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UC researcher uses microbes to treat smog-causing pollutants

A researcher at the University of Cincinnati is studying ways to dispose of volatile organic compounds (VOCs), a lead contributor of smog. Unchecked, smog can stay trapped in the atmosphere, hovering near the ground and causing sickness and affecting the long-term health of anyone who breathes it. 

As part of his master’s thesis, environmental engineering Ph.D. candidate Assem Dewidar is using a biological air treatment process to oxidize the harmful chemicals. Unlike traditional chemical or physical treatments, this biological process is both eco-friendly and economically efficient.

Dewidar’s work addresses common city health threats and leads to a more sustainable future. The research reflects the urban impact platform of UC’s strategic direction, Next Lives Here

Dewidar injects water into a test tube

UC Ph.D. candidate Assem Dewidar is studying how to oxidize volatile organic compounds, a lead contributor of smog, with a biological air treatment process. Photo/Corrie Stookey/CEAS Marketing

Summer can bring more than just sunshine and swimming pools. In many urban areas, smog is at its worst in the summer. Smog is a type of air pollution formed when volatile organic compounds and other combustion emissions interact with sunlight. This toxic mix is highly carcinogenic and can affect both human and environmental health.

Dewidar is addressing the harmful chemicals released by automotive shops that do car-coating and painting. When painters spray the finishing coat on a car, the nozzles they use release gaseous compounds. The EPA puts strict regulations on these emissions, but industry methods needed to meet these regulations require a lot of energy.

“Currently, these industries are using expensive and energy-intensive technologies to get rid of VOCs,” said Dewidar, referencing the high temperature needed to physically combust the compounds. “It is effective in oxidizing the VOCs, but if you consider the cost effectiveness for the whole operation over years, it costs a lot of money.”

Dewidar is proposing a biological solution, different from these conventional physical and chemical combustion processes. And it’s rooted in the same technology we use to treat our wastewater. 

Pollution in the air, microbes in the water

Dewidar injecting water into tube

UC Ph.D. candidate tests for volatile organic compounds in water samples in the laboratory. Photo/Corrie Stookey/CEAS Marketing

Biofiltration is a technology that dates back to the 1960s in wastewater treatment plants. Today, these plants still use biofiltration to control odors and, more importantly, eliminate contaminants from water.

Microbes, or microorganisms that feed on organic materials, are at the center of the biofiltration process. In wastewater treatment, microbes live in big water tanks, converting harmful pollutants in wastewater into energy. It’s a symbiotic relationship: The microbes happily feast on the harmful organic matter, and people get treated wastewater they can safely release back into the environment.

Now, Dewidar wants to entice these hungry microbes with organic compounds from paint booth emissions. But there are obvious challenges, the first being the very composition of the chemicals.

Paint booths release the compounds in their gaseous state. In this form, some of them are insoluble, a problem for microbes that exist in a biofilm that is mostly water.

“Wastewater treatment is less challenging because the contaminants are in the water itself. It’s not transferred from phase to phase,” Dewidar said. “In our case, the contaminants are in the air, but they need to be available in the water.” 

Dewidar's gloved hands point to green fluid in a glass beaker at the end of black tube

UC Ph.D. candidate Assem Dewidar points out volatile organic compounds in a laboratory test. These compounds are highly carcinogenic and can affect both human and environmental health. Photo/Corrie Stookey/CEAS Marketing

To increase the solubility of the chemicals, Dewidar is introducing a substance called biosurfactant. Biosurfactants, which are derived from microorganisms, mobilize insoluble contaminants by increasing their solubility.

“When you finish eating something and your hand is a little bit oily or greasy, you want to get some soap to get rid of that,” Dewidar said. “The biosurfactant is the same idea.”

Biosurfactants have properties that break down the force between atoms at the water’s surface, which reduces the surface tension between water molecules. Reduced surface tension makes it easier for the gaseous compounds to penetrate the water’s surface, where patiently waiting microbes will then consume it.

And since biosurfactants stem from an aerobic bacterium, they are naturally produced and less toxic than chemical alternatives. 

Unclogging the microbes

But microbes are tricky. When microbes grow and reproduce, they start sticking to each other, as well as other surfaces. Over time, this large mass of cells forms a thin, slimy film called a biofilm (a common example of a biofilm is dental plaque).

As more microbes stick to each other to form colonies, they enlarge this biofilm. The biofilm can grow so much that it affects the air flow and even clogs the biofiltration system. If that happens, the VOCs may sneak by the microbes, escaping the system still armed and dangerous.  

Close shot of microbes in a tube.

Microbes grow in the laboratory. UC Ph.D. candidate Assem Dewidar is using these microbes to oxidize volatile organic compounds, a process similarly deployed in wastewater treatment plants. Photo/Corrie Stookey/CEAS Marketing

We figured out that the biosurfactant that we’re examining not only enhances the bioavailability of the gas but also controls the biofilm. It has a double effect.

Assem Dewidar, UC Ph.D. candidate

Dewidar poses in lab

Ph.D. candidate Assem Dewidar poses in the laboratory. Dewidar has a bachelor's degree from Alexandria University in Egypt and is pursuing a Ph.D. in environmental engineering at UC. Photo/Corrie Stookey/CEAS Marketing

Dewidar found that biosurfactants can once again be effective.  

“We figured out that the biosurfactant that we’re examining not only enhances the bioavailability of the gas but also controls the biofilm,” said Dewidar. “It has a double effect.”

Rooted in their detergent properties, biosurfactants act as anti-biofilm agents, reducing microbes’ ability to cling to each other. This double effect bodes wells for using biosurfactants in biofiltration as a long-term solution for emissions control. 

For the last year, Dewidar has been exploring the possibilities of biosurfactants in the biofiltration treatment of toxic emissions. The results appear promising. In June, Dewidar will present his work at the annual Air & Waste Management Association conference in Quebec City. He hopes to publish a paper on the research with his mentor, UC professor and head of the Department of Chemical and Environmental Engineering George Sorial, Ph.D., and eventually scale up his work to industry.

If Dewidar can make the leap from benchmark research to commercial application, it will be a step forward in creating a healthier and more sustainable world.

“It’s our responsibility to leave this planet in better shape for the future generations than we found it,” said Dewidar. “The world is facing a lot of water and health crises because of pollution. I hope to someday develop an artificial platform to ensure VOC emissions everywhere are under control.”  

Featured image at top: UC Ph.D. candidate Assem Dewidar points to microbes in one of his laboratory tests. Microbes are central to the biolfiltration process Dewidar is researching for his master's thesis. Photo/Corrie Stookey/CEAS Marketing

Next Lives Here

Dewidar’s work can solve urban-based health issues and lead to a more sustainable future. Learn more about urban impact and UC’s strategic direction, Next Lives Here