By Paul Jackson

By now, most water professionals have heard of PFAS: those pesky little synthetic chemicals that can cause so much damage to human health but are so hard to get rid of. Thankfully, there are commonly available technologies that can remove them from tap water, but these solutions can be expensive. So how did these compounds get into the drinking water supply anyway, and what can be done about them?

Why PFAS Are Here to Stay…for Now Anyway
Our PFAS problem all began in 1938 when DuPont researchers accidentally discovered polytetrafluoroethylene (PTFE), a chemical that repels water and oil very effectively. It wasn’t until after WWII that the company got around to commercializing the discovery into a product called Teflon. Since then, they and other chemical manufacturers have developed thousands of PFAS to be used in everything from fire-fighting foams to waterproofed clothing. PFAS are also frequently used in the industry as a lubricant or surfactant.

What makes a PFAS a PFAS—and gives it such useful properties—is the chemical structure of the compounds. The scientific name for the category of chemicals we refer to as PFAS is per- and polyfluoroalkyl substances. To belong to this group, the compound must have at least one carbon-fluorine bond. This bond is the strongest in nature and one of the reasons why water professionals will be dealing with PFAS for many years to come. Those PFAS that were disposed of decades ago in long-forgotten landfills or wastewater ponds are still around today.

One of the most (in)famous examples involves the Wolverine shoe manufacturer in Michigan. Wolverine used a PFAS sup­plied by 3M to waterproof the shoes and boots made in its Rochester, MI, facility. Sludge from the tannery was disposed of in a landfill owned by the company. Although the landfill was closed decades ago, the tannery landfill was discovered much more recently to be a source of PFAS in the local water supply, leading to a slew of ongoing lawsuits.

The PFAS Keep Coming
The other reason PFAS are here to stay is because new PFAS can be produced to replace PFAS that are determined to be toxic. This statement is worth unpacking a bit: There are over 5,000 PFAS compounds known today. Some put the number at closer to 12,000. Regardless of the actual count, these compounds are all similarly structured, and it’s generally believed that they all have a similar impact on human health and the environment. The question is, to what degree?

While all PFAS contain at least one carbon-fluorine bond, studies suggest that the number of bonds in a chemical has an impact on toxicity. In general, long-chain compounds are those that contain seven or more bonds. Short-chain compounds are those that contain less than seven. Available toxicity assessments indicate that long-chain PFAS are likely to be more toxic than short-chain compounds.

PFOA and PFOS, for example, are two long-chain, toxic PFAS that were voluntarily discontinued in the U.S. years ago. (These compounds are still imported into the U.S. via commercial and industrial products.) The original U.S. manufacturers of PFOA and PFOS have created short-chain compounds to replace their more toxic predecessors. PFOA was largely replaced with a compound referred to as GenX that contains six carbon-fluorine bonds, and PFOS was replaced with PFBS, a compound that contains four carbon-fluorine bonds. The U.S. EPA recently completed toxicity assessments for GenX and PFBS. While these compounds are considered toxic, the resulting EPA health advisories for the nation’s public water systems are set at much higher levels than those for PFOA and PFOS.

At the end of the day, the typical consumer continues to want products that are waterproof, nonstick, and oil resistant, so PFAS will continue to be used. As some PFAS are more tightly regulated, other PFAS will take their place. A few states are attempting to outlaw products that include any PFAS—see California’s most recent ban on PFAS in textiles and cosmetics as an example—but laws like this aren’t gaining much traction at the federal level since not enough is known about the relative toxicity values of the PFAS family of compounds. So, again, PFAS are apparently here to stay.

Why Wastewater Treatment Isn’t the Answer
Most states do not allow reclaimed water to be used as a source of drinking water, but treated wastewater can impact drinking water indirectly when discharged into the environment. Today’s water treatment systems are highly sophisticated and can address contamination from a wide variety of chemicals and biological organisms, but unfortunately, traditional wastewater treatment does not remove PFAS. If you’ve discovered PFOA or PFOS in your water and can’t find the source, work with your local wastewater treatment partners to look for PFAS precursors in wastewater influent.

