CRPC-TR99797-S						September 1999

Title: Competition Between Chemical and Physical Processes in
Bioremediation

Authors: Xiaohong Wang, Mary F. Wheeler, and Steven Bryant

Submitted November 1999

Abstract:
     The performance of an in-situ groundwater remediation project is a
complicated function of many factors, including subsurface flow rates and
patterns, diffusion/dispersion, rate of contamination from the source,
retardation and rate of degradation of the contaminant(s), availability of
co-reactants for degradation, etc.  The complexity of the interaction
between these phenomena makes it difficult to interpret microscopic
behavior, e.g. variation in levels of contamination in an extraction well,
or to predict field-scale performance from small-scale data.
     This work illustrates the use of ParSSim, a parallel simulator of
subsurface flow, transport and reaction, to elucidate the mechanisms that
control performance of an intrinsic bioremediation project.  The coupling
of the chemical and physical processes leads to higher contaminant
concentrations.  Defferent chemical/physical factors may have the same
qualitative effects on the concentration of contaminant reaching an
observation well, and we illustrate how simulation can be used to
discriminate between these factors.  Finally we illustrate the use of the
simulator to quantify biogeochemical "domains of influence", the regions
of parameter space in which a particular reaction or mechanism dominates
the process.  Such knowledge is valuable in evaluating alternative
remediation strategies.

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Xiaohong Wang
Department of Petroleum and Geosystems Engineering
The University of Texas at Austin

Mary F. Wheeler
mfw@ticam.utexas.edu
Center for Subsurface Modeling
The University of Texas at Austin

Steven Bryant
sbryant@ticam.utexas.edu
Center for Subsurface Modeling   
The University of Texas at Austin