The advanced treatment of treated petrochemical water by Ozone-Biological Activated Carbon (O3-BAC) was carried out in this study. The effect of O3 on the removal of Chemical Oxygen Demand (COD) and Spectral Absorption Coefficient (UV254) were investigated. The characteristics of organic matter and the microbial consortium structure of BAC were also investigated at 20 mg·L-1 of O3 dosage concentration, 40 min of O3 single stage contact time and 1.5 h of the empty bed residence time of BAC. Results showed that the effluent COD concentration of O3-BAC was 24 mg·L-1 with the removal efficiency of 40.4%. The COD removal efficiency of O3-BAC was higher than that for the BAC process. The UV254 removal efficiency of O3-BAC was 55.1%. Meanwhile, UV254 correlated with COD with a correlation coefficient of 0.89. The percentage of dissolved organic matters with relative molecular weight less than 1×103 increased from 69.0% to 87.0% after O3 oxidation. The NPOC removal efficiency of O3-BAC (45.8%) was higher than that of the BAC process (23.0%). The NPOC removal efficiency of the BAC unit was mainly achieved by reduction of dissolved organic matters with relative molecular weight less than 1×103. GC-MS analysis results showed that organic substances such as alkanes, unsaturated esters, and phenols had been removed by O3 oxidation. The micro ecological environment of the BAC unit had been significantly improved after O3 oxidation, and the genera with relative abundance over 1.0% increased from 6 to 11. The combined O3-BAC system can be applied to the advanced treatment of petrochemical treated water.
Keywords: O3-BAC; advanced treatment; consortium structure; relative molecular weight; treated petrochemical water.