Growing up in Ann Arbor, Aditi Ganesan remembers learning about pollution that’s been around so long it’s part of the city’s lore. The Gelman Plume, a section of Ann Arbor’s groundwater contaminated with 1,4-dioxane, was part of school projects and field trips, she says.
So when the University of Michigan (U-M)
Synthetic Biology Team, of which Ganesan is co-president, decided to do its
2024 project on the plume, she felt she had a unique perspective on the problem.
“It really was personal to us,” says Ganesan, a junior studying biomedical engineering at U-M. “And it became more and more personal as we learned more and met more people.”
In
their project, dubbed Bioxane, Ganesan and her classmates tested bacteria to see if they could break down 1,4-dioxane, the contaminant present in the plume. They also explored whether such a system would be feasible as a filter for residential use.
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Doug CoombeAditi Ganesan and Grace Lombardo.
The Synthetic Biology Team is made up of 30 undergraduate students from different disciplines at the university. Students run the club and choose their experiments with help from faculty advisors. The Bioxane project was led by former co-presidents Sophia Tesic and Kimi Lillios and science directors Sriram Garapati, Sashider Rajesh, and Joel Groves. Their mission is to provide students with real-world experience in conducting scientific experiments while also engaging with those directly affected by their research, Ganesan says.
Gelman Sciences, LLC dumped wastewater containing dioxane on its property in Scio Township from 1966 to the 1980s. That wastewater seeped into the ground and has traveled with groundwater underneath Ann Arbor, which hundreds of residents rely on for drinking water. The plume has contaminated over a hundred private drinking water wells and a municipal well, and groundwater use in west Ann Arbor is prohibited.
A U-M graduate student discovered the plume in 1984 – before any of the current members of the Synthetic Biology Team were born.
“It’s kind of crazy that this has been around so long,” says Grace Lombardo, a junior studying biochemistry and co-president of the club with Ganesan.
A persistent problem
The U.S. Environmental Protection Agency classifies dioxane as a probable carcinogen. It’s a synthetic chemical that travels extremely well with water. Dioxane doesn’t readily degrade in the environment either, so once it’s in water, it’s there to stay – unless it’s stripped using other chemicals.
That’s what Gelman has been doing since 1997, using a process called ozone oxidation. A legal agreement between the state and Gelman requires the company to pump and treat contaminated water.
But that legal agreement doesn’t require Gelman to clean up the plume – just manage it. And the process Gelman currently uses creates another carcinogen as a byproduct. That’s not a solution to the contamination, Lombardo says.
An organic solution
One alternative is
bioremediation. That’s a way of cleaning up contaminants using microbes, says Sriram Garapati, the Synthetic Biology Team’s former science director. Garapati is now a U-M senior, also studying biomedical engineering.
“Bioremediation is basically just using biological applications, such as engineering a way in bacteria to take care of a certain problem,” he says.
Like Ganesan, Garapati grew up in Ann Arbor and remembers learning about the plume in school. The project was his proposal, voted on by the entire club.
“It's always been something I wanted to work on,” Garapati says.
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courtesy University of Michigan Synthetic Biology TeamUniversity of Michigan Synthetic Biology Team members working in the lab.
Bioremediation is a viable option that needs more research, according to
a review of current scientific knowledge of dioxane. It likely wouldn’t work in a deep aquifer, but could be used at the point of entry to a building or as part of a larger municipal system.
“It could be used because typical cleanup or remediation methods are not efficient or sustainable,” Garapati says. A “biological approach” may be better suited for the problem at hand.
The students modified a strain of bacteria,
Pseudomonas putida, so that it could break down 1,4-dioxane in water. They placed the bacteria in a bioreactor designed to treat water for human consumption.
“We were able to successfully degrade dioxane at rates that were similar to, if not better than, current treatment procedures,” Garapati says. That indicates more study is warranted, he says.
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Doug CoombeThe University of Michigan Synthetic Biology Team.
Those kinds of results are typical of a scientific experiment. They’re meant to add to the collective knowledge about remediation of dioxane. The results are encouraging, Ganesan says.
“The most valuable thing that may have come out of our experiments was seeing that bioremediation or biological methods of degradation have promise and can be optimized and further studied,” she says.
The team took the experiment to
iGem, an annual competition for undergraduate students in synthetic biology, where it received a nomination for Best Sustainable Development Impact.
A local perspective
But the experiment was only part of the work. The students also engaged with people directly affected by the plume. That includes residents and citizen advocates who have pushed for more aggressive cleanup of the plume for decades.
The students attended monthly meetings of The Coalition for Action on Remediation of Dioxane (
CARD). The coalition was founded in 2006 and works with local and state officials to advocate for stronger action on cleaning up the plume.
“It was instrumental in our project to witness their work,” Ganesan says.
Gelman’s pump-and-treat operation has reduced the concentration of dioxane in Ann Arbor’s ground water. But the plume is still there and Gelman isn’t doing enough, says Roger Rayle, the chair of the coalition.
“We need other kinds of treatment technologies,” he says. Rayle has been involved for over 30 years, cataloguing documents and data about the plume. The student group interviewed him about the plume and its 40-year history.
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Doug CoombeUniversity of Michigan Synthetic Biology Team co-president Grace Lombardo.
“We got the whole story from Roger,” Lombardo says.
The Synthetic Biology Team's effort is not the first student project done on the plume. In 1988, a group of master’s students at the U-M School of Natural Resources wrote their
thesis on the plume and its implications for environmental regulation in Michigan.
Dan Bicknell, the student who discovered the plume, also published
a report of his findings and circulated a petition among residents near the Gelman property. That led to the county testing residential drinking water wells for dioxane – and confirming his hypothesis that the plume was spreading under Scio Township. Bicknell is a member of the coalition, and continues to advocate for EPA intervention at the site.
The Synthetic Biology Team visited Third Sister Lake in Scio Township, where Bicknell first found the contamination while studying in the U-M School of Public Health. The students also
surveyed CARD members and other Ann Arbor residents. What did they know about the contamination? What would they like to see happen? Would they be interested in a bioreactor to treat water from their wells?
They also interviewed four residents, getting their personal experiences and perspectives on the plume.
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Doug CoombeUniversity of Michigan Synthetic Biology Team co-president Aditi Ganesan.
“It reflected the conversations that I had with my childhood friends about the plume,” Ganesan says.
The team also visited Ann Arbor’s water treatment plant to see what a large-scale, real-world application of their experiment might look like.
“We're making sure that what we're designing, what we're creating, really has a need and a place in this society or community,” Ganesan says.
Experiments like this are welcome news, Rayle says.
“It's important for the public to know that there are people trying to come up with innovative solutions to solve the problem,” he says.
“We won’t forget”
Although their results were promising, the students say their work with the project is done for now. As undergraduates, it’s difficult to get funding for additional research, Lombardo and Ganesan say. But the data is available
online for anyone to pick up where the team left off, Garapati says.
Ganesan says she didn’t expect the project to have so much impact.
“This project really surprised me,” she says.
As an engineering student, she didn’t think bioremediation would interest her. But she ended up loving it. And the human practices component – talking to residents, going to the plant – was just as important as the science.
“The community involvement is essential for our projects to be what they are, because it makes everything matter more,” Ganesan says. “Just doing the science alone is not as meaningful.”
Elinor Epperson is a freelance journalist based in Ypsilanti. She is currently pursuing a master’s degree in journalism at Michigan State University, focusing on environmental, health, and science reporting.
Photos by Doug Coombe.