Packed-bed reactors are widely used in biological treatment processes. The complete simulation of the reactions and concentration profiles of the reactors, which are necessary for a successful reactor design, operation, and scale-up, are now possible due to extensive improvements of numerical methods and computational power. In the present work, phenol biodegradation was studied in a packed-bed bioreactor operating in the recycling batch mode using the computational fluid dynamics (CFD) method. A transient comprehensive 3D CFD was developed to simulate the dynamic behavior of batch phenol biodegradation by Ralstonia eutropha in a Kissiris-immobilized cell bioreactor. The model combined the porous medium CFD model with two kinetic equations, namely the Haldane and Luong inhibition models, to consider the inhibitory effect of phenol at high concentrations. The simulation results of the phenol concentration variation in different initial phenol concentrations (2.13, 4.26, 6.39, and 8.52 mol/ m3) and recirculation flow rates (10, 25, and 40 ml/min) were validated against experimental data. Despite the assumptions, the simulation results create an acceptable assurance of the simulation precision with good agreement with experimental data.