• Journal of Korean Society of Water and Wastewater
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• v.12 no.1
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• pp.52-61
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• 1998

Nitrification and denitrification are important processes in the landfill site as they are deeply related with degradation and stabilization of refuse. Also nitrous oxide ($N_2O$) which is released from both nitrification and denitrification is known as greenhouse gas (GHG). The purpose of this study was to clarify the process by which $N_2O$ produced using $^{15}N$ isotope. Nitrate which was labeled to 10.08% with $^{15}KNO_3$ was used and $N_2O$ was analyzed with GC mass. Results was that even also when $O_2$ of bulk was 15%, $N_2O$ was released from denitrification. And as concentrations of $O_2$ increase, sum of $N_2O$ was released from denitrification. And as concentrations of $O_2$ increase, sum of $N_2O$ and $N_2$ was decreased and ratios of $N_2O$ in the reduced gases were increased. FISH technics also adaped to confirm whether which of nitrifiers existed in the substrates. When NEU was used of which the target was ammonia oxidizing bacteria, nitrifier was not detected at all. So it was confirmed that during the reaction denitrification was dominant process. Total bacteria distributions which were detected by EUB probe explained that as $O_2$ increase the number of bacteria also increase, but between the 10-15% of $O_2$ there was no any differences.

• Journal of the Korea Organic Resources Recycling Association
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• v.8 no.2
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• pp.146-153
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• 2000

To elucidate succession of bacterial populations, especially nitrifying bacteria during the composting of cattle manure with apple pomace, fluorescent in situ hybridization(FISH) using rRNA targeted oligonucleotide probes were applied. The density of ammonia-oxidizing bacteria was ranged from $3,3{\times}10^6cells/g$ dw to $13,4{\times}10^6cells/g$ dw with the peak value after 26 composting days whereas that of nitrite-oxidizing bacteria varied between $6.0{\times}10^6cells/g$ dw and $17.2{\times}10^6cells/g$ dw with the peak value after 7 composting days. And the tendency that the numbers of nitrite-oxidizing bacteria were higher than those of ammonia-oxidizing bacteria, and the peak-time of their densities were the same as that of data determined by the ratio of ammonia-oxidizing bacteria and nitrite-oxidizing bacteria to eubacteria. The peak of ammonia-oxidizing bacteria followed the peak of nitrite-oxidizing bacteria, at the late phase of composting process could be probably caused by the depletion of volatile ammonia of composting materials. Besides these results indicate that FISH method is a useful tool for detection of slow growing nitrifying bacteria.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.2
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• pp.138-144
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• 2005

This study was carried out to investigate the changes of nitrifying bacterial populations including Nitrosomonas sp. and Nitrobacter sp. in $A^2/O$ pilot plant with the configuration of anaerobic-anoxic-oxic reactors. The suspended nitrifying bacterial populations in mixed liquor and those of attached populations on granular carrier surface made by molded waste tire were analyzed by Fluorescent in situ Hybridization(FISH) method. The nitrification rate of a pilot plant showed the value of $1.97{\sim}2.98\;mg\;N/g$ MLVSS hr. The ratios of suspended ammonia oxidizer including Nitrosomonas sp. (NSO) to total bacteria in each reactor were oxic < anoxic < anaerobic. On the contrary, the ratios of suspended nitrite oxidizer including Nitrobacter sp. (NIT) were anaerobic < anoxic < oxic. The thickness, dry density and mass of the attached biomass on granular carriers were $180{\sim}188\;{\mu}m$, $38.5{\sim}43.9\;mg/cm^3$, $29.4{\sim}32.5\;mg/g$, respectively. Also, the ratios of attached nitrifier to total bacteria on granular carriers were similar regardless of ammonia/nitrite-oxidizer (NSO; 3.2%, NIT; 2.8%) and very low compared to those(NSO; $22.8{\sim}28.4%$, NIT; $17{\sim}26%$) of suspended nitrifier.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.3
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• pp.240-248
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• 2006

In this study, a retrofitting BNR process that was modified for the economical applicability was proposed and evaluated in the pilot plant($50m^3/d$). At the same time the bacterial community structure was investigated in the pilot plant by using FISH(fluorescent in situ hybridization) method. Economically 16% of the initial construction cost for the proposed process(introduction of a biological nutrient removal process of $60,000m^3/d$ scale basis) was reduced due to the absence of a bioreactor. Water treatment efficiencies and maintenance facilities of the modified process were satisfied with the strengthened discharge permits in Korea throughout a long term pilot plant operating including a winter season. Bacterial populations in the pilot plant and in the control plant(A2/O process, B SIP(Sewage Treatment Plant)) were remained uniformly during the test period, but bacterial structure in the bioreactor was changed drastically. Proportions of ${\beta}$-proteobacteria group including soil bacteria which play a important role in wastewater treatment increased $25{\sim}607%$ in population.