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‘It’s corn!’
Environmental engineering students explore new use of corn to improve public health
An estimated 2.5 billion bushels of corn are grown annually in the state of Iowa alone, according to the U.S. Department of Agriculture. It is used in the production of thousands of different products, from ethanol to livestock feed to corn sweeteners and corn starch.
But promising research being conducted in the University of Iowa’s College of Engineering is raising the possibility for another use for corn: using bacteria through a bioremediation process to clean up toxic chemicals in sediments contaminated with polychlorinated biphenyls, or PCBs.
PCBs are a group of man-made chemicals once commonly used in building materials and electrical equipment manufactured before 1980. Caulk, paint, glues, plastics, fluorescent lighting ballasts, transformers and capacitors are products that may contain PCBs. The United States banned these chemicals in 1979 because they harm human and environmental health, but the chemicals have made their way into the soil and are gradually emitted into the air.
“Only recently have we started looking at combing black carbon materials and microbes for PCB bioremediation,” explained Tim Mattes, a researcher and professor who’s been with the Department of Civil and Environmental Engineering at the University of Iowa since 2004. He noted that it is not a new idea, as other researchers have been investigating ways to use bacteria to clean up PCBs for over 30 years — but using ground corn is new.
This diagram, hand-drawn by David Ramotowski for his Three-Minute Thesis, is a visual representation of his research. It also won the Graduate Student Senate’s Research Imagery Award. Submitted photo.
Mattes leads this bioremediation research project, which is one of five under the umbrella of the Iowa Superfund Research Program, or ISRP, which looks at ways to improve public health and equity, aiming at protecting people in vulnerable communities that are exposed to airborne PCBs emitted from nearby contaminated sediments.
Funding for the ISRP comes through the National Institute of Environmental Health Sciences and comprises of 18 scientists and engineers, 10 staff members and 21 trainees.
Civil and environmental engineering Ph.D. candidates David Ramotowski and Qin Dong both work as research trainees under the direction of Mattes in this research effort.
“Right now, the main method of cleaning up PCBs in sediment is to dredge and remove the sediment and put it in a chemical waste landfill,” Ramotowski explained, “but those can leak, or the sediment can be incinerated, which then releases the PCBs back into the air.”
Their research aims to find a way to keep that from happening while cleaning up the contamination sites using bacteria delivered into the areas on a product called biochar — made from corn.
Ramotowski has been working to grow the bacteria on biochar, the charcoal-like substance made with organic material, which would solve the issue of keeping the bacteria alive and able to break down the PCBs.
“Biochar can be made from any organic substance,” he explained, “but fellow researcher Qin Dong discovered that corn worked best.”
Qin Dong conducts her research in the lab at the University of Iowa. Submitted photo.
Dong has been working with biochar since she began her Ph.D. in 2020. She tested different plant material sources — reeds, grasses, corn kernels — to see which types work best for growing the bacteria. Dong found that finely-ground corn-kernel biochar works best.
“Our project is special because it will look at the effects of this treatment on PCBs in soil, water and air, which is quite difficult to do, but which the ISRP is equipped to handle,” Ramotowski said.
Corn biochar is made by placing the corn in a furnace and heating it with limited oxygen, a process called pyrolysis, or decomposition, brought about by high temperatures. The product is essentially like charcoal.
Ramotowski recently took first place in The University of Iowa’s Three Minute Thesis competition with his presentation titled “Unlikely Heroes: Keeping Toxic PCBs Out of Our Air With Bacteria and Biochar.”
“The idea is to prevent PCBs from getting into the air by growing PCB-degrading bacteria on the surface of biochar made from corn kernels (called biofilm-coated biochar),” he said. “The idea is that the biochar will attract PCBs from the soil like a magnet while the bacteria on the surface breaks them down. The biochar will also provide a home for the bacteria, protecting it from harsh environments, which is one of the biggest problems with using bacteria to clean up chemicals outside the lab.”
Fellow researcher Dong’s focus concentrates on how to protect that bacteria function on the biochar to keep it from being washed away in the implementation process.
“We’ve been working to create a chemical cover,” she explained, adding that they have come up with an encapsulation cover they call sol-gel encapsulation.
“This sol-gel encapsulation would cover the whole unit of the bacteria plus the corn biochar so that we can achieve a much longer performance out of the bioremediation treatment process,” she added.
A diagram drawn by David Ramotowski illustrates how Qin Dong’s research into encapsulating biochar and bacteria with "sol gel" works to improve their concept even further. Submitted photo.
David Ramotowski with his first-place trophy that he earned in the 2023 Three-Minute Thesis competition for his project “Unlikely Heroes: Keeping Toxic PCBs Out of Our Air With Bacteria and Biochar.” Submitted photo.
Both Dong and Ramotowski came to the University of Iowa to pursue their passion and dedication to improving the environment and public health, as well as raising communication efforts to spread the word about their ongoing work that is easy for the public to understand.
But they both know there is more work to do.
“More data is needed,” Dong said.
Ramotowski said he is currently working on trying to figure out how much of the corn-kernel biochar to use in his experiments.
“I am not sure about how much biochar costs to produce since we got it from another research group in the Mechanical Engineering Department here at the university, but I am pretty sure that if we can get away with using less, then we should, since costs could increase rapidly when talking about cleaning up large areas,” he said.
“Now we need to find out how the biochar works by running preliminary experiments to see how much we need to add to the sediment for it to be effective against PCBs,” he added.
“Depending on those results, we will conduct a larger experiment to see how the bacteria performs over time. The goal is to grow this to a scale where it can be used in the environment.”
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