Determining Factors for Nitrite Accumulation in an Acidic Nitrifying System : Influent Ammonium Concentration, Operational pH, and Ammonia-Oxidizing Community

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

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Author(s)

  • Jia Meng
  • Zhetai Hu
  • Zhiyao Wang
  • Shihu Hu
  • Yanchen Liu
  • Hongguang Guo
  • Jianzheng Li
  • Min Zheng

Detail(s)

Original languageEnglish
Pages (from-to)11578-11588
Journal / PublicationEnvironmental Science and Technology
Volume56
Issue number16
Online published25 Jul 2022
Publication statusPublished - 16 Aug 2022
Externally publishedYes

Abstract

Acidic nitrification is attracting wide attention because it can enable robust suppression of nitrite-oxidizing bacteria (NOB) in wastewater treatment. This study reports a comprehensive assessment of the novel acidic nitrification process to identify the key factors that govern stable nitrite accumulation. A laboratory-scale moving-bed biofilm reactor receiving low-alkalinity wastewater was continuously operated under acidic conditions (pH < 6) for around two years, including nine stages varying influent and operational conditions. The results revealed that nitrite accumulation was related to three factors, i.e., influent ammonium concentration, operating pH, and ammonia-oxidizing microbial community. These three factors impact nitrite accumulation by altering the in situ concentration of free nitrous acid (FNA), which is a potent inhibitor of NOB. The critical FNA concentration is approximately one part per million (ppm, ∼1 mg HNO2-N/L), above which nitrite accumulation is stably maintained in an acidic nitrifying system. The findings of this study suggest that stable nitrite accumulation via acidic ammonia oxidation can be maintained under a range of influent and operational conditions, as long as a ppm-level of FNA is established. Taking low-strength mainstream wastewater (40-50 mg NH4+-N/L) with limited alkalinity as an example, stable nitrite accumulation was experimentally demonstrated at a pH of 4.35, under which an in situ FNA of 2.3 ± 0.6 mg HNO2-N/L was attained. Under these conditions, Candidatus Nitrosoglobus became the only ammonia oxidizer detectable by 16S rRNA gene sequencing. The results of this study deepen our understanding of acidic nitrifying systems, informing further development of novel wastewater treatment technologies. © 2022 American Chemical Society. All rights reserved.

Research Area(s)

  • acid-tolerant ammonia-oxidizing bacteria, acidic nitrification, low pH bioreactor, wastewater treatment

Citation Format(s)

Determining Factors for Nitrite Accumulation in an Acidic Nitrifying System: Influent Ammonium Concentration, Operational pH, and Ammonia-Oxidizing Community. / Meng, Jia; Hu, Zhetai; Wang, Zhiyao et al.
In: Environmental Science and Technology, Vol. 56, No. 16, 16.08.2022, p. 11578-11588.

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review