Reductive immobilization of U(VI) in Fe(III) oxide-reducing subsurface sediments: Analysis of coupled microbial-geochemical processes in experimental reactive transport systems

Roden, Eric E.; Barnett, Mark O.

doi:10.2172/838637

Cited by 1 publication

(4 citation statements)

References 10 publications

(13 reference statements)

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“…For the geochemical group, the significant contribution of surface area (G3), surface site density (G4) and initial Fe(III) oxides concentration (G5) further confirmed that oxide surface site concentration would limit the rate of Fe(III) reduction which in turn affects U(VI) reduction. This evidence justifies the large contribution from the half saturation constant of attached cells for growth (B13), since it would be possible to saturate the surface of Fe(III) oxides with cells, as reported in microbial reduction of Fe(III) in sediments (Roden and Zachara, 1996;Roden et al, 2002).…”

Section: Extended Fastsupporting

confidence: 80%

“…The 16 most-important factors are further analyzed by using Extended FAST, a variance-based method that has been described in detail elsewhere (Saltelli et al, 1999). The core idea of the Extended FAST is to explore the space of these 16 input factors by a transformed curve that scans the entire space using a separate frequency for each of 16 factors.…”

Section: Application Of Global Sensitivity Analysismentioning

confidence: 99%

“…The core idea of the Extended FAST is to explore the space of these 16 input factors by a transformed curve that scans the entire space using a separate frequency for each of 16 factors. Such a curve allows each factor to be explored globally, showing the advantage of robustness and computational efficiency by converting the high-dimensional integral in the factors into a one-dimensional integral (Saltelli et al, 1999).…”

Section: Application Of Global Sensitivity Analysismentioning

confidence: 99%

“…This fact further supports that Geobacter activities cannot be set too high in sediments. Similarly, any changes for growth parameter values associated with U(VI) reduction should be restricted by experimental evidence that the Ks of Geobacter for U(VI) has been found to be 10-100 fold higher than typical aqueous U(VI) concentrations in contaminated subsurface sediments (1$5 mM, see Roden et al, 2002) and V max should be remarkably lower than that on Fe(III) (Liu et al, 2002). Figure 3 quantitatively describes the effect of spatial distribution of initial biomass concentration on the amount of precipitated uranium over different parts of the column.…”

Section: Model Calibration and Validationmentioning

confidence: 99%

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Model‐based analysis of the role of biological, hydrological and geochemical factors affecting uranium bioremediation

Zhao

Scheibe

Mahadevan

2011

Biotech & Bioengineering

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Uranium contamination is a serious concern at several sites motivating the development of novel treatment strategies such as the Geobacter-mediated reductive immobilization of uranium. However, this bioremediation strategy has not yet been optimized for the sustained uranium removal. While several reactive-transport models have been developed to represent Geobacter-mediated bioremediation of uranium, these models often lack the detailed quantitative description of the microbial process (e.g., biomass build-up in both groundwater and sediments, electron transport system, etc.) and the interaction between biogeochemical and hydrological process. In this study, a novel multi-scale model was developed by integrating our recent model on electron capacitance of Geobacter (Zhao et al., 2010) with a comprehensive simulator of coupled fluid flow, hydrologic transport, heat transfer, and biogeochemical reactions. This mechanistic reactive-transport model accurately reproduces the experimental data for the bioremediation of uranium with acetate amendment. We subsequently performed global sensitivity analysis with the reactive-transport model in order to identify the main sources of prediction uncertainty caused by synergistic effects of biological, geochemical, and hydrological processes. The proposed approach successfully captured significant contributing factors across time and space, thereby improving the structure and parameterization of the comprehensive reactive-transport model. The global sensitivity analysis also provides a potentially useful tool to evaluate uranium bioremediation strategy. The simulations suggest that under difficult environments (e.g., highly contaminated with U(VI) at a high migration rate of solutes), the efficiency of uranium removal can be improved by adding Geobacter species to the contaminated site (bioaugmentation) in conjunction with the addition of electron donor (biostimulation). The simulations also highlight the interactive effect of initial cell concentration and flow rate on U(VI) reduction.

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Section: Extended Fastsupporting

confidence: 80%

Section: Application Of Global Sensitivity Analysismentioning

confidence: 99%

Section: Application Of Global Sensitivity Analysismentioning

confidence: 99%

Section: Model Calibration and Validationmentioning

confidence: 99%

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