Low oxygen start-up of partial nitrification-anammox process: mechanical or gas agitation?

Pamela Jara-Muñoz, Víctor Guzmán-Fierro, Constanza Arriagada, Víctor Campos, José L. Campos, Juan José Gallardo-Rodríguez, Katherina Fernández, Marlene Roeckel

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


BACKGROUND: Partial nitrification-anammox (PN-A) is a widely recognized technology to remove nitrogen from different types of wastewater. Low oxygen concentration is the most used strategy for PN-A start-up, but stability problems arise during the operation; thus, in the present study the effects of the type of agitation, oxygenation and shear stress on the sensitivity, energy consumption and performance were evaluated. Recognition of these parameters allows considered choice of the design of an industrial process for nitrogen abatement. RESULTS: A mechanically agitated reactor (MAR) was compared to a stable, long-term operation period bubble column reactor (BCR), both started under low dissolved oxygen concentration conditions. MAR microbial assays confirmed the destruction of the nitrifying layer and an imbalance of the entire process when the oxygen to nitrogen loading ratio (O2:N) decreased by 25%. The granule sedimentation rate and specific anammox activity were 17% and 87% higher (respectively) in BCR. Economic analysis determined that the cost of aeration for the MAR and for the BCR were 23.8% and 1% of the total PN-A energy consumption, respectively. CONCLUSIONS: The BCR showed better results than the MAR. This study highlights the importance of type of agitation, oxygenation and shear stress for industrial-scale PN-A designs.

Original languageEnglish
Pages (from-to)475-483
Number of pages9
JournalJournal of Chemical Technology and Biotechnology
Issue number2
StatePublished - Feb 2019
Externally publishedYes


  • dissolved oxygen
  • gas agitation
  • granule
  • mechanical agitation
  • partial nitrification anammox


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