WWRC 97-05cc
A Network Model For Biofilm Growth and Its Effects in Porous Media
Abstract
A new technique for controlling pollution in
groundwater is the use of biofilms. Biofilms are
bacteria that link themselves with extracellular
polymeric substances. The bacteria, already present
in the porous or injected into the porous medium, are
used to either destroy the contaminant or to plug the
medium by forming biobarriers, and, thus limiting the
spread of the pollutant.
We present a network model for the SCALE-UP of
flow, transport and biofilm growth in porous media.
We will start with calculations in straight tubes of
different diameters and will link them into
rectangular arrays. These arrays of tubes with random
diameters simulate the porous medium in two
dimensions. Cubic arrays are used in three
dimensions. The tubes are subdivided into cells and a
new scheme based on upwinded finite differences is
used to control numerical diffusion. As the pollutant
is transported the bacteria will consume it and grow.
This bacterial growth changes the diameter of the
tubes and therefore the flow and transport properties
of the whole network. Relations between amount of
bacteria present and macroscopic properties of the
medium, such as permeability and porosity, are
derived.
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