Subsurface Biofilm Barriers (SBBs)

Subsurface Biofilm Barriers (SBBs) can be used to manipulate the hydraulic conductivity (permeability) of subsurface formations enabling us to decrease or direct the flow of groundwater.

We are developing this technology for the creation of

Low Permeability SBBs,

Starved bacteria, which are sometimes also called ‘ultramicrobacteria’ (UMB), are better transported and more evenly distributed in porous media and therefore present an effective means of delivering and distributing bacteria with desired metabolic capabilities in the subsurface (bioaugmentation). See Bacterial Transport in Porous Media for more information.

Low Permeability and Reactive SBBs, and

Permeable and Reactive SBBs.

The low permeability SBB- and low permeability and reactive SBB-technology has been demonstrated in the field in collaboration with the Center for Innovation (CFI), a small Montana biotech company (http://www.cfi-mt.com/index_files/Page583.html). A field demonstration project was conducted at the Mike Mansfield Technology Center in Butte, MT (see: Cunningham, A.B, Sharp, R.R., Hiebert, R.,. James, G. (2003) Subsurface Biofilm Barriers for the Containment and Remediation of Contaminated Groundwater. Bioremediation Journal..7(3/4) 151-164).

Low Permeability and Reactive SBB-Technology for the control of nitrate contaminated groundwater has also been demonstrated in the field with CFI. The field demonstration was conducted at a USDA demonstration site in Albuquerque, NM (see: Dutta, L., Nuttall, H.E., Cunningham, A.B., James, G., Hiebert, R. (2005): In situ biofilm barriers: Case study of a nitrate groundwater plume, Albuquerque, New Mexico. Remediation Journal 15(4):101-111).
This technology was also investigated at the CBE laboratories by John Komlos (Komlos, J. (2001) Effect of co-substrate concentration on dual-species population distribution, permeability reduction and trichloroethylene (TCE) biodegradation in porous media. Ph.D. Thesis, Center for Biofilm Engineering, Montana State University). We were able to demonstrate that by careful control of the nutritional conditions, we could control the relative abundance of a strong extracellular polymeric substance (EPS) producer and thus good thick biofilm former (Klebsiella oxytoca) and a constitutive TCE degrader (Burkholderia cepacia PR1-pTOM_31c) in batch and biofilm systems (Komlos, J., A.B. Cunningham, A.K. Camper, and R.R. Sharp, "Effect of Substrate Concentration on Dual-Species Biofilm Population Densities of Klebsiella oxytoca and Burkholderia cepacia in Porous Media," Biotechnol. Bioeng., 93(3):434-442 (2006); Komlos, J., A.B. Cunningham, A.K. Camper and R.R. Sharp, "Interaction of Klebsiella oxytoca and Burkholderia cepacia in Dual-Species Batch Cultures and Biofilms as a Function of Growth Rate and Substrate Concentration," Microb. Ecol., 49:114-125 (2005)).

My own Ph.D. work demonstrated the use of bacteria to create permeable and reactive SBBs in the laboratory experiments (Gerlach, R. (2001) Transport and Activity of Dissimilatory Metal Reducing Bacteria in Porous Media for the Remediation of Heavy Metals and Chlorinated Hydrocarbons. Ph.D. Thesis, Center for Biofilm Engineering, Montana State University). Respiratory iron reducing bacteria such as Shewanella algae BrY can influence the performance of zero valent iron (ZVI) for carbon tetrachloride reduction (Gerlach, R., A.B. Cunningham, and F. Caccavo, Jr., "Dissimilatory Iron-Reducing Bacteria Can Influence the Reduction of Carbon Tetrachloride by Iron Metal," Environ. Sci. Technol., 34:2461-2464 (2000)). Furthermore, these bacteria can be used to establish zones of reduced and reactive iron minerals which can chemically reduce environmental contaminants such as chromate (Cr(VI)) (Nyman, J.L., F. Caccavo Jr., A.B. Cunningham, and R. Gerlach, "Biogeochemical Elimination of Chromium (VI) Contaminated Water," Bioremed. J., 6(1):39-55 (2002)), TNT (Borch, T., W.P. Inskeep, J.A. Harwood and R. Gerlach, "Impact of Ferrihydrite and Anthraquinone-2,6-Disulfonate on the Reductive Transformation of 2,4,6-Trinitrotoluene by a Gram-Positive Fermenting Bacterium," Environ. Sci. Technol., 39(18):7126-2133 (2005)), and other contaminants (work in progress).

By improving our ability to understand hydrodynamics in biofilm affected porous media and improve our ability to deliver bacteria and nutrients into the subsurface we can continue to improve future SBB design.