Too much nanotechnology may be killing beneficial bacteria

Apr 29, 2008

Too much of a good thing could be harmful to the environment. For years, scientists have known about silver’s ability to kill harmful bacteria and, recently, have used this knowledge to create consumer products containing silver nanoparticles. Now, a University of Missouri researcher has found that silver nanoparticles also may destroy benign bacteria that are used to remove ammonia from wastewater treatment systems.

Several products containing silver nanoparticles already are on the market, including socks containing silver nanoparticles designed to inhibit odor-causing bacteria and high-tech, energy-efficient washing machines that disinfect clothes by generating the tiny particles. The positive effects of that technology may be overshadowed by the potential negative environmental impact.

“Because of the increasing use of silver nanoparticles in consumer products, the risk that this material will be released into sewage lines, wastewater treatment facilities, and, eventually, to rivers, streams and lakes is of concern,” said Zhiqiang Hu, assistant professor of civil and environmental engineering in MU’s College of Engineering.

“We found that silver nanoparticles are extremely toxic. The nanoparticles destroy the benign species of bacteria that are used for wastewater treatment. It basically halts the reproduction activity of the good bacteria.”

Hu said silver nanoparticles generate more unique chemicals, known as highly reactive oxygen species, than do larger forms of silver. These oxygen species chemicals likely inhibit bacterial growth. For example, the use of wastewater treatment “sludge” as land-application fertilizer is a common practice, according to Hu. If high levels of silver nanoparticles are present in the sludge, soil used to grow food crops may be harmed.

Hu is launching a second study to determine the levels at which the presence of silver nanoparticles become toxic. He will determine how silver nanoparticles affect wastewater treatment processes by introducing nanomaterial into wastewater and sludge. He will then measure microbial growth to determine the nanosilver levels that harm wastewater treatment and sludge digestion.

The Water Environment Research Foundation recently awarded Hu $150,000 to determine when silver nanoparticles start to impair wastewater treatment. Hu said nanoparticles in wastewater can be better managed and regulated. Work on the follow-up research should be completed by 2010.

The study was funded by a grant from the National Science Foundation.

Source: University of Missouri-Columbia

Explore further: Nano-scale gold particles are good candidates for drug delivery

add to favorites email to friend print save as pdf

Related Stories

Ecotoxicity: All clear for silver nanoparticles?

Feb 25, 2014

It has long been known that, in the form of free ions, silver particles can be highly toxic to aquatic organisms. Yet to this day, there is a lack of detailed knowledge about the doses required to trigger ...

Silver nanoparticles trap mercury

Feb 16, 2012

(PhysOrg.com) -- Anyone who thinks amalgams are limited to tooth fillings is missing something: Amalgams, which are alloys of mercury and other metals, have been used for over 2500 years in the production ...

The promise and peril of nanotechnology

Mar 26, 2014

Scientists at Northwestern University have found a way to detect metastatic breast cancer by arranging strands of DNA into spherical shapes and using them to cover a tiny particle of gold, creating a "nano-flare" ...

Some antibacterials come with worrisome silver lining

Feb 24, 2014

Silver has long been known for its ability to kill some of the nasty microbes that can make people sick. In hospitals, it's used to help burn victims, to combat germs on catheters and even to wipe out dangerous "superbugs" ...

Bringing clean water to developing nations

Dec 10, 2013

"It's been a long, hard slog," says Susan Murcott, a senior lecturer in MIT's Department of Civil and Environmental Engineering, describing her efforts to disseminate water-filtration systems to some three ...

Recommended for you

User comments : 0