Biostimulation by Glycerol Phosphate to Precipitate Recalcitrant Uranium(IV) Phosphate.
Stimulating the microbial reduction of aqueous uranium(VI) to insoluble U(IV) via electron donor addition has been proposed as a strategy to remediate uranium-contaminated groundwater in situ. However, concerns have been raised regarding the longevity of microbially precipitated U(IV) in the subsurface, particularly given that it may become remobilized if the conditions change to become oxidizing. An alternative mechanism is to stimulate the precipitation of poorly soluble uranium phosphates via the addition of an organophosphate and promote the development of reducing conditions. Here, we selected a sediment sample from a U.K. nuclear site and stimulated the microbial community with glycerol phosphate under anaerobic conditions to assess whether uranium phosphate precipitation was a viable bioremediation strategy. Results showed that U(VI) was rapidly removed from solution and precipitated as a reduced crystalline U(IV) phosphate mineral similar to ningyoite. This mineral was considerably more recalcitrant to oxidative remobilization than the products of microbial U(VI) reduction. Bacteria closely related to Pelosinus species may have played a key role in uranium removal in these experiments. This work has implications for the stewardship of uranium-contaminated groundwater, with the formation of U(IV) phosphates potentially offering a more effective strategy for maintaining low concentrations of uranium in groundwater over long time periods.
Williamson Research Centre and Research Centre for Radwaste Disposal, School of Earth, Atmospheric and Environmental Sciences, The University of Manchester , Williamson Building, Oxford Road, Manchester M13 9PL, U.K.
Laura
L
Newsome
Williamson Research Centre and Research Centre for Radwaste Disposal, School of Earth, Atmospheric and Environmental Sciences, The University of Manchester , Williamson Building, Oxford Road, Manchester M13 9PL, U.K.
Katherine
K
Morris
National Nuclear Laboratory , Chadwick House, Birchwood, Warrington WA3 6AE, U.K.
Divyesh
D
Trivedi
Williamson Research Centre and Research Centre for Radwaste Disposal, School of Earth, Atmospheric and Environmental Sciences, The University of Manchester , Williamson Building, Oxford Road, Manchester M13 9PL, U.K.
Alastair
A
Bewsher
Williamson Research Centre and Research Centre for Radwaste Disposal, School of Earth, Atmospheric and Environmental Sciences, The University of Manchester , Williamson Building, Oxford Road, Manchester M13 9PL, U.K.|National Nuclear Laboratory , Chadwick House, Birchwood, Warrington WA3 6AE, U.K.
Jonathan R
JR
Lloyd
D000693:Anaerobiosis; D001419:Bacteria / Q000378:metabolism; D001673:Biodegradation, Environmental; D011232:Chemical Precipitation; D005990:Glycerol / Q000737:chemistry; D060587:Groundwater / Q000737:chemistry*; D059013:Microbial Consortia; D055848:Nuclear Power Plants; D010084:Oxidation-Reduction; D010710:Phosphates / Q000737:chemistry; D006113:United Kingdom; D017974:Uranium Compounds / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*
D010710:Phosphates; D017974:Uranium Compounds; D014874:Water Pollutants, Chemical; D005990:Glycerol