Removal of uranium from contaminated drinking water: a mini review of available treatment methods

In the present article, the major treatment methods applied for uranium removal from groundwater, with specific applications in drinking water treatment, are reviewed. These include pump-and-treat technologies, such as membrane filtration methods, anion exchange, and the use of adsorbents, such as iron oxides, or titanium dioxide, as well as the application of coagulation processes with the addition of Fe/Al salts, or by lime softening. In all cases, uranium removal is mainly dependent on its speciation, which is greatly affected by the (usually coexisting) carbonate ions in the contaminated water. Under circumneutral pH values, uranium forms anionic complexes with carbonate of the type UO2(CO3)(2)(2-) or UO2(CO3)(3)(4-). In situ treatment technologies comprise mainly the use of permeable reactive barriers. These contain reactive materials, such as zero valent iron or hydroxyapatite, and uranium is usually removed by reduction to the respective insoluble products of U(IV); reducing bacteria, when present, can play a supplementary role.