Uranium (U) contamination of groundwater poses a serious environmental problem in uranium mining areas and in the vicinity of nuclear processing facilities. Preliminary laboratory experiments and treatability studies indicated that the roots of terrestrial plants could be efficiently used to remove U from aqueous streams (rhizofiltration). Certain sunflower plants were found to have a high affinity for U and were selected for treatment of contaminated water. almost all of the U removed from the water in the laboratory was concentrated in the roots. Bioaccumulation coefficients based on the ratios of U concentrations In the roots vs U concentrations in the aqueous phase reached 30 000. Rhizofiltration technology has been tested in the field with U-contaminated water at concentrations of 21-874 mu g/L at a former U processing facility in Ashtabula, OH. The pilot-scale rhizofiltration system provided final treatment to the site source water and reduced U concentration to <20 mu g/L (EPA Water Quality Standard) before discharge to the environment. System performance was subsequently evaluated under different flow rates permitting the development of effectiveness estimates for the approach.
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