Removal of Color and Chemical Oxygen Demand Using a Coupled Coagulation-Electrocoagulation-Ozone Treatment of Industrial Wastewater that Contains Offset Printing Dyes

Industrial offset printing processes generate wastewater with highly colored obtaining values of 5x10 6 Pt-Co units and great values of chemical oxygen demand (COD) 5.3x10 -5 mg L -1 . Thus, conven- tional technologies such as biologicals treatment fail in reaching the discharge limits. In this research, a sequential treatment was applied: coagulation with aluminum hydroxychloride (AHC), electrocoagula- tion with Al anodes and finally ozonation. Optimal conditions are found when adding 20 mg L -1 AHC, followed by electrocoagulation at 4 A for 50 min, and finally alkaline ozonation for 15 min, resulting in an overall color removal of 99.99% color and 99.35% COD.