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. 

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. 

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. 

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.  

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