• KSBB Journal
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• v.20 no.2 s.91
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• pp.116-122
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• 2005

The feasibility of using bacterial cultures with the ultimate aim for the marine environmental clean-up was explored. The present study reports on the bacterial elimination of nitrogens and phosphorus by strains CK-10 and CK-13 isolated from shrimp farming pond. The strains were identified as genus Bacillus on the basis of BIOLOG test, and designated as Bacillus sp. CK-10 and Bacillus sp. CK-13, respectively. Removal of nitrogens $(NH_4^+,\;NO_2^-,\;or\;NO_3^-)$ or phosphorus $(PO_4^{-3})$ as single N or P source was studied with single cultures under aerobic conditions. Complete elimination of all nitrogens in the concentration range of $100-400{\mu}M$ was achieved in single cultures as well as co-cultures within the given incubation period. Similar results were obtained from the test cultures containing $125-599{\mu}M\;PO_4^{3-}$. Simultaneous removal of all N/P was monitored in the co-cultures. As the results, $400{\mu}M\;NH_4^+\;and\;NO_2^-$ were eliminated within 12hrs and $400{\mu}M\;NO_3^-\;and\;500{\mu}M\;PO_4^{-3}$ were completely disappeared within 36 hrs from the media. The work demonstrated that co-cultures improved the concurrent removal of N/P from the media.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.1
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• pp.39-46
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• 2011

NO oxidation is an important prerequisite step to assist the selective catalytic reduction (SCR) at low temperatures ($<200^{\circ}C$). Therefore, we conducted the lab- and bench-scales experiments appling the sodium chlorite powder ($NaClO_2(s)$) for the oxidation of NO to $NO_2$ and the carbon-based catalyst for the reduction of $NO_x$ and $SO_2$; the lab- and bench-scales experiments were conducted in laboratory and iron-ore sintering plant, respectively. In the lab-scale experiment, known concentrations of $NO_x$ (200 ppm), $SO_2$ (75 ppm), $H_2O$ (10%) and $NH_3$ (400 ppm) in 2.6 L/min were introduced into a packed-bed reactor containing $NaClO_2(s)$, then gases produced by the reaction with $NaClO_2(s)$ were fed into the carbon-based catalyst (space velocity = $2,000hr^{-1}$) at $130^{\circ}C$. In the bench-scale experiment, flue gases of $50Nm^3/hr$ containing 120 ppm NO and 150 ppm $SO_2$ were taken out from the duct of iron-ore sintering plant, then introduced into the flow reactor; $NaClO_2(s)$ were injected into the flow reactor using a screw feeder. Gases produced by the reaction with $NaClO_2(s)$ were introduced into the carbon-based catalyst (space velocity = $1,000hr^{-1}$). Results have shown that, in both lab- and bench-scales experiments, NO was oxidized to $NO_2$ by $NaClO_2(s)$. In addition, above 90% of $NO_x$ and $SO_2$ removal were obtained at the carbon-based catalyst. These results lead us to suggest that the combination of $NaClO_2(s)$ with the carbon-based catalyst has the potential to achieve the simultaneous removal of $NO_x$ and $SO_2$ at low temperature ($<200^{\circ}C$).

• Journal of Korean Society of Environmental Engineers
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• v.29 no.1
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• pp.62-67
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• 2007

It was investigated to develop the technology for simultaneous removal of $SO_2/NO$ in flue gas using liquid homogeneous catalyst. Test was carried out using a bench scale and a pilot scale experiment. The investigation led to the following results: 1) Removal efficiency of $SO_2$ gas showed good results regardless of operating condition. Removal efficiency of NO gas, however, proportionally increased with higher packing height, lower concentration and larger injection rate of catalyst 2) The optimum design parameters for simultaneous removal of $SO_2/NO$ gas using Fe(II)-EDTA catalyst were as follow: HTU(height of transfer unit) = 0.5 m, liquid gas ratio = 20 $L/m^3$, NTU (number of transfer unit) = 3 stages, cross dimension of scrubber=0.025 $m^2$ 3) The removal efficiencies of $SO_2$ and NO were 95% and 81%, repletely. 4) The high HTU is advantageous on removal of the NO, but the excessive HTU diminishes operating efficiency. Consequently, it is important to decide the HTU of optimum.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.11a
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• pp.143-144
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• 2003

