HR: 11:35h
AN: B32B-06    [Abstracts]
TI: A Scale-independent Rate Formulation for Bioreduction of Hematite in Sediments at a Field Site
AU: * Chen, C
EM: ch674162@pegasus.cc.ucf.edu
AF: University of Central Florida, 4000 Central Florida Blvd, Orlando, FL 32816 United States
AU: Yeh, G
EM: gyeh@mail.ucf.edu
AF: University of Central Florida, 4000 Central Florida Blvd, Orlando, FL 32816 United States
AU: Yu, J
EM: ji324333@pegasus.cc.ucf.edu
AF: University of Central Florida, 4000 Central Florida Blvd, Orlando, FL 32816 United States
AU: Burgos, W D
EM: wdb3@email.psu.edu
AF: The Pennsylvania State University, 212 Sackett, University Park, PA 16802 United States
AU: Minyard, M L
EM: mlm503@psu.edu
AF: The Pennsylvania State University, 212 Sackett, University Park, PA 16802 United States
AB: This presentation focuses on a systematic modeling approach in search of scale-independent rate formulations for the biological reduction of hematite. Biological and chemical processes controlling Fe(III) reduction are very complex including direct bioreduction of ferric irons, microbial growth, secondary reactions of biogenic ferrous iron adsorptions, iron complexation, precipitation of ferrous minerals, and re-oxidation. A reaction network of five reactions was proposed to describe these processes under laboratory-controlled batch and column experiments which were conducted using sediments taken from a field site. The key reaction in the experiments is the direct bioreduction of hematite. Four possible rate formulations were proposed to describe this key reaction. Two kinds of simulations were conducted to verify the rate formulations and reaction parameters: the first one is the batch modeling with BIOGEOCHEM 1.0 and the second one is the column modeling with HYDROGEOCHEM 4.0. While all rate formulations can adequately model batch experiments, only the formulation based on dual Monod kinetics with inhibition of ferrous iron and the effect of DMRB can be upscaled to column experiments. Iterative modeling between batch and column experiments revealed that the equilibrium assumptions for surface hydration of hematite and adsorption of biogenic ferrous irons onto hematite may have to be revoked and substituted with the kinetic rate formulations.
DE: 0409 Bioavailability: chemical speciation and complexation
DE: 0412 Biogeochemical kinetics and reaction modeling (0414, 0793, 1615, 4805, 4912)
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0418 Bioremediation
DE: 0466 Modeling
SC: Biogeosciences [B]
MN: Fall Meeting 2005