Jia Sijing, Chen Xiaoqiang, Suenaga Toshikazu, Terada Akihiko, Ishikawa Susumu, Nishimura Fumitake, Ding Shaolan, Fujiwara Taku
Research and Education Faculty, Natural Sciences Cluster, Agriculture Unit, Kochi University, 200 Monobe Otsu, Nankoku, Kochi 783-8502, Japan.
Research and Education Faculty, Natural Sciences Cluster, Agriculture Unit, Kochi University, 200 Monobe Otsu, Nankoku, Kochi 783-8502, Japan; Institute of Water and Environment Research, Faculty of Infrastructure Engineering, Dalian University of Technology, 2 Ling Gong, Ganjingzi, Dalian 116024, China.
J Biosci Bioeng. 2019 Mar;127(3):333-339. doi: 10.1016/j.jbiosc.2018.08.003. Epub 2018 Nov 10.
Nitrous oxide (NO) is an important greenhouse gas that can be emitted from wastewater treatment plants (WWTPs). Such emissions are reportedly process specific and related to operational parameters. This study was conducted to clarify spatial and daily variations of NO in a full-scale activated sludge anoxic/oxic process that consisted of an anoxic tank and three oxic tanks (oxic-1, oxic-2 and oxic-3), all of which except the final sedimentation tank were fully covered. Higher dissolved NO (D-NO) loading and gaseous NO (G-NO) emissions were observed for oxic-3 than for the anoxic, oxic-1, and oxic-2 tanks, implying that there was higher NO production potential via nitrification in the latter stage of the oxic tank. Moreover, the sudden decrease in dissolved oxygen concentration after the peak was found to lead to abrupt production of D-NO at oxic-3 in the anoxic/oxic process. The increases in AOB amoA, AOB nirK and the following AOB norB gene transcripts at the end of the oxic-2 tank suggested that nitrifier denitrification occurred to produce NO under low dissolved oxygen conditions when the NO peak was observed. Additionally, the much lower transcription levels of the two nosZ genes suggested lower NO consumption. The NO emission factors ranged from 0.087% to 0.302%, and lower NO emission factors were observed during summer.
一氧化二氮（NO）是一种重要的温室气体，可从污水处理厂（WWTPs）排放。据报道，此类排放具有特定工艺性且与运行参数相关。本研究旨在阐明一个全尺寸活性污泥缺氧/好氧工艺中NO的空间和日变化情况，该工艺由一个缺氧池和三个好氧池（好氧-1、好氧-2和好氧-3）组成，除最终沉淀池外均完全覆盖。与缺氧池、好氧-1池和好氧-2池相比，好氧-3池观察到更高的溶解态NO（D-NO）负荷和气态NO（G-NO）排放，这意味着在好氧池后期通过硝化作用产生NO的潜力更高。此外，发现在缺氧/好氧工艺中，峰值后溶解氧浓度的突然下降导致好氧-3池中D-NO的突然产生。在好氧-2池末端，氨氧化细菌amoA、氨氧化细菌nirK以及随后的氨氧化细菌norB基因转录本增加，这表明在观察到NO峰值时，在低溶解氧条件下发生了硝化反硝化作用以产生NO。此外，两个nosZ基因的转录水平低得多，表明NO消耗较低。NO排放因子范围为0.087%至0.302%，夏季观察到较低的NO排放因子。
