An Euler-Euler computational fluid model was developed successfully for the hydrodynamic prediction of a trickle-bed reactor (TBR) designed for advanced wastewater treatment facilities. Catalytic wet air oxidation of phenolic acids was simulated in a TBR by means of computational fluid dynamic (CFD) in the temperature range 170-200 degrees C and pressures 10-30bar. The hydrodynamic model validation was accomplished through the comparison of simulated pressure drop and liquid holdup with experimental data from the literature. In a broad range of gas and liquid flows studied (G = 0.10-0.70 and L = 0.5-5 kg/m(2) s) at different operation conditions, CFD demonstrated the considerable effect of operating pressure in pressure drop, whereas a minor influence was detected for the liquid holdup. CFD runs were then performed for the catalytic wet air oxidation of aqueous phenolic acids solution. The reactor behaviour was analysed by means of total organic carbon profiles which reflected the influence of temperature, pressure, gas-liquid flows and initial pollutant concentration. (C) 2007 Published by Elsevier Ltd.