May 16, 2018

Silver Nanoparticles Hinder Wastewater Treatment Process

Researchers suggest conventional toxicity testing for silver may be misleading

New research shows silver may hinder the wastewater treatment process

Researchers at Oregon State University have unveiled new findings regarding the effects of silver nanoparticles on the wastewater treatment process. The new study suggests that even a small presence of the nanoparticles can adversely affect the effectiveness of the treatment process.

Specifically, the researchers posit that the utilization of standard toxicity testing methods for silver concentration may be misleading and offer a false sense of security for plant operators. As noted in the research, silver includes broad-spectrum bacterial properties that could undo the positive work done by beneficial bacteria used by treatment plants, potentially leading to an excess of nutrients present in water supplies.

This potential excess of nutrients could then lead to a significant uptick in vegetation through eutrophication, often leading to algal blooms, detrimentally affecting animal life due to oxygen depletion. Beyond this, silver nanoparticles are becoming increasingly used in a variety of products, making this process even likelier.

“Silver nanoparticles are being incorporated into a range of products including wound dressings, clothing, water filters, toothpaste and even children’s toys,” said Tyler Radniecki, co-author of the study and assistant professor of environmental engineering at Oregon State University. “The nanoparticles can end up in wastewater streams through washing or just regular use of the product.”

An alternative presented by the study includes utilizing biofilms instead of planktonic bacteria to keep the potentially harmful effects of silver at bay.

“Biofilms showed higher resistance for multiple factors,” Radniecki said. “One was simply more mass of cells, and the top layer of cells acted like a sacrificial shield that allowed the bacteria below not to be inhibited. Slow growth rates were also a protection from silver toxicity because the enzymes that silver prevents from turning over aren’t turning over as frequently.”