Discoloration and mineralization of a textile azo dye using a hybrid UV/O3/SBR process

Yousef Dadban Shahamat,Susana Rodríguez-Couto,Hakimeh Mahdizadeh

doi:10.1007/s13201-021-01479-1

Abstract

Most synthetic dyes are toxic and hardly biodegradable compounds that enter the environment mainly through the discharged of non-treated textile industry effluents. The present study investigated the removal of the textile monoazo dye Reactive Red 198 (RR-198) from aqueous solutions using the ultraviolet light and ozonation alone and in combination (i.e., UV/O3) followed by a Sequencing Batch Reactor (SBR). The pH (5 ≤ pH ≤ 9) and dye initial concentration (50–300 mg/L) parameters were optimized in the ozonation process at reaction time of 0–60 min. Then, TOC removal and dye discoloration percentage was compared with the O3, UV and O3/UV processes. In order to compare the performance of the SBR in dye discoloration of RR-198 and TOC removal, four types of effluent, including Raw dye, O3-pretreated dye, UV-treated dye and UV/O3-pretreated dye were separately treated in the SBR system. In the ozonation process, by increasing the pH and reducing the initial dye concentration increased the discoloration percentage. The highest dye discoloration percentage and TOC removal obtained in the hybrid UV/O3/SBR process. Combining biological systems and Advanced Oxidation Processes is an appropriate option for the decomposition of resistant pollutants and increasing the biodegradability of these compounds and is applicable in the water and wastewater industry.

Highlights

Most synthetic dyes are recalcitrant and toxic compounds that are used in many industries such as the textile industry
In order to compare the performance of the Sequencing Batch Reactor (SBR) in dye discoloration of Reactive Red 198 (RR-198) and Total Organic Carbon (TOC) removal, four types of effluent, including (1) Raw dye, (2) O3-pretreated dye, (3) UV-treated dye and (4) UV/O3-pretreated dye were separately treated in the SBR system
In studies by Pachhade et al on the removal of reactive azo dye, ozone gas was used with a flow of 2 g/h in the presence of catalyst ions of Mn, Cu, Fe and Co under the ozonation process, and the results showed that discoloration was faster than organic matter removal

Summary

Introduction

Most synthetic dyes are recalcitrant and toxic compounds that are used in many industries such as the textile industry. The processes currently used to treat textile effluents include coagulation and flocculation, chemical oxidation, biological treatment, electrochemical techniques, ion exchange, adsorption and hybrid processes including ozonation and coagulation or coagulation and ion exchange (Gupta et al 2015; Khosravi et al 2017; Mahmoodi et al 2006; Moussavi and Mahmoudi 2009; Pourfadakari et al 2016; Satapanajaru et al 2011). The application of the abovementioned techniques in the industry is not practical

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Conclusion