Here are a few sources to look for:

  • Local industry. The first place most think to look is at the businesses in the area. Chemical manufacturers are the obvious choice, but other types of businesses such as metal finishing   and textile manufacturers can be a source.
  • Stormwater runoff. This runoff may be from an industrial site where PFAS is manufactured or used, but there are other sources to consider. For example, Boston has gone so far as to prohibit AstroTurf in public parks due to the potential of PFAS (and a variety of other harmful compounds) in runoff from these sites.
  • Airports and military sites. AFFF (aqueous film-forming foam), the foam used to fight Class-B chemical fires, often contains PFAS. Runoff from sites where this foam has been used, either in an emergency or training exercises, typically hits the storm sewer system and is then sent to the local wastewater treatment facility.

Landfill leachate. As liquid (rain, condensation, liquid waste) passes through a landfill, it can leach PFAS from solid waste containing PFAS. This contaminated leachate is frequently sent to the local wastewater treatment facility where it can enter the water supply.

Testing Wastewater for PFAS

One of the other challenges with PFAS in wastewater is testing a liquid that contains varying degrees of solids. The EPA-validated test methods for drinking water (533 and 537.1) aren’t appropriate, so the agency is actively working on a couple of test methods in conjunction with other organizations, including the DOD and authorized labs:

  • Draft Method 1633 can quantitate 40 unique PFAS across a wide range of solid and aqueous matrices, including wastewater and leachate.
  • Draft Method 1621 is a screening method designed to quantify total organic fluorine at the parts-per-billion level in aqueous matrices.

Once finalized, Draft Methods 1633 and 1621 will support a variety of U.S. EPA initiatives to monitor—and eventually regulate—PFAS in non-potable waters. In fact, even though 1633 and 1621 are still in draft form, EPA issued a memo in April 2022 stating “in the absence of a final 40 CFR § 136 method,” draft analytical method 1633 actively should be used for NPDES permitting. The use of Draft Method 1621 is also encouraged.

TOP Assay is another test method to be aware of. Some wastewater treatment processes can convert “PFAS precursors” into terminal PFAS like PFOA and PFOS. This method oxidizes these precursors to turn them into terminal PFAS that can then be measured. The increase in PFAS measured after the TOP Assay oxidation relative to pre-oxidation levels is a worst-case estimate of the total concentration of PFAS precursors present in a sample. This analysis is particularly useful in forensic studies designed to identify the source of elevated PFAS levels in finished drinking water.

Water Filtration’s Catch-22
Thankfully, there are solutions, such as granular activated carbon water filtration, that have been shown to remove PFAS from drinking water supplies. Many municipalities are spending thousands to implement these solutions locally.

However, while this approach provides immediate protection for the public, it’s not without its drawbacks. As noted, it can be expensive. But more than that, activated carbon filters do not destroy PFAS, they only contain it. Municipalities are then faced with the problem of disposing of the contaminated filters.
Incineration has been shown to spread PFAS particles through stack emissions, and sending the filters to the landfill just recycles the PFAS back into the water supply through the leachate.

The situation is not without hope. From PFAS-eating microbes to chemical “decapitation,” many companies and research facilities are working on ways to destroy PFAS in the environment. Until then, water professionals will need to monitor their water supply and search for the source of PFAS when elevated levels are discovered. Testing wastewater influent and effluent is often the place to start your forensic efforts.

About the author
Paul Jackson is the Program Manager at Pace® Analytical Services responsible for PFAS and Emerging Contaminants. Jackson is an expert in these areas as well as UCMR, 1, 4-Dioxane and Harmful Algal Blooms.

About the company
Pace® Analytical Services delivers the highest standard of testing and scientific services in the market. It offers the most advanced solutions in the industry, backed by truly transparent data, a highly trained team, and the service and support that comes from four decades of experience. Visit https://www.pacelabs.com/.

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