进水C/N对部分反硝化NO2-积累和微生物特性的影响

采用缺氧/好氧间歇运行模式，考察进水碳氮比（C/N=5.0，3.3，2.5，2.0）对部分反硝化过程亚硝态氮（NO₂^-）积累特性和污染物降解规律的影响，同时结合高通量测序，探究微生物多样性和功能菌群的演变规律.结果表明，C/N为2.5时，系统获得最佳处理效果，出水NO₂^-浓度为27.18mg/L，亚硝态氮转化率（NTR）高达67.96%；分析典型周期各污染物的降解规律发现，尽管4组工况均在缺氧30min时NO₂^-积累达到峰值（最高值分别为4.86（C/N=5.0），16.52（C/N=3.3），30.16（C/N=2.5），20.28（C/N=2.0） mg/L），但COD降解速率的不同直接影响了反硝化进程，且只有在低C/N条件（C/N=2.0~2.5）才能维持稳定的NO₂^-积累.高通量测序结果表明，除了Thauera（2.67%~24.04%）、Terrimonas（4.94%~21.19%）、Saprospiraceae（5.34%~13.50%）等常规功能菌属外，Flavobacterium（28.23%）是C/N为2.5时维持高NO₂^-积累的优势菌属.结合部分反硝化工艺的运行特点，探讨了NO₂^-作为中间产物的相关耦合工艺的应用可行性.

Effect of influent C/N rations on nitrite accumulation and microbial community in the partial denitrification process

Using the anoxic/aerobic intermittent operation mode, the influence of influent C/N ratios (C/N=5.0, 3.3, 2.5, 2.0) on nitrite (NO₂^-) accumulation and pollutant degradation in partial denitrification process was investigated, and the microbial diversity and functional bacteria evolution were explored with high-throughput sequencing. At the C/N ratio of 2.5, the system achieved the best treatment performance, and the effluent NO₂^- concentration was 27.18mg/L with the nitrite transformation ratio (NTR) of 67.96%. The analysis of the degradation rules of each pollutant in typical cycle revealed that the degradation rate of COD directly affected the process of denitrification and the stable NO₂^- accumulation can only be maintained under the condition of lower C/N ratios (C/N=2.0~2.5), although NO₂^-accumulation peaked at 30min of anoxic stage in all the four operations with the highest NO₂^- values of 4.86(C/N=5.0), 16.52(C/N=3.3), 30.16(C/N=2.5), and 20.28 (C/N=2.0) mg/L, respectively. High-throughput sequencing results showed that in addition to traditional functional bacteria of Thauera(2.67%~24.04%), Terrimonas(4.94%~21.19%) and Saprospiraceae(5.34%~13.50%), Flavobacterium(28.23%) was the dominant bacteria that maintained high NO₂^- accumulation when the C/N ratio was 2.5. Combined with the operational characteristics of partial denitrification process, the application feasibility of related coupling processes with NO₂^-as intermediate product was discussed.