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Wastewater treatment plays large role in spread of Minnesota’s PFAS contamination, report finds

Researchers found PFAS in the Mississippi River, as well as the Sauk River, Clearwater River and Johnson Creek in central Minnesota.

Mississippi River
A report released last week describes high levels of per- and polyfluoroalkyl substances, or PFAS, found in four waterways, including the Mississippi River.

A new report by the Minnesota Center for Environmental Advocacy (MCEA) shows wastewater treatment plays a large role in the widespread contamination of “forever chemicals” known as PFAS across the state.

In recent years, the Minnesota Legislature has passed some of the most robust legislation in the nation to help reduce how much PFAS makes it into the environment. But the report’s findings suggest state lawmakers and officials will now need to go beyond laws aimed at reducing the chemicals’ use and turn toward addressing PFAS that is already pervasive in the state’s environment. 

The report, released last week, was co-authored by the MCEA and Matt Simcik, an environmental health sciences professor at the University of Minnesota. It describes high levels of per- and polyfluoroalkyl substances, or PFAS, found in four waterways they tested over the summer: the Mississippi River, as well as the Sauk River, Clearwater River and Johnson Creek in central Minnesota.

According to their results, the highest concentrations of PFAS were found in the Mississippi River channel receiving water discharged from the Metro treatment plant in St. Paul. 

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The family of chemicals’ strong bonds make them impossible to break down in the environment. They can also bioaccumulate in humans and have been associated with health problems that include increased thyroid disease, lower birth weights and kidney cancer. 

“(The report) continues to show the broad extent of PFAS contamination in our environment,” said MCEA staff attorney Jay Eidsness. “It really highlights the wastewater process and wastewater as a source of PFAS contamination, which really hasn’t been studied or analyzed in the level of depth that we think it needs to be by our state.”

When wastewater enters a treatment facility, liquids and solids are first separated. The liquids then undergo a chemical treatment process, which is supposed to get rid of toxins, contaminants and pathogens before being released into a source of water like the Mississippi River. 

The problem arises when industrial or manufacturing wastewater entering the treatment plant contains PFAS, because its strong bonds prevent the treatment process from breaking down the chemicals. Therefore, depositing water potentially containing PFAS into the Mississippi River could further contaminate a body of water that millions rely on for drinking water. 

Further exposure can come from the solids that are separated from wastewater during the treatment process. The solids are either incinerated by these facilities — though the process isn’t hot enough to break up and destroy PFAS — or they are chemically treated and turned into nutrient-rich biosolids, which are then sold as fertilizer for gardens and lawns, or in bulk to farmers. 

“Those biosolids would also have PFAS in them, and they go on the soil and eventually they migrate down through the soil profile into the groundwater,” Eidsness said. “Groundwater is a source of drinking water for a lot of our rural communities, so that is another potential pathway to exposure, but also the plants that are grown up as soil, they will take up the PFAS and you can actually find contaminated plants that are later sold as food sources.”

Past, current and future state efforts

Earlier this year, the Legislature adopted Amara’s Law, named after Amara Strande, who advocated for stricter regulations on the forever chemicals before dying of cancer during the legislative session at the age of 20.

The law, which went into effect in July, prohibits manufacturers from intentionally adding PFAS to a wide range of products, including cleaning products, children’s products, cosmetics, cookware, textile furnishings like upholstered furniture and ski wax, among several others, starting in 2025. It will also require manufacturers to submit information on products that contain the chemicals to the Minnesota Pollution Control Agency (MPCA) starting in 2026, and culminates in 2032 in an almost total ban on products containing PFAS from being sold statewide. 

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In the meantime, the MPCA has been following its PFAS Blueprint — a roadmap of short- and long-term goals aimed at preventing, managing and cleaning up PFAS contamination statewide. 

“As part of this Blueprint, we are collecting valuable PFAS monitoring data from wastewater treatment plants and are actively working with municipalities to use newly developed tools to identify and reduce sources of PFAS within their communities,” MPCA spokesman Adam Olson said in a statement. “Monitoring will inform future permitting strategies in various programs, including the wastewater program.”

But advocates argue the state’s pace isn’t quick enough.

Some recommendations put forth by the report include adding PFAS as a pollutant under the Minnesota Sewage Sludge Management Rule, improving water quality standards, and monitoring groundwater for PFAS in case of leaching from the biosolids used as fertilizer.

Eidsness said the state should also place limits on the PFAS concentration in the water that is discharged by treatment facilities, and require industrial sources to treat their wastewater for PFAS before sending it to treatment plants. 

“One of the benefits of those pre-treatment programs I mentioned is that the cost of compliance falls on the industrial source, but if we’re requiring the wastewater treatment plant to clean it up, that’s going to be largely funded by the public,” he said. “Those industrial sources that are using PFAS to make profit, they should be suffering the financial penalty of contaminating our environment.”