• 멤브레인
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• 제20권3호
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• pp.241-248
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• 2010

$0.4\;{\mu}m$의 세공크기를 갖고 있는 평막이 침지된 연속회분식 반응기에서 유입 유기물 농도가 영양염류 제거에 미치는 영향을 조사하였다. 분리막의 여과성능과 영양염류 제거효과를 규명하기 위하여 유입 유기물의 농도를 200 mg/L (Run-1), 400 mg/L (Run-2) 및 800 mg/L (Run-3)로 연속적으로 변화시키면서 실험하였다. COD/N 및 COD/P의 비가 증가할수록 T-N 및 T-P의 제거율은 모두 증가하였다. Run-1, Run-2 및 Run-3에서 T-N의 평균 제거율은 각각 28.1, 32.6 및 90.4%이었으며, 투과수의 T-N 평균 농도는 각각 32.0, 30.0 및 4.3 mg/L 이었다. 또한 Run-1, Run-2 및 Run-3에서 T-P의 평균 제거율은 각각 13.6, 35.3 및 93.1%이었으며, 투과수의 T-P 평균 농도는 각각 3.11, 2.33 및 0.25 mg/L이었다.

• 환경위생공학
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• 제24권3호
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• pp.7-15
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• 2009

본 연구에서는 DEPHANOX공정을 변형한 두 개의 질산화 반응조를 둔 M-DEPHANOX 공정과 기존 변형된 질산화 반응조를 RBC로 대체한 형태로 단일 질산화 반응조로 운전된 M-DEPHANOX 공정을 운전하였다. 그리고 두 공정의 제거율을 비교하기 위하여 질소, 인 및 유기물 제거율과 질산화 반응조의 유기물 부하에 따른 $NH_3$-N 제거율을 조사하였다. 연구결과 $NH_3$-N 제거율은 M-DEPHANOX공정이 91.8%, M-eBNR 공정은 96.9%로서 두 공정 모두 높게 나타났다. TCOD와 SCOD 제거율은 M-DEPHANOX공정은 84.1와 78.2%, M-eBNR공정은 83.4%와 75.6%이었다. 또한 유기물이 $NH_3$-N 제거율에 미치는 영향은 M-eBNR 공정의 질산화 반응조에서는 1차 침전조에서 거의 나타나지 않았다. M-eBNR 공정의 $NH_3$-N 제거율은 도시하수의 유입성상이 달라지더라도 안정적으로 유지되었다.

• Advances in environmental research
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• 제4권4호
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• pp.263-271
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• 2015

In this study, the effect of initial nitrate loading on nitrate removal and byproduct selectivity was evaluated in a continuous system. Nitrate removal decreased from 100% to 25% with the increase in nitrate loading from 10 to $300mg/L\;NO_3-N$. Ammonium selectivity decreased and nitrite selectivity increased, while nitrogen selectivity showed a peak shape in the same range of nitrate loading. The nitrate removal was enhanced at low catalyst to nitrate ratios and 100% nitrate removal was achieved at catalyst to nitrate ratio of ${\geq}33mg\;catalyst/mg\;NO_3-N$. Maximum nitrogen selectivity (47%) was observed at $66mg\;catalyst/mg\;NO_3-N$, showing that continuous Cu-Pd-NZVI system has a maximum removal capacity of 37 mg $NO_3{^-}-N/g_{catalyst}/h$. The results from this study emphasize that nitrate reduction in a bimetallic catalytic system could be sensitive to changes in optimized regimes.

• 한국양식학회지
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• 제10권3호
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• pp.335-346
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• 1997

연구는 순환 여과식 어류 양식 시설에 일반적으로 이용되고 있는 선라이트 골판을 여과재료로 한 침지식 여과조의 적정 탈질 조건을 구명하기 위해 외부 탄소원으로 메탄올과 글루코스를 사용하여 수리학적 체류 시간 (hydraulic retention time, HRT)과 COD에 대한 NO 하(3) 상(-)-N 비율 변화에 따른 적정 탈질 조건을 알아보았다. 질산성 질소와 총무기질소(TIN)의 제거 효율은 HRT 4 시간보다는 8 시간이 좋았으며, 글루코스보다는 메탄올을 이용한 것이 좋았다(P<0.05). 최대 질산성 질소 제거는 글루코스의 경우 HRT 8 시간과 C : N 비율 4일 때 86.3%였고, 메탄올은 HRT 8시간과 C : N 비율 5일 때 97.8%, 6일 때 92.2%를 보여 C : N 비율 5가 가장 최적인 것으로 나타났다. 최대 총무기질소 제거 효율은 HRT 8 시간일 때 C : N 비율 5에서 글루코스는 71.5%, 메탄올은 96.9%을 보였다. 탈질화에 필수적인 혐기적 조건은 HRT 8 시간과 C : N 비율 5 이상이 되었을 때 이루어진 것으로 보아 적정 C : N 비율과 혐기적 조건이 이루어졌을 때의 최적의 탈질 효율을 보이는 것으로 나타났다.

