For years, scientists have known about silver's ability to kill harmful bacteria and, recently, have created 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.
Products containing silver nanoparticles are already on the market, including socks designed to inhibit odor-causing bacteria and energy-efficient washing machines that disinfect clothes by generating the tiny particles. "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.
Silver nanoparticles generate more unique chemicals, known as highly reactive oxygen species, than larger forms of silver generate. These oxygen species chemicals likely inhibit bacterial growth. Hu says the use of wastewater treatment "sludge" as land-application fertilizer is a common practice. If high levels of silver nanoparticles are present in the sludge, soil used to grow food crops may be harmed.
