A combined upflow anaerobic fixed-bed (UAF-B), using pumice as a biofilter material, and a suspended aerobic activated sludge bioreactor (SAR) equipped with a microfiltration (MF) unit has been designed. This system exhibited high performance on the removal of organic matter. COD removal efficiencies were in the range of 94-98.7% with organic loading rates (OLR) of 3.67-16.56 kg COD m(-3) per day. Phosphorous and nitrogenous materials were removed from the wastewater as well as COD. High PO4-P removal efficiencies (96-97%) were achieved in this study. NO2-N and NO3-N concentrations in the effluent of MF were less than 1.0 mg l(-1) through most experiments. Suspended solid concentrations measured in the effluent were below the detectable levels. Biofilm development and microbial communities were investigated using scanning electron microscopy (SEM). (C) 2004 Elsevier Ltd. All rights reserved.