Transport issues and bioremediation modeling for the in situ aerobic co-metabolism of chlorinated solvents

For aerobic co-metabolism of chlorinated solvents to occur, it is necessary that oxygen, a primary substrate, and the chlorinated compound all be avai lable to an appropriate microorganism - that is, a microorganism capable of producing the nonspecific enzyme that will promote degradation of the onta minant while the primary substrate is aerobically metabolized. Thus, the tr ansport processes that serve to mix the reactants are crucial in determinin g the rate and extent of biodegradation, particularly when considering in s itu biodegradation. These transport processes intersect, at a range of scal es, with the biochemical reactions. This paper reviews how the important pr ocesses contributing to aerobic co-metabolism of chlorinated solvents at di fferent scales can be integrated into mathematical models. The application of these models to field-scale bioremediation is critically examined. It is demonstrated that modeling can be a useful tool in gaining insight into th e physical, chemical, and biological processes relevant to aerobic co-metab olism, designing aerobic co-metabolic bioremediation systems, and predictin g system performance. Research needs are identified that primarily relate t o gaps in our current knowledge of inter-scale interactions.