In updated PFAS disposal and destruction guidance, EPA evaluates existing and emerging technologies

This week, the EPA published an update to its interim guidance on the available disposal and destruction technologies for PFAS-containing materials. This guidance provides valuable insight into the agency’s views on currently available technologies, as well as its plans to evaluate emerging technologies and address existing research gaps.

BY WALKER LIVINGSTON, ESQ | APR 12, 2024 4:54 PM CDT

Background: PFAS

• Per- and polyfluoroalkyl substances (PFAS) are a group of synthetic organic chemicals that have been used in the U.S. for decades in many different industrial, commercial and consumer applications. The term “PFAS” generally refers to a group of chemicals with at least one or two fully fluorinated carbon atoms, where each hydrogen bond has been replaced with a fluorine atom. These carbon-fluorine bonds are extremely strong, which allow the chemicals to repel both water and oil as well as exhibit stability through a wide range of environmental stressors.
• The EPA has previously defined PFAS as any chemical that contains at least one of the following three structures: (1) R-(CF₂)-CF(R’)R’’, where both the CF₂ and CF moieties are saturated carbons; (2) R-CF₂OCF₂-R’, where R and R’ can either be F, O, or saturated carbons; and (3) CF₃C(CF₃)R’R’’, where R’ and R’’ can either be F or saturated carbons. This means that at least one carbon atom has had all hydrogen atoms replaced with fluorine atoms. However, other groups, like the Organisation for Economic Co-operation and Development (OECD), have also issued their own definitions for PFAS.
• PFAS have been used in many different industrial and consumer products including textiles, high-performance coatings, semiconductor production, and firefighting foams (aqueous film-forming foams, or AFFFs).
• In 2020, the EPA published an interim guidance detailing the available methods for PFAS destruction and disposal. The guidance was mandated by section 7361 of the Fiscal Year (FY) 2020 National Defense Authorization Act (NDAA) as part of a larger Congressional focus on better understanding PFAS contamination and remediation around the country. The NDAA also requires that the EPA review and revise this guidance at least once every three years to ensure that it contains up-to-date information.

Now, the EPA has updated its interim guidance on the destruction and disposal of PFAS

• On April 9, 2024, the EPA published an updated interim guidance on destroying and disposing of PFAS. The guidance focuses on the currently available technologies for disposing PFAS-containing materials and the best practices for the use of these technologies so as to minimize releases of PFAS into the environment. The primary intended audience is decision-makers who are in the position to determine how PFAS-containing waste may be disposed of or destroyed; however, the guidance is also intended for review by interested members of the public.
• Scope: Six specific PFAS-containing materials identified in FY2020 NDAA section 7361: (1) AFFFs; (2) soil and biosolids; (3) textiles, other than consumer goods, treated with PFAS; (4) spent filters, membranes, resins, granular carbon and other waste from water treatment; (5) landfill leachate; and (6) solid, liquid or gas waste streams from facilities manufacturing or using PFAS. Although the methods included in the guidance are primarily centered on these six material groups, the EPA notes that these technologies may also be suitable for other PFAS-containing materials.
• Focus: Three “widely-used, commercially available” destruction and disposal methods: Thermal treatment, landfills and underground injection. The guidance also dedicates a short discussion to other emerging technologies (with a focus on non-thermal destruction of PFAS) that may become more widely used in the future.
• An important consideration: The relative potential of each technology to release PFAS into the environment. Although the EPA offers a discussion of this crucial consideration, it includes a caveat that performance and testing data for these methods remain “generally limited,” suggesting that these practices may be reconsidered in the future. Currently, the agency has determined that interim storage with controls and underground injection provide the lowest relative potential to release PFAS into the environment; construction and demolition landfills represent the highest relative chance of PFAS release.
• The table below details material type and proper destruction and disposal technologies:

