This study investigated the effects of hydraulic retention time (HRT) on nitrous oxide ($N_2$O) production during nitrification in a laboratory-scale biological aerated filter (BAF) reactor. Furthermore, its underlying mechanisms were explored by microelectrode technology and PCR-denaturing gradient gel electrophoresis (PCR-DGGE). The results showed that the N₂O production rate was at its maximum at HRT of 4 h and at its minimum at HRT of 6 h. And there was only a little increase in N₂O production rate at HRT of 8 h compared to HRT of 6 h. The average $N_2$O production rates were 0.2258, 0.0872, and 0.1015 mg/h for HRT of 4, 6, and 8 h, respectively. Results of analysis of the internal biofilm microenvironment were consistent with the results of the N₂O production rate. Production of $N_2$O decreased sharply when HRT was increased from 4 to 6 h, whereas a slight increase in $N_2$O production was observed when HRT was further increased from 6 to 8 h. Determination of DO, ORP, and nitrogen by microelectrode also demonstrated that the internal microenvironment of the biofilm was responsible for $N_2$O generation. DNA analysis showed that Proteobacteria and Bacteroidetes might be responsible for $N_2$O emission in the biofilm. These results indicate that HRT significantly affects the microbial community structures between the seed sludge and BAF biofilm, thereby affecting N₂O production ability and rates, and hence, should be taken into consideration during BAF application.

这项研究调查了水力停留时间（HRT）对一氧化二氮（${ñ}_2$O）在实验室规模的生物曝气滤池（BAF）反应器中进行硝化过程中的生产。此外，通过微电极技术和PCR-变性梯度凝胶电泳（PCR-DGGE）探索了其潜在的机制。结果表明，N ₂ O生成速率在HRT为4 h时最大，在HRT为6 h时最小。而HRT为8 h的N ₂ O生成速率与6 h的N ₂ O生成速率相比几乎没有增加。平均${ñ}_2$HRT为4、6和8小时的O生产率分别为0.2258、0.0872和0.1015 mg / h。内部生物膜微环境的分析结果与N ₂ O产生速率的结果一致。的产品${ñ}_2$当HRT从4小时增加到6小时时，O急剧下降，而HRT则略有增加 ${ñ}_2$当HRT从6小时进一步增加到8小时时，观察到O的产生。通过微电极测定DO，ORP和氮也证明了生物膜的内部微环境是导致${ñ}_2$O一代。DNA分析表明，变形杆菌和拟杆菌可能与${ñ}_2$生物膜中的O排放。这些结果表明HRT显着影响种子污泥和BAF生物膜之间的微生物群落结构，从而影响N ₂ O的生产能力和速率，因此在BAF施用过程中应予以考虑。