Simultaneous and sequential combination of electrocoagulation and ozonation by Al and Fe electrodes for DirectBlue71 treatment in a new reactor: Synergistic effect and kinetics study

In this study, the simultaneous combination of electrocoagulation and ozonation (EC-O3) was optimized in a new reactor for Direct Blue 71 treatment and compared to electrocoagulation (EC), ozonation (O3), and their sequential combination (EC -> O3) by considering the performance criteria (dye and naphthalene ring removal efficiency), economic assessment (energy and anode consumption), chemical degradability, mineralization rate, and kinetic study. Applying a middle wall in the reactor improved coagulation under ozone-induced rapid mixing on the first side and flocculation under flow-induced slow mixing on the other side which reduced the floc breakage at high ozone dosages. Dye, COD, and TOC removal rate was in the following order: EC(Al)-O3>EC (Fe)-O3>EC(Al)-> O3>EC(Fe)-> O3>EC(Al)>EC(Fe)>O3. The synergistic effect of simultaneous combined process on dye, COD, and TOC removal were obtained 1.97, 1.42, and 1.69 for EC(Al)-O3 and 1.37, 1.14, and 1.26 for EC (Fe)-O3, respectively, which showed more ozone activation in the presence of Al ions compared to Fe ions. Also, ozone-induced corrosion for Al electrode was less than Fe electrode, which reduced anode consumption and operation cost. Finally, EC(Al)-O3 due to best performance and EC(Fe)-> O3 due to optimal use of EC for decolorization and O3 for oxidation, with dye, COD, and TOC removal efficiency, energy and anode consumption, and operation cost equal to 99, 51, and 62%, 18.6 kWh m- 3, 0.05 kg m- 3 and 0.21 $ m- 3, respectively, for EC(Al)-O3 and 99, 44.5, and 51%, 6.7 kWh m- 3, 0.2 kg m- 3 and 0.14 $ m- 3, respectively, for EC(Fe)-> O3, are suggested as suitable options for dye wastewater treatment.

Automated summary

The study optimized the simultaneous combination of electrocoagulation and ozonation (EC-O3) for Direct Blue 71 treatment and compared it to electrocoagulation (EC), ozonation (O3), and their sequential combination (EC -> O3). Results showed that EC(Al)-O3 had the best performance, while EC(Fe)-> O3 effectively utilized EC and O3 for decolorization and oxidation.