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Effect of nitrite concentration on the distribution and competition of nitrite-oxidizing bacteria in nitratation reactor systems and their kinetic characteristics
Genus Nitrospira and Nitrobacter species are the key nitrite-oxidizing bacteria (NOB) in nitrifying wastewater treatment plants. It has been hypothesized that genus Nitrospira are K-strategists and can exploit low amounts of nitrite more efficiently than Nitrobacter. In contrast, Nitrobacter species...
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Published in: | Water research (Oxford) 2006-03, Vol.40 (5), p.887-894 |
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Main Authors: | , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Genus
Nitrospira and
Nitrobacter species are the key nitrite-oxidizing bacteria (NOB) in nitrifying wastewater treatment plants. It has been hypothesized that genus
Nitrospira are K-strategists and can exploit low amounts of nitrite more efficiently than
Nitrobacter. In contrast,
Nitrobacter species are r-strategists that can grow faster than
Nitrospira. To elucidate the K/r hypothesis and to analyze the effect of substrate (nitrite) concentration on the competition and distribution of the two NOB, two different reactor types were employed for nitrite oxidation (nitratation) and NOB growth. The continuous biofilm airlift reactor (CBAR) maintained low nitrite concentration due to the complete oxidation of nitrite in continuous operation while the sequencing batch reactor (SBR) was kept in a relatively high nitrite concentration environment due to a cyclic substrate concentration profile. Fluorescence in situ hybridization (FISH) and confocal laser scanning microscopy (CLSM) showed that both
Nitrobacter species and genus
Nitrospira were present in the CBAR and the SBR. Quantitative FISH analyses of the CBAR showed that
Nitrospira occupied 59% of the total bacteria while
Nitrobacter occupied only 5%. On the other hand,
Nitrobacter, occupying 64%, was the dominant NOB in the SBR, and only 3% of total bacteria belonged to genus
Nitrospira. Nitrite oxidation kinetics and quantitative FISH analyses revealed that the specific nitrite oxidation activities of
Nitrobacter and
Nitrospira are 93.8 and 10.5
mg/g NOB
h, respectively, and the specific activity of
Nitrobacter is about 9 times higher than that of
Nitrospira. In conclusion, the results confirm the K/r hypothesis and the distribution of
Nitrobacter and
Nitrospira is likely to depend mainly on nitrite concentration. It seems that nitrite load and starvation conditions do not give a direct effect on the distribution of NOB. |
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ISSN: | 0043-1354 1879-2448 |
DOI: | 10.1016/j.watres.2005.12.023 |