Modelowanie procesu biofiltracji

In the paper basic information dealing with biofiltration and then a qualitative description of the process carried on in a three-shift system with one active shift are given. Literature models of quasi - steady state biofiltration are discussed. A solution of the own biofiltration statics model under assumptions of first order reaction for low contaminated gas and zero order reaction for higher concentration of pollution is proposed. The method for process statics elaboration on the basis of experiments is presented. The Hodge and Devinny model assuming plug flow with axial dispersion of polluted gas, reaction in the stationary phase, linearity of adsorption isotherms and Danck-werts' boundary conditions for axial dispersion in a biofilter inlet/outlet was used. The modified Monod kinetics with exponent, n, was assumed. Verification of the experimental data was carried out in the butanol - fractionated pine tree bark system of 0.5÷3.0 mm granulation. It was stated that for low butanol concentrations biofiltration dynamics can be described by first-order kinetics, whereas for high concentrations - zero-order kinetics was preferable, however a certain discrepancy was observed in comparison with the experimental data. Accuracy of the model was significantly improved by assuming n = 1.5 in the Monod equation. Biofiltration dynamics was described for three-shift system with one active shift (ca' 8 hrs) and two passive (ca' 16 hrs). Experiments were carried out during about 6 months with no visible decreasing of bed activity. On the basis of previously undertaken tests it was stated that before biofiltration took place Aeromonas hydrofila and Bacillus bacteria prevailed in pine tree bark, whereas when the process was finished a number of Bacillus mycoides var mesentericus was higher, Pseudomonas vesicularis were created and Aeromonas practically disappeared.