• Environmental Engineering Research
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• 제18권4호
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• pp.235-239
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• 2013

In the present investigation, the efficiency of Chlorella vulgaris (C. vulgaris) was evaluated for the removal of ammonia-nitrogen from wastewater. Eight different wastewater samples were prepared with varied amounts of $NH_4-N$ concentrations from 15.22 to 205.29 mg/L. Experiments were conducted at pH $7.5{\pm}0.3$, temperature $25^{\circ}C{\pm}1^{\circ}C$, light intensity $100{\mu}E/m^2/s$, and dark-light cycles of 8-16 hr continuously for 8 days. From the results, it was found that $NH_4-N$ was completely removed by C. vulgaris, when the initial concentration was between 5.22-25.24 mg/L. However, only 50% removal was obtained when the $NH_4-N$ concentration was 85.52 mg/L, which further decreased to less than 32% when the $NH_4-N$ concentration exceeded 105.43 mg/L. The further influence of nitrogen on chlorophyll was studied by various $NH_4-N$ concentrations. The maximal value of chlorophyll a (Chl a) content was found to be 19.21 mg/L for 65.79 mg/L $NH_4-N$ concentration, and the maximum specific $NH_4-N$ removal rate of 1.79 mg/mg Chl a/day was recorded at an $NH_4-N$ concentration of 85.52 mg/L. These findings demonstrate that C. vulgaris could potentially be employed for the removal of $NH_4-N$ from wastewater.

• The Korean Journal of Ecology
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• 제18권2호
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• pp.219-230
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• 1995

Although many studies of nutrient cycling in forest ecosystems have reported that clearcutting creates increased organic matter decomposition and nitrogen (N) mineralization in soils, little is known about the change of these factors following various levels of canopy removal. A series of experimental plots with four levels of canopy cover, i.e., clearcut, 25％, 75％, and uncut, was established in northern red oak (Quercus rubra L.) stands in northern Lover Michigan, U.S.A. I examined decomposition of cellulose filter papers and N mineralization using an in situ soil incubation technique in the top 15cm of mineral soil during the second growing season (1992, May-October) following stand manipulation. Mass loss from cellulose filter papers was more rapid in the canopy removal treatments than in the uncut treatment. similarly, net N mineralization was significantly greater in the canopy removal treatments than in the uncut treatment. There was no significant difference in net N mineralization rates among the three levels of canopy removal. Net N mineralization for the growing season was 58 kg/ha for the clearcut, 54 kg/ha for the 25％ canopy cover, 51 kg/ha for the 75％ canopy cover, and 22 kg/ha for the uncut treatment. These results indicated that even only small amounts of canopy removal (leaving 75％ canopy cover) let to substantial increases of cellulose decomposition and the amount of available soil nitrogen.

• 한국환경과학회지
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• 제18권2호
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• pp.205-213
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• 2009

A laboratory experiment was conducted to investigate nitrogen removal from plating wastewater by a soil reactor. A combination of soil, waste oyster shell and activated sludge were used as a loading media in a soil reactor. The addition of 20% waste oyster shell and activated sludge to the soil accelerated nitrification (88.6% ${NH_4}^{+}-N$ removal efficiency) and denitrification (84.3% ${NO_3}^{-}-N$ removal) in the soil reactor, respectively. In continuous removal, the influent ${NH_4}^{+}-N$ was mostly converted to nitrate nitrogen in the nitrification soil reactor and only a small amount of ${NH_4}^{+}-N$ was found in the effluent. When methanol was added as a carbon source to the denitrification soil reactor, the average removal efficiency of ${NO_3}^{-}-N$ significantly increased. The ${NO_3}^{-}-N$ removal by methanol addition in the denitrification soil reactor was mainly due to denitrification. The phosphorus was removed by the waste oyster shell media in the nitrification soil reactor. Moreover, the phosphorus removal in the denitrification soil reactor was achieved by synthesis of bacteria and the denitrification under anaerobic conditions. The approximate number of nitrifiers and denitrifiers was $3.3{\times}10^5\;MPN/g$ soil at a depth of $1{\sim}10\;cm$ and $3.3{\times}10^6\;MPN/g$ soil at a depth of $10{\sim}20\;cm$, respectively, in the soil reactor mixed with a waste oyster shell media and activated sludge.

