ARGONNE RESEARCHERS STUDY CHALLENGES OF BIOREDUCTION

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ARGONNE RESEARCHERS STUDY CHALLENGES OF BIOREDUCTION
14 November 2002 - DOE/Argonne National Laboratory

Researchers at the U.S. Department of Energy's Argonne National Laboratory have discovered that using bacteria to remediate uranium-contaminated groundwater may not be as simple as originally thought. Their work was reported in a recent issue of Nature.

Actinide contamination of soils, sediments and water is a problem around the globe, especially at many Department of Energy sites. One approach to clean up of these areas is to convert the radionuclides to an insoluble form. This can be done through bioreduction, using bacteria to chemically reduce the contaminants, drastically hindering their further migration through the soil.

Researchers from Argonne's Environmental Research Division and the University of Wisconsin-Madison studied uranium-contaminated sediments and water from the Midnite Mine in Washington state. Researchers stimulated the growth of natural bacteria in the water and after one month found the concentration of uranium had been reduced by almost 99 percent.

Using the powerful X-rays of Argonne's Advanced Photon Source to study the materials, researchers found that bioreduction had converted the uranium to highly insoluble uraninite mineral particles only one to three nanometers across.

"In some instances, particles this small can still be transported through water and porous sediments," said Argonne researcher Ken Kemner. "Our results indicate that precipitation of uranium as uraninite cannot be presumed to immobilize the uranium. We intend to perform further studies to investigate the extent and impact of the movement of uraninite nanoparticles through a variety of porous media."

"Without the high brilliance X-ray beams provided by the APS, we never would have been able to study these small particles," Kemner added.

The group's work was funded by the Department of Energy's Natural and Accelerated Bioremediation program and Argonne's Laboratory Directed Research and Development program.

http://www.anl.gov

About: DOE/Argonne National Laboratory
Argonne National Laboratory is one of the US Department of Energy's largest research centres. It is also the nation's first national laboratory, chartered in 1946.

Argonne is a direct descendant of the University of Chicago's Metallurgical Laboratory, part of the World War Two Manhattan Project. After the war, Argonne was given the mission of developing nuclear reactors for peaceful purposes. Over the years, Argonne's research expanded to include many other areas of science, engineering and technology.

Today, the laboratory has about 4000 employees, including about 1200 scientists and engineers, of whom about 700 hold doctorate degrees.

Argonne occupies two sites. The Illinois site is surrounded by forest preserve about 25 miles southwest of Chicago's Loop. About 3200 of Argonne's 4000 employees work on the site's 1500 wooded acres. The site also houses the US Department of Energy's Chicago Operations Office.

Argonne-West occupies about 900 acres about 50 miles west of Idaho Falls in the Snake River Valley. It is the home of most of Argonne's major nuclear reactor research facilities. About 800 of Argonne's employees work there.

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