¹Center for Biofilm Engineering, Montana State University, Bozeman, MT 59717, and ²MSE Inc., PO Box 4078, Butte, MT 59702
The effectiveness of microbial biobarriers for reducing the hydraulic conductivity of porous media was evaluated using cylindrical columns (6" diameter x 36" length) packed with sand. The columns were inoculated with starved cell suspensions of Klebsiella pneumoniae. Resuscitation of starved bacteria resulted in a uniform increase in cell numbers throughout the column and a corresponding decrease in hydraulic conductivity. Reductions in hydraulic conductivity were compared for columns packed with F70 and F110 sand (initial permeabilities 27 and 5.3 Darcies, respectively). Although the F70 sand columns had an initial hydraulic conductivity approximately an order of magnitude higher than the F110 sand columns, biobarrier formation resulted in stabilization at a similar minimum hydraulic conductivity. Challenge of an established biobarrier with starvation conditions resulted in a loss of biobarrier integrity after five to ten days. However, the biobarrier rapidly reformed following reintroduction of nutrients. Souring of the columns also resulted in a loss of biobarrier effectiveness. Overall, the results of this study suggest that biobarrier technology is a feasible method for the manipulation of permeability and mass transport properties of porous media.
biobarrier, porous media, plugging, starved bacteria, bioremediation
This paper is from the Proceedings of the 10th Annual Conference on Hazardous Waste Research 1995, published in hard copy and on the Web by the Great Plains/Rocky Mountain Hazardous Substance Research Center.
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