While removing the chemicals from water sources can be accomplished several ways, there is no perfect solution to a difficult problem.
“No treatment option is going to be the sole solution,” said Dr. Cory Rusinek, whose team at Michigan State University’s Fraunhofer Center in Holland is testing out a new method for eliminating PFAS. “It’s going to be a puzzle with several pieces.”
Rusinek’s research involves using electrochemical oxidation with boron-doped diamond electrodes to destroy PFAS in complex water samples. The process entails introducing an electrical current to an anode surface. PFAS becomes oxidized when it comes into contact with the surface; and after long periods of treatment, it is destroyed.
The next challenge is scaling the process to apply it to actual contaminated water sources. The strategy won’t be able to treat millions of gallons of water, Rusinek said, but it can be used in tandem with other methods.
The common large-scale remediation process involves removing PFAS chemicals from a water supply using activated carbon. While it can be removed and incinerated, Rusinek explained, there remain concerns that short-chain compounds are not removed, making the process only partially effective. PFAS chemicals could also be transferred into the air through this process, he said.
The Fraunhofer Center is not the only lab working on the problem, Rusinek said, and several different strategies are being tested, and implemented, worldwide. A company in Maine is using resin to absorb long- and short-chain PFAS, according to Rusinek, and has been effective compared to activated carbon in 100-gallon feasibility testing.
The basic principles behind the Fraunhofer lab’s treatment have for a long time been applied to other applications, but PFAS is a new emphasis for the technology, Rusinek said.
‘An extreme analytical challenge’
The Michigan Department of Environmental Quality is in the midst of a statewide study of per- and polyfluoroalkyl substances (PFAS), which have been linked in human studies to thyroid disease, some forms of cancer, elevated cholesterol and other diseases. The substances are found throughout the environment, and are common in water-repellant materials, nonstick cookware, firefighting foam and fast-food wrappers.
The DEQ currently only investigates water sources with contamination above the U.S. Environmental Protection Agency’s 70 parts per trillion (ppt) advisory limit for the two chemicals, perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), but the compound group contains numerous known variants.
“You’ve got potentially over 1,000 precursor compounds,” Rusinek said. “Where do you draw the line on the amount of chains you should be looking at? That’s an extreme analytical challenge in itself.”
It is difficult to accurately quantify levels of PFAS, Rusinek said, and standards don’t exist for many of the precursor compounds. Lab results can vary depending on the lab.
Independent testing of the Northwest Ottawa Water System in Grand Haven found 8 ppt combined PFOS and PFOA in August, but DEQ testing in September did not detect any trace of the substances. Both labs used the same methodology, according to NOWS officials.
Single-digit parts per trillion are the low end of the detection limit, Rusinek noted.
“Certain labs can get fairly significant variation in the results just by the way they run the instruments,” he said. “The analytical instrumentation you need to measure parts per trillion is very expensive and very complex, and is an ever-evolving technology.”
In October, contamination above the EPA limit was discovered in the well water at Robinson Elementary School in Robinson Township, and further testing by the DEQ in November discovered one nearby residence with levels above the EPA limit and 12 total wells with both PFOS and PFOA. The DEQ and Ottawa County Department of Public Health are now testing 41 wells in the area, and those results are expected in 2-4 weeks.
PFAS is a health concern because the substances bioaccumulate, Rusinek explained, and low levels will remain in the body for a long time.
While PFAS contamination is an emergent problem, he added, it has gotten major attention from research and development labs working to improve analysis, remediation and policy.
“There’s a lot of different research on this on all fronts,” he said. “I suspect some fairly rapid progress in the next five years or so.”