Mohan Qin believes that not everything in wastewater actually has to go to waste.
“The nutrients in the water are all useful,” she says. “So we wanted to try to focus on extracting them. Instead of going to waste, the water is now a source.”
Qin, who joined the Department of Civil and Environmental Engineering as an assistant professor in January 2020, studies ways to recover this valuable resource.
She earned a bachelor’s degree from Shandong University in China in 2010, a master’s degree from Peking University in China in 2013, and her PhD from Virginia Tech in 2017. Her doctorate research focused on recovering resources from wastewater.
During her postdoctoral research at Yale University, Qin analyzed the energy consumption of desalination, with a focus on electro-driven desalination processes for brackish water, which has more salt than fresh water but less than seawater. Electro-driven desalination works by pushing ions through ion-exchange membranes to remove salt from water. It’s an area of increasing focus as researchers around the world search for sustainable, efficient ways to treat saltwater.
“We now use a lot of energy to separate salt from water,” Qin says. “We’re trying to evaluate which technology is the most efficient.”
While at UW-Madison, Qin plans to continue her work on brackish water desalination and sustainable wastewater treatment.
“Here in Wisconsin, we have a lot of farms, so there’s naturally a lot of animal waste and agricultural waste,” she says. “There are a lot of nutrients like nitrogen and phosphorus in farm wastewater. I’m trying to build bio-based and electrochemical-based technologies to recover those nutrients from the waste.”
According to the Environmental Protection Agency, nitrogen and phosphorus are vital nutrients that help farmers grow crops and produce the food we eat. However, excess nutrients can build up in the soil and wash away into streams and lakes when it rains or as snow melts.
Too much nitrogen and phosphorus can lead to eutrophication—an excess of nutrients in a body of water. That can deplete oxygen in the water—a condition known as hypoxia—and can create “dead zones” that kill fish and lead to an overall decrease in aquatic life in a body of water. Eutrophication can also hasten the growth of toxic algal blooms, which can threaten wildlife and humans.
“It’s a big issue here, with so many farms,” Qin says.
However, Qin’s research isn’t focused only on finding ways to remove extra nutrients from water before it drains into lakes or streams. She says her hope is to find efficient ways to extract them and put them back to use.
“We’re not just removing them from the water, but recovering them from the water,” she says. “We use nitrogen and phosphorus for fertilizers. We want to recover them so they can continue to be useful.”
Qin says a lot of factors played into her decision to join UW-Madison, but it was ultimately the people, research opportunities and collaborative spirit that drew her in.
“The people here are so nice and Madison is a wonderful town,” Qin says. “The university is great, and has amazing researchers who are very supportive.”
Author: Alex Holloway