Treatment of Wastewater Containing Acid Orange 7 Using Ozonation Process and Determination of the Intermediate By-products

• Main Authors: Farhad Ghaderi- Zafrei, Bita Ayati, Hossein Ganjidoost, Rasool Sarraf Mamoori
• Format: Article
• Language: English
• Published: Water and Wastewater Consulting Engineers Research Development 2015-05-01
• Series: آب و فاضلاب
• Subjects: Azo; COD; Light Absorbance; pH; Concentration
• Online Access: http://www.wwjournal.ir/article_7935_afb44580ac03f3ae92278ebf67097698.pdf
• ISSN: 1024-5936; 2383-0905

In this research, ozonation was used for treating wastewater containing acid orange 7 in a batch reactor. The independent parameters were initial dye concentration, pH, and ozone mass and volumetric flow rates. The experiments were conducted with initial concentration in the range of 5-250 mg/L, pH levels of 4-12, ozone mass flow rates of 12 and 20 mg/min, and volumetric flow rates of 0.5 and 1 L/min. Based on the results, the optimum conditions were achieved at a dye concentration of 100 mg/L, a pH level of 11, an ozone mass flow rate of 20 mg/min, and an ozone volumetric flow rate of 1 L/min. Dye and COD removal efficiencies in these conditions were 100% and 30%, respectively, after 150 minutes. According to the absorbance curves, light absorbance of wastewater increased by 100% in the range of 450-500 nm by ozonation under the optimum conditions after dye removal. Based on the GC-Mass test and the values of LD50, acid orange 7 was converted to toxic compounds of aniline, 1-naphthylamine, 2-naphthol, and 1, 4-naphthalenediol indicating that ozonation had to be continued until complete COD removal. Based on the Taguchi experimental design data for real textile wastewater, the optimum conditions were obtained for a pH level of 11, a gas flow rate of 1 L/min, and an ozonation injection rate of 20 mg/min.