HR: 1340h
AN: U43C-1397    [Abstracts]
TI: Biofilm enhanced subsurface sequestration of supercritical CO₂
AU: * Mitchell, A C
EM: andrew.mitchell@erc.montana.edu
AF: Center for Biofilm Engineering, Montana State University, Bozeman, MT 59717, United States
AU: Phillips, A
EM: aphillips@erc.montana.edu
AF: Center for Biofilm Engineering, Montana State University, Bozeman, MT 59717, United States
AU: Hiebert, R
EM: rhiebert@erc.montana.edu
AF: Center for Biofilm Engineering, Montana State University, Bozeman, MT 59717, United States
AU: Gerlach, R
EM: robin-g@coe.montana.edu
AF: Center for Biofilm Engineering, Montana State University, Bozeman, MT 59717, United States
AU: Kaszuba, J
EM: kaszuba@bnl.gov
AF: Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545, United States
AU: Cunningham, A
EM: al-c@erc.montana.edu
AF: Center for Biofilm Engineering, Montana State University, Bozeman, MT 59717, United States
AB: In order to develop subsurface CO₂ storage as a viable engineered mechanism to reduce concentrations of atmospheric CO₂, any potential ¡°leakage¡± of injected supercritical CO₂ (scCO₂) from the ground to the atmosphere must be reduced. Here, we investigate the utility of biofilms, which are microorganism assemblages firmly attached to a surface, as a means of reducing scCO₂ leakage. Firstly, experiments were performed to test whether biofilms were more resilient than planctonic cells to scCO₂. Bacillus mojavensis biofilms were grown on a sand support matrix in scCO₂ extractor cartridges at 30°C. B. mojavensis was also grown under suspended planctonic conditions in the same media overnight and aliquots were decanted into scCO₂ extractor cartridges. Biofilm and suspended B. mojavensis samples were processed on a Supercritical Fluid Extractor with pressurization to 2000 psi at 35°C, and a 20 minute flow of scCO₂. Suspended growth samples revealed a 3 log reduction in cell viability while biofilm only showed a 1 log reduction, demonstrating that B. mojavensis biofilms are more resilient than planctonic cells to scCO₂. Protective extra cellular polymeric substances which make up the biofilm matrix likely provide a protective barrier against scCO₂. Secondly, the ability of biofilms to grow under high pressure and reduce the permeability of porous geological matrices was investigated using a unique high pressure (8.9MPa), moderate temperature (¡Ý 32°C) flow reactor containing 40 millidarcy Berea sandstone cores. The flow reactor was inoculated with the biofilm forming organism Shewanella fridgidimarina. Electron microscopy of the rock core revealed substantial biofilm accumulation in rock pores which resulted in <99% reduction in core permeability. Permeability did not increase in response to starvation and scCO₂ challenges. Viable population assays of organisms in the effluent indicated survival of the microorganisms following scCO₂ challenges of <71h and starvation for <363h. Biofilms are more resilient to scCO₂ than planctonic cells, display continued viability under high pressure, and are able to significantly reduce porous media permeability under high pressure. This is extremely encouraging for the prospective use of engineered biofilm barriers for controlling leakage of geologically sequestered CO₂.
DE: 0418 Bioremediation
DE: 0428 Carbon cycling (4806)
DE: 5104 Fracture and flow
DE: 5114 Permeability and porosity
SC: Union [U]
MN: 2007 Fall Meeting