News Feature | March 27, 2014

Scientists Engineer Bacteria To Detect, Remove Lead From Wastewater

By Sara Jerome
@sarmje

BacteriaSolution

A team of researchers claims it has engineered bacteria to efficiently remove lead from wastewater. 

Currently, cost is a major barrier to effectively managing lead in wastewater. 

"The most current lead adsorption techniques rely on using expensive activated carbon and ion-exchange resin adsorbents that are difficult to adapt to large-scale wastewater treatment," the researchers said in their paper

Wastewater utilities often grapple with lead problems. "Lead pollution is present in wastewater, waste gases, or waste residues, which often contain other metals, including zinc, cadmium, and mercury.Simply selective detection and adsorption of lead has been a challenge," the paper said. 

A team of Chinese scientists thought they could find a better way to solve the lead problem. The group "developed a more sustainable approach to recover heavy metals from contaminated water for potential reuse in industry," Chemical & Engineering News, a publication of the American Chemical Society, reported

The effort was led by Jing Zhao of Nanjing University and Peking University’s Shenzhen Graduate School, according to Chemical & Engineering News.

In an initial project, the researchers engineered a bacteria to express a gold-binding protein, the report said. That enabled them to detect this metal in wastewater. 

The scientists decided to try a similar strategy with lead. 

"He and colleagues, including Zong-Wan Mao of Sun Yat-Sen University, engineered Escherichia coli to express a lead-binding protein on the cell’s surface. With the protein on the surface, the bacteria can grab large amounts of lead without letting the metal accumulate inside the cells, which can reduce their growth. The researchers also included a set of genes that allowed the bacteria to produce a fluorescent signal when lead binds to the surface proteins," the report said. 

How successful was the plan?

"The modified microbes could collect 5 to 12 percent of the lead in solutions with concentrations between 5 and 300 μM of the metal. In China, lead concentrations up to 5 μM are allowed in wastewater, but illegal discharge sites may have concentrations of 300 μM or more," the report said, citing Zhao.

In the U.S., lead in water is regulated under the Clean Water Act and Safe Drinking Water Act, according to the EPA. 

For case studies, check out Water Online's Drinking Water Analysis Solution Center

Image credit: "Bacteria solution," © 2007 kaibara87, used under an Attribution 2.0 Generic license: http://creativecommons.org/licenses/by/2.0/deed.en

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