When we pump shampoo from the dispenser into our hands, we expect just the right consistency—not so runny that it slips through our fingers, yet not so thick that it feels like massaging mayonnaise into our scalp.
The polymers behind this pleasant texture are called viscosifiers. They’re used in consumer products like shampoos, detergents, and cosmetics, keeping ingredients suspended and stable in solution. But what happens when those same polymers wash down the drain is less well understood.
READ MORE: Bacteria found to eat forever chemicals — and even some of their toxic byproducts
READ MORE: Wood-degrading fungal enzymes reprogrammed to biorecycle plastic
“Wastewater usually goes to a treatment plant, where the solids are filtered out, and the rest is either broken down by microbes, or precipitated as sludge before being tested then released into streams,” says Xuanhong Cheng, a professor of bioengineering and materials science and engineering in Lehigh University’s P.C. Rossin College of Engineering and Applied Science.
Breaking down polymers
Cheng and her team are collaborating with materials science company Dow Inc. to study how microbes—microscopic organisms that digest sewage—interact with and potentially biodegrade these polymers. Their proposal recently received a three-year GOALI award from the National Science Foundation. The program funds projects that support university-industry collaborations.
Her lab will first map how microbes break down the polymers—mixing them together and tracking microbe growth, as well as the effects of the resulting degradation products.
The team will also test whether mixed communities of microbes can break down polymers more effectively than any single strain.
“If a consortium of microbes works better, we could design strategies to mix them selectively, targeting different parts of the polymer for complete degradation,” she says.
The chemistry of degradation
The goals are twofold, says Cheng. First, to better understand the chemistry behind full degradation—knowledge that could influence product design. Second, to pinpoint microbial mixtures that could be deployed in treatment plants, reducing polymers in discharge from wastewater treatment plants.
The project isn’t just about biodegradation of polymers—it also gives Cheng the chance to mentor future engineers and scientists, an aspect of her work she finds especially fulfilling. She spent the summer working with four undergraduates who took ownership of the research and will help carry it forward this fall.
“It’s motivating to work with students with a clear passion for this problem, and to teach them the skills to help address it,” she says. “That’s very rewarding for me.”
No comments yet