[Enhanced ammonia removal and microbial community structure analysis using bacterial quinone profile in ITFB]

Water quality during the start-up period was changed in order to enhance the later nitrifying ability of the internal-circulation three-phase bio-fluidized bed (ITFB). The experimental results showed that high N/C ratio and low feeding concentration of COD were two key conditions for enhancing the ammonia removal. After the enhanced start-up, an efficient removal efficiency of both COD and ammonia was achieved with HRT 2h when treating sanitary wastewater, the average ammonia removal rate was 74% , the ammonia concentration in effluent was lower than 10 mg/L. Bacterial quinone profile of the system was also analyzed. The results showed that after the enhanced start-up, the number of nitrifying bacteria, such as Nitrosomonas europaea, in the biofilm in ITFB was increased, and the number of gamma-Proteobacteria, such as Acinetobacter sp. and Pseudomonas sp., was decreased. the equitability of the quinones (EQ) fluctuated around 0.5 showed that the distribution of the microbial community in the biofilm changed little. UQ/MK ratio of all the samples was greater than 1 indicated that Gram-negative bacteria was the dominant bacteria in the system.