REMEDIATION OF A URANIUM-CONTAMINATED GROUNDWATER USING THE PERMEABLE REACTIVE BARRIER TECHNIQUE COUPLED WITH HYDROXY APATITE-COATED QUARTZ SANDS

Treatment of uranium-contaminated groundwater remains a challenge for environmental scientists worldwide. In this study, a permeable reactive barrier (PRB) was coupled with hydroxyapatitecoated quartz sands to treat uranium-contaminated groundwater. The effects of quartz sand particle size, hydroxyapatite coating amount, and velocity and initial concentration of uranium on the removal of U(VI) from an aqueous solution was investigated by dynamic column tests, so as to determine the optimal conditions for uranium removal. The adsorption process was studied using a dynamic adsorption model. Results showed that when the diameter of quartz composite sand was 0.6–1.18 mm, the adsorption capacity of the composites reached the maximum of 6.26 mg/g. The Thomas and Yoon–Nelson models suitably described the influence of quartz sand diameter on the adsorption of U(VI) by the PRB. The equilibration adsorption capacities of the PRB for U(VI) estimated by the Thomas and Yoon–Nelson models were 5.62 and 5.88 mg/g, respectively. This study indicates that the combination of the PRB technique and hydroxyapatite-coated quartz sands is efficient and promising for uranium removal from groundwater.