Department of Earth and Environmental Engineering, Columbia University, New York, NY 10027, USA.
Center for Environmental Studies, Anna University, Chennai, India.
Water Res. 2015 Mar 1;70:246-54. doi: 10.1016/j.watres.2014.12.006. Epub 2014 Dec 12.
The overarching goal of this study was to determine the role of inorganic carbon (IC) in influencing the microbial ecology, performance and nitrogen turnover by individual microbial communities of a biofilm based combined nitritation-anammox process. IC limitation was transiently imposed by reducing the IC input from 350% to 40% of the stoichiometric requirement for 40 days. The principal impact observed during IC limitation was the overgrowth of nitrite oxidizing bacteria (NOB) at the expense of anaerobic ammonia oxidizing bacteria (AMX). On the other hand, the concentrations of ammonia oxidizing bacteria (AOB) were relatively stable during the imposition of and recovery from IC limitation. The resulting dominance of NOB, in terms of their concentration and contribution to nitrite consumption over AMX, resulted, in turn, in a decrease in overall nitrogen removal from 78 ± 2.0% before IC limitation to 46 ± 2.9% during IC limitation. Upon recovery back to non-limiting IC input, it took an inordinately long time (about 57*HRT) for the N-removal to recover back to pre-limitation conditions. Even after recovery, NOB were still persistent in the biofilm and could not be washed out to pre-limitation concentrations. The emission of nitrous oxide (N₂O) and nitric oxide (NO), likely from AOB, transiently increased in concert with transient increases in ammonia and hydroxylamine concentrations during the period of IC limitation. Therefore, an unintended consequence of IC limitation in nitritation-anammox systems can be an increase in their greenhouse gas footprint, in addition to compromised process performance. Most emphasis to date on nitritation and anammox studies has been on the nitrogen cycle. The results of this study demonstrate that the differing strategies used by AOB, NOB and AMX to compete for their preferred assimilative carbon source can also significantly influence the microbial ecology, performance and carbon footprint of such processes.
本研究的总体目标是确定无机碳（IC）在通过基于生物膜的组合亚硝化-厌氧氨氧化工艺的单个微生物群落的微生物生态学、性能和氮转化中所起的作用。通过将 IC 输入从化学计量需求的 350%减少到 40%，将 IC 限制在 40 天内短暂实施。在 IC 限制期间观察到的主要影响是亚硝酸氧化菌（NOB）的过度生长，以牺牲厌氧氨氧化菌（AMX）为代价。另一方面，在 IC 限制的实施和恢复过程中，氨氧化菌（AOB）的浓度相对稳定。NOB 的浓度及其对亚硝酸消耗的贡献相对于 AMX 的主导地位，反过来又导致整体氮去除率从 IC 限制前的 78±2.0%下降到 IC 限制期间的 46±2.9%。在恢复到非限制 IC 输入后，大约需要 57*HRT 的时间（水力停留时间）才能使氮去除恢复到限制前的条件。即使在恢复之后，NOB 仍然在生物膜中持续存在，并且无法冲洗到限制前的浓度。氮氧化物（N₂O）和一氧化氮（NO）的排放，可能来自 AOB，与 IC 限制期间氨和羟胺浓度的暂时增加协同增加。因此，IC 限制在亚硝化-厌氧氨氧化系统中除了会影响工艺性能外，还可能会增加其温室气体足迹。迄今为止，大多数关于亚硝化和厌氧氨氧化的研究都集中在氮循环上。本研究的结果表明，AOB、NOB 和 AMX 用于竞争其首选同化碳源的不同策略也会显著影响这些过程的微生物生态学、性能和碳足迹。
