PFAS and Water Remediation: Current Approaches to Treating These "Forever Chemicals"
PFAS, or per- and polyfluoroalkyl substances—often referred to as “forever chemicals”—pose a major environmental challenge due to their persistence and toxicity.
Today, in addition to better regulating their use, we need more effective ways to address these pollutants—that is, first removing them from the environment and then destroying them. This is a real challenge, since these molecules are both highly diverse and very resistant—which is precisely why they are so widespread.
Julie Mendret, University of Montpellier and Mathieu Gautier, INSA Lyon – University of Lyon
Measures to regulate and ban PFAS emissions—which are essential for limiting their release into the environment—are already underway. Under a law passed in February 2025, France must work toward a complete phase-out of industrial PFAS discharges within five years.
A recent investigation by Le Monde and 29 media partners revealed that the cleanup of soil and water contaminated by these substances could cost between 95 billion and 2 trillion euros over a twenty-year period.
As with other organic contaminants, there are two main categories of treatment processes.
Some technologies involve separating and sometimes concentrating PFAS from the contaminated medium to allow for the discharge of treated effluent, but they consequently generate byproducts that still contain the pollutants and must be managed. Other technologies involve degrading PFAS. These processes entail breaking the C-F (carbon-fluorine) bond, which is very stable, and often require significant amounts of energy.
In this article, we highlight some of the many processes currently being tested at various scales—from laboratory and pilot-scale to full-scale applications—ranging from innovative materials that can sometimes simultaneously separate and destroy PFAS to the use of living organisms, such as fungi or microbes.
Methods for separating and concentrating PFAS in water
Currently, the techniques used to remove PFAS from water are primarily separation processes designed to extract PFAS from water without breaking them down, requiring subsequent management of PFAS-saturated solids or liquid concentrates (waste concentrated with PFAS).
The most commonly used technique is “adsorption,” which relies on the affinity between the solid and the PFAS molecules that bind to the porous surface. Adsorption is an effective separation technique for many contaminants, including PFAS. It is widely used in water treatment, particularly because of its affordability and ease of use. The selection of the adsorbent is determined by its adsorption capacity for the target pollutant. Many adsorbent materials can be used (activated carbon, ion exchange resin, minerals, organic residues, etc.).
Among these methods, adsorption on activated carbon is highly effective for long-chain PFAS but less effective for medium- and short-chain PFAS. After adsorbing PFAS, the activated carbon can be reactivated using high-temperature thermal processes, which results in high energy costs and the need to manage the transfer of PFAS into the gas phase.
The first mobile unit for treating PFAS using activated carbon was recently deployed in Corbas, in the Rhône region, and is capable of treating 50 cubic meters of water per hour for drinking purposes.
Like other adsorption processes, ion exchange resins consist of beads that are positively charged (anions) or negatively charged (cations). PFAS, which are often negatively charged due to their carboxylic or sulfonic functional groups, are attracted to and can bind to positively charged anion exchange resins. Differences in efficiency have also been observed depending on the length of the PFAS chain. Once saturated, ion exchange resins can be regenerated through chemical processes, producing waste streams concentrated in PFAS that must be treated. It should be noted that ion exchange resins are not approved in France for use in drinking water production systems.
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The most effective technique currently available for removing a wide range of PFAS —both short-chain and long-chain—from water is filtration using nanofiltration or reverse osmosis membranes. Unfortunately, this technique is energy-intensive and generates separation byproducts known as “concentrates.” These concentrates contain high concentrations of PFAS, which pose management challenges (concentrates are sometimes discharged into the environment even though they require further treatment).
Finally, foam fractionation flotation exploits the properties of PFAS (hydrophilic head and hydrophobic tail), which form foam bubbles at the air-liquid interface and are recovered at the surface. Extraction rates of 99% are thus achieved for long-chain PFAS. Like the previous methods, this technique produces a concentrate that must be disposed of later.
