Background and purpose: Chemical dyes are widely used in textile industries and have harmful effects on the environment. They also contain carcinogenic and mutagenic substances. The goal of this study was optimization of the catalytic ozonation process using bone char ash modified by magnesium oxide in removal of reactive black 5dye from textile wastewater based on Taguchi design. Materials and methods: In this study ozonation was performed in a batch ozonation reactor. In order to remove the dyes, Bone char ash (BCA) was modified by magnesium oxide. The effect of various parameters such as reaction time, initial dye concentration, adsorbent dose, and initial pH at 4 different levels were investigated using an L-16 Taguchi method. Analysis and interpretation of data was done using Minitab 16. Results: The optimum conditions for removal of dye were found to be contact time of 20 min, pH 8, dye concentration of 50 mg/l, adsorbent dosage of 0.3 g/L. The efficiency of dye removal was 98% and COD removal was 85%. Analysis of variance indicated that the dye concentration was the most important variable influencing the dye removal percentage (51.8%) and pH was the least influencing variable (3.8%) in removal of dye. Conclusion: The results showed that ozonation process was an effective method in reducing the concentration of pollutants in textile wastewater effluent.

Keywords: Catalytic ozonation, reactive black5, bone char ash, magnesium oxide, Taguchi

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