Bioremediation

Microbial reduction of soluble U(VI) to insoluble U(IV) represents a promising strategy for immobilizing uranium from contaminated groundwaters. This strategy may also be coupled with a soil washing technique for concentrating uranium from contaminated soils. As we have recently reported, the U(VI)-reducing capacity of the Geobacter species that are naturally present in subsurface environments can be simply and effectively stimulated with the addition of an acetate solution to the groundwater. This precipitates uranium from the groundwater preventing its further mobility and concentrations uranium dispersed in a large volume of groundwater into a discrete zone for subsequent removal.

Geobacter species have been shown to play important roles in the bioremediation of groundwater contaminated with petroleum and landfill leachate. Soluble organic contaminants are oxidized to carbon dioxide with the reduction of iron oxides that are abundant in most subsurface environments. Molecular analysis of a diversity of contaminated subsurface environments in which oxidation of pollutants coupled to iron oxide reduction is important have consistently found that these environments are enriched in Geobacter species.

Our laboratory also investigates other forms of anaerobic bioremediation, most notably the anaerobic degradation of polycyclic aromatic hydrocarbons coupled to the reduction of sulfate in contaminated harbor sediments.

Photos

(click each for a larger image)

Overall view of the Rifle site

Injection gallery and shed

Flowmeters connected to injection manifold and injection wells

Site layout looking downgadient

References

Anderson RT, Vrionis HA, Ortiz-Bernad I, Resch CT, Long PE, Dayvault R, Karp K, Marutzky S, Metzler DR, Peacock A,
White DC, Lowe M, Lovley DR. Stimulating the In Situ Activity of Geobacter Species To RemoveUranium from the Groundwater of a Uranium-Contaminated Aquifer,2003, Applied and Environmental Microbiology 69(10):5884–5891

Lovley DR, Cleaning Up With Genomics: Applying Molecular Biology to Bioremediation, 2003, Nature Reviews|Microbiology 1 (October 2003):36-44.

Lovley DR, Anderson RT. The influence of dissimilatory metal reduction on the fate of organic and metal contaminants in the subsurface, 2002, Journal of Hydrology 8:77–88.

Lovley DR. Anaerobes to the rescue, 2001, Science 293:1444-6.

Press Links

Bugs boost Cold War Clean-up, Nature ScienceUpdate, Nature (online), Oct. 13, 2003.

Microbes that can mop up uranium, The Guardian (online), Oct. 16, 2003.

Mining bacteria's appetite for toxic waste - Researchers try to clean nuclear sites with microbes, San Francisco Chronicle, July 14, 2003.