Treatment of textile dye bath wastewater with ozone, persulfate and peroxymonosulphate oxidation

In this study, the treatment of wastewater of two different reactive dye bath wastewater (WW1, WW2) belonging to a yarn dyeing textile industry was evaluated by ozone, heat-activated persulfate (PS) and heat-activated peroxymonosulfate (PMS) oxidation methods. WW1 and WW2 contains azo group dyes and BOD₅ values are 245 and 105 mg/L, Total Organic Carbon (TOC) values are 793 and 3016 mg/L respectively. TOC and color removal and BOD₅ /TOC ratio were investigated in samples taken at specific time intervals (15, 30, 45, 60, 90 and 120 min). For WW1, the TOC and color removal rates for heat-activated PS oxidation were 19% and 100%, respectively, and these removal rates were higher than the oxidation results for ozonation (15% and 76%) and heat-activated PMS (16% and 99%). Although the ozone dose applied to WW1 was about 3 times that of the ozone dose applied to WW2, the color removal rate in WW2 (94%) was higher than WW1 (76%) and the TOC removal rates were almost the same. In the result of oxidation studies,no significant increase in BOD value was observed for both wastewater. However, an increase in BOD₅ /TOC was achieved by decreasing the TOC value in heat-activated PS oxidation for WW1.