• Journal of Microbiology and Biotechnology
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• v.10 no.3
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• pp.410-414
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• 2000

The effect of the COD/N ratio on denitrification characteristics was evaluated for the development of a denitrification process. Activated sludge, acclimated to an anoxic condition, was used as the denitrifier consortium (mixture of denitrifying organisms) for enhanced nitrogen removal in a recirculating aquarium system. Synthetic wastewater containing nitrate was used as the influent solution and glucose was used as the carbon source for denitrification. The COD/N ratio varied within a range of 1.5-7.2. The denitrification efficiency was higher than 97% even at a COD/N ratio of 1.5. Under a theoretical COD/N ratio of 3.0, nitrite was detected, however, the amount was less than 1% of the total influent nitrogen. The number of both nitrate-reducing bacteria and denitrifying bacteria reached $3.5{\times}10^5/ml$ with a COD/N ratio of 1.5 after 45 days of operation.

• Journal of Life Science
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• v.8 no.1
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• pp.85-90
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• 1998

Pseudomonas sp. KH2-2 had the denitrifying ability adn was isolated from the denitrifier consortium in order to remove nitrogen compounds from waste water in aquaculture system. When this strain was reached stationary phase, it has the maxium denitrification activity. Denitrification activity of the isolated strain was shown the growth associated pattern. Optimal temperature for cell growth and denitrification activity was 40$\circ$C and optimal pH was 7.

• Journal of Soil and Groundwater Environment
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• v.11 no.2
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• pp.38-44
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• 2006

Two sulfur-based column reactors inoculated with a bacterial consortium containing autotrophic denitrifiers were operated for 100 and 500 days, respectively and nitrate removal efficiency and the adaptation of microbial communities in the columns were monitored with column depths and time. For better understanding the adaptation phenomenon, molecular techniques including 16S rDNA sequencing and DGGE analysis were employed. Although both columns showed about 99% of nitrate removal efficiency heterotrophic denitrifiers such as Cenibacterium arsenioxidans and Geothrix fermentans were found to a significant portion at the initial stage of the 100-day reactor operation. However, as operation time increased, an autotrophic denitrifier Thiobacillus denitrificans became a dominant bacterial species throughout the column. A similar trend was also observed in the 500-day column. In addition, nitrate removal efficiencies were different with column depths and thus bacterial species with different metabolic activities were found at the corresponding depths. Especially, T. denitrificans was successfully adapted and colonized at the bottom parts of the columns where most nitrate was reduced.