Due to growing concerns about PFAS, there’s a renewed interest in finding ways to destroy these chemicals permanently. WSP is progressing fast on implementing a proven and commercial solution to destroy PFAS in liquids. 

WSP researchers are seeing exciting progress in their quest to find a practical and sustainable solution to the PFAS challenge. 

Per-and Polyfluoroalkyl Substances, commonly referred to as PFAS, have found extensive application for over seven decades across various products such as firefighting foam, paints, cosmetics, breathable outerwear, and non-stick cookware. While initially commended for their perceived particularly due to the robust carbon-fluorine bond—one of the most durable in nature, earning them the moniker "forever chemicals" -- there is now an expanding body of scientific understanding and heightened regulatory concern regarding the adverse impacts that PFAS have on the environment and all living organisms, including human beings and human health. 

But Valérie Lévéillé, PhD, Senior Consultant for Waters Treatment in WSP Canada, and her team based in Montréal, are diligently working to challenge the notion of “forever” in relation to PFAS. Their efforts include pioneering methods to break the PFAS molecules down into less harmful constituent atoms. 

The story of how this happened says a lot about the PFAS problem – how it occurred, and what can be done about it. 

What’s so difficult about PFAS? 

Several factors make PFAS impacts particularly challenging to remediate: 

• Many PFAS molecules are persistent, which means they do not break down easily through natural processes 

• There is significant variation in physical and chemical properties between the various PFAS and their response to treatment varies 

• Some of the PFAS mass cannot be measured as individual compounds, thereby needing other analyses to quantify their presence and impact on remedial design

• The urgent need to address PFAS destruction arises from stringent regulations, often requiring compliance with very low concentrations, measured in parts per trillion (PPT)

• Numerous sites affected by PFAS contamination have low concentrations, complicating efforts to aggregate the molecules for effective breakdown and mitigation 

One of the most common uses of PFAS comes from the strength of the carbon-fluorine bond, a characteristic that allows certain types of PFAS to withstand high temperatures. This quality makes them a key ingredient in fire-fighting foam, crucial for suppressing particularly hot fires.  

However, the aftermath of using this foam poses environmental challenges. Residues often seep into the soil and groundwater at firefighting training areas and other sites, where the foam is repeatedly used. From there, PFAS can often travel significant distances underground through groundwater, posing potential threats to surface water and water wells intended for human consumption.  

The use of PFAS-containing firefighting foam at airports adds another layer to the issue. Airport safety mandates having firefighting capacity on site, requiring regular training, which has often involved the use of firefighting foam. Consequently, firefighter training sites worldwide – whether at airports, military bases or municipal fire departments – have emerged as significant focal points for PFAS impacts. 

Electro-oxidation proves successful in destroying PFAS in liquid 

The technology incorporates a distinctive type of long-lasting boron-doped diamond (BDD) electrodes. Their anticipated lifespan of up to 25 years allows for the distribution of upfront expenses over an extended operational period. 

In BDD electrodes, the anode initiates the oxidation process, generating oxidizing radicals and electrons. Through a complex chemical process, these components break down PFAS molecules into shorter molecules, ultimately resulting in carbon dioxide and fluorides. Meanwhile, the cathode primarily produces hydrogen gas, facilitating reduction reactions. Electro-oxidation can be likened to a chemical combustion of organic compounds in water. 

Advantages: 

 About the author 

Valerie Leveille, Eng. M.Eng, PhD, WSP Montreal’s water treatment group Dr Leveille has been developing and put to market novel electrochemical water treatment technologies since more than 16 years. She co-authored several patents and peer-review scientific papers as well as presenting to numerous conferences. She focusses now on PFAS destruction in water using electro-oxidation alone or combined with other technologies.