최근 들어 플라즈마 촉매 복합공정을 이용하여 NOx를 제거시키기 위한 연구가 활발히 이루어지고 있다. 저온 플라즈마 공정중 하나인 DBD (Dielectric barrier discharge) 공정 내에서 NO는 NO$_2$로 매우 효과적으로 전환된다. 촉매공정의 경우 NO보다 NO$_2$가 주입되는 경우 NOx 제거 효율이 높고 촉매의 피독 현상도 줄어들게 된다. 따라서 DBD를 이용하여 NO의 전환율을 높일 수 있다면 플라즈마 촉매 복합공정의 NOx 제거 효율은 매우 높아진다. DBD 반응기 내에서 NO를 NO2로 전환시키는데 가장 중요한 역할을 하는 것 중 하나는 오존 (O$_3$)이다. (중략)

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.9 no.3
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• pp.121-129
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• 2011

The effects of the applied current density, the $AgNO_3$ concentration, the scrubbing liquid flow rate and the NO-air mixed gas flow rate on the NO removal efficiency were investigated by using $Ag^{2+}$ mediated electrochemical oxidation (MEO). Results showed that the NO removal efficiency increased with increasing the applied current density. The effect of the $AgNO_3$ concentration on the NO removal efficiency was negligibly small in the concentration of $AgNO_3$ above 0.1 M. When the scrubbing liquid flow rate increased, the NO removal efficiency was gradually increased. On the other hands, the NO removal efficiency decreased with increasing the NO-air mixed gas flow rate. As a result of the treatment of NO-air mixed gas by using the MEO process with the optimum operating condition and the chemical absorption process using 3 M $HNO_3$ solution as a scrubbing liquid, the removal efficiency of NO and $NO_x$ was achieved as 95% and 63%, respectively.

• Journal of the Korean Applied Science and Technology
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• v.36 no.2
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• pp.668-675
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• 2019

Fine dust in air pollutants is recognized as one of the most serious social environmental problems. Most of the NOx is generated in a combustion process such as that of a coal-fired power plant, and therefore efficient elimination of the NOx from the coal-fired power plants is needed. This study investigates the removal efficiency of using $TiO_2$, a photocatalyst, to remove NOx by Selective Catalytic Reduction (SCR). To evaluate the NOx removal efficiency, $TiO_2$ catalyst and phosphate binder were mixed on the surface of the $Al_2O_3$ substrate with the exothermic agent, and the substrate was heat-treated. The NOx removal efficiency of the catalysts was evaluated according to the temperature, and XRD, SEM, TG-DTA and BET analyzes were performed to investigate the physicochemical properties of the catalysts. NOx removal efficiency was 58.7%~65.9% at 20min, 63.7~66.0% at 30min with temperature change according to time($250^{\circ}C{\sim}500^{\circ}C$). The $TiO_2$ used in the SCR for NOx removal is judged to have the most efficient removal efficiency at $300^{\circ}C$.

• Analytical Science and Technology
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• v.15 no.3
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• pp.256-262
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• 2002

After porous filters were manufactured using cordierite powder whose mean paricle size was 200${\mu}m$, they were loaded with catalysts such as $V_2O_5$, CuO and $LaCoO_3$ by vacuum impregnation method. And the NOx/SOx simultaneous removal efficiency was measured by passing NO and $SO_2$ through catalyst-loaded ceramic filters. The cordierite porous filters had the apparent porosity of 61.6%, the compressive strength of 12.3 MPa and the pressure drop of 147 pa at the face velocity of 5 cm/sec. According to the analysis of NO/$SO_2$ simultaneous removal efficiency, perovskite $LaCoO_3$ catalyst was the most efficient for the simultaneous NO and $SO_2$ removal. The $LaCoO_3$ catalyst-loaded filter could remove more than 90% for NO and more than 80% for $SO_2$.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.9
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• pp.851-856
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• 2010

