The University of Tennessee, Department of Biosystems Engineering and Soil Science, 310 Biosystems Engineering And Environmental Sciences Office, 2506 E.J. Chapman Drive, Knoxville, TN 37996-4531, USA.
Bioresour Technol. 2010 Jun;101(12):4513-9. doi: 10.1016/j.biortech.2010.01.090. Epub 2010 Feb 13.
Free ammonia has long been identified as a nitrite oxidation inhibitor. However, past attempts to use this compound to eliminate nitrite oxidation and thereby promote more efficient nitrogen removal strategies during biological wastewater treatment have often failed. Additionally, contradictory results exist in the literature where direct measurements of free ammonia inhibition of nitrite oxidation have been reported. In this study, suspended biomass samples (nitrifier enriched activated sludge) were collected from a bench scale nitrification reactor with Nitrobacter spp. as the dominant nitrite oxidizer and subjected to batch respirometric experiments designed to quantify free ammonia inhibition of nitrite oxidization. A variety of data including ammonia, nitrite, and nitrate conversion rates, oxygen consumption rates, and Nitrobacter ribosomal RNA transcript abundance, a molecular indicator of growth activity, were used to assess nitrite oxidation and growth activity. Both the traditional and molecular activity assessments indicated that free ammonia had a limited inhibitory effect on Nitrobacter spp. In fact, the pH changes necessary to induce high free ammonia concentrations (>10mg-N/L) had a demonstrably more important inhibiting effect on nitrite oxidation than free ammonia. In contrast, during high ammonia oxidizing activity (5.3mg-N/L/h), low nitrite oxidation rates (0.2mg-N/L/h) and severely impaired Nitrobacter spp. growth activity, indicated by a low abundance of the Nitrobacter spp. ribosomal gene transcript relative to the ribosomal gene (0.08), were measured. The findings suggest that pH changes and ammonia oxidizing bacteria activity are more important factors limiting Nitrobacter spp. mediated nitrite oxidation, rather than the free ammonia concentration.
游离氨一直被认为是亚硝酸盐氧化的抑制剂。然而，过去试图使用这种化合物来消除亚硝酸盐氧化，从而在生物废水处理中促进更有效的氮去除策略的尝试往往失败了。此外，文献中存在相互矛盾的结果，其中报告了直接测量游离氨对亚硝酸盐氧化的抑制作用。在这项研究中，从一个带有 Nitrobacter spp. 的硝化反应器中收集了悬浮生物量样品（硝化菌富集活性污泥），作为优势亚硝酸盐氧化菌，并进行了批式呼吸测量实验，旨在量化游离氨对亚硝酸盐氧化的抑制作用。使用各种数据，包括氨、亚硝酸盐和硝酸盐转化率、耗氧率以及 Nitrobacter 核糖体 RNA 转录物丰度（生长活性的分子指标）来评估亚硝酸盐氧化和生长活性。传统和分子活性评估都表明游离氨对 Nitrobacter spp. 的抑制作用有限。实际上，为了诱导高游离氨浓度（>10mg-N/L）而发生的 pH 变化对亚硝酸盐氧化的抑制作用比游离氨更为明显。相比之下，在高氨氧化活性（5.3mg-N/L/h）下，亚硝酸盐氧化速率较低（0.2mg-N/L/h），Nitrobacter spp. 生长活性受到严重损害，相对于核糖体基因，Nitrobacter spp. 核糖体基因转录物的丰度较低（0.08）。研究结果表明，pH 变化和氨氧化细菌活性是限制 Nitrobacter spp. 介导的亚硝酸盐氧化的更重要因素，而不是游离氨浓度。
