Last month the U.S. Environmental Protection Agency (EPA) updated the drinking water guidelines for PFOA (Perfluorooctanoic Acid) and PFOS (Perfluorooctanesulfonic Acid) in response to the rising attention paid to the dangers of these chemicals in drinking water. The agency’s assessment is that drinking water with concentrations of PFOA and PFOS below 70 parts per trillion will not result in adverse health effects over a lifetime of exposure.
Joel Beauvais wrote on the agency’s blog, “If these chemicals are found in drinking water systems above these levels, system operators should quickly conduct another sampling to assess the level, scope, and source of the contamination. They should promptly notify customers and consult with their state drinking water agency to discuss appropriate next steps.”
Beauvais’ blog post did not contain any precise steps for removing PFOA and PFOS. When the EPA placed the chemicals on its “Contaminant Candidate List 3” and “Third Unregulated Contaminant Monitoring Rule,” the Water Research Foundation (WRF) conducted a study into the “Treatment and Mitigation Strategies for Poly- and Perfluoroalkyl Substances.” WRF investigators evaluated 15 full-scale water systems throughout the country to see how they were dealing with the contamination.
The facilities used a wide range of treatment methods, like anion exchange, reverse osmosis, micro-filtration, river bank filtration and more. The WRF found that aeration, chlorine dioxide, dissolved air flotation, coagulation, flocculation, sedimentation, granular filtration and microfiltration were all ineffective for removing PFAS, including PFOA and PFOS. Nano-filtration and reverse osmosis proved to be the most effective methods of removing even the smallest PFASs. Granular-activated carbon (GAC) removed most PFASs and may be the average utilities’ best bet for removing PFOA and PFOS contamination. GAC will need to be tested at each water utility to determine site-specific performance. In many cases, it will be the most cost-effective treatment method.
According to the WRF, PFOA and/or PFOS has been discovered in 30 states. They recommend that any water treatment facility near a chemical manufacturing operation or military base should be on alert for these chemicals. While the EPA’s recent guidelines are a nonenforceable guideline, municipalities should take notice. Some states could choose to regulate PFOA and PFAS based on these guidelines or lower existing regulated levels to these new proposed levels.