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Emerging PFAS destruction technologies

March 9, 2023
Emerging PFAS destruction technologies To address PFAS in the city of Bemidji's water supply, Barr designed an 8,500-square-foot plant for fast-track construction. The plant began continuous operations in March 2021—only 14 months after the start of design.

PFAS are persistent in the environment, accumulating in soils, groundwater, surface water, and the atmosphere until they are actively removed and destroyed. PFAS waste management has increasingly focused on final fate and the need to destroy (mineralize) these chemicals to avoid potential future liability associated with the potential for re-release to the environment. High-temperature technologies such as incineration, thermal oxidation, and granular activated carbon (GAC) thermal reactivation are the only PFAS destruction technologies currently applied on a large scale (e.g., over 100 tons of material per day) and operate at temperatures of over 1,000°C. The future regulatory climate for these high-temperature technologies remains uncertain under recent moratoriums on incinerating specific PFAS-containing wastes by the Department of Defense and the states of New York and Illinois. Disposal costs via high-temperature incineration are around $1,000 to $2,000 per ton of material, based on information summarized in recent EPA guidance.1 

Due to the high cost of disposal as well as uncertainties concerning the final fate of PFAS, there is a growing need for new PFAS destruction technologies.

Due to the high cost of disposal as well as uncertainties concerning the final fate of PFAS, there is a growing need for new PFAS destruction technologies. Generally, PFAS destruction technologies are most cost-effective for concentrated waste streams rather than dilute aqueous streams. These concentrated streams include solid material like spent sorption media such as GAC or anion exchange resin (AER) and concentrated liquid streams like aqueous film-forming foam (AFFF), foam fractionation foamate, and ion exchange still-bottoms.

The PFAS destruction market is likely to have space for multiple technologies, each of which has different strengths and weaknesses. Which PFAS destruction technologies are relevant or useful to a specific project will depend on required throughput, the type of water or waste requiring treatment, upstream PFAS separation and concentration processes, and which PFAS are targeted for destruction. 

Priorities by which these technologies should be evaluated include: 

  • Demonstrated PFAS destruction efficacy at real sites with complete fluorine mass balances (or as complete as current analytical capabilities allow) showing mineralization of PFAS to non-PFAS end products

  • Potential for PFAS to escape to the atmosphere in gaseous or vapor phase, especially for high-temperature processes such as pyrolysis and incineration

  • Ability to remove short-chain PFAS (short-chain PFAS are typically more challenging to remove and mineralize relative to long-chain PFAS)

  • Net energy costs of treatment, which depends strongly on the ability to recover and/or produce energy 

  • Potential for enhanced performance with salty feed streams 

  • Regulatory uncertainty, especially considering existing moratoriums on incineration of PFAS; however, ongoing uncertainty regarding PFAS waste designations and permitted disposal routes is likely to continue into the foreseeable future

Both academic researchers and technology startups have recently flooded the market with emerging PFAS destruction technologies. Supercritical water oxidation (SCWO), pyrolysis/gasification, hydrothermal alkaline treatment (HALT), and electrochemical oxidation (EO) are current market forerunners, but there is still relatively limited data available for all four technologies at commercial scales.2 SCWO and pyrolysis/gasification are most applicable for slurries and solid waste streams while HALT and EO are most applicable for aqueous and liquid wastes. 

Technologies to destroy PFAS in slurries or solid wastes: 

  • SCWO uses a combination of heat and pressure to destroy PFAS and other organic materials and has demonstrated destruction of short-chain PFAS. It is most applicable for wastes that have high energy contents, such as biosolids or sorption media, and is less applicable for water. SCWO also has the potential to be energy-positive through recovery of heat from high-energy feedstocks. 

  • Pyrolysis and gasification are related technologies that limit oxygen inputs during high-temperature treatment. They are likely to be most applicable to wastewater biosolids and would be paired with thermal oxidation to manage off-gas. However, the destruction efficacy of PFAS in the gas phase needs further evaluation. 

