Background and Objective: PACT is an adsorption- degradation process through which slowly or non-biodegradable waste water compounds such as dye can be degraded. This study was carried out to evaluate the efficacy of PACT in removal of dyes form textile industry wastewaters.
Materials and Methods: This research was carried out in pilot scale. The pilot design had two parts: an aeration tank with 40L volume and a clarifier with 12L volume. The dyes used in this research were acid and reactive dyes in different concentrations which are mostly used in textile industries. First, the biodegradability of the dye was studied through Zahen-Wellens method (ISO 9888, 1999). Then, dye removal efficiency in different conditions of powdered-activated carbon concentration and operational conditions were evaluated. American Dye Manufacture Institute (ADMI) method was utilized for determination of dye removal in samples.
Results: Biodegradability of acid dyes and basic dyes in 100 mg/L dye concentration, were 60 and 80% respectively. On the other hand, the best efficiency for application of PAC in activated sludge process, was obtained in 1500 mg/L PAC concentration. In this situation, with 30 hydraulic retention time, and 30^oC temperature, the rejection percent of dye was 98.8%. 
Conclusion: PACT process could be the best method for removal of different dyes  used in textile industry with high efficiency (up to 90%). Application of this method in treatment of textile wastewaters is an important economic improvement, which in a single step, allows the removal of COD and color from textile wastewater without additional physicochemical treatment.