Muhandisī-i Bihdāsht-i Muḥīṭ (Aug 2022)
Investigating the effect of the simultaneous presence of bromide ions in the removal of dye from textile wastewater by the UV/Cl process
Abstract
Background and Objective: UV and chlorination processes are widely used for wastewater and water disinfection. In recent years, they have been used integrative under the name of Advance oxidation process (AOP) method known as UV/chlorine process. In the UV/Cl process, Cl•, Cl2•−, and HO• radicals are produced during the process and are able to remove hard degradable pollutants. In this study, the effect of the simultaneous presence of bromide in the application of UV/Cl process to dye removal from textile wastewater and synthetic wastewater containing Direct Red 83:1 (DR83:1) is studied and investigated. Materials and Methods: The wastewater used in this study was prepared from one of the textile units of Isfahan province. Operating parameters affecting the process including chlorine dose (0.2, 0.5, 1, 1.5 and 2 mmol), bromide dose (0.25, 1, 1.25 and 1.5 mmol) and Different initial pH values of textile industry wastewater (3, 5, 7, 8.3, and 11) were investigated to determine the optimal values of the process for dye removal. Also, the effect of the presence of bromide in the UV/Cl process in the degradation of DR83:1 from synthetic wastewater at different pH has been investigated (3, 5, 7, 9 and 11). Results: Based on the experiments, the results showed that in both wastewaters, the UV/Cl/Br process performs better in dye removal than the UV/Cl process. The most favorable performance of the UV/Cl/Br process for dye degradation from textile wastewater was achieved under the conditions of bromide dose equal to 1.25 mmol, chlorine dose equal to 1.5 mmol and the actual initial pH of the wastewater equal to 8.3 (dye removal efficiency equal to 92.04 %). The optimal performance of the UV/Cl/Br process in the degradation of DR83:1 from synthetic wastewater was obtained under the conditions of bromide dose of 5 mmol, chlorine dose of 0.1 mmol and pH of 3. The pH parameter was investigated in both wastewaters and the results showed that the optimal performance of the UV/Cl/Br process to remove dye from textile wastewater occurs in alkaline pHs, while the performance of the UV/Cl process to remove DR83:1 from synthetic wastewater in Acidic pHs is more favorable. The effect of different dosages of key parameters revealed that by increasing the dosage of bromine and chlorine, the performance of the system in dye removal efficiency does not improve. Conclusion: The UV/Cl advanced oxidation process has a high potential to remove dye from wastewater, and the presence of bromide ion increases the efficiency of this system, which can be used as a stable and capable system in dye treatment from textile industry wastewater
