内循环比对反硝化除磷工艺处理效果和群落结构的影响

反硝化除磷作为一种新型可持续发展技术受到广泛关注. 前期在多级缺氧-好氧工艺的基础上开发了一种新型反硝化除磷工艺(DPR-MAO). 为探明内循环系统对DPR-MAO工艺脱氮除磷效能的影响，考察了不同内循环比条件下的氮磷去除效果，分析了各反应池的脱氮除磷过程以及微生物群落特征. 结果表明:当内循环比由100%提至200%时，总氮和总磷的平均去除率由76.05%和86.39%分别提至87.46%和93.42%. 通过氮磷质量平衡分析发现，提高内循环比可以使工艺表现出优良的反硝化除磷性能. 高通量测序结果表明，DPR-MAO工艺中具有反硝化除磷功能的菌属主要有Thiothrix、Dokdonella、Candidatus accumulibacter、Thauera、Comamonas、Dechloromonas和Pseudomonas. 当内循环比由100%提至200%时，具有反硝化除磷功能的菌属的相对丰度总和增加了约4倍，其中Thiothrix的相对丰度由0.36%~0.52%增至53.58%~56.64%. 研究显示，提高内循环比可以强化DPR-MAO工艺的反硝化除磷效果以及反硝化聚磷菌在微生物群落中的优势地位. 

Effect of Internal Return System on Removal Performance and Microbial Community Structure of Novel Denitrifying Phosphorus Removal Process

As a novel sustainable development technology, denitrifying phosphorus removal process (DPR) has attracted wide attention. In previous work, a novel denitrifying phosphorus removal process based on multistage anoxic-oxic process (DPR-MAO) was developed. In order to reveal the effect of the internal return system on nitrogen and phosphorus removal performance, the nitrogen and phosphorus removal efficiency of the DPR-MAO process under different internal return ratios was investigated. Meanwhile, the nitrogen and phosphorus removal process and the characteristics of the microbial community in each reaction tank were analyzed. As the internal return ratios increased from 100% to 200%, the total nitrogen (TN) and total phosphorus (TP) removal efficiency increased from 76.05% and 86.39% to 87.46% and 93.42%, respectively. The analysis of nitrogen and phosphorus mass balance revealed that the denitrifying phosphorus removal performance could be enhanced by increasing the internal return ratio. High-throughput sequencing results indicated that Thiothrix, Dokdonella, Candidatus accumulibacter, Thaurea, Comamonas, Dechloromonas and Pseudomonas were the dominant genus for denitrifying phosphorus removal. When the two internal return ratios were increased from 100% to 200%, the sum of relative abundance of genera with denitrifying phosphorus removal functions increased by 4 times, and the relative abundance of Thiothrix increased from 0.36% and 0.52% to 53.58% and 56.64%. The study demonstrated that the denitrifying phosphorus removal performance of DPR-MAO process and the dominant position of bacteria for denitrifying phosphorus removal could be enhanced by increasing internal return ratios.