In this research, the ability of preformed aerobic granules, which were formed in slaughterhouse wastewater, was investigated for treatment of real dyeing wastewater. The percentages of real dyeing wastewater in the influent were increased gradually from 50% to 100% in orders to investigate the ability of granules in treating of real dyeing wastewater. According to outcomes, maximum chemical oxygen demand (COD) elimination was up to 87%, while the best percentage of dye removal was about 42.6%. Due to the toxic effect of dyeing wastewater, 43.3% reduction in the amount of specific oxygen uptake rate (SOUR) was observed after 90 day of operation. Furthermore, when the percentages of real dyeing wastewater increased to 100%, the granules collapsed, which lead to decrement of granular ratio (GR). Granules collapsing led to 86.5%, 49.73% and 40% reduction in GR0.3, GR0.5 and GR1, respectively.
