This research focuses on the development of a mathematical model for performance prediction/simulation of the membrane bioadsorber reactor (MBR) process. The MBR process integrates biodegradation, adsorption and membrane filtration, for water or wastewater treatment and water reclamation. The model sub-processes include the following phenomenological aspects: (a) biological reaction in bulk liquid solution, (b) film transfer from bulk liquid phase to the biofilm, (c) diffusion with biological reaction inside biofilm, (d) adsorption equilibrium at the biofilm-adsorbent interface, and (e) diffusion within the adsorbent (powder activated carbon) particles. The model exhibited good simulative capability for three model organic compounds, namely, phenol, para-nitrophenol, and toluene, chosen based on their varying adsorption and biodegradation characteristics. A phenomenological approach was employed to examine the relative contributions of adsorption and biodegradation to contaminant removal, and to obtain insights into adsorbent bioregeneration. Therefore, simulation studies were conducted under three different scenarios: (a) adsorption and biodegradation in biofilm and liquid phase suspension are operative, conforming to the assumptions of the generalized model; (b) biodegradation is operative in biofilm as well as liquid phase suspension, but adsorption is absent; and (c) adsorption alone is operative without biodegradation. Sensitivity studies were preformed to investigate the dependence of process dynamics on model parameters pertaining to adsorption equilibrium and kinetics, liquid film transport, biofilm diffusion, biochemical reaction kinetics, influent concentration, and reactor flow conditions. (c) 2005 Elsevier Ltd. All rights reserved.