• Carbon letters
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• 제7권2호
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• pp.105-113
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• 2006

The electro-chemical removal (ECR) of water pollutants by metal-ACF electrodes from wastewater was investigated over wide range of ECR time. The ECR capacities of metallic ACF electrodes were related to physical properties such as adsorption isotherm, surface area and pore size and to reaction time. Surface morphologies and elemental analysis for the metal supported ACFs after electro-catalytic reaction were investigated by scanning electron microscopy (SEM) and energy disperse X-ray (EDX) to explain the changes in adsorption properties. The IR spectra of metallic ACFs for the investigation of functional groups show that the electro-catalytic treatment is consequently associated with the removal of pollutants with the increasing surface reactivity of the activated carbon fibers. The metal-ACFs were electro-catalytically reacted to waste water to investigate the removal efficiency for the COD, T-N, $NH_4$-N, $NO_3$-N and $NO_2$-N. From these removal results of the piggery waste using metallic ACFs substrate, satisfactory removal performance was achieved. The removal efficiency of the metallic ACFs substrate was mainly determined by the properties of the material for adsorption and trapping of organics, and catalytic effects.

• 한국물환경학회지
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• 제22권2호
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• pp.250-257
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• 2006

The objective of this study is to propose an alternative process for the small sewage treatment plants in rural communities. A biofilter has been used for biological wastewater treatment, which is becoming the alternative to the conventional activated sludge system. The proposed process used in this study, which is packed with floating media (i.e. expanded polystylene), has advantages of biofilter system and alternative flow system and they are incorporated into one process. Pilot and bench scale studies were performed using domestic wastewater. In the results of pilot plant study, it was observed that the stable effluent water quality was achieved and it met the present effluent criteria of suspended solid (SS), organic matters, T-N and T-P. In the study for determination of the cycle of backwashing, it was observed that the cycle of backwashing depended on BOD loading rates of influents. In the BOD loading rates of $0.5kg\;BOD/m^3{\cdot}day$ and $1.0kg\;BOD/m^3{\cdot}day$, the backwashing cycle of 28 hour and 16 hour were needed, respectively. The optimum backwashing time was 120~80 seconds at the media expansion rate of 50%. In the removal of SS, organic matters, T-N and T-P, SS removal was rather achieved by physical filtration than biological mechanism and the removal of organic matters except for SS, T-N and T-P were mainly rather achieved by biological mechanism than physical filtration. In bench-scale study, the effects of recirculation rate was investigated on removal of SS, TCOD, T-N and T-P. It was observed that the recirculation made removal efficiencies of SS, TCOD, T-N and T-P increased. Especially, in T-N removal, the increase of T-N removal efficiency of 40% was observed in the reicirculation rate of 1Q compared with 0Q.

• Journal of Microbiology and Biotechnology
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• 제15권1호
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• pp.14-21
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• 2005

By using PCR with nirS gene primers, three nirSharboring denitrifying bacteria (strain N6, strain N23, and strain R13) were newly isolated from activated sludge of a weak municipal wastewater treatment plant. Small-subunit rRNA gene-based analysis indicated that strain N6, strain N23, and strain R13 were closely related to Arthrobacter sp.,Staphylococcus sp., and Bacillus sp., respectively. In an attempt to identify their roles in biological nitrate and nitrite removal from sewage, we investigated their specific denitrification rates (SDNRs) for $NO_-^3$ - and $NO_-^2$ - in various cultures. All purecultures of each isolated nirS-harboring bacterial strain could remove $NO_-^3$ - and $NO_-^2$ - simultaneously in high efficiency, and the carbon requirements for $NO_-^3$ - removal of strain N6 and strain R13 were effectively low at 3.1 and 4.1 g COD/g $NO_3N$, respectively. In the case of mix-cultures of the strains (N6+N23, N6+R13, N23+R13, and N6+N23+R13), their SDNRs for $NO_-^3$ - were also effective, and their carbon requirements for $NO_-^3$ - removal were also effective at 3.0- 3.8 g COD/g NO3N. However, all tested mix-cultures accumulated $NO_-^2$ - in their culture media. On the other hand, the continuous culture of activated sludge mixed with strain N6 showed no significant increase of $NO_-^3$ - removal in comparison with strain N6's pure culture. These results suggest that nitrate and nitrite removal in biological wastewater treatment might be dependent on complicated bacterial interactions, including several effective denitrifying bacteria isolated in this study, rather than the specific bacterial types present and the number of bacterial types in activated sludge.