A sulfur utilizing nitrite denitrification process could be placed after the shortcut biological nitrogen removal (SBNR) process. In this study, removal of nitrite using sulfur oxidizing denitrifier was characterized in batch tests with granular elemental sulfur as an electron donor and nitrite as an electro acceptor. At sufficient alkalinity, initial nitrite nitrogen concentration of 100 mg/L was almost completely reduced in the batch reactor within a incubation time of 22 h. Sulfate production with nitrite was 4.8 g ${SO_4}^{2-}/g$ ${NO_2}^-$-N, while with nitrate 13.5 g ${SO_4}^{2-}/g$ ${NO_3}^-$-N. Under the conditions of low alkalinity, nitrite removal was over 95% but 15 h of a lag phase was shown. For nitrate with low alkalinity, no denitrification occurred. Sulfate production was 2.6 g ${SO_4}^{2-}/g$ ${NO_2}^-$-N and alkalinity consumption was 1.2 g $CaCO_3/g$ ${NO_2}^-$. The concentration range of organics used in this experiment did not inhibit autotrophic denitrification at both low and high alkalinity. This kind of method may solve the problems of autotrophic nitrate denitrification, i.e. high sulfate production and alkalinity deficiency, to some extent.

• Journal of Life Science
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• v.12 no.6
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• pp.700-707
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• 2002

To study the characteristics of organic and nutrient removal by Bacillus species at high COD concentration of influent, three lab-scale batch reactors(R1, R2, R3), each of which has different substrate composition, were operated. More than 95% of $NH_4^+$-N and $COD_{cr}$, concentrations were removed under an aerobic condition, and their removal efficiencies were found to be 22.6 and 90.5%(R1), 23.9 and 65.8%(R2), 30.2 and 86.4%(R3), respectively. The removal efficiency of $NH_4^+$-N was high when an enough amount of $NO_3^{-}$-N was supplied, and that of $COD_{cr}$. was low when a high concentration of initial $NO_2^{-}$-N was added. The amount of carbon utilized in denitrification was a little. In all reactors,$NO_3^{-}$-N was removed under an anoxic condition, but in the R3 reactor, 10% of $NO_3^{-}$-N could be removed even undo, an aerobic condition. The removal efficiencies of TN and TP were 41.8 and 49.5%(R1), 40.1 and 35.8%(R2), 47.0 and 57.6%(R3), respectively. Alkalinities destructed under an aerobic condition for each reactor were 4.96, 5.41 and 3.93 mg/L (as $CaCO_3$) per each gram of $NH_4^+$-N oxidized, respectively, while 3.06, 3.17 and 2.60 mg/L (as $CaCO_3$) of alkalinities were produced for each gram of ,$NO_3^{-}$-N reduced to $N_2$. The SOUR were found to be 38.5, 52.7 and 42.0 mg $O_2$/g MLSS/hr, which indicated that Bacillus sp. had a higher cell activity than activated sludge. The OLR and sludge production were estimated to be 0.69 and 0.28(Rl), 0.77 and 0.20(R2), 0.61 kg COD/$m^3$/day and 0.25 kg MLSS/kg COD(R3), respectively. From the N-balance, the highest percentage(40.9%) of nitrogen lost to $N_2$ was obtained in the R3 reactor. From all the results, the possibility of aerobic denitrification Bacillus sp. has been shown and the B3 process seemed to have two advantages: a little amount of carbon was required in denitrification and not much amount of alkalinity was destructed under an aerobic condition.

• Korean Journal of Ecology and Environment
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• v.50 no.2
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• pp.187-194
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• 2017

This study was intended to evaluate the removal efficiency of nutrients in effluents of wastewater using microalgae. Microalgae used in the culture experiment collected in stream and reservoir located in Gyeongsangbuk-do. Dominant species in prior-culture tank were Monoraphidium contortum, Scenedesmus acutus, Coelastrum microporum and Chlorella sp. Dominant species in synthetic wastewater culture under the 4000 Lux and 8000 Lux were Chlorella sp. and Scenedesmus obliquus. The removal efficiency of $NO_3-N$ under the 4000 Lux and 8000 Lux were 27.2%~88.1% and 63.0%~83.6% respectively. The removal efficiency of $PO_4-P$ under the 4000 Lux and 8000 Lux showed above 93%. Removal efficiency of nutrients of $1.0{\times}10^6cells\;mL^{-1}$ inoculation concentration was more higher than that of nutrients of $1.0{\times}10^5cells\;mL^{-1}$ and $1.0{\times}10^7cells\;mL^{-1}$ inoculation concentration. Microalgae cultured in synthetic wastewater removed 94.9% of TN and 90.0% of TP. The removal rate of TN and TP in synthetic wastewater were $1.961mg\;L^{-1}\;day^{-1}$ and $0.200mg\;L^{-1}\;day^{-1}$ respectively. Nutrient removal efficiency of microalgae according to kinds of wastewater showed the highest in the private sewage.