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Destroying "forever chemicals" in wastewater from sewage treatment and landfills in Minnesota could cost at least $14 billion, and potentially up to $28 billion, over two decades, according to a first-ever estimate released Tuesday.

The study evaluates the cost of different technologies that could remove the chemicals, known as PFAS, which currently escape into the state's waterways and onto land treated with sewage sludge because existing treatment methods don't filter them out.

The report was prepared by consultants Barr Engineering and Hazen and Sawyer for the Minnesota Pollution Control Agency.

"These data are not just relevant to Minnesota," MPCA Commissioner Katrina Kessler said in a news conference. "States and municipalities across the country are also struggling with PFAS and needing to think about how to remove it effectively ... So we believe that this can also help others beyond Minnesota."

PFAS, or per- and polyfluoroalkyl substances, are a class of thousands of chemicals that have been used to make products nonstick, water- and grease-resistant, and extinguish powerful fuel fires. The chemicals do not break down in the environment, they build up in the bodies of people who consume them, spread easily in water, and have been linked with certain cancers, immune deficiencies and developmental problems.

Compared to the current costs of running sewage systems, the bill to treat for PFAS by retrofitting plants or adding new facilities "is orders of magnitude higher than wastewater costs have historically been considered," Kessler said.

How to pay for the additional cost is still an open question. Kessler said the new report would help to make state and federal lawmakers more aware of the challenge of cleaning up the pollution at sewage plants and landfills.

Increasingly, the companies that manufactured PFAS are paying for the pollution through court settlements. Three companies — DuPont, Chemours and Corteva — struck a $1.19 billion agreement last week to settle with thousands of plaintiffs asking for damages to pay for PFAS pollution in drinking water.

Maplewood-based 3M, which pioneered the chemicals, asked to delay a test case for the same set of suits this week, saying it was nearing its own settlement.

The company had previously been sued by Minnesota over PFAS that polluted drinking water in the eastern Twin Cities. That case settled in 2018 for $850 million.

But removing the chemicals from wastewater across the state will cost far more.

Asked about the $14 billion difference between high and low cost estimates in the study, Scott Kyser, a wastewater effluent engineer with MPCA, said that there's a lot of uncertainty in how to build the relatively new technologies to remove and destroy the PFAS in water and sewage sludge. The study considered such methods as incinerating the chemicals, heating them with additives to break them apart and rupturing them under high pressure.

Minnesota has tested some of the new technologies available to filter PFAS from water, but destroying the chemicals is a more complex problem. The technological race to find a reliable solution is creating a booming industry — but no methods are yet deployed on a broad scale.

Minnesota started looking for PFAS chemicals in raw sewage, treated wastewater and sludge as early as 2007. It found that in urban areas, the chemicals consistently showed up in all three.

Sewage sludge, also known as biosolids, is sometimes applied to farm fields, Kessler said. The sludge is also sent to landfills and incinerated. Minnesota doesn't test for the amount of PFAS in the sludge that ends up on fields.

The state and others are waiting on the EPA, Kyser said, to complete a study that will recommend limits on how much of the chemicals should be allowed in the sludge, which is expected by the end of 2024.

"That will help us decide how to address PFAS and biosolids, and land application," Kyser said.