Rapid start-up of a nitrifying reactor using aerobic granular sludge as seed sludge

Naohiro Kishida, Goro Saeki, Satoshi Tsuneda*, Ryuichi Sudo

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)


In this study, the effectiveness of aerobic granular sludge as seed sludge for rapid start-up of nitrifying processes was investigated using a laboratory-scale continuous stirred-tank reactor (CSTR) fed with completely inorganic wastewater which contained a high concentration of ammonia. Even when a large amount of granular biomass was inoculated in the reactor, and the characteristics of influent wastewater were abruptly changed, excess biomass washout was not observed, and biomass concentration was kept high at the start-up period due to high settling ability of the aerobic granular sludge. As a result, an ammonia removal rate immediately increased and reached more than 1.0 kg N/m 3/d within 20 days and up to 1.8 kg N/m 3/d on day 39. Subsequently, high rate nitritation was stably attained during 100 days. However, nitrite accumulation had been observed for 140 days before attaining complete nitrification to nitrate. Fluorescence in situ hybridization analysis revealed the increase in amount of ammonia-oxidizing bacteria which existed in the outer edge of the granular sludge during the start-up period. This microbial ecological change would make it possible to attain high rate ammonia removal.

Original languageEnglish
Pages (from-to)581-588
Number of pages8
JournalWater Science and Technology
Issue number3
Publication statusPublished - 2012 Feb 1


  • Aerobic granule
  • Biofilm
  • Continuous stirred-tank reactor (CSTR)
  • Nitrification

ASJC Scopus subject areas

  • Environmental Engineering
  • Water Science and Technology


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