Covered materials

• Solid, liquid or gas waste streams that contain PFAS from facilities manufacturing or using PFAS. Solid phase wastes can be generated via primary manufacturing or secondary processing of industrial uses of PFAS. This can include tars and polymers containing high molecular-weight byproducts that are fully or partially fluorinated. Liquid phase waste can be generated in the same manner, as well as via wastewater effluent discharged directly from a primary manufacturer or secondary processor. Gas phase wastes are generally understood to be emitted from manufacturing facilities, which can be deposited locally or across long distances.
• Aqueous film-forming foams (AFFFs). In 2004, there were about 4.6 million gallons of legacy PFAS-containing AFFF in the U.S. Due to the long shelf-life of the product, the EPA does not anticipate significant expiration-related disposal of AFFF products, which are still used in many federal facilities, airports, military installations and oil refineries, as well as in some civilian fire departments. According to the interim guidance, the federal government is currently working to identify federal properties where AFFF use occurred so as to better characterize the extent of contamination and the need for clean-up.
• Soil and biosolids. The focus of this subsection is mainly on the use of sewage sludge that is applied to land as a fertilizer or soil amendment, disposed of, or incinerated. One of the ways that PFAS contamination of land can occur is by the spreading of contaminated biosolids on farmland, which introduces the potential for leaching or runoff. The EPA does not currently have data on the occurrence of PFAS in biosolids, but is planning to include PFAS studies in the next National Sewage Sludge Survey.
• Non-consumer good textiles treated with PFAS. This category includes outdoor equipment, technical and occupational textiles (such as firefighting turnout gear), medical garments, and other fabrics treated with PFAS. The subsection is relatively short but does note that the most applicable destruction and disposal technologies for these applications would be landfill disposal or thermal treatment.
• Spent water treatment materials. These treatment materials include GAC filters, anion exchange (AIX) resins, and high-pressure membranes (e.g., for reverse osmosis (RO) and nanofiltration (NF)). This category will become much more relevant once the EPA’s National Primary Drinking Water Regulation for six different PFAS comes into effect in five years, after which time these materials will be disposed of much more frequently. While there is an available process to reactivate GAC filters, other filter types may be disposed of or destroyed via incineration or landfills.
• Landfill leachate. This liquid is formed by rainwater running through waste at landfills and can continue to accrue even after the closure of a landfill, either due to the presence of liquids in the waste or failure of the landfill cap. According to the guidance, this leachate can be treated either on- or off-site, with some options for off-site treatment including incineration, underground injection, or transport to wastewater treatment plants.

Technologies for disposal and destruction

• The third section of the guidance dives into the three major technologies currently available for PFAS destruction and disposal: Thermal treatment, landfilling and underground injection. For the purposes of this guidance, PFAS destruction is currently defined as “the severing of all carbon–fluorine bonds in a PFAS molecule and the mineralization of carbon and fluorine to CO2, [hydrogen fluoride] HF, and water.”
• Thermal treatment: This is the only technology discussed which offers a method of destruction. Traditional thermal treatment technologies include hazardous waste combustors (HWCs), industrial furnaces, municipal waste combustors (MWCs), thermal oxidizers and more. Although this technique does prevent further release of PFAS into the environment, the strength of the carbon-fluorine bonds requires the use of extremely high temperatures. The process must utilize a significant amount of hydrogen radicals (e.g., flames) to promote the breakdown of the molecule and the formation of HF. Each thermal treatment technology yields a different level of potential PFAS destruction, and each individual unit of that technology may operate at differing levels of efficiency. For example, HWCs have the potential to achieve destruction levels greater than 99.99% and reduce products of incomplete combustion (PICs); however, the EPA notes that “not every unit currently operates at those conditions and those that do may not operate at those conditions at all times.”
• Landfilling: Although not a method of destruction, landfilling can be extremely effective for minimizing PFAS release into the environment. The breadth of PFAS-containing wastes that can be addressed by this technology includes those with biodegradable elements (such as biosolids) as well as non-biodegradable elements from other industrial or commercial sites. Many hazardous waste landfills do not contain biodegradable waste, so PFAS-containing biodegradable wastes may not be able to be disposed in those landfills and may need to be disposed instead in municipal solid waste (MSW) landfills that have appropriate control systems to contain the release of PFAS into the environment. The subsection also contains a discussion of PFAS-containing materials, and which PFAS may be proper to dispose of in different types of landfills.
• Underground injection: This method of disposal is only suitable for liquid wastes in areas with appropriate geology due to the depth of the injection wells. PFAS-containing liquids are injected far below available drinking water resources via wells reaching thousands of feet into the earth. The EPA has determined that the use of Class I hazardous and non-hazardous waste wells for high-concentration liquid PFAS waste has a “lower potential for environmental release” than other PFAS destruction and disposal methods. These wells must be properly sited and permitted, however, and are covered under significant regulation in the Code of Federal Regulations. The country currently has 925 different Class I wells, with less than half permitted for non-hazardous industrial waste injection and about 15% permitted for hazardous waste injection.

