Community changes during star-up in methanogenic bioreactors exposed to increasing levels of ammonia

B. Calli*, B. Mertoglu, B. Inanc, O. Yenigun

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

58 Citations (Scopus)


To investigate the methanogenic population dynamics during the start-up under gradually increasing free ammonia levels, five mesophilic UASB reactors seeded with different sludges were operated for 140 days. Changes in the methanogenic community investigated by using 16S rDNA/rRNA based molecular methods such as denaturing gradient gel electrophoresis (DGGE), fluorescent in-situ hybridization (FISH), cloning and DNA sequencing. Free ammonia nitrogen (FAN) in the reactors was gradually increased from 50 to 130 mg l-1 by increasing total ammonia nitrogen (TAN) from 1000 to 2500 mg l-1 in the feed and keeping reactor pH at 7.7 in the active zone. Even at highest FAN level, COD and VFA removal efficiencies above 90 and 98% were obtained, respectively. However, Methanosaeta-related species mainly prevailing in seed sludges were substituted for Methanosarcina as the abundant methanogens although reactor performances were almost comparable and constant.

Original languageEnglish
Pages (from-to)85-91
Number of pages7
JournalEnvironmental Technology (United Kingdom)
Issue number1
Publication statusPublished - Jan 2005
Externally publishedYes


The authors would like to acknowledge the financial supports of Bogazici University Research Fund, (Project No: 01Y101D) and TUBITAK (Project No: ICTAG A034 and A036).

FundersFunder number
Bogazici University Research Fund01Y101D


    • DGGE
    • FISH
    • Free ammonia
    • Methanosaeta
    • Methanosarcina


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