The removal of aromatic amines was evaluated by decolorization of CI Direct Black 38 (DB 38) dye varying between 100 and 3200 mg l(-1) using an anaerobic upflow anaerobic sludge blanket reactor and an aerobic completely stirred tank reactor system. The effect of increasing dye loadings from 6.1 to 213.0 g m(-3) h(-1) on decolorization and COD removal efficiency was investigated at constant glucose-COD (2000 mg l(-1)) concentrations in an UASB reactor. For 3200 mg l(-1) of DB 38 and 2000 mg l(-1) glucose-COD as co-substrate in the feed, 48.4% COD and 80% color removal efficiencies were observed at a maximum COD and dye loading rates of 5.37 kg COD m(-3) per day and 213 g dye m(-3) h(-1), respectively at a hydraulic retention time (HRT) of 15 h in the UASB reactor. Sixty seven percentage remaining COD was removed at an HRT of 2.3 days and a maximum organic loading rate of 0.77 kg COD m(-3) per day in the aerobic stage. Eighty four percentage COD, 86% color and 52.2% total aromatic amine (TAA) was removed at an HRT of 2.9 days and at an organic loading rate of 1.17 kg COD m(-3) per day and a maximum DB 38 dye loading rate of 46.4 g dye m(-3) h(-1), respectively in a total system treating 3200 mg l(-1) Cl Direct Black 38 dye. The TAA produced under anaerobic conditions was ultimately removed in the aerobic stage and aromatic amine recoveries such as 45-50% were obtained in the aerobic reactor. The anaerobic/aerobic sequential process provides simultaneous color, COD and carcinogenic amine removal. (C) 2003 Elsevier Ltd. All rights reserved.