Population considerations, identified research gaps and emerging technologies

• An entire section of the interim guidance is dedicated to ongoing concerns and considerations for vulnerable populations. The FY2020 NDAA required that the EPA consider potentially vulnerable populations living near destruction or disposal sites alongside the potential for PFAS to be released into the environment during destruction or disposal.
• Certain treatment activities could release PFAS into the environment during destruction or disposal; however, many of these releases would come from inadequate combustion conditions or uncontrolled leachate. The EPA points to risk assessment and communication as essential tools for helping protect communities and the environment from the release of PFAS. The agency recommends utilizing certain tools like EJScreen to help determine potentially vulnerable populations near PFAS destruction or disposal sites, as well as a suite of other tools that should help decisionmakers understand what communities may be affected.
• An entire section also focuses on uncertainties and research gaps, providing a table that delineates research needs (and priority levels) for each topic. Some recurring research needs that apply across topics include new methods for sampling and analyzing PFAS across all matrices, better characterization of PFAS releases, better ways to solidify and stabilize PFAS-containing wastes, and more. The EPA is attempting to help coordinate research across government, academic and private institutions to better address some of these research gaps for the future.
• Finally, a short section reviews four emerging destruction and disposal technologies: mechanochemical degradation, electrochemical oxidation, gasification and pyrolysis, and supercritical water oxidation. The guidance offers a focused discussion on a New Zealand proof-of-concept study evaluating mechanochemical degradation via a “high-energy ball-milling device, which produces “highly reactive conditions to degrade contaminants.” It also notes that research on the use of pyrolysis as another thermal treatment option for dried biosolids indicates removal efficiencies between 81.3% and 99.9%. Additionally, research on the use of supercritical water oxidation on dilute AFFF suggests a potential overall destruction efficiency of greater than 99%.

Insights from the guidance

• Although the guidance is not a regulation, it does provide key insights into the EPA’s current views on PFAS destruction and disposal technologies. With the release of the agency’s NPDWR for six PFAS (and several other regulations percolating up to final rules), the clock has begun ticking for improved destruction and disposal processes to ensure that municipalities, companies, and other organizations can meet both PFAS standards and the need for effective disposal and destruction technologies. While this guidance will undergo at least one additional revision prior to the effective date of the PFAS NPDWR, this version will likely serve as a cornerstone for many water system treatment decisions due to the capital contributions and time necessary to construct PFAS remediation technology. [ See AgencyIQ’s analysis of the PFAS NPDWR here.]
• With looming enforceable PFAS regulations, the EPA and other organizations are committing significant resources to identifying cheaper and more efficient methods for the destruction of PFAS. According to a study commissioned by the Minnesota Pollution Control Agency (MPCA), the cost of treating PFAS may range from $0.2 million to $18 million per pound, foretelling significant costs that will be borne by a variety of organizations. If the EPA and other organizations can determine cheaper and more effective methods of destruction, the costs to remediate PFAS will likely fall significantly, translating to lower costs for ratepayers for water utilities and other entities that will be required to remediate PFAS.

To contact the author of this analysis, please email Walker Livingston ( [email protected]).
To contact the editor of this analysis, please email Chelsey McIntyre ( [email protected]).

Key Documents and Dates

• • • Interim Guidance on Destroying and Disposing of Certain PFAS and PFAS-Containing Materials That Are Not Consumer Products (April 8, 2024)
    • Press release (April 9, 2024)
    • Docket: EPA-HQ-OLEM-2020-0527