Distinctive microbial ecology and biokinetics of autotrophic ammonia and nitrite oxidation in a partial nitrification bioreactor

Biological nitrogen removal (BNR) based on partial nitrification and denitrification via nitrite is a cost-effective alternate to conventional nitrification and denitrification (via nitrate). The goal of this study was to investigate the microbial ecology, biokinetics, and stability of partial nitri...

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Bibliographic Details
Published in:Biotechnology and bioengineering 2008-08, Vol.100 (6), p.1078-1087
Main Authors: Ahn, Joon Ho, Yu, Ran, Chandran, Kartik
Format: Article
Language:English
Subjects:
Ammonia
Ammonia - metabolism
Biodegradation, Environmental
biokinetics
Biological and medical sciences
Biomass
Bioreactors
Bioreactors - microbiology
Biotechnology
Ecology
Fundamental and applied biological sciences. Psychology
Kinetics
Membrane reactors
Methods. Procedures. Technologies
microbial ecology
Microbiology
Nitrates
Nitrates - metabolism
Nitrification
Nitrites - metabolism
Nitrobacter
Nitrobacter - cytology
Nitrobacter - enzymology
Nitrogen Fixation
Nitrosomonas europaea
Nitrosomonas europaea - cytology
Nitrosomonas europaea - enzymology
Oxidation
Oxidation-Reduction
partial nitrification
qPCR
respirometry
Various methods and equipments
Water Microbiology
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Summary:Biological nitrogen removal (BNR) based on partial nitrification and denitrification via nitrite is a cost-effective alternate to conventional nitrification and denitrification (via nitrate). The goal of this study was to investigate the microbial ecology, biokinetics, and stability of partial nitrification. Stable long-term partial nitrification resulting in 82.1 ± 17.2% ammonia oxidation, primarily to nitrite (77.3 ± 19.5% of the ammonia oxidized) was achieved in a lab-scale bioreactor by operation at a pH, dissolved oxygen and solids retention time of 7.5 ± 0.1, 1.54 ± 0.87 mg O₂/L, and 3.0 days, respectively. Bioreactor ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) populations were most closely related to Nitrosomonas europaea and Nitrobacter spp., respectively. The AOB population fraction varied in the range 61 ± 45% and was much higher than the NOB fraction, 0.71 ± 1.1%. Using direct measures of bacterial concentrations in conjunction with independent activity measures and mass balances, the maximum specific growth rate (μmax), specific decay (b) and observed biomass yield coefficients (Yobs) for AOB were 1.08 ± 1.03 day⁻¹, 0.32 ± 0.34 day⁻¹, and 0.15 ± 0.06 mg biomass COD/mg N oxidized, respectively. Corresponding μmax, b, and Yobs values for NOB were 2.6 ± 2.05 day⁻¹, 1.7 ± 1.9 day⁻¹, and 0.04 ± 0.02 mg biomass COD/mg N oxidized, respectively. The results of this study demonstrate that the highly selective partial nitrification operating conditions enriched for a narrow diversity of rapidly growing AOB and NOB populations unlike conventional BNR reactors, which host a broader diversity of nitrifying bacteria. Further, direct measures of microbial abundance enabled not only elucidation of mixed community microbial ecology but also estimation of key engineering parameters describing bioreactor systems supporting these communities. Biotechnol. Bioeng. 2008;100: 1078-1087.
ISSN:0006-3592
1097-0290
DOI:10.1002/bit.21863