Treatment of textile wastewater by electrooxidation using Ti/Ru-Ir electrode

There are many compounds with complex structure in the wastewaters originating from the textile industryof dyestuffs and surfactants that are manyauxiliary chemicals and have surface active agent property. The content of the wastewater produced varies depending on the production processes and usually contains a high amount of pollution load due to its characteristics such as dissolved solid, high COD, strong color and salt. This type of wastewater known to be dangerous and toxic and carcinogenic due to its high COD and strong color properties can then be discharged to the receiving environment when purified by appropriate methods. Traditional treatment methods are insufficient to treat the existing wastewater. For this reason, Advanced Oxidation Processes (IOP) which have gained importance in recent years are highly effective in the treatment of this type of wastewater. In this study, it was carried out that the wastewater taken from the textile industry dyeing tank was purified by EO, EC and EC followed EO (EC+EO) methods. In the EO processes have been used Ti/Ru-Ir as anode and stainless steel electrode as cathode while in EC processes have been used iron electrode as anode and cathode. The conductivity of the existing wastewater has been provided with NaCl salt. For EO process, optimum conditions have been determined NaCl dose: 0.75 g/L, pH: 2, current density: 4.77 mA/cm2, duration: 240 min. In optimum conditions determined was found as COD removal efficiency 56.87 %, color removal efficiency values at λ: 436, 525, 620 nm 56.12, 71.59, 49.26 % respectively; in terms of kinetics, the correlation coefficient (R2) 0.9541 and k: 0.0026 1/min by using the first order equation, energy consumption value 269.67 kWh/kg KOI; for EC process, optimum conditions have been determined NaCl dose: 1 g/L, pH: 8, current density: 1.65 mA/cm2, duration: 20 min. In optimum conditions determined was found as COD removal efficiency 69.81 %, color removal efficiency values at λ: 436, 525, 620 nm 96.37, 98.38, 98.47 % respectively; in terms of kinetics, by using the pseudo second order equation was calculated as R2: 0.9564 and k: 2.22E-04 1/min, energy consumption value 5.80 kWh/kg KOI; in EC+EO processes, for EC have been used optimum results obtained from EC prosses, and determined pH: 6, current density: 8,97 mA/cm2, duration: 240 min. In optimum conditions determined was found as COD removal efficiency 86.91 %, in terms of kinetics, R2: 0.9963 and k: 9.42E-05 1/min by using the pseudo second order equation, energy consumption value 1500.08 kWh/kg KOI. Keywords: Textile industry dyeing wastewater, electrooxidation, electrocoagulation, electrocoagulation followed electrooxidation, Ti/Ru-Ir electrode