The Bioproducts and Biosystems Engineering department is active in a wide range of research, including natural systems restoration. Learn how their prairie and stream work is helping restore the Cedar Creek Ecosystem Science Reserve in Anoka County.
A landfill is where the discarded residue of everyone’s lives is buried out of sight. But out of sight is far from out of mind for the people entrusted to handle what happens next. One of the most vexing issues created in landfills today is the presence of “forever chemicals,” officially known as per- and polyfluoroalkyl substances or PFAS, which do not break down in water, soil or air. In Rice County’s Bridgewater Township, an innovative approach to remove forever chemicals from the water that leaches out of the landfill is being explored with the University of Minnesota through the Empowering Small Minnesota Communities (ESMC) program.
It started with a fire
Rice County’s 450-acre landfill in Bridgewater Township sits east of I-35 and serves 68,000 people. Each year, the country generates 100,000 tons of solid waste. Half ends up in the landfill. Two years ago, a fire at the site lasted three days and took several more days to contain.
“That raised the awareness of quite a few people. It sits right here in the township. People asked, ‘What are we doing? What can we do?’” says Bridgewater Township supervisor Glen Castore. That conversation turned to increased awareness and concern about forever chemicals in the landfill.
Forever chemicals are by-products of thousands of items like nonstick cookware, water-resistant fabrics, and personal care products that make our lives easier. But research increasingly connects them to various human health threats, including several types of cancer.
New state and federal prohibitions are intended to address the problem. But when it comes to landfills, early approaches to removing them involve massive facilities that are financially out of reach for smaller jurisdictions, notes University of Minnesota Extension Southeast Regional Sustainable Development Partnerships (RSDP) Executive Director Andi Sutton.
“What happens when a regulation is put in place without a financially accessible solution?” Sutton observes. “What happens is folks on the ground are left holding the bag. They don’t have millions of dollars.”
About 16 percent of Minnesotans live in townships, which provide essential services including snow plowing, road and bridge maintenance, flood recovery, permitting and elections. State law allows jurisdictions that host landfills to charge annual fees; in Bridgewater Township, that provides about $150,000 annually. Of that amount, the township is required to designate 25 percent for landfill remediation.
But the landfill is projected to reach capacity in about 15 to 20 years, ending the revenue for the township. The funds available in the remediation account gave township supervisors the opportunity to pursue an approach that will not only remove and destroy the forever chemicals in the leachate (the gunky stew created by decaying garbage), but also extend the life of the landfill.
“We wanted to see if there’s a way we can use some of those funds to extend the landfill and mitigate the problems that it causes,” says Castore.
Science in the making
The ESMC program was established during the 2023 legislative session and provides small Minnesota communities with resources to research and advance key infrastructure projects. Sutton was part of an ESMC program team that connected the dots between Bridgewater’s forever chemicals challenge and University expertise.
Sutton’s team started by enlisting University of Minnesota Professor Roger Ruan and his team in the Department of Bioproducts and Biosystems Engineering. In his lab, Ruan introduced microscopic algae into landfill leachate. The microalgae ate about half of the forever chemicals. Then, the team used carbon filters and electricity to remove even more of the forever chemicals. In the final step they subjected the material to extreme heat in an oxygen-free environment, a process called catalytic pyrolysis.
The results? The multi-stepped process eliminated more than 97 percent of the forever chemicals. The process also resulted in the production of potentially valuable synthesis gas, bio oil and biochar.
Extension economist Bill Lazarus carried out an economic analysis of the process. Lazarus, who is an emeritus professor in the Department of Applied Economics, studied various scenarios based on the steps Ruan’s team carried out and determined that all are economically viable.
University research, public value
Inspired by the positive initial results, the township funded $60,000 towards the University’s efforts for the next steps, determining how a solution might make the jump from laboratory to everyday use.
This will allow Ruan’s 10-member team to build a small prototype for a field test. It’s been a long slog, Castore says, and it will take longer to determine whether the system Ruan and his students devised is workable—and economically feasible—in everyday settings.
“The township’s goal is to get to the end of this project and have enough detailed information that we can approach some companies about picking this up as a product. It’s ambitious,” says Castore.
The process also delivered valuable experience to Ruan’s team, ranging from undergraduates to doctoral candidates. Says Ruan: “It’s important for them to understand the real needs outside of the school. And then they help develop practical solutions.”
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