How To Remove PFOA And PFOS
Last month the U.S. EPA updated its drinking water guidelines for PFOA and PFOS (also known as perfluorooctanoic acid and perfluorooctanesulfonic acid, respectively) apparently in response to rising attention paid to the dangers of these chemicals in drinking water.
Small communities in New York, Pennsylvania, Alabama, and West Virginia have all recently become concerned with their exposure to PFOA and PFOS, which found their way into drinking water supplies through nearby industrial plants and military bases. The health risks of exposure to the chemicals include developmental effects to fetuses during pregnancy or to breastfed infants, cancer, liver effects, immune effects, thyroid effects, and more. Citizens are rightly concerned over the years they’ve spent drinking contaminated water and the new EPA guidelines were designed to set stricter limits on the chemicals.
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.
“If these chemicals are found in drinking water systems above these levels, system operators should quickly conduct additional sampling to assess the level, scope, and source of contamination,” Joel Beauvais, the EPA’s deputy assistant administrator for the office of water, wrote on an agency blog. “They should also promptly notify consumers and consult with their state drinking water agency to discuss appropriate next steps.”
However, Beauvais’ blog post was notably devoid of any precise steps for treatment strategies for removing PFOA and PFOS. When the EPA placed the chemicals on its “Contaminant Candidate List 3” and “Third Unregulated Contaminant Monitoring Rule” years ago, the Water Research Foundation (WRF) was prompted to conduct a study into “Treatment Mitigation Strategies for Poly- and Perfluoroalkyl Substances” which has now been released.
To test for PFOA, PFOS, and other poly- and perfluoroalkyl substances (PFASs), principal investigators Eric R.V. Dickenson and Christopher Higgins evaluated 15 full-scale water treatment systems throughout the country to see how they were dealing with the contamination.
“We thought the information would be most credible if it were obtained by sampling actual water treatment facilities before and after treatment, as opposed to investigating removal in laboratory and research facilities,” the WRF said. “This approach required involving utilities in areas known or suspected to have PFOS and PFOA in their water supplies. We also wanted to involve utilities with a variety of water treatment technologies and processes.”
The facilities used a wide range of treatment methods, like anion exchange, reverse osmosis, microfiltration, river bank flotation, and more.
The WRF found that aeration, chlorine dioxide, dissolved air flotation, coagulation, flocculation, sedimentation, granular filtration, and microfiltration were all ineffective for removing PFASs including PFOA and PFOS. Anion exchange was moderately effective in treating PFOA, highly effective for PFOS, and failed to remove several other PFASs. Nanofiltration and reverse osmosis proved to be the most effective methods of removing even the smallest PFASs. Granular activated carbon (GAC) was shown to be adept at removing most PFASs and it may be the average utility’s best bet for PFOA and PFOS contamination.
“In many cases, the most cost-effective treatment for removing PFOA and PFOS will be GAC, though water utilities will need to test GAC to determine site-specific performance,” the WRF said.
According to the WRF, PFOA and/or PFOS occurrence has been discovered in 30 states. The WRF advised that any water treatment plant that’s near a chemical manufacturing operation or military base should be on alert for PFASs contamination. While the EPA’s recent guidelines are a non-enforceable suggestion, municipalities should still take heed.
“Some states may choose to regulate PFOA and PFOS based on these guidelines or, in the case of states that already have regulations for PFOA and PFOS set higher than the health advisory levels, lower the maximum amount allowed in water,” the WRF said.
At this stage, it’s difficult to determine whether PFOA and PFOS will continue to be a pressing issue around the country or if requirements to stop using the chemicals and the new EPA guidelines will be enough to curb the threat. Either way, if these contaminants are a problem we now have the information necessary to fight back.