Manuela Lageiro and Maria Costa-Ferreira1 Bioengineering and Bioprocessing Unit, Department of Biotechnology, National Institute for Industrial Engineering and Technology (INETI), Portugal Abstract An enzymatic cocktail was used for the decolorization of process wastewater, containing mainly three reactive azo dyes, from a textile dyeing and printing company. Water sampled from different processing streams and combinations thereof was decolorized to different extents. The decolorization was greatest for C.I. Reactive Black 5, followed by C.I. Reactive Red 158, whereas C.I. Reactive Yellow 27 was the least decolorized. As wastewater from the printing process was inhibitory, the 1 mistirred tank type reactor prototype was installed near the outlet prior to the discharge of wastewater from the printing process. Temperature and pH control systems were installed to ensure optimal enzymatic decolorization, this being about 45 ° C and pH 6.4. The average temperature observed at the reactor was 42.1 ° C, which indicated the need for improved temperature control. Laboratory scale tests were done to assess the reuseability of the biotreated wastewater for the washing of dyed cotton fabrics.