Toward Technologies That Break Down PFAS
Other processes aim to break down contaminants in water to provide a more sustainable solution. There are various technologies for destroying pollutants in water, including advanced oxidation processes, sonolysis, and plasma technology. These processes can be deployed either in addition to or as a replacement for certain concentration technologies.
The breakdown of a pollutant is influenced by its biodegradability and oxidation/reduction potential. The natural degradation of PFAS is very difficult due to the stability of the C-F bond, which has a low biodegradability potential (i.e., it is not easily broken down by natural processes, such as those driven by bacteria or enzymes).
Advanced oxidation processes are techniques that use highly reactive free radicals, which are potentially effective at breaking C–F bonds. These include, among others, ozonation, UV/hydrogen peroxide, and electrochemical processes.
The electrochemical treatment of PFAS is an innovative and effective method for breaking down these highly persistent compounds. This process involves applying an electric current through specialized electrodes, generating powerful oxidizing radicals capable of breaking carbon-fluorine bonds—which are among the most stable in organic chemistry.
For all these advanced oxidation processes, one key monitoring parameter is essential: it is crucial to prevent the formation of PFAS with shorter chains than the initially treated material.
Recently, a spin-off company from the Swiss Federal Institute of Technology in Zurich (Switzerland) developed an innovative technology capable of destroying more than 99% of PFAS in industrial wastewater using piezoelectric catalysis. The PFAS are first separated and concentrated through foam fractionation. The concentrated foam is then treated in two reactor modules where piezoelectric catalysis technology breaks down and mineralizes all short-, medium-, and long-chain PFAS.
The sonochemical degradation of PFAS is also an avenue currently being explored. When high-frequency ultrasonic waves are applied to a liquid, they create so-called “cavitation bubbles,” inside which chemical reactions take place. These bubbles eventually implode, generating extremely high temperatures and pressures (several thousand degrees and several hundred bars), which create reactive chemical species. The phenomenon of cavitation is thus capable of breaking carbon-fluorine bonds, ultimately yielding less harmful and more easily degradable components. While very promising in the laboratory, it remains difficult to apply on a large scale due to its energy costs and complexity.
Thus, despite these recent advances, several challenges remain regarding the commercialization of these technologies, due in particular to their high cost, the generation of potentially toxic byproducts that require additional management, and the need to determine the optimal operating conditions for large-scale application.
What does the future hold?
Given the limitations of current solutions, new approaches are emerging.
One approach involves developing hybrid treatment processes, that is, combining multiple technologies. For example , researchers at the University of Illinois (United States) have developed an innovative system capable of capturing, concentrating, and destroying mixtures of PFAS—including ultra-short-chain PFAS—in a single process. By combining electrochemistry and membrane filtration, it is thus possible to combine the strengths of both processes while overcoming the challenge of managing concentrates.
Innovative materials for PFAS adsorption are also currently being studied. Researchers are working on 3D printing using stereolithography integrated into the manufacturing process for adsorbent materials. A liquid resin containing polymers and photosensitive macrocycles is solidified layer by layer using UV light to form the desired object and optimize the material’s properties to improve its adsorption performance. These adsorbent materials can be combined with electrooxidation.
Finally, research is underway in the field of bioremediation to harness microorganisms—particularly bacteria and fungi—capable of degrading certain PFAS. The principle involves using PFAS as a carbon source to facilitate the defluorination of these compounds, but the degradation process can take a long time. Thus, this promising biological approach could be combined with other techniques capable of making the molecules more “accessible” to microorganisms in order to accelerate the removal of PFAS. For example, a technology developed by researchers in Texas uses a plant-based material that adsorbs PFAS, combined with fungi that degrade these substances.
Nevertheless, despite these technical advances, it remains essential to implement regulations and measures to address PFAS pollution at its source in order to limit the damage to ecosystems and human health.
Julie Mendret, Associate Professor, HDR, University of Montpellier and Mathieu Gautier, University Professor, INSA Lyon – University of Lyon
This article is republished from The Conversation under a Creative Commons license. Readthe original article.