상추, 배추, 무순, 미나리를 이용한 뿌리여과법(rhizofiltration)의 우라늄으로 오염된 지하수 정화 효율 규명

Abstract

Lab scale rhizofiltration by using four plants was performed to investigate the uranium removal efficiency from groundwater. Lettuce (Lactuca sativa L.), Chinese cabbage (Brassica campestris L.), radish sprouts (Raphanus sativus L.) and buttercup (Oenanthe javanica) were cultivated during 3 weeks in the phytotron. Glass jar (<TEX>$12cm{\times}12cm{\times}8cm$</TEX> for each), containing 350 ml of the artificially uranium contaminated solution was used for 72 hours of the rhizofiltration. In experiments with different initial uranium concentration (<TEX>$18.00{\mu}g/L$</TEX>, <TEX>$31.00{\mu}g/L$</TEX>, <TEX>$84.00{\mu}g/L$</TEX> and <TEX>$116.00{\mu}g/L$</TEX>) in solution, more than 70% of the initial uranium were removed by using lettuce, Chinese cabbage and radish sprouts and the residual uranium concentration in solution maintained lower than USEPA water tolerance limit (<TEX>$30{\mu}g/L$</TEX>). From the rhizofiltration experiments at various pH conditions, the highest uranium removal for all four plants was acquired at pH 3 in solution. Rhizofiltration experiments testing two field samples of groundwaters having high uranium concentrations (<TEX>$86.00{\mu}g/L$</TEX> and <TEX>$173.00{\mu}g/L$</TEX>) were duplicated and more than 83% of the initial uranium were removed from the groundwater within 72 hours of rhizofiltration by using radish sprouts, which, suggests that the rhizofiltration can be a useful process to remediate uranium contaminated groundwater in the field. After the rhizofiltration experiment, the SEM and EDS analyses for the root surface of the radish sprouts were conducted, suggesting that the main mechanism of the rhizofiltration for the removal of uranium from groundwater would be surface precipitation on the root surface of the plant.