HR: 0800h
AN: H21E-1048    [Abstracts]
TI: Comparison of Modeling Approaches for Simulating Cometabolic Biodegradation in Sorbent-Water Systems
AU: * Haws, N W
EM: nhaws@jhu.edu
AF: Dept. of Geography and Environmental Engineering, 3400 N. Charles Street, Baltimore, MD 21218-2686 United States
AU: Ball, W P
EM: bball@jhu.edu
AF: Dept. of Geography and Environmental Engineering, 3400 N. Charles Street, Baltimore, MD 21218-2686 United States
AU: Bouwer, E J
AF: Dept. of Geography and Environmental Engineering, 3400 N. Charles Street, Baltimore, MD 21218-2686 United States
AB: Numerical models are useful for predicting the effectiveness of the bioremediation of organic contaminants in sorbent-water systems. Modeling methods can range from simple approaches (e.g. equilibrium, linear sorption and first-order biodegradation) to much more sophisticated models (nonlinear, multi-domain sorption, Monod biodegradation kinetics, and co-contaminant effects). The relative sensitivity of different modeling methods is investigated for the bio-attenuation of two co-existing contaminants. Eighteen models with different combinations of alternative representations for sorption, mass transfer, and biodegradation are used to simulate the simultaneous biodegradation of toluene (primary substrate) and TCE (cometabolic nongrowth substrate) in completely-mixed batch systems with the various combinations of sorption strength, mass transfer rates, biodegradation rates, and initial contaminant mass loadings. The sensitivity of results to the modeling approach varies with system conditions. For example, the simulations are insensitive to the representation of sorption in systems with low sorption strength and slow biodegradation rates. For such systems, however, predictions can be very sensitive to the model's biodegradation component. Differences among the various modeling results are greater when evaluated in terms of mass removal rather than aqueous concentration reduction. Also, and as expected, the fate of the non-growth cometabolite is more sensitive to the proper consideration of co-contaminant effects than is the fate of the primary growth substrate. These simulations show how the determination of the appropriate level of model complexity can be guided by preliminary assessments of the extent to which the various sorption, mass transfer, and biodegradation processes are expected to control contaminant bioavailability.
DE: 1829 Groundwater hydrology
DE: 1831 Groundwater quality
DE: 1832 Groundwater transport
DE: 0400 Biogeosciences
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting