Predicting clogging in biofilters through a straightforward and comprehensive mathematical model

Most mathematical models consider a constant and uniform biomass distribution even though experimental observations do not correspond with this common assumption. Biomass accumulation is the most important limitation for stable, long-term operation. In this work, a dynamic model describing toluene abatement and the corresponding biomass growth is developed, calibrated and validated. The model was calibrated and validated using experimental data obtained from a biofilter packed with clay pellets in a long-term operation from inoculation to clogging. Decay coefficient for microorganisms, semi-saturation constant for toluene and maximum growth rate were determined for biofilter operation. Kinetic parameters were fitted by means of an optimization routine using profile concentrations along the height of the biofilter in 5 sampling ports distributed uniformly. Kinetic parameters estimated were satisfactory validated in the operation of the biofilter under different process conditions. The model developed satisfactorily predicted both experimental concentration profiles under different process conditions and parameters affected by the expansion of the biofilm on the material surface, especially pressure drop, which is a rapid and easy measurable operational parameter to follow biomass accumulation. A sensitivity analysis of the main parameters of model shows which ones are the most influential in model predictions.