REDUCTION OF POROUS-MEDIA PERMEABILITY FROM IN-SITU LEUCONOSTOC-MESENTEROIDES GROWTH AND DEXTRAN PRODUCTION

In situ growth of bacteria in a porous medium can alter the permeabili ty of that media. This article reveals that the rate of permeability a lteration can be controlled by the inoculation strategy, nutrient conc entrations, and injection rates. Based on experimental observations a phenomenological model has been developed to describe the inoculation of the porous medium, the in situ growth of bacteria, and the permeabi lity decline of the porous medium. This model consists of two phases t hat describe the bacteria in the porous medium: (1) the nongrowth phas e in which cell transport and retention are occurring; and (2) the gro wth phase in which the retained cells grow and plug the porous media. Transition from the transport phase to the growth phase is governed by the growth lag ti me of the eel Is within the porous medium. The impo rtance of the inoculum injection strategy and the nutrient injection s trategy is illustrated by the model. (C) 1996 John Wiley & Sons, Inc.