• 한국물환경학회지
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• 제21권6호
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• pp.630-636
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• 2005

Groundwater contamination by nitrate exceeding water quality criteria (10 mg $NO_3{^-}-N/L$) occurs frequently. Fumarate, acetate, formate, lactate, propionate, ethanol, methane and hydrogen gas were evaluated for their nitrate removal efficiencies and removal rates for in situ bioremediation of nitrate contaminated groundwater. Denitrification rate for each substrate was in the order of: fumarate > hydrogen > formate/lactate > ethanol > propionate > methanol > acetate. Microcosm studies were performed with fumarate and acetate. When fumarate was used as a substrate, nitrate was removed 100 percent with rate of 0.66 mmol/day while conversion rate from nitrate to nitrogen gas or another by-product was 87 percent. 42 mg of fumarate was needed to remove 30 mg $NO_3{^-}-N/L$. When using acetate as carbon source, 31 percent of nitrate was removed during initial adjustment period. Among removed fraction, however, 83 percent of nitrate removed by cell growth. Overall nitrate removal rate was 0.37 mmol/day. Acetate showed longer lag time in consumption compared to that of nitrate, which implying that acetate would be better carbon source compared to fumarate as more amount was utilized for nitrate removal than cell growth.

• 한국토양비료학회지
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• 제33권6호
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• pp.384-392
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• 2000

토양중 질산태 질소 함량이 $14{\sim}225mg\;kg^{-1}$의 범위를 갖는 시설재배지 9개 토양에서 배추를 공시작물로 하여 무비구, 3요소 표준시비량의 50%구, 100%구 및 150%구의 4개 시비수준에서 포트재배로 수량반응, 비료효과 및 시비효율 등을 검토하였다. 무비구 배추 건물중과 토양의 질산태 질소 함량은 유의성 있는 정의 상관을 나타냈고 시비구와 무비구의 건물중, 질소흡수량 및 질산태 질소흡수량의 차이로 평가한 비료효과 및 시비효율과는 유의성 있는 부의 상관을 보였다. 질산태 질소함량에 따른 시비수준별 건물중 반응의 관계로부터 표준시비량이 적용되는 질산태 질소의 하한기준은 $50mg\;kg^{-1}$ 미만으로 추정되었고, 질산태질소 함량과 비료효과 및 시비효율과의 회귀관계로부터 평가된 무비 재배를 위한 질산태 질소 함량은 $200mg\;kg^{-1}$ 이상으로 추정되었다. 따라서 시설재배지 토양중 질산태 질소 함량 $50mg\;kg^{-1}$에서 $200mg\;kg^{-1}$ 범위는 질소 표준시비량에 대한 비율로서 추천식은 $Y=-0.6667{\chi}+133.33$ 이었다 (Y:질소 표준시비량에 대한 %, ${\chi}$: 시험전 토양의 $NO_3-Nmg\;kg^{-1}$).

• 한국환경농학회지
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• 제22권1호
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• pp.70-73
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• 2003

Nitrate contamination in the aquatic systems is the primary indicator of poor agricultural management. The influence of sewage sludge application rates (0, 10, 25, 50 and 100 dry Mg/ha) on distribution of nitrate originating from the sewage sludge in soil profiles was investigated. Soil profile monitoring of nitrate was carried out with a Lakeland clay soil in 1997. Irrespectively of the sewage sludge application rates up to 50 dry Mg/ha, the concentration of $NO_3$-N at the 120 cm depth was below 10 mg/kg and the difference due to the amount of sewage sludge application was negligible at this depth. There was virtually no $NO_3$-N below 120 cm depth and this was confirmed by a deep sampling up to 300 cm depth. Most of the nitrate remained in the surface 60 cm of the soil. Below 120 cm depth nitrate concentration was very low because of the denitrification even at high sewage sludge rate of 100 dry Mg/ha. The $NO_3$-N concentrations in the soil fluctuated over the growing season due to plant uptake and denitrification. The risk of groundwater contamination by nitrate from sewage sludge application up to high rate of 100 dry Mg/ha was very low in a wheat grown clay soil with high water table ( < 3 m).

