What is PFAS?
PFAS, or per- and polyfluoroalkyl substances, also known as highly fluorinated substances, are a group of compounds that are ubiquitous in today's society, found both in the environment and in the human body. They are synthetically produced and consist of carbon chains (C) surrounded by fluorine atoms (F) with varying terminal groups. These chemicals have been manufactured since the 1950s and are often referred to as "forever chemicals" due to their notorious resistance to breaking down in the environment.
PFAS gained popularity due to their unique technical properties, such as repelling oil and water and withstanding high temperatures. Consequently, they were used to treat textiles, leather, and paper packaging. Their surfactant properties also made them useful in cleaning agents, paints, ski wax, and cosmetics. Certain types of PFAS are also utilized in firefighting foams designed to extinguish liquid-based fires.
PFAS substances are often categorized into short- and long-chain types based on the length of their fluorinated carbon chains. Chains with fewer than seven carbon atoms are considered short-chain, while chains with seven or more carbon atoms are classified as long-chain.
What are the risks of PFAS?
PFAS substances are incredibly persistent chemicals, resistant to degradation. This means that as long as they continue to be used and spread, humans and other organisms will likely face increasing exposure. Studies have shown that PFAS can negatively impact both humans and animals. Effects include associations with elevated cholesterol levels, liver enzyme alterations, reduced birth weights, and an increased risk of certain cancers.
How can PFAS be removed from water?
There are currently several technologies on the market for treating PFAS-contaminated water. In 2021, IVL Swedish Environmental Institute conducted a project testing different methods for treating PFAS-contaminated leachate from waste facilities. The results showed that granular activated carbon and ion exchangers are the most promising technologies for this purpose. In addition to these techniques, Surface Active Foam Fraction (SAFF) and Dissolved Air Flotation (DAF) are also available.
Ion Exchange Technology
FluorofIX™ is a specially developed ion exchange technology for water treatment that involves the use of ion exchange media, which selectively binds PFAS molecules and removes them from water through ion exchange. RegenIX™ is integrated into the system design, allowing the ion exchange resin to be regenerated on-site, which saves on costly filter replacements, minimizes waste, and can reduce operating costs by 79%.
Activated Carbon (GAC) and BioMedia®
Activated carbon and BioMedia® are both filter materials used to bind and adsorb contaminants, including long-chain PFAS compounds, but they operate in different ways. They can also reduce short-chain PFAS contaminants, but these break through the filter more quickly. Therefore, these technologies are particularly suitable for water where the majority, or all, of the PFAS compounds consist of long-chain variants.
When using activated carbon for treatment, water is filtered through filters filled with activated carbon, which adsorbs PFAS molecules from the water. This process is called adsorption and involves utilizing the intermolecular forces between the PFAS molecules and the carbon surface for binding.
BioMedia® is a biodegradable filter material that combines physical and biological filtration, particularly suitable for long-term water treatment and sustainable solutions. It can also promote the biological degradation of certain substances, making it effective for long-term applications.
These materials are often combined to manage both PFAS-contaminated water and elevated levels of other substances such as metals.
The right treatment technology for different PFAS chains
PFAS encompass thousands of variations and are highly resistant to degradation. Their complex nature means that not all PFAS contaminants behave the same way, necessitating tailored treatment techniques for different types. This variability makes it unrealistic to expect a solution that worked in one project to perform identically in the next. As previously mentioned, short- and long-chain PFAS chemicals are often discussed, and it is crucial to consider their unique risk assessments when selecting treatment methods.
Short-chain PFAS
Short-chain PFAS generally exhibit higher solubility in water, allowing them to spread more easily in water sources. Due to their weaker binding affinity to activated carbon, this method is often less effective for short-chain PFAS. Ion exchange techniques are typically a better choice for removing short-chain PFAS, as they selectively target and eliminate these contaminants from water.
Long-chain PFAS
Long-chain PFAS, on the other hand, tend to have lower solubility in water and bind more strongly to particles and sediments. This makes them more amenable to treatment with activated carbon and other adsorption media. However, effectively addressing long-chain PFAS may require combining multiple treatment methods—such as activated carbon, advanced oxidation, and ion exchange—to ensure comprehensive removal.
A thorough risk and needs analysis is crucial for identifying the most effective treatment technology. Therefore, a careful review of the project's documentation and conditions is always conducted before a solution is proposed. Water samples and treatment tests are used to ensure that the treatment technology is tailored to the specific needs of each project. As mentioned above, it is important to understand that solutions that work for certain types of PFAS may not necessarily be effective for others, making an individual assessment and adaptation essential.
If you have any questions regarding PFAS or PFAS-contaminated water, feel free to contact our water treatment specialists!
