Traveling Wave Behavior During Subsurface Transport of Biologically Reactive Contaminants: Implications for In Situ BioremediationEPA Grant Number: R824785
Title: Traveling Wave Behavior During Subsurface Transport of Biologically Reactive Contaminants: Implications for In Situ Bioremediation
Investigators: Valocchi, Albert J.
Institution: University of Illinois at Urbana-Champaign
EPA Project Officer: Hiscock, Michael
Project Period: January 1, 1996 through December 1, 1998 (Extended to December 31, 1999)
Project Amount: $200,000
RFA: Water and Watersheds (1995) Recipients Lists
Research Category: Water and Watersheds , Water
Description:The project objectives are to use mathematical modeling techniques to investigate the significance of traveling wave behavior during transport of biodegradable solutes in groundwater and to evaluate the impact of this behavior upon the effectiveness of field-scale in situ bioremediation.
Mathematical models are being developed for a hypothetical bioremediation scenario in which a uniformly distributed sorbing organic contaminant is degraded by indigenous soil microbes that are stimulated by an injected nonsorbing electron acceptor. For a one-dimensional homogeneous aquifer setting, preliminary model results demonstrate that the solute fronts often form traveling waves; that is, the spatial profiles of the organic pollutant, electron acceptor, and biomass attain constant shapes which travel in unison at the same velocity. Traveling waves only exist when the concentrations are large enough to prevent occurrence of nutrient-limiting conditions. Under one-dimensional traveling wave conditions it is possible to derive analytically a simple formula for the long-term pollutant removal rate, showing that it is independent of the parameters for dispersion and biodegradation kinetics. The results are significant in that they indicate conditions for which the long-term pollutant removal rate does not depend upon the intrinsic biodegradation kinetic rate parameters. Our studies are being extended to more realistic multidimensional aquifer settings having spatial heterogeneity. In these cases traveling wave behavior should lead to similar simplification of estimates for the overall contaminant removal; this would reduce significantly the computational burden of evaluating the efficiency of a remedial design.