Understanding PFAS and the Challenges of Effective Treatment

What is PFAS?

The term PFAS encompasses thousands of synthetic chemicals containing multiple fluorine atoms. The physical and chemical properties of these compounds, such as water and grease resistance, have resulted in a wide range of uses across multiple industries and in a variety of products including firefighting foams, clothing, and food packaging. PFAS compounds are increasingly being detected in soil, water, and air as products containing these compounds are exposed to the environment. Although they may enter the environment at extremely low concentrations, scientists and government regulators have not found a concentration that is safe for human exposure in environmental samples such as drinking water.

​​Why is PFAS so difficult to treat?​

Traditional water treatment technologies, such as granular activated carbon (GAC) or ion exchange resin (IX) can be used to remove PFAS from contaminated water. However, these PFAS removal technologies concentrate the PFAS on a solid material and do not destroy the contaminant. The fluorine atoms that are characteristic of PFAS compounds are attached to carbon atoms in the chemical structure. The bond between carbon and fluorine atoms is one of the strongest bonds in chemistry and thus nearly impossible to break without implementing extreme conditions such as high temperatures, high pressures, high pH, or a combination of all these extremes. Furthermore, it is not clear whether current destructive treatments, while effective at destroying the target contaminant, might also create products of incomplete breakdown that pose additional hazards.

How does Tetra Tech address PFAS treatment?

Tetra Tech leverages our Leading with Science® approach and best-in-class environmental management resources to provide cutting-edge consulting and engineering services for emerging contaminants.

In addition to leading the development of advanced technologies, our teams also seek to identify the best technology for the problem at hand. Our technical professionals collaborate with highly specialized small businesses and university researchers to evaluate technologies and support the treatment and ultimate destruction of PFAS in multiple environmental media, including soil, groundwater, surface water, and spent treatment media.

In our role as a large business partner, we offer access to our technical experts as well as access to our client sites. If our clients are willing to share samples for bench-scale tests or host a field demonstration for scaled-up testing, we will facilitate the planning and implementation. As a client’s engineer, our goal is to understand the technical details of the treatment technology, help the vendor improve performance, and quantify the treatment costs. Ultimately, we are looking for the most effective and economical technologies to address the challenges of PFAS.

Do treatment technologies differ depending on the media where PFAS is found?

Yes, definitely. PFAS compounds are present in all the environmental media, soil, groundwater, surface water, and air, we routinely investigate. In addition, due to the use of conventional water treatment techniques, such as GAC and IX, we are also dealing with PFAS concentrated in spent treatment media solids. Our teams work with universities and commercial vendors to identify efficient and cost-effective PFAS treatment methods for all those media. For example:

• Our drinking water experts have designed and installed municipal-scale water treatment facilities utilizing innovative IX resins as well as reverse osmosis (RO)
• We collaborate with universities on the use of electron beam technology to treat PFAS-contaminated soils and sediments
• Our teams partner with universities on development and a scaled-up demonstration of sonolysis (ultrasound) technology for mineralization of PFAS in highly contaminated water
• We continue to support university research in the development of unique metal alloy electrodes for electrochemical destruction of PFAS in water

These efforts are just the beginning. As new treatment technologies develop rapidly, Tetra Tech remains at the forefront of innovation by building relationships with inventors and offering our combined science and engineering expertise.