• Journal of Korean Society of Water and Wastewater
• /
• v.8 no.3
• /
• pp.19-25
• /
• 1994

In this research, characteristics of nitrification and denitrification using the microorganism attached on sponge and plates were examined. The denitrification and nitrification performance were investigated under the anaerobic and aerobic condition for about 2 months. Because the basins of denitrification and nitrification were connected in series, wastewater was flowed from denitrification basin to nitrification one. The 90% of influent flowrate was returned from nitrification basin to denitrification one. Most of organic material was removed in nitrification basin, wherease the only exact amount of organics required in denitrification process was removed in denitrification one. This experiment resulted in that heterotrophic bacteria existing in aerobic basin governed the removal efficiency of organic compounds. In case the influent BOD concentration into nitrification basin was 80mg/l, it did not affect to accumulation of nitrifying bacteria, the balance of heterotrophic bacteria was proved to be an important factor in nitrification/denitrification method such as anaerobic and aerobic cycling type.

• Journal of Korean Society of Water and Wastewater
• /
• v.33 no.1
• /
• pp.55-62
• /
• 2019

The respirometric technique has been used to analyze the nitrification process in a sequencing batch reactor(SBR) treating municipal wastewater. Especially the profile of the respiration rate very well expressed the reaction characteristics of nitrification. As the nitrification process required a significant amount of oxygen for nitrogen oxidation, the respiration rate due to nitrification was high. The maximum nitrification respiration rate, which was about $50mg\;O_2/L{\cdot}h$ under the period of sufficient nitrification, was related directly to the nitrification reaction rate and showed the nitrifiers activity. The growth rate of nitrifiers is the most critical parameter in the design of the biological nutrient removal systems. On the basis of nitrification kinetics, the maximum specific growth rate of nitrifiers in the SBR was estimated as $0.91d^{-1}$ at $20^{\circ}C$, and the active biomass of nitrifiers was calculated as 23 mg VSS/L and it was about 2% of total biomass.

• Journal of Environmental Science International
• /
• v.22 no.1
• /
• pp.1-6
• /
• 2013

A fixed biofilm reactor system composed of anaerobic, anoxic(1), anoxic(2), aerobic(1) and aerobic(2) reactor was packed with synthetic activated ceramic (SAC) media and adopted to reduce the inhibition effect of low temperature on nitrification activities. The changes of nitrification activity at different wastewater temperature were investigated through the evaluation of temperature coefficient, volatile attached solid (VAS), specific nitrification rate and alkalinity consumption. Operating temperature was varied from 20 to $5^{\circ}C$. In this biofilm system, the specific nitrification rates of $15^{\circ}C$, $10^{\circ}C$ and $5^{\circ}C$ were 0.972, 0.859 and 0.613 when the specific nitrification rate of $20^{\circ}C$ was assumed to 1.00. Moreover the nitrification activity was also observed at $5^{\circ}C$ which is lower temperature than the critical temperature condition for the microorganism of activated sludge system. The specific amount of volatile attached solid (VAS) on media was maintained the range of 13.6-12.5 mg VAS/g media at $20{\sim}10^{\circ}C$. As the temperature was downed to $5^{\circ}C$, VAS was rapidly decreased to 10.9 mg VAS/g media and effluent suspended solids was increased from 3.2 mg/L to 12.0 mg/L due to the detachment of microorganism from SAC media. And alkalinity consumption was lower than theoretical value with 5.23 mg as $CaCO_3$/mg ${NH_4}^+$-N removal at $20^{\circ}C$. Temperature coefficient (${\Theta}$) of nitrification rate ($20^{\circ}C{\sim}5^{\circ}C$) was 1.033. Therefore, this fixed film nitrogen removal process showed superior stability for low temperature condition than conventional suspended growth process.

• 한국생물공학회:학술대회논문집
• /
• 2001.11a
• /
• pp.590-593
• /
• 2001

The effect of salinity on the nitrification efficiency of the nitrifier consortium was evaluated for the nitrification of saline wastewater. The nitrifier consortium, which was the activated sludge acclimated with ammonium as the only energy source, was used as the nitrifier for the salt acclimation. Airlift reactors for the nitrification of ammonia with increasing concentration in saline synthetic wastewater (35 g/I NaCD, and synthetic wastewater without salt as a control, were continuously operated with the nitrifier consortium for 43 days. The ammonia removal rate was about 23g ammonia-N/$m^3$/day in both the absence and presence of the salt. An accumulation of nitrite was observed in the saline nitrification reactor at an early period. However, the nitrite decreased to less than 1 mg/l after 39 days of operation. The salinity increased the acclimation time of the nitrifier consortium to obtain a stable marine nitrification system. However, the salt acclimated system showed the efficient removal of ammonia which was same as that without salt.

• Journal of Wetlands Research
• /
• v.19 no.4
• /
• pp.501-507
• /
• 2017

The heavy metal such as Nikel (Ni) in industrial wastewater is one of the major reasons of decreasing nitrification efficiency in municipal wastewater treatment plants (MWTPs). In this study, laboratory scale reactors were operated in order to analyse of nitrification efficiency and improvement measures. As a result, nitrification efficiency during high Ni concentration (0.295 mg/L) was about 20%. However nitrification efficiency during low Ni concentration (0.114 mg/L) was over 70%. The changes of the micro-organism activity according to Ni concentration was investigated as being the major reason behind the gap of nitrification efficiency through analysing AUR and SNR. Increasing the HRT in high Ni concentration also increased the nitrification efficiency. Thus, maintenance of microorganisms and increasing the HRT in nitrification reactors suggests that measures taken to treat wastewater is positively correlated with high concentration of heavy metal.

