ABSTRACT
The rate of biodegradation in contaminated aquifers depends to a large extent on dispersive mixing processes which are now generally accepted to result from spatial variations in the velocity field. It has been suggested, however, that transient flow fields can also contribute, perhaps significantly, to this dispersive mixing process. The influence of transient flow on reactive, biodegrading contaminants is particularly important since it can enhance the mixing with possible electron acceptors further promoting the reactive process. The effect of transient flow on the behaviour of a biodegradable contaminant (benzene) was evaluated both with respect to the development of apparently large horizontal dispersion and with respect to enhanced mixing between substrate and electron acceptor. All simulations are compared to base cases involving a conservative tracer.
