Nitrite (not free nitrous acid) is the main inhibitor of the anammox process at common pH conditions

D. Puyol, J. M. Carvajal-Arroyo, R. Sierra-Alvarez, J. A. Field

Research output: Contribution to journalArticlepeer-review

83 Scopus citations


Nitrite is a substrate but also an inhibitor of anaerobic ammonium oxidation (anammox).There is currently no consensus on whether ionized nitrite (INi) or free nitrous acid (FNA) is the actual inhibitor of the process. The inhibition by INi and FNA on the anammox process has been analysed using a wide range of INi and FNA concentrations and by altering the pH and total nitrite conditions. The inhibitory impacts of both species were quantified through a rational inhibition equation, considering INi and FNA as substrate inhibitor and non-competitive inhibitor, respectively. Inhibitory constants were calculated with strong statistical support as 561 mg INi-N l-1 and 0.117 mg FNA-N l-1. Based on the model, INi is the main inhibiting species of the anammox process at pH > 7.1, which are the most common conditions occurring in field applications of anammox.

Original languageEnglish (US)
Pages (from-to)547-551
Number of pages5
JournalBiotechnology Letters
Issue number3
StatePublished - Mar 2014


  • Anaerobic ammonium oxidation
  • Anammox
  • Free nitrous acid
  • Inhibition
  • Kinetics
  • Nitrite

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Applied Microbiology and Biotechnology


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