Chalk as the carrier for nitrifying biofilm in a fluidized bed reactor

M. Green*, Y. Ruskol, O. Lahav, S. Tarre

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


A fluidized bed reactor for nitrification with chalk as the biomass carrier and the sole buffer agent was studied. Chalk dissolution in the reactor was found to follow the stoichiometric ratio of 1 mole of CaCO3 dissolved for each mole of NH+4 oxidized. Three batches of chalk, each one having a different dissolution rate, were used to replace the dissolved chalk. The three dissolution rates resulted in three different steady state pH levels in the reactor (4.7-6.6) and nitrification rates. Nitrification was found to be limited by either the chalk dissolution rate or dissolved oxygen concentration depending on the type of chalk used. A maximal nitrification rate of 1.44 g NH+4-N/l reactor . d was observed. The average cell yield was 0.1 g cells/g N oxidized, similar to the cell yield during reactor start-up when the pH was 7. The specific ammonium oxidation rates varied between 0.08 and 0.15 mg NH+4-N oxidized/mg protein . h, values which are in the reported range for nitrification at pH 7 to 8. Oxygen update rate (OUR) results indicated that the major mechanism responsible for the high nitrification rate observed in the reactor operating at low pH seems to be the favorable microenvironment provided by the chalk. Copyright (C) 2000 Elsevier Science Ltd.

Original languageEnglish
Pages (from-to)284-290
Number of pages7
JournalWater Research
Issue number1
StatePublished - 2001
Externally publishedYes


  • Chalk
  • Fluidized bed
  • Nitrification
  • pH


Dive into the research topics of 'Chalk as the carrier for nitrifying biofilm in a fluidized bed reactor'. Together they form a unique fingerprint.

Cite this