Micro-Polluted Water Treatment by Biological Contact Oxidation Process: Aeration Mode and Bacteria Community Analysis

摘要

Traditional biological contact oxidation (BCO) process was modified; influent, stirring, aeration, sedimentation, and effluent were carried out alternately in the same BCO reactor to realize anaerobic reaction, anoxic reaction, and aerobic reaction. Micro-polluted water with low carbon-to-nitrogen (C/N) ratio was treated by the modified BCO process. Effects of aeration mode, hydraulic retention time (HRT), and ratio of air to water (A/W) on the removal of CODCr (chemical oxygen demand), NH4+-N, total nitrogen (TN), and total phosphorus (TP) were investigated, and the analysis of microbial community structure was also conducted. Results showed that when the A/W ratio was 6:1 and the HRT was 9 h, better removal effect was achieved for the operation mode of intermittent influent and intermittent aeration; the removal efficiencies of CODCr, NH4+-N, TN, and TP were 72.45%, 94.50%, 83.38%, and 74.23%, respectively. While for the operation mode of continuous influent and continuous aeration, when the HRT was 9 h and the A/W ratio was 6:1, removal efficiencies of CODCr, NH4+-N, TN, and TP were 71.90%, 99.10%, 28.48%, and 45.45%, respectively. Results of microbial community analysis showed that Ignavibacterium, Pirellula, Gemmata, and Candidatus Hydrogenedens with anaerobic ammonia oxidation (Anammox) function existed in the dominant populations; the relative abundances of the four bacteria in the intermittent aeration reactors were higher than those in the continuous aeration reactors. Relative abundances of Defluviimonas, Hyphomicrobium, and Longilinea with denitrification function were also higher in the intermittent aeration reactors. Results of microbial population analysis also showed that higher nitrogen removal efficiencies were observed for the intermittent aeration reactors. The modified BCO process was suitable for the treatment of micro-polluted water with low C/N ratio characteristics.