Modeling NAPL dissolution and biodegradation interactions: effect of toxicity and biomass growth limitations

摘要

This work focuses on some aspects of the interactions between NAPL dissolution, molecular diffusion and biodegradation processes. Starting from a test problem based on a real field scenario, a one-dimensional model is set up. A number of simulations are run using different biomass distributions, varying diffusion coefficients and biological kinetic rates. Results indicate that under ideal conditions biomass distribution along the column does not make a real difference in terms of total amount of dissolved oil degraded. Results change dramatically when introducing limitations in the growth of biomass and the effects of toxicity into the model. Both of these are modelled as functions for which some threshold or bounding levels are specified. In particular, toxicity function is derived from some phenornenogical considerations, since, at least to the author's knowledge, no documentation in the literature is available in this regard. Constrained biomass growth and contaminant toxicity have been found to yield results consistent with field data on contaminant distribution. This would support our presumption that biomass growth constraint and toxicity play a major role in reducing natural attenuation efficiency.