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Search and Destroy: The Future of PFAS Remediation

Dora Chiang, PhD, PE
CDM Smith has been inves­ti­gat­ing PFAS destruction for nearly a decade. Discover the oppor­tu­ni­ties and risks associated with this approach.

With one of the strongest chemical bonds, per- and poly­flu­o­roalkyl substances (PFAS) upend conven­tional approaches and call for creative solutions. In our Februrary 2019 PFAS Newsletter we introduced two treatment tech­nolo­gies—granular activated carbon (GAC) and anion exchange resin (AIX). These methods use a sorbent (GAC or AIX) to separate PFAS from a drinking water or groundwater source. Though successful pilot and full-scale appli­ca­tions have elevated the profile of these separation tech­nolo­gies, they have not entirely solved the PFAS problem.  

Recir­cu­lat­ing PFAS in the environment from one media to another without destruction draws significant concern globally. Currently, there is no clear guidance on managing PFAS-laden wastes. As such, spent GAC or AIX are often disposed in local landfills or are incinerated at temperature below 1000°C, which removes PFAS from spent sorbent but does not destroy them. In addition, there are concerns about accidental PFAS releases during shipping and handling PFAS-laden wastes off site. To effectively neutralize PFAS as a threat to human health, researchers are increas­ingly testing the power of destruction tech­nolo­gies. 

When Destruction Works
Destruction technology, in the context of PFAS, is defined as a technology that can completely deflu­o­ri­nate PFAAs (such as PFOS and PFOA) to innocuous end products. PFAS destruction tech­nolo­gies typically require large amounts of energy and have higher price tags. Therefore, it’s important to selectively employ them on highly-concen­trated, low-volume targets, including: 
  • AFFF concen­trates 
  • Groundwater within PFAS source areas
  • Remediation waste streams (such as wastewater generated from regen­er­a­tion of GAC or regenerable ion exchange resin, foam frac­tion­a­tion, soil washing, rejected reverse osmosis concen­trates, chemical or electro-coagulation)
  • Landfill leachate
Often, the destruction technology is coupled with another form of treatment to generate a high-strength, low-volume concen­trated waste stream. 
Destruction technology...can completely defluorinate PFAAs (such as PFOS and PFOA) to innocuous end products.
Tread Carefully
There are numerous PFAS destruction tech­nolo­gies under development, conve­niently summarized in this ITRC PFAS Fact Sheet. Promising ex-situ destruction tech­nolo­gies include elec­tro­chem­i­cal, plasma and reductive options. These approaches have success­fully degraded an array of high-concen­tra­tion PFAS at the laboratory scale. However, none are suffi­ciently mature yet to assess PFAS treatment costs and overall effec­tive­ness with confidence at the field scale. 

Because of the emerging market for destructive PFAS tech­nolo­gies, they are often promoted hastily without demon­strat­ing complete deflu­o­ri­na­tion and without confidence the technology can meet stringent effluent discharge require­ments. Carefully consider the applic­a­bil­ity of these tech­nolo­gies for a specific site and/or application before investment in full-scale treatment systems.

 

The Road Ahead
The development and commer­cial­iza­tion of PFAS destruction tech­nolo­gies will not be easy. Several ex-situ destructive tech­nolo­gies have moved from flask to field, which include sonolysis, elec­tro­chem­i­cal oxidation and ultraviolet oxidative/reductive destruction. Careful consid­er­a­tion and under­stand­ing of PFAS trans­for­ma­tion and deflu­o­ri­na­tion must be incor­po­rated into the technology evaluation for a particular site/application with thoughtful design of bench and pilot scale systems to demonstrate technology and incorporate economic feasibility in the selection process. 

Consid­er­a­tion of balanced technology benefits and limitations that should be discussed with technology providers include: 
  • High energy demand and feasibility of high energy/cost at the scale required for the system
  • Health and safety concerns
  • Feasibility of operating large-scale systems, if required
  • Incomplete PFAS destruction resulting in accu­mu­la­tion of fluorinated inter­me­di­ates that are generated but not measurable
  • Feasibility of achieving stringent (i.e. very low) treatment require­ments
  • Effec­tive­ness in destroying all PFAS chemicals, including short chain PFAS    
  • Generation of non-PFAS toxic byproducts

At CDM Smith, our approach to assessing PFAS destructive tech­nolo­gies includes treata­bil­ity testing at the bench, pilot and full-scale using three lines of evidence, which results in more accurate veri­fi­ca­tion of PFAS destruction. And our collab­o­ra­tions with univer­si­ties and research foundations allow us to explore the latest analytical methods for under­stand­ing the destructive mechanisms, including Total Oxidizable Precursor Assay, nontarget PFAS analysis, and total extractable organic fluorine analysis. 

Read Dora's full white paper to learn more.

Dora Chiang Dora Chiang
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Full White Paper
Download Dora's full article, including additional information on risks associated with rushing into a destruction strategy. 
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