进水C/N对部分反硝化NO2-积累和微生物特性的影响

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

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(NO_(2)^(-))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NO_(2)^(-)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NO_(2)^(-)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NO_(2)^(-)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NO_(2)^(-)积累的优势菌属.结合部分反硝化工艺的运行特点,探讨了NO_(2)^(-)作为中间产物的相关耦合工艺的应用可行性.

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(NO_(2)^(-))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 NO_(2)^(-)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 NO_(2)^(-)accumulation can only be maintained under the condition of lower C/N ratios(C/N=2.0~2.5),although NO_(2)^(-)accumulation peaked at 30min of anoxic stage in all the four operations with the highest NO_(2)^(-)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 NO_(2)^(-)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 NO_(2)^(-)as intermediate product was discussed.