A lack of data hinders efforts to adequately address the effects of per- and polyfluoroalkyl substances (PFAS) on U.S. drinking water sources and the broader environment, says a U.S. Government Accountability Office report released last month.
The July report outlines some challenges facing managers of drinking and wastewater systems as well as federal policymakers. PFAS chemicals—found in common household products as well as in industrial firefighting foam—are virtually everywhere in the ambient environment, and are extremely hard to eliminate.
Public concern has grown in recent years as more has become known about the chemicals and their potentially harmful effects.
Federal lawmakers included funding in the 2021 Infrastructure Investment and Jobs Act to address the PFAS issue. In June, the U.S. Environmental Protection Agency released health advisories for four different PFAS substances, which are usually the first step toward developing a federal drinking water standard under the Safe Drinking Water Act.
Karen Howard, a report author who is director of science and technology assessment at GAO, told ENR, “There’s so much we need to learn in order to make data-informed decisions on what to do about PFAS.”
Some PFAS chemicals are known to be carcinogenic, but little is understood about how many of the thousands of different substances are hazardous to human health, and at what levels. The report also states that although current technologies can reliably detect and quantify about 50 specific PFAS substances, thousands of others could be present in a variety of settings because current technologies are not equipped to find them. Some methods to screen for or quantify unknown PFAS are under development, including use of high-resolution mass spectrometry and total fluorine analysis.
Howard notes that EPA is trying to determine how to assess and regulate PFAS, but there are still so many unknowns. “We don’t fully understand what happens to PFAS in the body, we don’t understand what levels are actually harmful, and EPA is trying to figure out what those levels should be under a great deal of external pressure with not enough data.”
The primary methods for PFAS treatment typically involve removing PFAS from contaminated soil or water, and disposing the substances in landfills or through incineration. But questions remain about whether the latter could potentially cause some PFAS to be released into the air.
As awareness builds, options for disposal at non-hazardous landfills are becoming more limited, says Tamzen Macbeth, environmental remediation practice leader and a senior vice president at CDM Smith. “The first step in improving the ability to regulate and manage PFAS waste is in the development of robust and reliable analytical methods that can provide confidence when measuring PFAS before and after treatment or disposal. This will provide the basis that regulators and facilities need to determine the appropriateness and protectiveness of PFAS waste management options.”
The three primary methods to treat PFAS in drinking water—granular activated carbon (GAC), ion-exchange, and reverse osmosis—are effective, but each comes with its own disadvantages. All concentrate PFAS in waste that itself must be safely destroyed, the GAO report noted.
Other emerging technologies include supercritical water oxidation and pyrolysis, says the agency report.
CDM Smith’s Macbeth says her firm is actively researching and demonstrating a number of destructive technologies, including electrochemical oxidation, non-thermal plasma, supercritical water oxidation, hydrothermal alkaline treatment, and UV-sulfite.
All of these emerging technologies completely break down PFAS and are being piloted but they are energy intensive and costly. “Unfortunately, there’s no silver bullet,” Macbeth says. Because each of the emergent technologies have their own benefits and limitations, “site specific evaluations are necessary to develop a treatment process that will most cost-effectively treat PFAS-impacted water.”