Differential distribution of ammonia- and nitrite-oxidising bacteria in flocs and granules from a nitrifying/denitrifying sequencing batch reactor

Gilda Carvalho, Rikke L. Meyer, Zhiguo Yuan, Jürg Keller

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

A lab-scale sequencing batch reactor was operated with alternating anoxic/aerobic conditions for nitrogen removal. Flocs and granules co-existed in the same reactor, with distinct aggregate structure and size, for over 180 days of reactor operation. Process data showed complete nitrogen removal, with temporary nitrite accumulation before full depletion of ammonia in the aerobic phase. Microbial quantification of the biomass by fluorescence in situ hybridisation showed that granules contained most of the nitrite-oxidising bacteria (NOB) whereas the ammonium-oxidising bacteria (AOB) seemed to be more abundant in the flocs. This was supported by microsensor measurements, which showed a higher potential of NO 2 - uptake than NH 4 uptake in the granules. The segregation is possibly linked to the different growth rates of the two types of nitrifiers and the reactor operational conditions, which produced different sludge retention time for flocs and granules. The apparent physical separation of AOB and NOB in two growth forms could potentially affect mass transfer of NO 2 - from AOB to NOB, but the data presented here shows that it did not impact negatively on the overall nitrogen removal.

Original languageEnglish
Pages (from-to)1392-1398
Number of pages7
JournalEnzyme And Microbial Technology
Volume39
Issue number7
DOIs
Publication statusPublished - 3 Nov 2006

Keywords

  • Aerobic granules
  • Ammonium oxidation
  • Flocs
  • Microbial population distribution
  • Nitrite oxidation

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