Decolorization of Wastewater Containing C. I. Reactive Red 120 by UV-Enhanced Ozonation

In the present study the treatment efficiency of O3 and UV+O3 processes were compared for the oxidation of simulated dyebath effluent containing a mixture of C.I. Reactive Red 120 (RR-120) and various dye auxiliaries. The color, COD and TOC removalrates were assessed for different processes. The effects of solution pH, initial dye concentration and presence of sodium hydroxide and sodium carbonate on rates of decolorization were studied. The rate of decolorization decreased by increasing of the initial dye concentration and addition of sodium hydroxide. No change in decolorization was observed by addition of sodium carbonate. The experimental results showed that ozonation combined with UV irradiation (9-watt low-pressure mercury lamp) was slightly more efficient than ozonation alone in COD removal with no change in color removal kinetics. At an initial pH of 6.2, bulk temperature of 25°C, ozone dosage of 55 g/m3 and initial dye concentration of 800 mg/L, the TOC removal efficiency of RR-120 reached 27% and 36% after 90 min for O3 and UV+O3 processes respectively. J. Color Sci. Tech. 4(2010), 151-160© Institute for Color Science and Technology.