PFAS chemicals are in the water supply, including our drinking water. One way they are getting there: sewage sludge that is used as fertilizer. Pennsylvania and other states are looking to limit contamination from these so-called forever chemicals.
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A tour of the wastewater treatment plant
One crucial pathway for PFAS to enter the environment is through sewage treatment plants, like the Allegheny County Sanitary Authority (ALCOSAN) in Pittsburgh.
On a rainy morning in August, Doug Jackson, the authority’s director of operations and maintenance, pointed down into a series of concrete holding blocks.
“This is the first part of the process that we deal with addressing the majority of the human waste,” said Jackson.
Wastewater from about 850,000 homes, and 100 industrial sites enters the sewage treatment plant, along the Ohio River in Pittsburgh, and sits in these tanks for a few hours.
Once the human waste settles to the bottom of the tanks, it’s sent to big centrifuge machines that work kind of like the spin cycle on a washing machine, removing water from the waste.
“We spin that, and ultimately that produces a dewatered sludge product,” he explained, pointing to the resulting clumpy dirt as it moved along on a conveyor belt. “That’s the byproduct that we then have to dispose of.”
That sewage sludge is known as biosolids, a source of fertilizer at farms around the country. It’s at the heart of a pervasive environmental problem, because scientists have found that it contains PFAS. These “forever chemicals” can come from industrial sources that send wastewater to sewage plants; they can also come from people, after they absorb PFAS in consumer products and the environment, and pass the chemicals through their waste.
The biosolids are treated for pathogens, and tested, before ALCOSAN trucks 30,000 tons of it a year to farms to spread on fields. You can even buy a bag of biosolids at Lowe’s or Home Depot for the garden.
Proponents say this re-use is good for the environment.
“The soil health that can be provided by land application is incredible,” said Mary Baker, executive director of the Mid-Atlantic Biosolids Association.
She said the practice puts what would otherwise be a waste product to good use. If it’s not spread on fields, it is sent to a landfill or incinerated.
“It’s something that we won’t stop seeing as a byproduct of our society; we’re not going to stop flushing anytime soon,” Baker said.
PFAS chemicals in the sludge
PFAS, or per- and polyfluoroalkyl substances, are a group of thousands of chemicals that have been used in consumer products for decades. They are found in everything from non-stick pans to waterproof clothes to firefighting foam. They are known as “forever chemicals” because they don’t break down, and accumulate in the environment, lasting for centuries. PFAS are linked to serious health risks, including developmental delays in children, decreased fertility, and cancer.
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What happens to biosolids on the farm?
PFAS chemicals have been found on farm fields, in the milk from cows that graze on them, and in nearby waterways in Maine and other states.
But Pennsylvania has not done an assessment of contamination on farms in the state. Researchers at the Stroud Water Research Center in Chester County, in southeastern Pennsylvania surveyed 10 farms. They compared fields where farmers used biosolids, with fields where they did not.
“We generally found that definitely the use of biosolids, the fields with the biosolid use, had significantly higher concentrations of PFAS,” said associate research scientist Diana Oviedo-Vargas.
The group found that some types of PFAS chemicals moved from the land into waterways.
“In a couple of farms, we found that the PFAS had been migrating to the stream,” she said.“They were contaminating the surface water and very likely the groundwater as well.”
In fact, last year the Pennsylvania Department of Environmental Protection discovered dangerously high levels of PFAS in the groundwater and drinking water wells in Columbia County, in Northeast Pennsylvania, likely from the farm application of biosolids, the DEP said.
This year, the agency issued a “Do Not Eat” advisory for all fish species from portions of nearby creeks because of the PFAS contamination.
States have started regulating for PFAS in biosolids
Incidents like this have led Maine and Connecticut to ban the use of biosolids on farm fields entirely.
Pennsylvania is moving to regulate PFAS, but it is not banning biosolid use.
“We’re ensuring clean water, we’re protecting the environment,” said Jill Whitcomb, deputy secretary of DEP’s office of water programs. “And we’re ensuring that farmers are able to use this material.”
The DEP is proposing quarterly testing of biosolids at wastewater treatment plants for two of the most common of these chemicals, PFOA and PFOS, before the sludge is sent to farms.
“We are forging ahead based on what we know, and what a lot of our mid-Atlantic neighbor states are doing,” Whitcomb said. “We don’t want to be the path of least resistance for some of these waste streams coming from other states into our farm fields.”
Pennsylvania is following the lead of Michigan, which allows PFAS levels up to 20 parts per billion.
“[Michigan] found, and other states found, that 20 or less could be considered ‘domestic’, meaning it’s coming from our own bodies, and it’s coming out of our own bodies,” Whitcomb said. “So that could be considered…background.”
She said higher levels of PFAS are more likely to come from industrial customers of the wastewater treatment plant, and will require action.
Pa. DEP and U.S. EPA proposals for PFAS in biosolids
Water watchdog Tracy Carluccio, deputy director of the Delaware Riverkeeper Network, said the DEP’s proposal to allow PFAS levels up to 20 parts per billion in biosolids is too lenient.
The U.S. Environmental Protection Agency under President Biden found human health risks in biosolids with PFAS levels at only one part per billion.
“There really is no way to avoid the stark fact that what Pennsylvania DEP is proposing is a compromise that does still expose people to PFAS in dangerous amounts,” Carluccio said.
The U.S. EPA also has a proposal, but it does not include any standards or limits. It’s a voluntary guidance that recommends people who buy bags of biosolids at retail stores check with the supplier if they contain the chemicals PFOA and PFOS.
It also suggests that farmers don’t apply biosolids near waterways, or near children under 5.
“This guidance is absurd,” said Laura Dumais, an attorney with the non-profit Public Employees for Environmental Responsibility, at a recent EPA listening session on the draft guidance.
Dumais said the EPA is shifting the burden onto farmers and consumers.
“It’s ridiculous and it needs to be thrown out in its entirety and replaced with actual regulations on PFOS and PFOA and sewage sludge,” she said.
Testing at the wastewater treatment plant
Back at ALCOSAN, chemists test the biosolids for heavy metals and other contaminants before it is loaded into trucks and sent to farms. ALCOSAN operators say adding a quarterly test for the PFAS chemicals, as the DEP is proposing, will provide new data, and build understanding of the source of these pervasive chemicals.
DEP is accepting public comment on its biosolids proposal draft permits until September 2.
