Modeling and sensitivity analysis of electron capacitance for Geobacter in sedimentary environments

Journal Article · Mon Mar 01 04:00:00 EST 2010 · Journal of Contaminant Hydrology, 112(1-4):30-44

DOI:https://doi.org/10.1016/j.jconhyd.2009.10.002· OSTI ID:992362

Zhao, Jiao; Fang, Yilin; Scheibe, Timothy D; Lovley, Derek R; Mahadevan, Radhakrishnan

In situ stimulation of the metabolic activity of Geobacter species through acetate amendment has been shown to be a promising bioremediation strategy to reduce and immobilize hexavalent uranium [U(VI)] as insoluble U(IV). Although Geobacter species are reducing U(VI), they primarily grow via Fe(III) reduction. Unfortunately, the biogeochemistry and the physiology of simultaneous reduction of multiple metals are still poorly understood. A detailed model is therefore required to better understand the pathways leading to U(VI) and Fe(III) reduction by Geobacter species. Based on recent experimental evidence of temporary electron sinks in Geobacter we propose a novel kinetic model that physically distinguishes Geobacter species into neutral and electron-charged states. This model shows that the existence of an electron load-unload cycle might be responsible for efficient U(VI) reduction, and elucidates the relationship between U(VI) and Fe(III)-reducing activity and further explains the correlation of high U(VI) removal with high proportions of Geobacter species in a planktonic state in groundwater. Global sensitivity analysis was used to validate the beneficial effects of electron capacitance and determine the level of importance and interactions of physicochemical and biogeochemical processes controlling Geobacter growth and U(VI) reduction. As compared with current modeling approaches in which biomass is often assumed to maintain the same metabolic state over all conditions, the structured two-state model accounts for important aspects of the dynamic electron capacitance of subsurface Geobacter, thereby facilitating further applications in the optimal bioremediation design strategy.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 992362
• Report Number(s): PNNL-SA-64401; KP1702030
• Journal Information: Journal of Contaminant Hydrology, 112(1-4):30-44, Journal Name: Journal of Contaminant Hydrology, 112(1-4):30-44 Journal Issue: 1-4 Vol. 112; ISSN JCOHE6; ISSN 0169-7722
• Country of Publication: United States
• Language: English

Related Subjects

09 BIOMASS FUELS
ACETATES
BIOGEOCHEMISTRY
BIOMASS
BIOREMEDIATION
CAPACITANCE
DESIGN
ELECTRONS
Fe(III) oxides
Geobacter
KINETICS
PHYSIOLOGY
REMOVAL
SENSITIVITY ANALYSIS
SIMULATION
STIMULATION
URANIUM
bioremediation
electron capacitance
global sensitivity analysis
uranium