[Start-up Characteristics of Four-zone Integrated Reactor for Nitrogen Removal in Winter and Analysis of Nitrobacteria Community].

The treatment of decentralized sewage has gained more and more attention in China in recent years. A four-zone integrated reactor was designed by combining biofilm system and activated sludge system and start-up by gradient shorten the HRT. The removal of COD, NH4+ -N and TN were studied at 8-15°C. Fluorescence in situ hybridization(FISH) was used to detect nitrobacteria population (AOB,NOB) so as to study the relationship between the reactor effect and functional micro-bacteria. The results showed that, when the HRT was 9.2 h, the removal efficiencies of COD, ammonia and TN were 92. 11%, 99. 21% and 61. 63%, respectively. Compared to the initial stage, the numbers of AOB and NOB in the late phase were increased by 5. 82 and 6. 14 times, respectively. In addition, the proportion of nitrobacteria was increased from 6. 12% to 16. 38% , which became the dominant bacteria in biofilms. Moreover, the nitrification efficiency was increased from 78. 49% to 97. 52% , while the number of NOB was 5. 61-fold increased and the value of AOB/NOB was optimized to 1. 47. The effluent quality is guaranteed by the enrichment of AOB and NOB and suitable value of AOB/NOB.