好氧和缺氧条件下游离亚硝酸对氨氧化菌和亚硝酸盐氧化菌的选择性抑制

Inhibitory of FNA on the activity of AOB and NOB under aerobic and anoxic conditions

摘要:

【背景】稳定短程硝化是实现城市污水厌氧氨氧化技术的瓶颈，目前国内外关于游离亚硝酸(Free nitrous acid，FNA)对硝化菌活性的影响大多是在曝气条件下进行研究，鲜有关于缺氧条件下FNA对硝化菌活性影响的报道。【目的】探究好氧和缺氧下FNA对氨氧化菌(Ammonia oxidizing bacteria，AOB)和亚硝酸盐氧化菌(Nitrite oxidizing bacteria，NOB：Nitrospira和Nitrobacter)活性的抑制影响。【方法】采用序批式反应器(Sequencing batch reactor，SBR)，基于混合液悬浮固体浓度(Mixed liquid suspended solids，MLSS)为8 300 mg/L的全程硝化污泥条件，通过批次试验分别考察好氧和缺氧下FNA (初始浓度为1.16 mg/L)处理48 h后，AOB和NOB活性的变化情况。【结果】好氧FNA处理活性污泥48 h后，FNA浓度维持在1.16?1.17 mg/L，游离氨(Free ammonia，FA)浓度小于0.017 mg/L，AOB、Nitrospira、Nitrobacter丰度均未发生明显变化；过曝气至99 h时，与空白组相比，比氨氮氧化速率(rNH+ 4-N)、比亚硝酸盐氮氧化速率(rNO- 2-N)均出现小幅下降，分别由3.5、4.828 mg N/(g VSS·h)降至3.3、4.668 mg N/(g VSS·h)，且亚硝酸盐氮累积率(Nitrite accumulation rate，NAR)始终低于33.2%。缺氧FNA处理活性污泥48 h后，FNA浓度维持在0.64?1.16 mg/L，FA浓度低于0.039 mg/L，AOB丰度变化较小，而Nitrospira、Nitrobacter丰度均明显下降，分别由3.002 9×109、4.245×108 copies/g VSS降至1.666 5×108、5.163 8×107 copies/g VSS；过曝气至99 h时，与空白组相比，rNH+ 4?N值下降幅度较小，而rNO- 2-N值明显降低，由4.828 mg N/(g VSS·h) 降至0.007 mg N/(g VSS·h)，且在过曝气0?292 h内，NAR均大于94%。【结论】好氧FNA处理活性污泥48 h后对AOB和NOB无明显抑制作用，但缺氧FNA处理活性污泥48 h后对AOB具有轻微抑制作用，而对NOB具有强烈的抑制作用，可以实现稳定的短程硝化。

Abstract:

[Background] Stable partial nitritation is the bottleneck to achieve the anammox technology of municipal wastewater. At present, the effect of free nitrous acid (FNA) on the activity of nitrifying bacteria at home and abroad are mostly studied under aeration conditions, while not much research has been reported to discussed the effect of FNA on the activity of nitrifying bacteria under anoxic conditions. [Objective] To investigate the inhibitory effect of FNA on the activities of ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB: Nitrospira and Nitrobacter) under aerobic and anoxic conditions. [Methods] The activities of AOB and NOB were investigated in a sequencing batch reactor (SBR) after FNA (initial concentration 1.16 mg/L) treatment under aerobic and anoxic conditions for 48?hours, based on the condition that the suspended solid concentration of mixed solution (MLSS) was 8?300 mg/L. [Results] After treatment under aerobic conditions with FNA for 48 hours, the FNA concentration was maintained at 1.16?1.17 mg/L, and the FA concentration was less than 0.017 mg/L after 48 hours, results showed that the abundance of AOB, Nitrospira and Nitrobacter did not change significantly; Compared with the blank group, the specific ammonia oxidation rate (rNH+ 4-N) and specific nitrite oxidation rate (rNO- 2-N) after aeration to 99 h decreased slightly, which decreased from 3.5 and 4.828?mg N/(g VSS·h) to 3.3 and 4.668 mg N/(g VSS·h) respectively, and the nitrite accumulation rate (NAR) was always lower than 33.2%. After treatment under anoxic conditions with FNA for 48 hours, the FNA concentration was maintained at 0.64?1.16 mg/L, and the FA concentration was lower than 0.039?mg/L, the AOB abundance changed slightly, while the Nitrospira and Nitrobacter abundance decreased significantly, which decreased from 3.002 9×109 and 4.245×108 copies/g VSS to 1.666 5×108 and 5.163?8×107 copies/g VSS, respectively; Compared with the blank group, the rNH+ 4-N decreased slightly, but the rNO- 2?N decreased significantly, which decreased from 4.828 mg N/(g VSS·h) to 0.007 mg N/(g VSS·h), and the NAR is maintained above 94% during over-aeration from 0 h to 292 h. [Conclusion] AOB and NOB were not significantly inhibited by FNA treatment for 48 hours under aeration conditions, but under anoxic conditions, NOB was strongly inhibited while AOB was slightly inhibited by FNA treatment for 48?hours, and stable partial nitrification could be achieved.