Comparison of Bioenhancement of Nonaqueous Phase Liquid Pool Dissolution with First- and Zero-Order Biokinetics

Dissolution is one of the key physiochemical processes controlling subsurface remediation of nonaqueous phase liquid (NAPL) pools. One process that can accelerate NAPL pool dissolution is in situ biodegradation. The bioenhancement of NAPL pool dissolution has been studied previously using an analytical solution for the case of first-order biodegradation kinetics. However, data suggest that at typical NAPL source zone concentrations, mathematical description of dissolution bioenhancement may require biokinetic models ranging from first to zero order. In this work, it was determined that an nthorder approximation could be derived using the first-order case and bioenhancement was compared under first- and zeroorder conditions. Two example scenarios demonstrate that predictions of the potential magnitude of the bioenhancement effect are erroneously high when the first- and zero-order cases are incorrectly applied.