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Wash U Engineers Use Bacteria And Nanotechnology To Purify Dirty Water

Girls in Vemasse, Timor-Leste carry containers of water across a rice field after heavy rains.
UN Photo/Martine Perret
Water-stressed areas, such as the island nation of Timor-Leste in southeast Asia, could someday benefit from water filtration technologies being developed at Washington University and elsewhere.

Researchers at Washington University in St. Louis are developing a water filter that could help people in countries where there is not enough clean drinking water.

Engineers at WashU are combining bacteria and tiny engineered particles to create a filter that can kill harmful bacteria. The United Nations expects that by 2025, about half of the world’s population will be living in areas where water is scarce. That’s put pressure on scientists to develop water-purifying technologies to help increase global access to drinking water.

The filter under development at Wash U blends fibers generated from bacteria. They combined the fibers with graphene oxide, an extremely thin material that can convert sunlight into heat, which then kills the bacteria on the surface of the filter’s membrane.

Because the technology just requires sunlight to work, that could help rural communities without reliable access to electricity, said Young-Shin Jun, an environmental engineering professor at Wash U.

“Where we don’t have electricity, we’ll still be able to utilize this membrane to kill bacteria that we worry about,” Jun said.

Bacteria buildup in the device is a common problem in developing water filtration technology. The membranes end up needing to be changed, said Srikanth Singameneni, a Wash U engineering professor. Using graphene oxide to heat and kill bacteria helps solves that issue.

The researchers are working on scaling up the technology. The filter Singamaneni and Jun developed still has years to go before hitting the market, so it’s too early to estimate its cost. The cost of water filtering membranes remains the biggest challenge to delivering them to water-stressed communities, said Eric Hoek, a civil engineering professor at University of California-Los Angeles.

“In order to assure that the whole world has clean, safe drinking water, we do not need a better membrane,” Hoek said. “The most impactful contribution would be to make a membrane that performs the function of a commercially available membrane but cost 10 times less.”

It’s possible that the Wash U researchers’ bacteria-based filter could be less costly compared to others on the market. Because it uses sunlight to kill microbes that accumulate on the membrane, it “can reduce the membrane maintenance cost,” Jun said.

“The new membrane can extend the membrane lifetime due to less accumulation of microorganisms and less usage of harsh chemicals,” she said.

Follow Eli on Twitter: @StoriesByEli

Eli is the science and environment reporter at St. Louis Public Radio.