Ammonium oxidation activity promotes stable nitritation and granulation of ammonium oxidizing bacteria

X. Juan-Díaz, Julián Carrera Muyo, J. Pérez

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Two-stage partial nitritation/anammox (PN/AMX) processes have been pointed out as a feasible configuration for achieving mainstream anammox. For two-stage configurations, stable partial nitritation has been reported feasible in granular sludge reactors. This study aimed to explore the operating conditions involved in the development of an autotrophic aerobic granular sludge using floccular sludge as inoculum. The influence of different parameters such as free ammonia concentration, settling time, superficial gas flow velocity and ammonium oxidation rate was investigated. Enhancing ammonium oxidation activity since the early phase of the operation (i.e. using conventional activated sludge as inoculum enriched with a fraction of a floccular nitrifying biomass) promoted a fast development (ca. 30 days) of an autotrophic aerobic granular sludge performing stable nitritation. When the seeded sludge presented a low nitrifying activity (lower than 0.1 g N L −1 d −1), the increase of the air-flow rate triggered the formation of an autotrophic aerobic granular sludge since ammonium oxidation activity was promoted. Contrarily, imposing low settling times (10 min) or strong free ammonia inhibitory conditions (FA concentrations higher than 50 mg N L −1) were shown to negatively influence the achievement of high ammonium oxidation rates, hampering the development of an autotrophic aerobic granular sludge. This study demonstrated the importance of ensuring high ammonium oxidation rates (higher than 0.2 g N L −1 d −1) for the proper development of an autotrophic partial nitritation granular sludge.

Original languageEnglish
Article number102505
Number of pages9
JournalJournal of Water Process Engineering
Volume45
DOIs
Publication statusPublished - Feb 2022

Keywords

  • AEROBIC GRANULATION
  • Ammonium oxidation rate
  • Autotrophic aerobic granular sludge
  • Conventional activated sludge
  • INHIBITION
  • NITRIFYING GRANULES
  • NITROGEN REMOVAL
  • OXYGEN
  • Operational start-up strategy
  • REACTOR
  • SLUDGE
  • STRENGTH WASTE-WATER
  • Superficial gas flow velocity

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