PFAS Treatment is a rapidly growing segment of the broader water treatment industry. As a pervasive and persistent bio-accumulative, man-made compound, PFAS represents a unique challenge for water treatment professionals. So what is PFAS, where is it found, and how can we treat it?
What is PFAS?
Per- and polyfluoroalkyl substances (PFAS) are a family of more than 5,000 man-made chemical compounds. They are generally grouped into long-chain or short-chain designations depending on the number of carbons in the chemical composition of the compound. Long-chain PFAS such as Perfluorooctane sulfonic acid (PFOS) and Perfluorooctanoic acid (PFOA) generally contain 6 or more carbons. Short-chain PFAS like Perfluorobutane sulfonic acid (PFBS), and Perfluorobutanoic acid (PFBA) generally contain 5 or fewer carbons. These compounds were developed as early as the 1940s and are used in many industries for a wide variety of purposes. The compounds were often used as surfactants and valued for their hydrophobic (repels water) and oleophobic (repels oil, fat, and grease) properties.
Where is PFAS found?
PFAS is found in many consumer products like non-stick pans, cleaning products, and water repellent fabrics. Food packaging and processing equipment frequently utilize PFAS as well. A common source of PFAS in groundwater and soil is runoff from industrial sites that use, process, or apply PFAS or locations downstream of where firefighting foams have been utilized. Additionally, as a bio-accumulative compound, PFAS is found in living organisms like fish, animals, and humans.
Why is PFAS a problem?
PFAS has developed the nickname “the forever chemical” because the molecular structures can take thousands of years to break down under typical environmental conditions. PFAS can be detected in the blood of 99% of the US population and has been associated with adverse health effects. According to Scientific American, “Scientists have found links between a number of the chemicals and many health concerns—including kidney and testicular cancer, thyroid disease, liver damage, developmental toxicity, ulcerative colitis, high cholesterol, pregnancy-induced preeclampsia and hypertension, and immune dysfunction.” PFAS contamination is so serious, it is generally analyzed at the parts per trillion level (ppt). While it is not currently regulated, the US Environmental Protection Agency recommends a limit of 70 ppt.
PFAS treatment Options
There are currently three technologies available to treat water that is contaminated with PFAS. The optimal technology (or combination) will depend on the specific PFAS molecules present in the water, and other details of the project. WaterSurplus engineers have expertise in all three PFAS treatment technologies.
- Granular Activated Carbon: Granular Activated Carbon (GAC) systems are the most common way to treat PFAS. Typically two vessels are used in a lead-lag fashion to allow for a 10 minute empty bed contact time (EBCT). The PFAS laden carbon is then reactivated, incinerated, or disposed of in a hazardous waste landfill. GAC systems are most effective at treating long-chain PFAS molecules like PFOA and PFOS.
- Ion Exchange: An ion exchange system containing anion resin requires a larger capital investment than a GAC system. However, because it requires less EBCT (1.5-3 minutes typically) than GAC and can handle more bed volumes before replacement of the resin is required, the operating costs tend to be lower. As with GAC systems, two vessels are typically deployed. The anion resin is not regenerated when saturated but is either incinerated or disposed of in a hazardous waste landfill. Ion exchange systems are most effective at treating short-chain PFAS molecules like PFBS and PFBA.
- Reverse Osmosis: Using a high recovery reverse osmosis system, PFAS compounds are concentrated into the waste stream. The RO process does not destroy the PFAS molecule, but the relatively small volume of concentrate can then be treated with a significantly smaller GAC or anion exchange system depending on the PFAS being removed. An additional advantage of concentrating the PFAS is that the capacity of the media, particularly GAC to remove PFAS increases with the concentration. For example, when the PFAS concentration increases by 10x, the GAC media’s capacity to remove PFAS increases by 2x, significantly increasing the lifespan of the media. A similar, but less significant increase in capacity occurs with anion resin as well.
Our application engineers will gather the specific details about your project including water analysis, project goals, and budget considerations to help determine the process or combination of processes that are best suited for your project.
Contact us to speak with a PFAS expert about your project today.