(71d) Comparison of Treatment Efficiencies of Various Advanced Oxidation Processes for Dye Removal from Wastewater

Textile wastewaters are usually treated by biological processes to removed most organic compounds (BOD), followed by advanced treatments to remove remaining dye to meet strict COD effluent standards. Although some advanced treatment such as activated carbon adsorption is quite effective to remove dye, dye-saturated activated carbon is not easy to be regenerated and is classified as hazardous solid waste. Advanced oxidation processes (AOPs) using powerful hydroxyl radicals to non-selectively decompose organic compounds in wastewaters have received great attention in industry. In this study, various AOPs, namely UV/H₂O₂, UV/TiO₂ (suspended and immobilized), Fenton's reagent, and ozone were employed to decompose pink acid dye in simulated wastewaters. The experiments were carried out in a batch reactor with varying operating conditions and the dye concentration was continuously monitored to compare the performance of different AOPs. Among the AOPs tested, the ozone system has the highest dye removal efficiency. The experimental results also show that the dye decomposition rate increases with increasing initial dye concentration. Increasing the reaction temperature can increase the treatment efficiencies in UV/TiO₂ and UV/H₂O₂ systems, but decrease the treatment efficiencies in Fenton's reagent and ozone system. Higher solution pH favors the treatment efficiency in the ozone system but does not favor the UV/TiO₂, UV/H₂O₂ and Fenton treatment systems. The results of this study can be used to choose a proper AOP to treat dye-containing wastewaters.