• Journal of Microbiology and Biotechnology
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• v.21 no.3
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• pp.293-298
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• 2011

Nitrifying bacterial community structures of suspended and attached biomasses in a full-scale integrated fixed-film activated sludge process were investigated by analyzing 16S rRNA gene sequences obtained from pyrosequencing. The suspended biomass had a higher number of ammonia-oxidizing bacterial sequences (0.8% of total sequences) than the attached biomass (0.07%), although most of the sequences were within the Nitrosomonas oligotropha lineage in both biomasses. Nitrospira-like nitrite-oxidizing bacterial sequences were retrieved in the suspended biomass (0.06%), not in the attached biomass, whereas the existence of Nitrobacter-like sequences was not evident. The suspended biomass had higher nitrification activity (1.13 mg N/TSS/h) than the attached biomass (0.07 mg N/TSS/h). Overall, the results made it possible to conclude the importance of the suspended biomass, rather than the attached biomass, in nitrification in the wastewater treatment process studied.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.5
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• pp.507-516
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• 2008

This research was conducted to elucidate the effect of temperature on the nitrogen removal of municipal wastewater with waste-tire media. The experiments were carried out in laboratory-scale batch reactor and pilot-scale moving bed biofilm reactor filled at a 0.15 filling ratio with waste-tire media, respectively. In batch tests, specific nitrification rate(SNR) with media was 3.4 mg NH$_4^+$-N/g Mixed-Liquor Volatile Suspended Solid(MLVSS)$\cdot$hr, compared with 1.7 mg NH$_4^+$-N/g MLVSS$\cdot$hr without media. In pilot-scale test with media, total nitrogen removal efficiency increased from 53 $\pm$ 8% to 76 $\pm$ 5% as the temperature increased from 9$\sim$10$^{\circ}C$ to 20$\sim$24$^{\circ}C$. At the temperature of 9$\sim$10$^{\circ}C$, 10$\sim$20$^{\circ}C$, and 20$\sim$24$^{\circ}C$, the SNRs were 0.8 $\pm$ 0.5, 3.1 $\pm$ 1.9, and 3.4 $\pm$ 2.1 mg NH$_4^+$-N/g MLVSS$\cdot$hr and the specific denitrification rates(SDNR) were 0.6 $\pm$ 0.2, 1.1 $\pm$ 0.6, 1.4 $\pm$ 0.6 mg NO$_3^-$-N/g MLVSS.hr, respectively. The overall activities of biomass in anaerobic, anoxic, and oxic zones at 20$\sim$24$^{\circ}C$ increased to 22, 20, and 15%, compared with those at 9$\sim$10$^{\circ}C$, respectively. The activity distribution of Nitrosomonas and Nitrobacter also increased with the increase of temperature.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.11
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• pp.983-988
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• 2009

This study was performed to evaluate the toxicity and seek the control method of the wastewater in which nickel (Ni) was included into an industrial wastewater treatment plant. Nickel concentration of the wastewater, of which samples were taken every hour during 24hours, were various from 0.33 to 116.0 mg/L, with 24.0 mg/L of the average concentration. IC50 values against nitrosomonas and nitorbactor, a toxic level against bacteria which could inhibit 50% of nitrification bacteria in the wastewater, are 5.5 and 4.9 mg/L respectively. Nickel in this industrial wastewater can inhibit the 50% of nitrification bacteria even after diluting this wastewater 5 times. Also, this research, which reduced the nickel concentraion, forming nickel hydroxide compounds by increasing pH of the wastewater, shows that nickel concentraion can be obtained under 1.7 mg/L at pH 11 and 0.6 mg/L at pH 12. Consequently, the result of this study is that the nitrification efficiencies can be obtained from 83.8 to 99.4% with 97.6% of the average in the biological treatment after removing nickel in the wastewater by increasing the pH above 11~12, which is forming the nickel hydroxide compounds.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.4
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• pp.428-434
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• 1995

