Modeling of biomass-plug development and propagation in porous media

Microbial biomass (cells and their metabolic byproducts) accumulation and evolution in porous media were simulated using a combination of biofilm evolution model and a biofilm removal model. Theses models describe biomass-plug development, removal, and propagation in biological applications such as microbial enhanced oil recovery, in situ bioremediation, and bio-barrier techniques. The biofilm evolution model includes the cell growth rate and exopolymer production kinetics. The biofilm removal model was used for describing the biomass-plug propagation and channel breakthrough using Bingham yield stress of biofilm, which represents the stability of biofilm against shear stress. Network model was used to describe a porous medium. The network model consists of pore body and pore bond of which the sizes were determined based on the pore size distribution of ceramic cores. The simulation results showed that the biofilm models based on Bingham yield stress predicted the biomass accumulation and channel breakthrough reasonably well. The pressure oscillation (or, permeability oscillation) was also well demonstrated indicating the process of biomass accumulation and breakthrough-channel formation. In addition, the effects of cell and biofilm sucrose concentration were significant on the biomass-plug development and permeability reduction rates. The modeling elucidated some deficiencies in our knowledge of the biomass yield stress that enables us to predict the stability of biomass plug against shear stress. (C) 2003 Elsevier B.V. All rights reserved.