A comparative study on the performance of different advanced oxidation processes (UV/O3/H2O2) treating linear alkyl benzene (LAB) production plant's wastewater

A detailed investigation on photooxidation of linear alkyl benzene (LAB) industrial wastewater is presented in this study. The process analysis was performed by varying four significant independent variables including two numerical factors (initial pH (3-11) and initial H2O2 concentration (0-20 mM)) and two categorical factors (UV irradiation and ozonation). The experiments were conducted based on a central composite design (CCD) and analyzed using response surface methodology (RSM). To assess the process performance, two parameters viz. TCOD removal efficiency and BOD5/COD were measured throughout the experiments. A maximum reduction in TCOD was 58, 53, 51, and 49%, respectively for UV/H2O2/O-3, H2O2/O-3, UV/O-3 and UV/H2O2 processes at the optimum conditions (initial pH of 7, initial H2O2 concentration of 100 mM, and reaction time of 180 min). A considerable increase in BOD5/COD ratio was obtained in the combined processes (0.46, 0.51, 0.53, and 0.55 for UV/H2O2, UV/O-3, H2O2/O-3 and UV/H2O2/O-3, respectively) compared to the single oxidant process (0.35). The results showed that mineralization of the LAB industrial wastewater in neutral pH is more favored than in acidic and basic pH. Gas chromatography-mass spectrometry (GC-MS) was applied to show the fate of organic compounds. In conclusion, the photooxidation process (UV/H2O2/O-3, H2O2/O-3, UV/O-3 and UV/H2O2) could be an appropriate pretreatment method prior to a biological treatment process. (C) 2013 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.