In the present study, the accelerating effect of co-immobilized anthraquinone and quinone-reducing consortium was investigated in the bio-decolorization process. The anthraquinone and quinone-reducing consortium were co-immobilized by entrapment in calcium alginate. The co-immobilized beads exhibited good catalytic activity and increased the decolorization rate for many kinds of azo dyes. The reusability of the co-immobilized beads was evaluated with repeated-batch decolorization experiments. After ten repeated experiments, the decolorization rate of co-immobilized beads retained over 92.8% of their original value. Furthermore, acclimatized quinone-reducing consortium was analyzed by denaturing gradient gel electrophoresis (DGGE) and 16S rDNA gene sequencing to get the complete picture of its diversity. This study explored a great improvement of conventional treatment system and the new bio-treatment concept. (C) 2009 Elsevier Ltd. All rights reserved.