Predictions of bioenhancement of nonaqueous phase liquid ganglia dissolution using first- and zero-order biokinetic models

The bioenhanced dissolution of nonaqueous phase liquid (NAPL) contaminants that occurs as a result of an increased concentration gradient is influenced by several factors, including the biokinetics. This is important because available data suggest that at typical NAPL source zone concentrations, descriptions of dissolution bioenhancement may require kinetic expressions ranging from first- to zero-order. In this work, an analytical model for the bioenhancement factor, E, is developed for NAPL ganglia dissolution with zero-order kinetics, and compared to a model for E with first-order kinetics. The models are analyzed and an illustrative example is provided to demonstrate the importance of using the correct biokinetics when estimating the potential magnitude of the bioenhancement of NAPL ganglia dissolution.