Membrane-aerated biofilms (MABs) have shown potential for removing contaminants from wastewater. However, the inability to control biofilm thickness and overcome mass transport limitations have prevented the commercial application of MABs in wastewater treatment. In this paper, we explore the merits of a novel configuration in which advective flow through an MAB is used to overcome these mass transport limitations and improve process performance. A steady-state, single-species model was developed to characterize the performance of a biofilm that was supplied substrate by advective flow. The MAB was supported by stitched hollow fiber fabric and the wastewater was pumped through the biofilm. The results show that oxygen flux across the membrane increases significantly and higher chemical oxygen demand (COD) removal rates can be achieved. The effects of membrane spacing and oxygen partial pressure on the system performance were investigated. Model predictions indicate that high COD removal efficiencies can be achieved with effective contact times between the wastewater and biofilm, on the order of minutes. These simple model predictions suggest there is merit in exploring the performance of this configuration experimentally. (c) 2005 Elsevier B.V. All rights reserved.