The purpose of this study is to develop a sanitary aquarium for the safety slices of raw fish by using U.V. light. Water re-circulating system was composed of two tanks. One of the tanks $(90\times45\times45cm\;in\;size),$ was used for rearing fish and the other $(90\times45\times45cm\;in\;size),$ with 37 pieces of corrugated plastic plates was used for the growth of Nitrosomonas and Nitrobacter to remove ammonia from the water. Consequently, bactericidal effects of U.V. light were examined under the controlled condition of water with flow rate 730m1/sec (water flow thickness: 10mm), the width 41cm of water flow route, and the distance 4.75cm from the lamp to its water bottom, and U.V. light 75W (5 lamps). The water of the aquarium tank will be theroetically circulated 1 cycle per 18 min. In these conditions the bactericidal effect was $85\%$ just after passing through U,V. light and 3 log cycle in aquarium tank water. The count of Vibrio parahaemolyticus just after irradiation was decreased by about over than 3 log cycle. Under the irradiation for 72 hours, viable cell counts in both skin and gill of fish reared were decreased into about 2 log cycle, but there was no significant decrease in viscera. When the temperature of the tank was controlled at about $20-23^{\circ}C$ under the same condition, viable cell counts were reduced about 2 log cycle, and fecal coliforms were reduced about 1 log rycle and 3 log cycle in Crassostrea gigas and Mytilus edulis, respectively.

• Journal of Korean Society of Water and Wastewater
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• v.9 no.3
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• pp.116-126
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• 1995

The purpose of this study was to investigate the removal of ammonium nitrogen by biological nitrification in raw water containing LAS using BAC. At batch teats, LAS removal by ozone followed the first order reaction, and the rate constants(k) by ozone dose 1, 3mg/min.L were $0.040min^{-1}$, $0.062min^{-1}$ respectively. Therefore, the more ozone was dosed, the higher LAS was removed The reaction between ozone and ammonium nitrogen also followed the first order, and rate constants(k) at pH7,8 and 9 were $8.9{\times}10^{-4}min-1$, $3.8{\times}10^{-3}min^{-1}$, and $2.9{\times}10^{-2}min^{-1}$ respectively at ozone dose of 3mg/min.L . Therefore, ammonium nitrogen was little removed by ozone under neutral pH of 7. The continuous flow apparatus had four sets composed of a ozone contacter and a GAC column. Through continuous filtration test for 50days, the following conclusions were derived; (1) LAS was removed 23%, 30% respectively by ozone dose 1, 3mg/L, and was not detected in all column effluents during the period of experiment. Therefore, it appeared that adsorption capacities of each column still remained. (2) Ammonium nitrogen concentration after ozone contact varied little in raw Water because pH of raw water was from 6 to 7, and was transfered to nitrite and nitrate within GAC columns as the result of staged nitrification. After 30days, nitrite was not detected in all column effluents due to biological equilbrium between nitro semonas and nitrobacter Average removals of ammonium nitrogen in each column after the lapse of 30days were the following; ${\cdot}$ column A (ozone dose 3mg/L, EBCT 9.5min): about 100% ${\cdot}$ column B (ozone dose 1mg/L, EBCT 9.5min): 91% ${\cdot}$ column C (ozone dose 3mg/L, EBCT 14.2min): about 100% ${\cdot}$ column D (ozone dose 0mg/L, EBCT 9.5min): 53% Though column A and C reached nitrification of about 100%, column C (longer EBCT than column A) was more stable than column A. (3) After backwash, nitrification reached steady state within 5 to 8 hours. Therefore, nitrification was not greatly affected by backwash. (4) According to the nitrification capacity in depth of column A, C, where 100% nitrification occured. LAS was removed within 20cm, while ammonium nitrogen required more depth to be removed by nitrification.

• Food Science of Animal Resources
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• v.22 no.3
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• pp.259-266
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• 2002

The egg shell membrane degrading isolated from soil was identified as Bacillus licheniformis by 16S rDNA identification method. A keratinase was isolated from the Baciilu licheniformis culture. DEAE-cellulose ion-exchange and Sephadex C-75 gel chromatograhies were used to purify the enzyme. The specific activity was increased 17.3-fold by the purification procedures. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis and Sephadex G-75 chromatography indicated that the purified keratinase was monomeric and had a molecular weight of 65 kDa. The enzyme showed optimum activity at pH 9.0, and was stable above pH 9.0. The optimum temperature was 50$\^{C}$ and the enzyme was stable in the temperature ranges from 20$\^{C}$ to 50t. By the addition of 1 mM and 10 mM FeSO4, the activities of the enzyme were increased to 111$\pm$4.6% and 133$\pm$3.79%, respectively. The keratinase was an alkaline serine pretense because it was inhibited only by phenylmethylsulfonylfluorice (PMSF).