Predictive mathematical models which describe the adsorption and biological phenomena in the plug-flow stationary solid phase column and completely mixed recycle fluidized bed were developed. The models incorporate liquid film transfer, biodegradation and diffusion in the biofilm, adsorption onto the adsorbent, as well as biofilm growth. The model equations are solved by a combination of orthogonal collocation and finite difference techniques. Computer simulations were conducted to compare the performance of the two models. Sensitivity tests were also performed to determine the effects of physical and biological parameters on model profiles.