Bioremediation Field Experiment Successfully Removes Uranium from Contaminated Ground Water


Researchers in the Natural and Accelerated Bioremediation Research (NABIR) program have demonstrated that a novel bioremediation strategy precipitates uranium from ground water at a Uranium Mill Tailings Remedial Action (UMTRA) site in Rifle, Colorado. Until now, there have been no cost-effective mechanisms for preventing uranium contamination from migrating with ground water and threatening important water resources. Researchers from the University of Massachusetts discovered that microorganisms from the genus Geobacter effectively strip uranium from contaminated ground water by transferring electrons onto uranium. This electron transfer process converts soluble uranium to an insoluble form that precipitates from the ground water. To stimulate the activity of Geobacter at the Old Rifle site, an interdisciplinary team of researchers from the University of Massachusetts, the Pacific Northwest National Laboratory, and the UMTRA program added a dilute solution of acetate (i.e. vinegar) to the ground water. From mid-June through mid-August, more than 70% of the uranium was precipitated from the ground water within the treatment zone. In some areas, uranium concentrations were below UMTRA s maximum contaminant level (MCL) of 0.044mg/L. The Geobacter species responsible for uranium removal at the Old Rifle site is also being investigated in the Genomes to Life Program to better understand the mechanisms by which Geobacter transforms radionuclides such as uranium.