DEVELOPMENT, EXPERIMENTAL VALIDATION AND DYNAMIC ANALYSIS OF A GENERAL TRANSIENT BIOFILTER MODEL

In this study, a general transient biofiltration model, which incorpor ates general mixing phenomena, oxygen limitation effects, adsorption p henomena and general biodegradation reaction kinetics, is developed. S olutions are presented with and without the assumption of pseudo-stead y state for the biofilm leading to approximate and general models, res pectively. Solutions of the model are presented and validated with exp erimental transient data of benzene and toluene. Significant improveme nt in the model prediction is observed in comparison to earlier simpli fied models. However, the general model predictions seem to be better and it is superior to the approximate model as it does not require any correlations for film thickness or effectiveness factors. Dynamic ana lysis of the model is performed and compared with experimental data fr om the literature. Transient behavior during shut-down and restart-up are also well predicted by the model and the transient period does not seem to be long. Model predictions show that the biofilter is able to withstand extreme practical conditions such as random variations in t he inlet concentration and gas flow rate. Theoretical analysis shows t hat the assumption of excess oxygen availability is not a good one, sp ecially at high inlet concentration levels. Sensitivity studies show t hat mixing in the gas phase is an important phenomenon which should no t be neglected and that some parameters need to be accurately estimate d. (C) 1997 Elsevier Science Ltd.