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The present study deals with the treatment of complex waste (WW) treated for removal of chemical oxygen demand (COD) of the food industry by a sono-Fenton process using a batch reactor. The response surface methodology (RSM) was employed to investigate the five independent variables, such as reaction time, the molar ratio of H2O2/Fe2+, volume ratio of H2O2/WW, pH of waste, and ultrasonic density on COD removal. The experimental data was optimized. The optimization yields the conditions: Reaction time of 24 min, HP:Fe molar ratio of 2.8, HP:WW volume ratio of 1.9 ml/L, pH of 3.6 and an ultrasonic density of 1.8 W/L. The predicted value of COD was 91% and the experimental result was 90%. The composite desirability value (D) of the predicted percent of COD removal at the optimized level of variables was close to one (D = 0.991).

In the present work, evaluation of two catalysts, Activated carbon (AC) synthesized from agricultural waste and Multiwalled carbon nanotubes (MWCNT) synthesized from plastic waste, were done for the ozonation of real textile wastewater using para- chloro benzoic acid (p-CBA) as a probe compound. The effect of pH and catalyst dose were studied in terms of •OH exposure, Rct, rate of p-CBA degradation and ozone degradation. The rate constant for the reaction of organic matter with hydroxyl radicals was determined using competition kinetics. The threshold ozone dose for real textile wastewater was found to be 0.51 gm/gm of TOC. With an increase in specific ozone dose, the rate of p-CBA degradation was found to be increasing and has shown a positive effect on •OH exposure and Rct. The increasing pH had shown a positive effect on the rate of degradation and decomposition of p-CBA and ozone respectively in the case of AC catalyzed ozonation. A similar trend was observed in the case of MWCNTs catalyzed ozonation. A positive effect of pH was observed on •OH exposure and Rct, in AC as well as MWCNTs catalyzed ozonation. The effect of catalyst loading has shown significant enhancement in p-CBA degradation, ozone decomposition, •OH exposure and Rct in both AC as well as MWCNTs catalyzed ozonation. However, MWCNTs have proved better than AC as a catalyst for ozonation in studied experimental parameters.

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