Abstract：
The anammox reaction simultaneously utilizes ammonia and nitrite as substrates; however, high nitrite concentrations act as strong inhibitors of the reaction. In this study, inhibition by NO2- and free nitrous acid (FNA) was separately evaluated in continuous feeding tests using different biomass carriers. The influent NO2- concentration was increased under pH 7.6, where FNA is less likely to affect anammox activity. A continuous test using polyethylene glycol (PEG) gel carriers containing immobilized anammox bacteria showed that the inhibition ratio was 13% when the NO2--N concentration in the reactor was 350 mg L-1 (FNA ≤0.06 mg L-1). The relationship between NO2- concentration in the reactor and inhibition ratio increased linearly. Evaluation of the inhibitory effect of FNA by increasing the influent NO2- concentration at pH 6.4, where FNA is easily formed, demonstrated that the relationship between FNA and inhibition ratio could be fitted to a sigmoid curve, and the 50% inhibitory concentration (IC50) of FNA was 0.88 mg L-1. A similar test performed using polyvinyl alcohol carriers containing anammox bacteria on their surface showed the same trend as the PEG gel carriers, with the IC50 for FNA at 0.70 mg L-1. These results indicate that the inhibitory effect of FNA on anammox activity was greater than that of NO2-. The evaluation of these two factors helped identify important operational indicators of the stable application of anammox processes.
摘要：
厌氧氨氧化反应同时利用氨和亚硝酸盐作为底物；然而，高亚硝酸盐浓度作为反应的强抑制剂。在这项研究中,在使用不同生物质载体的连续饲喂试验中，分别评估了NO2-和游离亚硝酸（FNA）的抑制作用。在pH7.6下，进水NO2浓度增加，其中FNA不太可能影响anammox活性。使用含有固定化厌氧氨氧化菌的聚乙二醇（PEG）凝胶载体进行的连续测试表明，当反应器中NO2--N浓度为350mgL-1（FNA≤0.06mgL-1）时，抑制率为13％。反应器中NO2-浓度与抑制率呈线性增加关系。通过在容易形成FNA的pH6.4下增加进水NO2-浓度来评估FNA的抑制作用，证明FNA与抑制率之间的关系可以拟合为S形曲线，FNA的50%抑制浓度(IC50)为0.88mgL-1。使用表面含有厌氧氨氧化细菌的聚乙烯醇载体进行的类似测试显示出与PEG凝胶载体相同的趋势，FNA的IC50为0.70mgL-1。这些结果表明，FNA对anammox活性的抑制作用大于NO2-。对这两个因素的评估有助于确定稳定应用厌氧氨氧化工艺的重要操作指标。