Technologies to destroy PFAS in liquid wastes: 

  • HALT also uses heat and pressure to degrade PFAS molecules but adds alkaline chemicals to raise the pH, which enables PFAS degradation at lower temperatures and pressures compared to SCWO. HALT has demonstrated short-chain PFAS destruction and can likely be implemented at smaller sites to treat concentrated aqueous streams.  

  • EO is a low-temperature process that uses electricity to oxidize PFAS but has not demonstrated the same ability to mineralize short-chain PFAS as the other three processes listed here. It has the advantage of being implementable at smaller sites. EO is most applicable to aqueous-phase PFAS in salty liquids and can operate at lower temperatures than SCWO or HALT. However, EO typically requires more energy input to oxidize PFAS.  

Barr has been evaluating commercially available technologies to support ongoing water treatment projects related to PFAS for several years. Barr is currently working with the Minnesota Pollution Control Agency (MPCA) to evaluate PFAS technologies and their commercial viability for a variety of waste streams, including municipal wastewater, biosolids, and landfill leachate. For additional information, contact our team of PFAS experts.

1 “Interim Guidance on the Destruction and Disposal of Perfluoroalkyl and Polyfluoroalkyl Substances and Materials Containing Perfluoroalkyl and Polyfluoroalkyl Substances,” U.S. EPA, December 18, 2020. 

2 “PFAS destruction vendors look to shatter short-chains as commercial projects loom,” Global Water Intelligence Magazine, November 17, 2022. 

Related projects 

Water reuse system design

When a confidential manufacturing client needed help addressing PFAS in their wastewater, Barr was hired to design a treatment system for PFAS as well as a pre-treatment system that enhances PFAS removal. Later, when the client wanted to convert their facility to “zero discharge” to save the costs and time involved in permitting with the local municipality—and to further protect human health and the environment—they turned to Barr to add a second system that reroutes discharge for additional treatment followed by reuse as process water.

Worker using high-pressure water spray

Multi-site PFAS remedial investigation and remediation

PFAS have been detected in public water supplies and private wells at or near active and former manufacturing facilities owned by Saint-Gobain. At these sites in the eastern United States, a group of potentially responsible parties is working with local, state, and federal regulatory authorities. Barr is part of a collaborative consulting team conducting remedial investigations and feasibility studies. Barr has conducted PFAS water-treatment bench- and pilot-testing, evaluated treatment-technology options such as granular activated carbon and ion exchange, and designed a full-scale pretreatment system.

Well drilling observation for contaminated site investigation.

PFAS treatment during power plant decommissioning

While decommissioning a former power plant, a confidential client found water contaminated with PFAS in the process of dewatering the facility’s basement. After discovering the PFAS, the client hired Barr to characterize impacts and develop a water treatment system.

About the authors 

Andy McCabe, PhD, environmental engineer, is passionate about all facets of water chemistry and water/wastewater treatment, especially those involving treatment and management of PFAS and other emerging contaminants. At Barr, Andy has the opportunity to help industrial and municipal clients identify, design, and optimize water and wastewater treatment systems. He has been with Barr since 2018. He has a BS in biochemistry from the University of Minnesota-Duluth and a PhD in civil engineering from the University of Minnesota-Twin Cities.

Ali Ling, PhD, former environmental engineer and water/wastewater process engineer at Barr, specialized in connecting basic science to engineering outcomes for clients in various industries, using tools like bench and pilot testing and process modeling. Her work included helping clients solve challenging problems associated with PFAS, active pharmaceuticals, and other contaminants of emerging concern. Ali helped facilitate Barr’s involvement in applied research and university collaborations. She has an academic background in microbial ecology and applied microbiology.

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PFAS PFOA PFOS Technology Water

 

Andy McCabe, PhD
Andy McCabe
PhD, Environmental Engineer
Ali Ling, PhD, Environmental Engineer
Ali Ling
PhD, Environmental Engineer
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