• 한국환경과학회지
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• 제18권3호
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• pp.325-331
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• 2009

This study was aimed to behaviour of organics and nitrogen on the upflow anaerobic reactor when a acid fermenter is added. Up flow anaerobic reactor (UAR) reaction will result which operates, COD removal efficiencies of reactor with nitrate loading rate 0.11, 0.66g/L/d were over 77%, but one with 1.0g/L/d was 73.5%. Especially, on NLR 0.11g/L/d, COD removal was 77% and nitrate removal efficiency was 93% simultaneously. The other side upflow anaerobic reactor and acid fermenter (UAR+AF) reaction will result witch operates, COD removal efficiencies of reactor with nitrate loading rate 0.11, 0.66g/L/d were over 85%, but one with 1.0g/L/d was 80%. Especially, on NLR 0.11g/L/d, COD removal was 85% and nitrate removal efficiency was 98% simultaneously. Also, without in reaction condition increase of influent nitrate concentration resulted in the linear decrease of nitrate removal efficiency and nitrate removal efficiency at influent nitrate-nitrogen 800mg/L was 50%. Alkalinity was increased theoretically by denitrification at low nitrate-N concentration, however, it was not increased theoretically at high nitrate-No 40% nitrate-N of UAR was denitrified until 70% height of reactor and 90% nitrate-N of UAR+AF was denitrified until 30% height of reactor Upflow anaerobic reactor was to occur accumulate acid, which TVA/Alkalinity is 0.3$\sim$0.47. Increase of NLR resulted increase of effluent alkalinity and TVA production

• 대한환경공학회지
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• 제27권7호
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• pp.739-745
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• 2005

포도당을 사용하여 적응된 전형적인 혐기성 소화 슬러지와 포도당과 질산성 질소를 동시에 사용하여 적응된 혐기성 소화 슬러지, 두 가지를 이용하여 다양한 C/N 비에서의 탈질반응 및 메탄반응의 동시연구가 수행되었다. 세 가지 다른 serum bottle에 잘 적응된 혐기성 소화 슬러지를 넣어 잘 혼합한 후, 탄소 기질로는 포도당을 사용하여 1,000 mg/L로 고정하였다. 질산칼륨을 이용하여 질산염을 주입하여 C/N 비를 30, 20, 및 10으로 변화시키면서 시간에 따른 가스 발생량, 가스 조성 및 유기물질 제거를 관찰하였다. C/N 비가 높을수록 메탄생성반응에 의한 유기물질제거가 우세한 반면, C/N 비가 낮을수록 메탄생성 반응보다는 탈질에 의한 유기물질제거가 주를 이룸을 알 수 있었다. 10 이하의 낮은 C/N 비에 적응된 슬러지에서 다른 종류의 탄소기질을 이용한 SMA실험 결과, 순수 혐기성 슬러지에서 아세테이트를 사용하였을 경우에 가장 높은 0.76 g COD/g VSS day을 보여주었고, SDNR실험 결과, 낮은 C/N 비 5에서 적응된 슬러지에서 아세테이트를 탄소기질로 사용하였을 경우에 가장 높은 SDNR 값 1.38 g ${NO_3}^--N/g$ VSS day를 나타내었다.

• 상하수도학회지
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• 제25권5호
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• pp.651-658
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• 2011

Nitrate is a common contaminant in industrial wastewater and ground water. The maximum contaminant level set by EPA for nitrate of 10 mg/L as N. In this study, nitrate was removed using bipolar ZVI packed bed electrolytic cell that maximized the contact area between each electrode and contaminants under 600 V. Also this study investigates the simultaneously deals with removal of ammonia by operating air stripping tower. In addition to the air stripping also helped to precipitate iron ions to the form of iron oxides. Bipolar ZVI packed bed electrolytic cell was also effective in removing coliform by electrical power. In the continuous experiments for the simulated wastewater (initial nitrate for 25 mg/L as N), maximum 96.3% removal of nitrate was achieved in the applied 600 V at the flow rate of 6 mL/min.

