences in metabolic capacity, protein binding characteristics and lipid classes. Insights into how this information can be used to establish TRVs in birds that include the use of tissue normalization approaches and chemical activities will be discussed.

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Biotransformation of 6:2 Fluorotelomer Sulfonate in AFFF-Impacted Soil: Microcosm and Column Studies

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The Promise (or Limitations) of Anion Exchange Resins for Treatment of PFAS-Impacted Groundwater: Removal and Regeneration

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Bioavailability, Bioaccumulation, and Toxicity of PFAS in Benthic Biota Exposed to Impacted Marine Sediments

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Structure-Specificity of Microbial Biotransformation of PFAS and its Implications

Carbon-fluorine (C–F) bond is the strongest single bond in nature. Per- and polyfluoroalkyl substances (PFAS) are a large group of man-made chemicals with broad applications causing severe environmental concerns due to their persistence and toxicity. Although microbial defluorination of naturally occurring and less fluorinated compounds, such as monofluoroacetate, has been well studied, biodefluorination pathways and mechanisms of highly fluorinated PFAS have not been clearly understood. The first and critical questions to address include which PFAS structures could be biotransformed by which microorganisms in which conditions. In this presentation, the specific moieties in PFAS structures, which are preferred by different microorganisms to attack, will be summarized according to experimental studies so far. The involved biotransformation reactions and pathways will be explained. The implications of the structure-biodegradability relationships on the assessment of environmental fate, source-tracking, cost-effective treatment of PFAS, and the design of biodegradable alternative PFAS will be discussed at the end.

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Bioremediation 3.0: Programming Biology for Bioremediation

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Recent Advances in Surface Active Foam Fractionation for PFAS-Contaminated Water Treatment

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PFAS: Novel Toxicity Mechanisms Based on Their Surfactant Properties

Often referred to as “forever chemicals,” per- and polyfluoroalkyl substances (PFAS) are a large class of human-made chemicals that exhibit high persistence in the environment and that have been found in a variety of consumer products, environmental media, and biological samples across the globe. Due to concerns about their health effects and persistence, some PFAS, such as PFOS, have seen their manufacturing and use restricted in most countries by an international agreement in 2009. However, PFOS remains detectable in environmental and biological samples and many other PFAS are still in production. Here, we will briefly review some of the well-accepted toxicity mechanisms associated with PFAS exposure before presenting some of our recent work comparing the toxicity of a legacy PFAS (PFOS) and an emerging PFAS (6:2 Cl-PFESA). We propose that a unifying mechanism of their toxicity can be found in their surfactant properties that disrupt the function of intracellular molecular condensates, essential for proper cellular functioning and for reproduction.

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Biodegradation of Fluorotelomer-Based PFAS by Soil Cultures Enriched with Various Carbon Sources

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Technology Readiness of Electric Induction for Onsite Treatment of PFAS Contaminated Soils

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Influence of Activated Carbon on Microbial Transformation of Chlorinated Solvents and Explosives

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Remediation of Benzene and Attenuation of Metals in Groundwater Using Activated Carbon-Based Amendment

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The Impact of Activated Carbon Grain Size on Bioremediation

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Employing Solid Phase Colloidal Organic Amendments for Sustained Biodegradation in Permeable Reactive Barriers

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