School of Environmental Science and Engineering, Chang'an University, Xi'an, 710064, China E-mail:
Water Sci Technol. 2020 Jan;81(1):138-147. doi: 10.2166/wst.2020.089.
In this study, the effects of elevated chemical oxygen demand/nitrogen (COD/N) ratios on nitrogen removal, production and composition of the extracellular polymer substances (EPS) and microbial community of a completely autotrophic nitrogen removal via nitrite (CANON) process were studied in a sequencing batch membrane bioreactor (SBMBR). The whole experiment was divided into two stages: the CANON stage (without organic matter in influent) and the simultaneous partial nitrification, anaerobic ammonia oxidation and denitrification (SNAD) stage (with organic matter in influent). When the inflow ammonia nitrogen was 420 mg/L and the COD/N ratio was no higher than 0.8, the addition of COD was helpful to the CANON process; the total nitrogen removal efficiency (TNE) was improved from approximately 65% to more than 75%, and the nitrogen removal rate (NRR) was improved from approximately 0.255 kgN/(m·d) to approximately 0.278 kgN/(m•d), while the TNE decreased to 60%, and the NRR decreased to 0.236 kgN/(m•d) when the COD/N ratio was elevated to 1.0. For the EPS, the amounts of soluble EPS (SEPS) and loosely bound EPS (LB-EPS) were both higher in the CANON stage than in the SNAD stage, while the amount of tightly bound EPS (TB-EPS) in the SNAD stage was significantly higher due to the proliferation of heterotrophic bacteria. The metagenome sequencing technique was used to analyse the microbial community in the SBMBR. The results showed that the addition of COD altered the structure of the bacterial community in the SBMBR. The amounts of Candidatus 'Anammoxoglobus' of anaerobic ammonia oxidation bacteria (AAOB) and Nitrosomonas of ammonia oxidizing bacteria (AOB) both decreased significantly, and Nitrospira of nitrite oxidizing bacteria (NOB) was always in the reactor, although the amount changed slightly. A proliferation of denitrifiers related to the genera of Thauera, Dokdonella and Azospira was found in the SBMBR.
在这项研究中，采用序批式膜生物反应器（SBMBR），研究了升高的化学需氧量/氮（COD/N）比对完全自养脱氮通过亚硝酸盐（CANON）工艺的脱氮效果、胞外聚合物物质（EPS）的产生和组成以及微生物群落的影响。整个实验分为两个阶段：CANON 阶段（进水无有机物）和同时部分硝化、厌氧氨氧化和反硝化（SNAD）阶段（进水有有机物）。当进水氨氮为 420mg/L，COD/N 比不高于 0.8 时，添加 COD 有利于 CANON 工艺；总氮去除效率（TNE）从约 65%提高到 75%以上，氮去除率（NRR）从约 0.255kgN/（m·d）提高到约 0.278kgN/（m·d），而当 COD/N 比升高到 1.0 时，TNE 下降到 60%，NRR 下降到 0.236kgN/（m·d）。对于 EPS，CANON 阶段的可溶 EPS（SEPS）和松散结合 EPS（LB-EPS）的量均高于 SNAD 阶段，而由于异养细菌的增殖，SNAD 阶段的紧密结合 EPS（TB-EPS）的量显著增加。采用宏基因组测序技术分析 SBMBR 中的微生物群落。结果表明，COD 的添加改变了 SBMBR 中细菌群落的结构。厌氧氨氧化菌（AAOB）的Candidatus 'Anammoxoglobus'和氨氧化菌（AOB）的Nitrosomonas 的数量均显著减少，而亚硝酸盐氧化菌（NOB）的Nitrospira 始终存在于反应器中，尽管数量略有变化。在 SBMBR 中发现了与 Thauera、Dokdonella 和 Azospira 属相关的脱氮菌的增殖。
