Got a credit card? Stick it in your mouth.
All of it. In your mouth.
That’s about the amount of plastic you’re ingesting daily through the food and water you eat, said Dr. Jejal-Reddy Bathi, assistant professor of civil and environmental engineering at the University of Tennessee at Chattanooga.
Bathi and a team of other faculty members and graduate and undergraduate students are researching ways to determine the exact amounts and types of microplastics—plastics broken down to their smallest state—in the water of the Chattanooga metro area. The research also explores ways to filter out microplastics, which are usually carried into water supplies through stormwater drainage.
“Our microplastic levels are significantly high here in the city, in and around our area, so it’s time we should act. We’re doing wonderful things, but it’s not enough,” Bathi said.
In 2022, his research team—which is working with the Center for Urban and Informatics Progress at UTC and the city of Chattanooga—received a $30,000 grant from the U.S. Geological Survey to research ways to filter microplastics from stormwater. The $30,000 was matched by UTC.
This year, the team received $25,000 from the U.S. Environmental Protection Agency to research methods of sampling stormwater. Along with Bathi, the team is led by Dr. Kidambi Sreenivas, associate professor in mechanical engineering, and Dr. Ashley Manning-Berg, assistant professor in the Department of Biology, Geology and Environmental Science.
Student teams from 21 colleges nationwide received the EPA grants as part of the agency’s Phase 1 Environmental Assessment program. The money will help the teams further develop the concept for their proposed projects and make them eligible to compete for a Phase 2 grant of up to $100,000 to continue their research.
“The primary aim is to get the new generation of researchers and engineers to start thinking of innovative ideas to limit microplastic pollution, to mitigate microplastic pollution,” Bathi said.
Bathi and several students—both graduate and undergraduate—are taking samples from ponds, creeks and green spaces around the city and bringing them back to labs at UTC to test them for microplastics.
“These microplastics are bio-magnified into the food system, the food chain, and we cannot stop eating food,” he said. “Researchers have proven that these microplastics exist almost everywhere.”
To collect samples, students on the team have gone out to such areas as Warner Park on McCallie Avenue, Heritage Park in East Brainerd, sites on Amnicola Highway, and creeks and streams before they reach the Tennessee River.
“We have to go out into the field to collect the samples, then we’ll bring them back to the lab to do the further analysis and processing,” said Laura Wright, who’s pursuing a master’s degree in civil engineering with a focus on environmental engineering.
“Microplastics” is an all-inclusive word, and there’s a lot to include. More than 200 polymers—the ingredients, so to speak, that make various types of plastic—are used by industries worldwide. Those can be combined in various ways to make thousands of different plastics.
“Not every particle is the same size,” Bathi said. “They could be anywhere from nano size to millimeter size. They will behave differently in the environment.”
If they settle into the sediment at the bottom of a pond, river or creek, they must be separated from the other substances, which adds another level of difficulty.
“There are hundreds of different things that look like plastic. They behave like plastic. There is sand; there is clay; there is natural, organic material. There are metals, heavy metals. So trying to separate them out to pinpoint one out of thousands of different things is the challenge.”
Another issue is the lack of standardization when reporting the amount of microplastics found in a water supply, in sediment on the bottom of ponds and other water sources, or in the soil surrounding these sources. Some researchers use milligrams in a liter of water; others will use the percentage found in a square kilometer of water; some will use the exact number of microplastics found.
“Everybody’s reporting in different ways. It’s challenging. We need to come to some standardization, trying to understand these aspects, the largest stakes, when reporting data,” Bathi said. “So we are talking about how to sample in the field. How to analyze this in the lab. How to report them back so it’s meaningful.”