Is PFAS a Problem in Municipal Compost?

MnDRIVE brings industry and regulators together to weigh costs, benefits, solutions

by Mary Hoff 

What should researchers be researching? With many needs and finite resources, that’s an important question for MnDRIVE Environment, a partnership between the University of Minnesota and the State of Minnesota that brings the power of University inquiry and innovation to bear on challenges industries face related to clean air, water, and land.

In early 2020, the initiative invited private sector and state agency representatives to discuss issues in need of attention related to per- and polyfluoroalkyl substances or PFAS. This class of chemicals historically has been used in a wide spectrum of consumer goods and has since been implicated as a land and water contaminant linked to a range of health risks. Of particular concern is the fact that PFAS chemicals have started cropping up at municipal compost facilities that turn materials such as grass clippings and food waste into a nutrient-filled substance that is used to enrich soil.  

One of the businesses represented at the meeting was the Shakopee Mdewakanton Sioux Community (SMSC) Organics Recycling Facility. The facility takes in 70,000 tons of materials every year to make compost, compost blends, and landscaping mulch. It has tested its products and found PFAS levels to be well below those that the Minnesota Pollution Control Agency (MPCA) considers a health concern in residential soils. PFAS has shown up in water that drains off piles of materials that are in the process of breaking down, says MPCA composting and recycling specialist Kayla Walsh (as it has for other composting facilities around the state). The test results have facility managers looking for ways to continue to do good while preventing future problems.

The topic is a particularly hot one for SMSC because it would like to open a larger facility to meet increasing demand from community composting.

“We know composting is good. We’re amending the soil,” says SMSC biomass processing assistant manager Dustin Montey. At the same time, he adds, “we don’t want to be introducing a harmful substance back into society” by producing soil amendments containing PFAS.

Erin Skelly, environmental and compliance technician for the facility, notes that SMSC is grounded in the Native American principle of caring for the Earth with the next seven generations in mind. A participant in the 2020 MnDRIVE-hosted meeting, Skelly sees a need for research to find the source of the PFAS and how to get it out of the waste stream so it doesn’t end up in compost.

“There’s a lot that’s unknown about PFAS,” she says. “If it’s in compost and in soil, does it leach out? Does it get into groundwater? Do plants absorb that? There’s a lot of opportunity for research.”

MnDRIVE Environment funding is earmarked specifically for remediation. However, it also works upstream to stimulate discussion and connect stakeholders to collaborate on identifying and characterizing problems that remediation can help solve.

“Once we know where PFAS is and where it is coming from, then these issues can be put forward to remediate. That’s sort of the sweet spot where MnDRIVE funding programs come into play,” says MnDRIVE Environment industry and government liaison Jeff Standish.

For example, University of Minnesota environmental health researcher Matt Simcik and environmental engineering researcher William Arnold have been developing technology to keep PFAS from moving from landfills into groundwater. MnDRIVE Environment funding is supporting this work which, upon completion, might be used to protect water at compost sites.

MnDRIVE Environment will be continuing conversations this spring around strategies for addressing PFAS contamination in the environment. Between entities like SMSC that are seeking to protect the planet, and MnDRIVE, which stands ready to bring the power of University research to the task, the hope is that society can continue to reap the benefits of composting without exacerbating the PFAS problem, and perhaps proactively solving it.