Permeable reactive barriers (PRBs) offer an alternative to more cost-intensive active methods for groundwater remediation, e.g. pump-and-treat. The long-term performance of PRBs, however, is crucial for the technology’s success. This paper summarizes the results of long-term column experiments with elemental iron (Fe0) and hydroxyapatite (HAP) as reactive materials for the removal of uranium from groundwater. Good removal results have been achieved using elemental iron, with possible reaction paths being reductive precipitation and adsorption on to corrosion products of Fe0. Uranium can also be removed by dissolution of HAP and subsequent precipitation of low-solubility uranyl phosphates such as autunite Ca(UO2)2(PO4)2 or chernikovite H2(UO2)2(PO4)2. Other possible reaction mechanisms for uranium removal with HAP are ion exchange processes and surface sorption with HAP (on two possible surface groups). At the former uranium mining site in Pécs (southern Hungary) a pilot PRB system was installed. Results from the operation are reported.

Key words: groundwater, hydroxyapatite, permeable reactive barriers, uranium

Land Contamination & Reclamation, 15 (1), 31-39 (2007)

DOI 10.2462/09670513.787