Dyes released by the textile industries pose a threat to the environmental safety. Recently, dye decolourisation through biological means has gained momentum as these methods are cheap and can be applied to a wide range of dyes. The objective of this study was to investigate the biological decolourisation of a widely used textile reactive dye in Tunisia, the Blue Bezaktiv S-GLD 150 dye, using a sequencing batch reactor (SBR). SBR was inoculated with an acclimated novel microbial consortia 'Bx'. Decolourisation efficiency was studied for different volumetric dye loading rates (3-20 g dye/m(3).d) at room temperature, under aerobic conditions and at pH 7. The experimental results indicated that Bx displayed highest purification capabilities under aerobic conditions giving maximum decolourisation rates in the range of 88-97% and COD removal percentages of about 95-98% when volumetric dye loading rates were under 15 g dye/m(3).d. Whereas, when volumetric dye loading rates were increased to 20 g dye/m(3).d, the means rates of decolourisation and COD removal were decreased to 70% and 90% respectively. Obtained results indicate that the volumetric dye loading rate can influence the efficiency of dye removal through a sequencing batch reactor. (C) 2011 Elsevier B.V. All rights reserved.