Mitigation of Uranium Mining Impacts—A Review on Groundwater Remediation Technologies

Groundwater contamination is one of the most concerning issues from uranium mining activities. Radionuclides cannot be destroyed or degraded, unlike some organic contaminants (and similar to metals). Besides, sites, where radionuclides may be found, are mainly radioactive and mixed waste disposal areas, and therefore many other contaminants may also be present in groundwater. The state-of-the-art of environmental technology is continually changing, and thus a review on technologies application is of utmost relevance. This work gives an overview of the available remediation technologies for groundwater contaminated with radionuclides resulting mainly from uranium mining. For each technology, a theoretical background is provided; the state of development, limitations, efficiency, and potential adverse effects are also approached. Examples of application and performance monitoring of remediation progress are described, and criteria for the selection of the appropriate remediation technology are given. The most effective remediation technology will always be site-specific as a result of the multitude of geographic and operational factors that influence the effluent quality and impact the technical feasibility of treatment methods. Ion exchange, chemical precipitation, and membrane filtration have been considered by the U.S. Environmental Protection Agency (US EPA) as best demonstrated available technologies for radium and uranium removal. Several factors have been demonstrated to influence the selection of a remediation technology (technological aspects and non-technical factors), but even for the technologies demonstrated or industrial proven, two important challenges remain; the (still) mobile radionuclides and the generation of secondary wastes. Besides, remediation technologies are constantly evolving, but future advancement depends on rigorously monitored, documented efficiency, and results achieved. Therefore, the technologies approached in this paper are by no means exhaustive