Permeable reactive barriers (PRB) provide an efficient technology for passive in situ groundwater remediation. In the European research project PEREBAR, the long-term behaviour of PRBs was studied, with special emphasis on reactive material properties and physico-chemical processes. Laboratory and field studies showed that the most efficient materials for the removal of uranium from contaminated groundwater are elemental iron and hydroxyapatite. Geochemical studies of ageing processes were conducted on these materials and on activated carbon used for the sorption of hydrocarbons, in order to analyse their long-term behaviour in PRB systems. Innovative materials for the selective sorption of uranium were developed. The concept of electrokinetic curtains to enhance the performance of PRB systems was evaluated, and this proved to be the most promising approach in this respect. Pilot-scale studies carried out in the former Hungarian uranium mining area near Pécs showed excellent uranium removal results and reduced the groundwater contamination to about one hundredth of the original concentration. The project contributed to the knowledge and expertise in the field of passive groundwater remediation using permeable reactive barriers. More recent developments substantiate these findings and indicate that the use of permeable reactive barriers offers good prospects for groundwater remediation in the future.

Key words: ageing, degradation, electrokinetic curtains, groundwater contamination, hydroxyapatite, iron,  long-term behaviour, passive groundwater remediation, permeable reactive barrier, precipitation, selective sorption

Land Contamination & Reclamation, 17 (3-4), 635-650 (2009)

DOI 10.2462/09670513.964