From the results of this study, it could be suggested that the resting bio-sludge of a domestic wastewater treatment system could be used as an adsorbent of both organic matter and disperse dye due to its high adsorption ability and its ability to be reused after washing with a diluted alkali solution. The biological treatment system, especially the GAC–SBR system, was more suitable for treating raw TWW due to the high removal efficiencies of disperse dyes, as well as organic matter, under low excess sludge production and low SVI. The advantage of using GAC in the GAC–SBR system is that the GAC acts mainly as the media for bio-film to attach to, but the GAC does not absorb the disperse dyes directly onto its surface. Therefore, the GAC can be used for a long time in the SBR system because it is the attached bio-film that is largely responsible for dye and organic matter removal (Dewalle and Chain, 1977 and Perrich, 1981). This study also found that dye removal could be improved by increasing the SRT. Moreover, further increases in dye removal could be achieved with the addition of glucose into the systems.