[rockfan4]

Originally Posted by LWJ

As I have not studied Chemistry is decades, please don't consider me an expert. But isn't PFAS relatively inert? If so, a carbon filter won't bond with it. My understanding is that Carbon isn't a filter but rather a chemical "magnet" that connects with impurities and keeps them out of down stream.

Anybody?

From the EPA website -
https://www.epa.gov/sciencematters/reducing-pfas-drinking-water-treatment-technologies

Activated Carbon Treatment

Activated carbon treatment is the most studied treatment for PFAS removal. Activated carbon is commonly used to adsorb natural organic compounds, taste and odor compounds, and synthetic organic chemicals in drinking water treatment systems. Adsorption is both the physical and chemical process of accumulating a substance, such as PFAS, at the interface between liquid and solids phases. Activated carbon is an effective adsorbent because it is a highly porous material and provides a large surface area to which contaminants may adsorb. Activated carbon (GAC) is made from organic materials with high carbon contents such as wood, lignite, and coal; and is often used in granular form called granular activated carbon (GAC).

GAC has been shown to effectively remove PFAS from drinking water when it is used in a flow through filter mode after particulates have already been removed. EPA researcher Thomas Speth says, “GAC can be 100 percent effective for a period of time, depending on the type of carbon used, the depth of the bed of carbon, flow rate of the water, the specific PFAS you need to remove, temperature, and the degree and type of organic matter as well as other contaminants, or constituents, in the water.”

For example, GAC works well on longer-chain PFAS like PFOA and PFOS, but shorter chain PFAS like Perfluorobutanesulfonic acid (PFBS) and Perfluorobutyrate (PFBA) do not adsorb as well.

Another type of activated carbon treatment is powdered activated carbon (PAC) which is the same material as GAC, but it is smaller in size, powder like. Because of the small particle size, PAC cannot be used in a flow through bed, but can be added directly to the water and then removed with the other natural particulates in the clarification stage (conventional water treatment or low-pressure membranes - microfiltration or ultrafiltration). Used in this way, PAC is not as efficient or economical as GAC at removing PFAS. Speth says, “Even at very high PAC doses with the very best carbon, it is unlikely to remove a high percentage PFAS; however, it can be used for modest percent removals. If used, however, there is an additional problem with what to do with the sludge that contains adsorbed PFAS.”

I live just outside La Crosse, near the airport, where they've been using foam for firefighting practice and actual crashes for years. I don't have it near as bad as some other areas, but our town is looking at installing a town water system. We're on wells right now.