Abstract

Bioremediation is an attractive alternative to traditional remediation methods for a variety of ground water contaminants.  However, widespread implementation of biorememdiation is currently limited by the complexity of the dynamic chemical and biological processes that need to be understood and incorporated into the design approach.  Reactive transport models provide a powerful tool to simulate these complex interactions and, thus, can be used to improve and guide the design of bioremediation systems.  We present a remediation design approach for intermittently stimulated biodegradation using multicomponent reactive transport models, parameterized using a series of nondimensional Damköhler numbers.  Designs were based on either (1) a target aqueous phase concentration at the exit of the treatment system, or (2) the total contaminant mass fraction removed from a region of interest.  The equation set used to develop this design approach is specific to the case of intermittent electron donor addition to drive cometabolic transformations.  We illustrate the design procedure for a biocurtain that removes carbon tetrachloride.  Our results for this case indicate that intermittent injection is significantly more efficient than strategies based on continuous pumping.  Example design parameters include the length of the biologically active zone (i.e., biocurtain), the effective rate of degradation in the zone, and the interval between electron donor injection cycles.  The presented dimensionless parametric approach can be used to design bench-scale column studies and should be helpful for scale-up to field-scale remediation systems.

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Phanikumar, et al (2002)