abstract
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The current study presents the treatment of water contaminated with the dye Direct Red 28 in the presence of Na
2 SO4 at three different concentrations (10, 40 and 80 g/L) by simple ozonation. This wastewater treatment was considered in a wastewater recycling process. At the end of each ozonation cycle, ozonation dynamics, ozone consumption, pH, electrical conductivity and UV/Vis spectra variation were analyzed and correlated with the stoichiometric analysis balance. The efficiency of the wastewater treatment in each reuse cycle was evaluated by a novel image processing method. The image results show that the presence of sulfate improves more than 45% the dye fixation on a cotton sample. However, at high additive concentrations, the color quality decreases 25%, compared with the system with low additive concentration, due to the presence of peroxysulfate ions and the compounds accumulated through the ozonation process. © 2019 International Ozone Association.