BACKGROUND: The removal of styrene from air streams in a co-current gas-liquid downflow trickle-bed bioreactor (TBB) inoculated with Pseudomonas sp. E-93486 strain was studied experimentally. The experiments were conducted to determine such parameters of the bioprocess as gas and liquid flow rates and specific styrene loading for which maximum elimination capacity was achieved. RESULT: The effect of inlet styrene concentration in gas phase on its degradation was studied in the range from 0.08 to 1.1 g m-3. The recirculation rate of the liquid medium was changed from 0.17 to 0.35 m3 h-1 whereas the gas flow rate was changed in the range from 1.2 to 6 m3 h-1. The treatment of air streams contaminated with styrene in a trickle-bed bioreactor was described with a mathematical model. The model incorporates mass transfer in both the gas and liquid phases and a biological reaction in biofilm. The rate of the partial stages of the process was determined experimentally. Microbial growth tests in the presence of styrene as the sole carbon and energy source were performed both in batch and continuous cultures. The Haldane model was used to describe Pseudomonas sp. E-93486 strain growth kinetics on styrene. CONCLUSION: The experiments conducted showed high activity of the examined bacterial strain in the styrene biodegradation process and relatively low sensitivity to inhibition of its growth at higher concentrations of styrene in the solution. The results of the experiments carried out in TBB were compared with the values obtained from a mathematical model. Satisfactory compatibility of the calculated and experimental data was obtained. Copyright (c) 2012 Society of Chemical Industry