Advanced oxidative treatment of dyehouse effluents using Fenton's reagent, O₃ and O₃/H₂O₂ processes

Ozone (O₃) and hydroxyl radicals (OH^•) are the mightiest oxidizing agents used for remediation of contaminated groundwater, drinking water and refractory industrial wastewater. In the present study effluents from a dyeing factory, processing mainly wool and wool blends, yarn and fabric were treated by several Advanced Oxidation Processes (AOPs) using Fenton's reagent, O₃/OH^- and O₃/H ₂O₂ combinations as oxidants. Under appropriate reaction conditions (oxidant and ferrous iron catalyst dose, and pH) complete color and COD removal were achieved quite feasibly. The study also considered the improvement of ozonation and Fenton processes by H₂O₂ addition at a critical dose and ferrous iron co-precipitation accompanied with Fenton's oxidation, respectively. With respect to traditional oxidation methods and "phase transfer" treatment systems, the combined Fenton's oxidation + Fenton's coagulation as well as H₂O₂ - enhanced ozonation processes can be regarded as efficient, economically feasible and environmentally friendly alternatives.