Ammonium removal performance of anaerobic ammonium-oxidizing bacteria immobilized in polyethylene glycol gel carrier: Anammox bacteria immobilized in gel carrier

Kazuichi Isaka, Yasuhiro Date, Tatsuo Sumino, Satoshi Tsuneda

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Anaerobic ammonium-oxidizing (anammox) bacteria were immobilized in polyethylene glycol gel carriers. A small amount of seed sludge [0.24% (w/v)] was entrapped in the carriers, and continuous feeding tests were performed. Nitrogen removal activity increased gradually, reaching 3.7 kg N/m3 reactor per day on day 67. The average of nitrogen conversion rate was calculated as 3.4 kg N/m3 reactor per day. Microscopic examination clearly showed that small red clusters formed in the gel carrier. Moreover, fluorescence in situ hybridization analysis revealed that these clusters consisted of anammox bacteria. From real-time polymerase chain reaction analysis, the growth of anammox bacteria in the gel carriers was clearly shown by increased concentration of 16S rRNA gene of planctomycete from 4.3×108 to 4.2×109 copies/ml between days 41 and 55. To determine the effects of inoculation on the start-up of the reactor, the amount of seed sludge in the gel carrier was varied and it was found that the start-up period could be reduced to as little as 25 days when a sludge concentration of 1.4% (w/v) was used. This is the first report of successful immobilization and cultivation of anammox bacteria in a gel carrier.

Original languageEnglish
Pages (from-to)1457-1465
Number of pages9
JournalApplied Microbiology and Biotechnology
Issue number6
Publication statusPublished - 2007 Oct 1



  • Ammonium
  • Anammox
  • Gel entrapment
  • Immobilization
  • Nitrite
  • Nitrogen removal

ASJC Scopus subject areas

  • Biotechnology
  • Applied Microbiology and Biotechnology

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