Effect of organic carbon on nitrification e ciency and community compositionof nitrifying biofilms
HU Jie , LI Daping , LIU Qiang , TAO Yong , HE Xiaohong , WANG Xiaomei , LI Xudong , GAO Ping
DOI:
Received April 04, 2008,Revised July 15, 2008, Accepted , Available online
Volume 21,2009,Pages 387-394
- Summary
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The effects of organic carbon/inorganic nitrogen (C/N) ratio on the nitrification processes and the community shifts of nitrifying
biofilms were investigated by kinetic comparison and denaturing gradient gel electrophoresis (DGGE) analysis. The results showed
that the nitrification rate decreased with an increasing organic concentration. However, the e ect became weak when the carbon
concentration reached a su ciently high level. Denitrification was detected after organic carbon was added. The 12 h ammonium
removal rate ranged from 85% to 30% at C/N = 0.5, 1, 2, 4, 8, and 16, as compared to the control (C/N = 0). The loss of nitrogen after
24 h at C/N = 0.5, 1, 2, 4, 8, and 16 was 31%, 18%, 24%, 65%, 59%, and 62%, respectively. The sequence analysis of 16S rRNA gene
fragments revealed that the dominant populations changed from nitrifying bacteria (Nitrosomonas europaea and Nitrobacter sp.) to
denitrifying bacteria (Pseudomonas sp., Acidovorax sp. and Comamonas sp.) with an increasing C/N ratio. Although at high C/N ratio
the denitrifying bacteria were the dominant populations, nitrifying bacteria grew simultaneously. Consequently, nitrification process
coexisted with denitrification.
