Comparison between industrial and simulated textile wastewater treatment by AOPs - Biodegradability, toxicity and cost assessment

Despite the fact that there are many literature reports concerning textile wastewater treatment by advanced oxidation processes (AOPs), mostly they are not oriented on the industrial applications. The research focused on Reactive Black 5 (RB5) and its industrial form (Setazol Black DPT), which, despite being hazardous, is still one of the most commonly used dyestuffs in industrial practice. Several ozone-based AOPs (e.g., O-3, UV/O-3, O-3/H2O2, and O-3/UV/H2O2) and H2O2/UV processes have been compared in terms of their effectiveness in removing RB5 (purified and commercial form) from simulated and industrial textile wastewater. The color, COD, TOC and BOD reduction were considered. Almost completely color reduction was achieved for the simulated as well as industrial wastewater, but only in case of ozone-based AOPs. The H2O2/UV processes were found highly not effective for industrial application. For industrial wastewater the COD and TOC decrease were not very high (10% of COD and 20% of TOC) in contrast to simulated one (90% and 50%, respectively). However, the mineralization, biodegradability and Average Oxidation State (AOS) assessment indicated that the application of AOPs resulted in more oxidized by-products. The toxicity assessment based on V. fischeri bacteria proved extremely high toxicity of BR5 (EC50 = 3.86 +/- 0.32 mg/L). All of the tested ozone-based AOPs increased biodegradability and decreased toxicity, proving that oxidation should be performed before biological treatment. The cost analysis and the obtained results showed that O-3 and O-3/H2O2 (0.005 M) can be effectively used in the industry. (C) 2016 The Authors. Published by Elsevier B.V.