title: Nitrite (not free nitrous acid) is the main inhibitor of the anammox process at common pH conditions.
abstract: 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.
authors.affiliation: Department of Chemical and Environmental Engineering, The University of Arizona, Tucson, AZ, 85721-0011, USA, danielpuyol@email.arizona.edu.
authors.forename: D
authors.initials: D
authors.lastname: Puyol
authors.forename: J M
authors.initials: JM
authors.lastname: Carvajal-Arroyo
authors.forename: R
authors.initials: R
authors.lastname: Sierra-Alvarez
authors.forename: J A
authors.initials: JA
authors.lastname: Field
mesh_terms: D064751:Ammonium Compounds / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D009573:Nitrites / Q000378:metabolism*; D009608:Nitrous Acid / Q000378:metabolism; D010084:Oxidation-Reduction
chemical_list: D064751:Ammonium Compounds; D009573:Nitrites; D009608:Nitrous Acid