Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Review
. 2024 Oct 17;10(21):e39438.
doi: 10.1016/j.heliyon.2024.e39438. eCollection 2024 Nov 15.

Nitrate formation in anammox process: Mechanisms and operating conditions

Heng Yu  1   2 , Yue Dong  1   2 , Sike Wang  3 , Weiyi Jia  1   2 , Yating Wang  4 , Jiane Zuo  5   6 , Chengtun Qu  1   2
Affiliations
Review

Nitrate formation in anammox process: Mechanisms and operating conditions

Heng Yu et al. Heliyon. .

Abstract

Anaerobic ammonium oxidation (anammox) is an energy-efficient technology for wastewater nitrogen removal. However, the byproduct nitrate has hindered development and application of anammox process. Meanwhile, the knowledge of nitrate formation during anammox process is insufficient, which prohibits high nitrogen removal. This review firstly summaries and discusses valuable findings on nitrate formation, including molecular mechanism of nitrate production, microbial pathway of nitrate reduction and its net formation. Specially, influences of operating conditions on mechanisms and patterns of nitrate formation are analyzed. Then, based on nitrate formation mechanism, current strategies of nitrate removal from anammox process are reevaluated. Finally, the key knowledge gaps and further process development are presented. Overall, this review sheds light on the understanding of nitrate formation of anammox process, which would further facilitate and optimize the process design and operation for high performance nitrogen removal.

Keywords: Anammox; Biological nitrogen removal; Nitrate formation; Operating conditions; Synergic effect.

PubMed Disclaimer

Conflict of interest statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Image 1
Graphical abstract
Fig. 1
Fig. 1
Ammonium, nitrite and nitrogen are highlighted black and nitrate is highlighted red. Reactions are numbered (octagon with black numbers) and are catalyzed by the following enzymes (cloud shape): Nir, nitrite reductase; HZS, hydrazine synthase; HDH, hydrazine dehydrogenase; HOX, hydroxylamine oxidase; NXR, nitrite oxidoreductase; Nrf, nitrite reductase forming ammonium; ATPase, ATP synthase. Chemicals and electron flows are indicated by black and red arrows, respectively. Reactions and processes indicated by broken black and red lines are not completely established yet. Membrane ladderane is indicated by ladder shape.
Fig. 2
Fig. 2
A win-win cooperation for nitrate formation among AnAOB, denitrifiers and DNRA bacteria. AnAOB, anammox bacteria; DNRA, dissimilatory nitrate reduction to ammonium; EPS, extracellular polymeric substances; SMP, soluble microbial products; VFA, Volatile fatty acids.
Fig. 3
Fig. 3
Coupling of biological nitrate removal process with anammox process. (a) Partial denitrification and anammox process (PD/A); (b) Anammox process coupled with DNRA bacteria; (c) Anammox process coupled with DNRA pathway of AnAOB; AnAOB, anammox bacteria; DNRA, dissimilatory nitrate reduction to ammonium; Partial DNRA, dissimilatory nitrate reduction to nitrite.
See this image and copyright information in PMC

Similar articles

See all similar articles

References

    1. Jetten M.S., et al. The anaerobic oxidation of ammonium. FEMS (Fed. Eur. Microbiol. Soc.) Microbiol. Rev. 1998;22:421–437. - PubMed
    1. Lackner S., et al. Full-scale partial nitritation/anammox experiences--an application survey. Water Res. 2014;55:292–303. - PubMed
    1. Cao Y., et al. Mainstream partial nitritation–anammox in municipal wastewater treatment: status, bottlenecks, and further studies. Appl. Microbiol. Biotechnol. 2017;101:1365–1383. - PubMed
    1. Wang C., et al. Strategy of nitrate removal in anaerobic ammonia oxidation-dependent processes. Chemosphere. 2023;313 - PubMed
    1. Wang L., et al. Challenges, solutions and prospects of mainstream anammox-based process for municipal wastewater treatment. Sci. Total Environ. 2022;820 - PubMed

LinkOut - more resources