RHIZOFILTRATION TO REMOVE URANIUM FROM GROUNDWATER BY USING PHASEOLUS VULGARIS VAR. HUMILIS, BRASSICA JUNCEA (L.) CZERN., AND HELIANTHUS ANNUUS L.

Uranium contaminated groundwater has become a serious environmental problem in uranium mining areas and in the vicinity of nuclear processing facilities. Rhizofiltration is one of the clean up process by using plants (mainly their roots) to remove heavy metal from water. In this study, the uranium removal ability of bean (Phaseolus vulgaris var. humilis), Indian mustard (Brassica juncea (L.) Czern.), and sunflower (Helianthus annuus L.) was investigated under various conditions of the lab scale rhizofiltration process.

Three different plant cultivars were used to evaluate their uranium removal efficiencies from artificially contaminated groundwater having uranium concentration of 50 μg/L. Results of the experiment using sunflower showed that the uranium concentration of groundwater reduced to 50 % in 12 h. After 24 h, its concentration maintained at 8 μg/L and its removal efficiency was 86 %. Analysis of uranium accumulation for each plant part showed that practically all of the uranium was concentrated in its roots. The amount of uranium transported to the shoot from the root was negligible. To identify the effect of different uranium concentration on the uranium removal rate from groundwater, three different plant cultivars were exposed to groundwater having 135, 270, and 540 μg/L of uranium for 72 h. In case of sunflower, the rate of uranium removal was independent of the initial uranium concentration of the solution, showing that the uranium concentration in groundwater reduced to 3 % within 24 h. Results of these experiments suggest that the rhizofiltration process using bean, Indian mustard, and sunflower is a great possibility to remove uranium from groundwater.