Exploring the opportunity for emerging PFAS destruction technologies

The presence of per- and polyfluoroalkyl substances (PFAS) in drinking water sources across the globe is raising concern, as evidence of the negative health and environmental effects of certain PFAS is growing. Additionally, the PFAS problem cannot be ignored in the hope of time alleviating the issue, as the two characteristic properties of PFAS are that they are persistent and bio-accumulative. 

As such, the issue of PFAS contamination can only be addressed through active intervention using treatment technologies designed to remove PFAS from contaminated water streams. Such PFAS treatment technologies for contaminated water streams are extensively covered in IDTechEx's market report, "PFAS Treatment 2025-2035: Technologies, Regulations, Players, Applications". 

Established water treatment technologies, such as adsorption filtration using granular activated carbon (GAC) and/or ion exchange resin (IER), can be utilized to effectively remove the most commonly regulated PFAS, like PFOA (perfluorooctanoic acid) and PFOS (perfluorooctane sulfonic acid), from groundwater and surface water. 

While these technologies are effective at removing PFAS from the environment, they cannot guarantee that captured PFAS will be permanently removed from the environment because they do not destroy the captured PFAS. Many advocates are concerned that removed PFAS may find its way back into the environment, creating a never-ending cycle of PFAS removal. 

For example, spent adsorption media (i.e., spent GAC, IER) that is landfilled could leach captured PFAS into the ground, allowing for previously removed PFAS to re-enter the environment. This creates a need for another category of PFAS treatment technologies to ensure that captured PFAS can never return to the environment: PFAS destruction technologies.

Current status of PFAS destruction technologies
PFAS destruction is defined by the US Environmental Protection Agency (EPA) as "the severing of all carbon-fluorine bonds in a PFAS molecule and the mineralization of carbon and fluorine to CO2, HF, and water." With any PFAS destruction technology, ensuring the complete severing of all carbon-fluorine bonds within the molecule is essential. Otherwise, more mobile short-chain PFAS may be formed and released during the destruction process.

The incumbent PFAS destruction technology is incineration, which has been used to destroy other contaminants and hazardous substances, including chlorinated solvents, polychlorinated biphenyls (PCBs), dioxin-laden wastes, and brominated flame retardants. Its application to destroy PFAS is comparatively newer than these other contaminants.

However, key authorities, like the US EPA, have been reluctant to fully endorse incineration as a strategy for PFAS waste management. In its Interim Guidance on the Destruction and Disposal of PFAS - Version 2, the US EPA highlights the uncertainties that continue to surround incineration for PFAS destruction -- namely the research and data gaps on its effectiveness and its production of PICs (products of incomplete combustion). 

Some advocacy groups express concerns over the energy-intensive nature of incineration and the potential production of harmful emissions. These concerns were enough to prompt the US Department of Defense (DOD) in 2022 to issue a moratorium on the incineration of PFAS-containing firefighting foam by the DOD.

Landscape of emerging PFAS destruction technologies
Concerns over incumbent strategies for PFAS waste management have created opportunities for novel PFAS destruction technologies to potentially disrupt the status quo. Universities and independent start-ups are developing numerous different destruction technologies. Six of the most advanced emerging PFAS destruction technologies are outlined below:

Electrochemical oxidation (EO): EO utilizes an electrochemical cell with an anode and cathode that generate reactive species (i.e. hydroxyl radicals, electrons) through two mechanisms (direct anodic oxidation, indirect oxidation). These reactive species break the carbon-fluorine bond of PFAS.

Supercritical water oxidation (SCWO): PFAS-contaminated water is pumped through a reactor, where liquid waste is heated and compressed above the critical point of water (374°C and 22 MPa). In this supercritical state, oxygen becomes soluble, and an oxidation reaction breaks the carbon-fluorine bond in PFAS.

Hydrothermal alkaline treatment (HALT): HALT is similar to SCWO, but it operates with a catalyst (i.e. sodium hydroxide), enabling the process to run at lower temperatures than SCWO (i.e. about 350°C in the subcritical phase).

Photochemical processes: This field can be segmented in multiple ways. In all photochemical destruction processes, UV light is used to activate certain compounds to break carbon-fluorine bonds in PFAS. When the process utilizes a photocatalyst (as opposed to a nonregenerative reagent), it can be categorized as a photocatalytic destruction process (or photocatalysis). This field can be broadly split into two categories, depending on the mechanism of PFAS destruction: advanced oxidation processes (AOP) and advanced reduction processes (ARP).

Plasma treatment: Plasma treatment utilizes thermal or non-thermal electrical discharge plasma to cleave the carbon-fluorine bond in PFAS.

Sonolysis: Also known as sonochemical oxidation, this relies on ultrasonic and/or megasonic sound waves causing cavitation in water. PFAS collect on the surface of these cavities; when the cavities implode, they create extreme temperatures and pressure to destroy the carbon-fluorine bond in PFAS.

Factors impacting trajectory of emerging PFAS destruction technologies
While concerns surrounding the incineration and landfilling of PFAS have supported the emergence of new PFAS destruction technologies, other factors impact its potential growth. 

For example, the common denominator between the most commercially advanced technologies is that all have limited commercial deployment, if at all, given how new this field is. This relative lack of case studies and data from full commercial applications may make it difficult for potential end-users to commit to adopting these new technologies.

Additionally, most of these emerging technologies can destroy PFAS in the liquid phase (i.e. in contaminated water streams) but not in the solid phase (i.e. on spent adsorption media). Only two, SCWO and HALT, can destroy PFAS-contaminated waste in both the liquid and solid phases. 

This is relevant as many technologies position themselves as an alternative to incineration for PFAS-containing solid waste like spent adsorption media, when in reality, a separate treatment step would be required to strip PFAS from the adsorption media into liquid-phase media that these destruction technologies could process.

Lastly, the single most important factor impacting the trajectory of emerging PFAS destruction technologies is regulations. While the reluctance from US regulatory authorities to fully support incineration has afforded emerging PFAS destruction technologies an opportunity to displace incineration, the lack of a permanent ban on incineration presents obstacles to its growth. 

It is possible that US regulatory authorities and/or the DOD reverse their course and support incineration as a PFAS waste management strategy, making it more difficult for emerging PFAS destruction technologies to gain traction. 

Additionally, there is a current lack of action against incineration in Europe, a key market for PFAS treatment. Changes in regulations surrounding the incineration of PFAS will be key to watch for the future trajectory of this field. Any changes to regulations outside of incineration (i.e. acceptable levels of PFAS in industrial process and wastewater) could also heavily impact PFAS destruction technologies.

-- Sona Dadhania, Senior Technology Analyst at IDTechEx, USA.