• Journal of Korean Society of Forest Science
• /
• v.87 no.1
• /
• pp.20-26
• /
• 1998

The objective of this study was to determine the rate of nitrogen mineralization and nitrification in a mature sawtooth oak(Quercus acutissima $C_{ARRUTH}$) stand in the Chungbu Forest Experiment Station, Kyonggi Province. Nitrogen mineralization and nitrification in the top 15cm of mineral soil were examined from November 1995 to November 1996 using an in situ buried bag method. Net nitrogen mineralization was 95.2mg/kg/yr and nitrification was 65.4mg/kg/yr. Nitrification consisted of 69% of annual nitrogen mineralization. Neither nitrogen mineralization nor nitrification was significantly correlated with the monthly soil temperature and soil moisture content.

• Journal of Soil and Groundwater Environment
• /
• v.21 no.4
• /
• pp.50-59
• /
• 2016

Spatial and temporal changes in nitrification activities and distribution of microbial population of ammonia oxidizing bacteria (AOB) and ammonia oxidizing archaea (AOA) in paddy soils were investigated. Soil samples were collected in March and October 2015 from rice paddy with and without the presence of confined animal feeding operations. Incubation experiments and quantitative polymerase chain reaction showed that AOA's contribution to nitrification kinetics was much higher in locations where organic nitrogen in animal waste is expected to significantly contribute to overall nitrogen budget, and temporal variations in nitrification kinetics were much smaller for AOA than AOB. These differences were interpreted to indicate that different microbial responses of two microbial populations to the types and concentrations of nitrogen substrates were the main determining factors of nitrification processes in the paddy soils. The copy numbers of ammonium monooxygenase gene showed that AOA colonized the paddy soils in higher numbers than AOB with stable distribution while AOB showed variation especially in March. Although small in numbers, AOB population turned out to exert more influence on nitrification potential than AOA, which was attributed to higher fluctuation in AOB cell numbers and nitrification reaction rate per cells.

• Microbiology and Biotechnology Letters
• /
• v.47 no.2
• /
• pp.296-302
• /
• 2019

In this study, the effects of ammonium concentration ($117.5-1155.0mg-N{\cdot}l^{-1}$), nitrite concentration ($0-50.0mg-N{\cdot}l^{-1}$), and temperature ($15-35^{\circ}C$) on nitrification performance and its functional genes (amoA-arc, amoA-bac, hao) in an enriched consortium inoculated with humic acid were determined. Notably, the maximum nitrification rate value was observed at $315mg-N{\cdot}l^{-1}$ of ammonium, but the highest functional gene copy numbers were obtained at $630mg-N{\cdot}l^{-1}$ of ammonium. No inhibition of the nitrification rate and functional gene copy numbers was observed via the added nitrites. The optimum temperature for maximum nitrification performance was observed to be $30^{\circ}C$. The amoA-bac copy numbers were also greater than those of amoA-arc under all test conditions. Notably, amoA-arc copy numbers and nitrification efficiency showed a positive relationship in network analysis. These results indicate that ammonium-oxidizing archaea and bacteria play important roles in the nitrification process.

• Journal of Korean Society of Water and Wastewater
• /
• v.19 no.6
• /
• pp.720-727
• /
• 2005

This study was performed to advance nitrogen removal efficiency by employing an single biofilter packed with granular sulfur, which consists of nitrification occurring at upper part and denitrification at lower part of the reactor. Continuos nitrification/denitrification was carried out with different alkalinity sources, which were $NaHCO_3$ and $CaCO_3$(limestone). In the downflow nitrification/denitrification biofilter packed with granular sulfur, first, terms for nitrogen removal was decided. As results, nitrification and denitrification rate with NaHCO3 at 0.85 kg $NH_4^+-N/m^3{\cdot}d$ were accomplished $0.80kg\;N/m_3{\cdot}d$, $0.43kg\;N/m^3{\cdot}d$, respectively. In the sulfur/limestone packed downflow nitrification/denitrification biofilter, sulfur and limestone were mixed packed, preliminary test showed sulfur/limestone mixing ratio was 3:1 and that was ideal. In the result, nitrification and denitrification rate at $0.7kg\;NH_4^+-N/m^3{\cdot}d$ were accomplished$0.65kg\;N/m^3{\cdot}d$, $0.34kg\;N/m^3{\cdot}d$, respectively. In general, employing granular sulfur can be implemented for only denitrification, but this system can accomplish nitrification as well as denitrification in a single reactor even though low carbon concentration was present in influent limiting to nutrient removal process. This biofilter system of limestone and granular sulfur packed together can successfully apply for nutrient removal effectively.

• KSBB Journal
• /
• v.15 no.5
• /
• pp.514-520
• /
• 2000

Simultaneous nitrification and denitrification of ammonia and organic compounds-containing wastewater were performed in a fluidized bed biofilm reactor with polysulfone(PS) hollow fiber as a double layer biomass carrier. The PS hollow fiber fragment has both aerobic and anoxic environments for the nitrifiaction and denitrification at the shell and lumen-side respectively. The reactor system showed about 80% nitrification efficiency stably throughout the ammonia load conditions applied in the experiment. Denitrification efficiency depended on organic load and C/N ratio. High free ammonia concentration and low dissolved oxygen resulted in nitrite accumulation which leads to enhance organic carbon efficiency in denitrification when compared to nitrate denitrification. The simultaneous nitrification and denitrification reactor system has an economic advantages in reduced chemical cost of organic carbon for denitrification as well as compact reactor configuration.