The treatment of flexographic cyan dye synthetic solution and real printing effluent has been studied by using homogeneous Fenton process with the addition of FeSO4*7H2O as a catalyst. The study demonstrate that applied treatment could significantly reduce dye concentration in the examined aqueous solutions. Operating parameters, such as initial dye concentration, iron dosage, hydrogen peroxide concentration and pH were varied to investigate their influence on decolorization efficiency, as well as their mutual interactions. The optimal conditions, found with definitive screening design (DSD) statistical method, were: dye concentration = 123 mgL-1 , Fe concentration = 60 mgL-1 , H2O2 concentration = 5.44 mM and a pH value = 2. Under these conditions decolorization efficiency resulted with 87% and 37% for cyan synthetic solution and real printing effluent, respectively
