Fast start-up of PN/A process in a single-stage packed bed and mechanism of nitrogen removal
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RESEARCH ARTICLE
Fast start-up of PN/A process in a single-stage packed bed and mechanism of nitrogen removal Yaqi Xie 1 & Chuanyi Zhang 1 & Limei Yuan 1 & Qieyuan Gao 2 & Hai Liang 1 & Nana Lu 1 Received: 13 January 2020 / Accepted: 6 July 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The single-stage partial nitritation–anammox (PN/A) process is severely limited by a long start-up time and unstable removal efficiency. In this study, PN/A was developed in 67 days in a novel packed bed equipped with porous bio-carriers by gradually increasing the influent nitrogen loading rate (0.15–0.73 kg-N m−3·d−1) and controlling the dissolved oxygen (< 1.2 mg L−1). An average ammonium nitrogen removal efficiency (ARE) and total nitrogen removal efficiency (TNR) of 87.01 and 72.41%, respectively, were obtained. This represents a reliable alternative method of achieving rapid PN/A start-up. The results of 16S rRNA sequencing showed that Proteobacteria and Planctomycetes, with which ammonia-oxidizing bacteria and anammox bacteria were affiliated, accounted for 38.8%, representing the dominant phylum in the system after acclimation. The abundance of Nitrosomonas and Candidatus Brocadia increased by 16 and 1.79%, respectively. The results of metagenomics and metatranscriptomics revealed that the nitrite oxidation process was blocked by the transcriptional suppression of nitrite oxidoreductase and the entire nitrogen metabolism process was dominated by the partial nitritation and anammox process. Moreover, a high abundance of heterotrophic bacteria with potential for nitrogen removal was detected. In the nitrogen cycle, a widespread nitrite-accumulated denitrification helps to form a nitrite loop, which promotes the efficiency of total nitrogen removal. This is crucial for further improving the nitrogen removal mechanism in the PN/A system. Keywords Single-stage packed bed . Partial nitritation–anammox . Bio-carrier . Metagenomics and metatranscriptomics . Nitrite-accumulated denitrification . Nitrite loop
Introduction Anaerobic ammonium oxidation (anammox) is a novel process developed by the Kluyver Biotechnology Laboratory in the 1990s, which directly oxidizes NH4+-N to N2 with NO2−N (Mulder et al. 1995). This process advances the basic theory of traditional biological nitrogen removal (Fernández et al. Responsible editor: Gerald Thouand Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11356-020-10030-9) contains supplementary material, which is available to authorized users. * Chuanyi Zhang [email protected] 1
School of Environmental Science and Spatial Informatics, China University of Mining and Technology, Xuzhou 221116, China
2
School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou 221116, China
2016) and has been acknowledged as one of the most efficient and economical techniques for biological nitrogen removal. It is particularly suitable for the treatment of high ammonia nitrogen and low carbon wast
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