Large amounts of sludge are being produced in biological wastewater treatment processes, and the treatment of excess sludge may account for up to 60% of the total operation costs of the wastewater treatment. In smaller wastewater treatment facilities, especially, on-site sludge treatment is difficult. therefore new technology which is low costs and simple to operate is required for this purpose. In this work, bench scale sequencing batch reactors (SBRs) equipped with mesh filter modules, were applied to the aerobic bio-degradation of excess sludge under the following conditions: the pore size of the mesh was 100 mu m, SS of the fed sludge was in the range of 4000-6000 mg 1(-1), and the reactors operated at HRT = 10 days for more than 360 days at ambient temperature. The reactors retained 25,000-32,000 mg1(-1) of MLSS, and more than 80% of the fed SS was reduced. The system was able to reduce the sludge effectively under aerobic conditions because the reactors retained a very high concentration of biomass. In addition, the effluent from the reactor (Run-1) contained low organic pollutants: SS < 57 mg 1(-1), CODMn, < 61 mg 1(-1), and colority < 24 mgPt 1(-1). The filtration time, which means the period of the effluent withdrawal, was influenced by the contents of the extracellular polymers (ECPs) of the microbes in the reactors, although filtration was commonly conducted within 2 h. (c) 2005 Elsevier Ltd. All rights reserved.