[Study on the nitrogen removal performance and the characteristics of denitrification bacterial community structure of biological aerated filter].

The nitrogen removal performance and the denitrification bacterial community structure of two pre-denitrification biological aeration filter (BAF) processes with different media combinations, the ceramic-zeolite BAF process (C-Z BAF) and the zeolite-ceramic BAF process (Z-C BAF), were compared at different C/N ratios. The results showed that the average TN removal efficiency of Z-C BAF was higher than that of C-Z BAF, and the advantage was more notable at low C/N ratio. When the C/N ratio decreased to 3.3, the average TN removal efficiency of Z-C BAF was 20% higher than that of C-Z BAF. Comparing the microbial community structure of the two combinations at different C/N ratios, it was found that the richness and diversity of denitrification bacterial community decreased significantly with the decrease of C/N ratio. At low C/N ratio, within the whole oxic filter of Z-C BAF, nosZ genetic T-RFs were detected with more than 20% relative abundance, whereas no nosZ genetic T-RFs were detected at the upper oxic filter of C-Z BAF by PCR amplification. The results indicated that the simultaneous nitrification and denitrification function of Z-C BAF was better than that of C-Z BAF. At low C/N ratio, the nitrogen removal efficiency of Z-C BAF was obviously higher than that of C-Z BAF. Thus, compared to C-Z BAF, Z-C BAF had greater potential on the treatment of wastewater with low organic concentration and low C/N ratio.