不同阳离子和碳氮比对反硝化性能及亚硝酸盐氮积累的影响

在序批式反应器(SBR)中，采用乙酸钠为碳源，通过硝酸钠和硝酸钙的交替投加、微量元素的投加以及碳氮比(COD/NO₃⁻-N)的改变，探究了不同控制条件对反硝化性能及NO₂⁻-N积累的影响，并分析了反应器中微生物种群演替特征。结果表明，在以乙酸钠为碳源的SBR中，Ca²⁺浓度过高会抑制反硝化。以NaNO₃为NO₃⁻-N来源时，硝酸盐氮还原率维持在50%左右；相同条件下，以Ca(NO₃)₂为NO₃⁻-N来源时，硝酸盐氮还原率仅有20%。反应器中补充适量磷元素后，硝酸盐氮还原率提高至62%，同时有少量的亚硝酸盐氮积累。当C/N比提高为4后，硝酸盐氮还原率大于98%，长期运行下亚硝酸盐氮积累率平均为83.8%。高通量测序分析结果表明，变形菌门和拟杆菌门在系统中占主导地位。NO₂⁻-N积累的关键功能菌属是Thauera菌属，其最高占比为17.25%。以Ca(NO₃)₂为NO₃⁻-N来源时，Thauera菌属占比仅为0.14%。以上研究结果为短程反硝化的快速启动和稳定运行提供参考。

Effects of different cations and C/N on denitrification performance and nitrite accumulation

Sodium acetate was used as the carbon source in a sequencing batch reactor (SBR), and the effects of different control conditions on denitrification performance and NO2−-N accumulation were investigated by alternate dosing of sodium nitrate and calcium nitrate, the dosing of trace elements and the change of C/N ratio, and the characteristics of microbial population succession in SBR were also analyzed. The results showed that high Ca2+ concentration inhibited denitrification performance in the SBR reactor with sodium acetate as the carbon source. The nitrate nitrogen reduction rate was maintained at about 50% when NaNO3 was used as the NO3−-N source; under the same conditions, the nitrate nitrogen reduction rate was only 20% when Ca(NO3)2 was used as the NO3−-N source. When SBR was supplemented with appropriate amount of phosphorus, the nitrate reduction rate could increase to 62%, while the accumulation of a small amount of nitrite occurred. When the carbon to nitrate ratio (COD/NO3−-N) increased to 4, the nitrate reduction rate was greater than 98%, and the nitrite accumulation rate was 83.8% on average under long-term operation. High-throughput sequencing analysis showed that Proteobacteria and Bacteroidetes dominated the system, the key functional genus for NO3−-N accumulation was Thauera, which had the highest percentage of 17.25%. The percentage of Thauera was only 0.14% when Ca(NO3)2 was used as the source of NO3−-N. These results provide a theoretical support for the rapid start-up and stable operation of partial denitrification.