Groundwater Remediation of Radionuclides Using a Novel Permeable Reactive Barrier: Laboratory and Field Studies

Zhovty Vody city, located in Dnipropetrovsk Oblast in south-central Ukraine, has long been an important center for the Ukrainian uranium and iron industries. Mining and processing activities during the Cold War resulted in poorly managed sources of radionuclides and heavy metals in waste rock, tailings storage facilities, and waste materials associated with hydrometallurgy production facilities. Widespread groundwater and surface water contamination has occurred, which creates a significant risk to drinking water supplies and aquatic and riparian communities that depend on the Zhovta River and the hydraulically connected shallow groundwater. Hydrogeologic and geochemical conditions in the vicinity of a large uranium mine tailings storage facility (TSF), a major source of contamination, were characterized to provide data to locate, design, and install a permeable reactive barrier (PRB) to treat groundwater contaminated by leachate infiltrating from the TSF.

Using a novel design and installation, the effectiveness of three different permeable reactive materials was investigated: zero-valent iron, phosphate material, and sulphate-reducing bacteria. To evaluate reactivity of the materials, batch and column experiments were conducted in the Kiev Polytechnic University laboratory using Zhovty Vody site groundwater. Reaction rates, residence time, and comparison with site-specific clean-up standards were determined. In the PRB installation, three separate rows of cylinders were filled with different permeable reactive materials, and groundwater sampling was conducted within and around the PRB. Key sampling parameters included field parameters, inorganic analytes, and contaminants of concern (radionuclides and heavy metals). Groundwater levels were also measured periodically throughout the study. Results of the study demonstrate the effectiveness of zero-valent iron and a mixture of sewage sludge, bone meal, sawdust, and water for remediating uranium contaminated groundwater when utilized in a PRB with this design.