This paper discusses completed efforts in the treatment of dyes and pigments processing wastewater utilizing the activated sludge process (ASP) enhanced with powdered activated carbon (PAC). The independent variables of the study were solids retention time (SRT) and PAC dosage. Three SRTs were studies (about 4 days, about 8 days, about 20 days) with a control system (no PAC) and experimental system (PAC added) operated in parallel. PAC dosages of 70, 130, 290, 1000 and 1800 mg/L were evaluated, although not at all SRTs studied. Gross organics, color, metals and toxicity reduction data are presented. Development of biokinetic constants from the control systems' gross organics data are also presented. The addition of PAC to the ASP did enhance the removal of organics and color and showed a reduction in toxicity of the final effluent to fathead minnow and Daphnia magna as compared to the control systems.