Uranium immobilization by sulfate-reducing biofilms.
Environ Sci Technol
; 38(7): 2067-74, 2004 Apr 01.
Article
en En
| MEDLINE
| ID: mdl-15112808
ABSTRACT
Hexavalent uranium [U(VI)] was immobilized using biofilms of the sulfate-reducing bacterium (SRB) Desulfovibrio desulfuricans G20. The biofilms were grown in flat-plate continuous-flow reactors using lactate as the electron donor and sulfate as the electron acceptor. U(VI)was continuously fed into the reactor for 32 weeks at a concentration of 126 microM. During this time, the soluble U(VI) was removed (between 88 and 96% of feed) from solution and immobilized in the biofilms. The dynamics of U immobilization in the sulfate-reducing biofilms were quantified by estimating (1) microbial activity in the SRB biofilm, defined as the hydrogen sulfide (H2S) production rate and estimated from the H2S concentration profiles measured using microelectrodes across the biofilms; (2) concentration of dissolved U in the solution; and (3) the mass of U precipitated in the biofilm. Results suggest that U was immobilized in the biofilms as a result of two processes (1) enzymatically and (2) chemically, by reacting with microbially generated H2S. Visual inspection showed that the dissolved sulfide species reacted with U(VI) to produce a black precipitate. Synchrotron-based U L3-edge X-ray absorption near edge structure (XANES) spectroscopy analysis of U precipitated abiotically by sodium sulfide indicated that U(VI) had been reduced to U(IV). Selected-area electron diffraction pattern and crystallographic analysis of transmission electron microscope lattice-fringe images confirmed the structure of precipitated U as being that of uraninite.
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Base de datos:
MEDLINE
Asunto principal:
Contaminantes Radiactivos del Agua
/
Uranio
/
Bacterias Reductoras del Azufre
/
Biopelículas
Idioma:
En
Revista:
Environ Sci Technol
Año:
2004
Tipo del documento:
Article
País de afiliación:
Estados Unidos