Biomass plug development and propagation in porous media

Abstract

Exopolymer‐producing bacteria can be used to modify soil profiles for enhanced oil recovery or bioremediation. Understanding the mechanisms associated with biomass plug development and propagation is needed for successful application of this technology. These mechanisms were determined from packed‐bed and micromodel experiments that simulate plugging in porous media. Leuconostoc mesenteroides was used, because production of dextran, a water‐insoluble exopolymer, can be controlled by using different carbon sources. As dextran was produced, the pressure drop across the porous media increased and began to oscillate. Three pressure phases were identified under exopolymer‐producing conditions: the exopolymer‐induction phase, the plugging phase, and the plug‐propagation phase. The exopolymer‐induction phase extended from the time that exopolymer‐producing conditions were induced until there was a measurable increase in pressure drop across the porous media. The plugging phase extended from the first increase in pressure drop until a maximum pressure drop was reached. Changes in pressure drop in these two phases were directly related to biomass distribution. Specifically, flow channels within the porous media filled with biomass creating a plugged region where convective flow occurred only in water channels within the biofilm. These water channels were more restrictive to flow causing the pressure drop to increase. At a maximum pressure drop across the porous media, the biomass yielded much like a Bingham plastic, and a flow channel was formed. This behavior marked the onset of the plug‐propagation phase which was characterized by sequential development and breakthrough of biomass plugs. This development and breakthrough propagated the biomass plug in the direction of nutrient flow. The dominant mechanism associated with all three phases of plugging in porous media was exopolymer production; yield stress is an additional mechanism in the plug‐propagation phase. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 72: 353–363, 2001.

Characterization of Multiporous Structure and Oxygen Transfer Inside Aerobic Granules with the Percolation Model

“…It implies that some of the pores in the meso-pore regime expanded at a higher degassing temperature, which might be attributed to the fact that the pores in the granules were gradually plugged by EPS (28). The macromolecules polymers inhabited the channels and isolated groupings of pores (7).…”

Recent Advances in Petroleum Microbiology

“…Residual oil in reservoirs can be recovered when highly permeable watered-out regions of oil reservoirs are plugged with bacterial cells and biopolymers (584). Bacteria and nutrients are injected into the reservoir, and the system is shut in to allow the biomass to plug the more permeable region as it grows (280,585).…”

Some geomechanical properties of a biopolymer treated medium sand

“…Several works (Li et al 1993, Martin et al 1996, Stewart and Fogler 2001 took into affair biopolymer applications and producing some microorganisms in the soil as plugging agents used for construction of impervious barriers. Cabalar and Canakci (2005), Cabalar et al (2009) claimed that biopolymers inclusion improved the shear strength of sand and DeJong et al (2010) wrote that soil stiffness, compressibility, hydraulic conductivity and volumetric response could be arbitrated by means of biological processes.…”