Heightened public perception and fear have put per- and polyfluoroalkyl substances (PFAS) remediation efforts under regulatory scrutiny, particularly when it comes to landfill leachate and public drinking water. But regulations on how to handle PFAS are constantly changing, as public and political concerns are driving action faster than the science can keep up with.
During a PFAS Characterization session at Global Waste Management Symposium (GWMS) 2020, Laura Carpenter, a principal scientist and PFAS stormwater liaison from Brown and Caldwell, kicked off the discussion with a basic overview of PFAS.
PFAS is in everything, she explained—from raingear to packaged food products like microwave popcorn.
“There are public and political concerns that are driving this faster than our science can keep up with,” said Carpenter. “We are really just trying to keep up with what the public is saying they want. They want more regulations, and they are scared it’s in their body. It’s in everyone’s blood stream, and it is being found in the arctic, where there are really no human influences.”
PFAS contamination and human health effects have been referenced in films such as “The Devil We Know” and “Dark Waters,” which are driving that public perception. There are more than 5,000 compounds of PFAS, which emerged in the 1940s by major chemical corporations DuPont and 3M.
The U.S. Environmental Protection Agency (EPA) has established a drinking water advisory of 70 parts per trillion (ppt) of PFAS in drinking water. For perspective, 1 ppt is equivalent to a grain of sand in an Olympic-sized swimming pool, noted Carpenter.
Kevin Torrens, vice president at Brown and Caldwell, discussed how PFAS in landfill leachate and transport in publicly owned treatment works (POTWs) intersect, as well as some of the ongoing risks and solutions for landfill owners and operators. Torrens has more than 35 years of experience in industrial wastewater, leachate treatment and hazardous waste site remediation groundwater treatment projects. Has led several projects to assess PFAS management and treatment in leachate.
“We know it’s in leachate—leachate goes to POTWs,” noted Torrens. “Regardless if it’s a significant contributor, it’s point source they can regulate.”
“POTWs and landfills are not sources of PFAS; they are intermediaries,” he added. “Manufacturers are the source of PFAS. I think that term gets thrown around sometimes that leachate or landfills are a source, and they are not.”
There has been a lot of talk around two particular PFAS compounds— perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS)—but not as much on the other shorter-chain compounds, which are prevalent in leachate but not being looked at as much by regulators. PFOA and PFOS are no longer manufactured in the U.S. and were banned in the early 2000s, but they are still found in landfills and imported products.
When it comes to PFAS removal, a physical partitioning to sludge and removal can be used, but it does not destruct PFAS compounds. The compounds continue to move from one place to another; they never go away, hence their nickname “forever chemicals.”
“We have to be careful on how data are interpreted and jumping to the conclusion that leachate is a major source,” he explained. “But like I said, it almost doesn’t matter because they are going to regulate what they can regulate.”
Today, the industry is limited on what can be used for the effective removal of PFAS. Torrens said it boils down to granular activated carbon (GAC), ion exchange in resins and reverse osmosis. And any of these technologies benefit from pretreatment of the leachate, and each have their advantages and disadvantages, he noted.
GAC has been shown to effectively remove PFAS from drinking water when it is used in a flow through filter mode after particulates have already been removed.
“To me, there is a great opportunity for these landfills and POTWs to work collaboratively to help solve this problem,” explained Torrens. “I don’t think there is a well-thought-out approach for how we can do that. I think there are a lot of challenges here to be worked out, but we’re all in it together to find an approach.”
Torrens also detailed opportunities and risks for landfill owners and operators. Opportunities include a positive public image of pulling PFAS out of the environment and “locking it down” to protect human health and the environment. Risks include changing regulations, analytical uncertainty, lost investment and new treatment reduction technologies.
“One of the questions we’re all wondering is what is the right level of treatment and what is required,” Torrens pointed out. “Regulations are farther than the science. Regulations don’t necessarily support the science, and it’s not going to backtrack once the regulations are out there, even if the science says something different.”