Sequestration of Radionuclides and Metal Contaminants through Microbially-Induced Carbonate Precipitation

Microbially induced carbonate precipitation (MICP), an emerging technology for soil improvement, also may be used to sequester (biomineralize) radionuclides and metal contaminants (e.g., 90 Sr 2+ , Cd 2+ ) in groundwater, a significant problem at some U.S. Department of Energy sites. Previous work using the bacterium Bacillus pasteurii suggests that in-situ sequestration of these contaminants can be achieved through MICP via hydrolytic ureolysis. However, ureolysis produces harmful byproducts, such as ammonium, and requires aerobic conditions. Biomineralization through bacterial denitrification offers a promising alternative for in-situ remediation in these cases. In contrast to ureolysis, highly ubiquitous denitrifying bacteria, including Pseudomonas denitrificans, are capable of MICP without the production of harmful byproducts. Biomineralization of metal contaminants through the stimulation of native denitrifying bacteria may provide a more sustainable means of remediating groundwater impacted by radionuclides and metal contaminants than hydrolytic ureolysis.