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Fate of nitrogen gas produced by denitrification during U and Tc bioreduction


EMSL Project ID
6516

Abstract

Uranium and technetium are common contaminants at DOE legacy waste sites. At the DOE?s Natural and Accelerated Bioremediation Research?s Field Research Center (FRC) at Oak Ridge National Laboratory, researchers are investigating the possibility of using in situ microbial communities to create anaerobic and reducing conditions that favor the bioreduction of U and Tc to their less soluble oxidation states. However, the high levels of nitrate co-contamination at this site (and many other sites) inhibit microbial U and Tc bioreduction. Once nitrate is removed, U and Tc reduction occur rapidly. Thus, by stimulating the activity of indigenous denitrifiying organisms, nitrate can be reduced nitrogen gas allowing metal reducing organisms to reduce U and Tc. However, nitrate concentrations at the site are very large (up to 150 mM) and there is concern that the large quantities of nitrogen gas produced during denitrification will clog the pore space of the treated aquifer. Thus, understanding the fate and transport of nitrogen gas produced in situ is important to evaluating the effectiveness of U and Tc bioreduction.

Project Details

Project type
Exploratory Research
Start Date
2004-01-02
End Date
2006-01-10
Status
Closed

Team

Principal Investigator

Jonathan Istok
Institution
Oregon State University