Degradation efficiency of eight kinds of dyes individually and in mixture in aqueous solution by ozone/micro electrolysis process

The degradation efficiencies of simulated wastewater of eight dyes (individually and in mixtures) with different structures treated with an ozone/micro electrolysis process were studied. The results revealed that all eight dyes could be effectively removed by the ozone/micro electrolysis process. Color removal rates of all simulated wastewater samples were higher than 96.9%, and COD removal rates were between 40% and 80%. In particular, this process showed excellent aniline (which was produced at the same time as dye degradation) removal performance, and aniline cannot be detected in treated wastewater. Furthermore, the biodegradability of the simulated wastewater was improved from lower than 0.1 (before treatment) to higher than 0.2 (after treatment). The dye decolorization reaction followed first-order kinetics. For simulated wastewater with 50 mg/L mixed dyes, a pH from 8 to 10 was suitable; the ozone dosage was 30 mg/L with a dosage rate of 1.3 mg/(L·min) and the reaction time was 25 min. In addition, color removal efficiency was affected by the total ozone added, but COD removal efficiency increased at higher ozone dosage rates.