• Journal of the korean society of oceanography
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• 제37권1호
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• pp.45-50
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• 2002

New production (NP) values in well-mixed waters of the Yellow Sea were estimated using two different methods and were compared with each other; one is from the quantum yield model of nitrate uptake and chlorophyll ${\alpha}$-specific light absorption coefficient, and the other is from a traditional $^{15}N$-labelled stable isotope uptake technique. The quantum yields of nitrate uptake were highly variable, ranging from 0.0001 to 0.04 mol $NO_3Ein^{-1}$, and the small values in this study might have resulted from either the partitioning into nitrate uptake of little portions of light energy absorbed by phytoplankton or that phytoplankton may predominantly utilize other N sources (E. G. ammonium and/or urea) than nitrate. The estimates (0.54-8.47 nM $h^{-1}$) of NP from the quantum yield model correlated well ($r^2$=0.67, p<0.1) with those (0.01-4.93 nM $h^{-1}$) obtained using the $^{15}NO_3$ uptake technique. To improve the ability of estimating NP values using this model in the Yellow Sea, more data need to be accumulated in the future over a variety of time and space scales.

• Ocean and Polar Research
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• 제30권4호
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• pp.407-418
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• 2008

Seawater samples were collected at discrete depths from five stations across the polar front in the Drake Passage (Antarctic Ocean) by the $20^{th}$ Korea Antarctic Research Program in December, 2006. Nitrate concentrations of seawater increase with depth within the photic zone above the depth of Upper Circumpolar Deep Water (UCDW). In contrast, ${\delta}^{15}N$ values of seawater nitrate decrease with depth, showing a mirror image to the nitrate variation. Such a distinct vertical variation is mainly attributed to the degree of nitrate assimilation by phytoplankton as well as organic matter degradation of sinking particles within the surface layer. The preferential $^{14}{NO_3}^-$ assimilation by the phytoplankton causes $^{15}{NO_3}^-$ concentration to become high in a closedsystem surface-water environment during the primary production, whereas more $^{14}{NO_3}^-$ is added to the seawater during the degradation of sinking organic particles. The water-mass mixing seems to play an important role in the alteration of ${\delta}^{15}N$ values in the deep layer below the UCDW. Across the polar front, nitrate concentrations of surface seawater decrease and corresponding ${\delta}^{15}N$ values increase northward, which is likely due to the degree of nitrate utilization during the primary production. Based on the Rayleigh model, the calculated ${\varepsilon}$ (isotope effect of nitrate uptake) values between 4.0%o and 5.8%o were validated by the previously reported data, although the preformed ${\delta}^{15}{{NO_3}^-}_{initial}$ value of UCDW is important in the calculation of ${\varepsilon}$ values.

• Journal of Applied Biological Chemistry
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• 제42권4호
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• pp.186-190
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• 1999

Isotope ratio ($^{15}N/^{14}N$) and nitrate-nitrogen concentration in groundwater were measured to investigate the effect of chemical fertilizer and livestock manure on temporal variations in nitrate-nitrogen concentration and to estimate the contribution of fertilizer and manure to groundwater contamination by nitrate. Four study wells from a rural area in Kyonggi province were selected. One well was located on an upper site from a livestock feedlot, and the others were situated at lower sites from the feedlot. The ${\delta}^{15}N$ values were analyzed by a stable isotope ratio mass spectrometer (Micromass, VG Optima IRMS). Reproducibility of the method and precision of the mass spectrometer were below 1.0 and 0.1‰, respectively Even though study wells were located at the same area, nitrate-nitrogen concentrations and ${\delta}^{15}N$ values differed and fluctuated during the sampling period. The ${\delta}^{15}N$ values of well located at upper site from the feedlot were extremely variable (-1.48~20.80‰). The ranges of ${\delta}^{15}N$ value of three wells situated at lower sites from the feedlot were 11.83~20.73 (ave. 16.11), 8.90~11.73 (ave.11.01), and 5.29~12.73‰ (ave. 8.21‰) with increasing distance from the feedlot. The average values of contribution proportion of nitrogen derived from livestock manure to nitrate-nitrogen in groundwater were 79% for the well closet to the feedlot, 44% for the well most distant from the feedlot, and 56% for the well in between the two wells.

• 한국토양비료학회지
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• 제45권2호
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• pp.223-226
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• 2012

가축분뇨 액비 중의 총 질소함량이 많고 적음에 관계없이 일정부분 질산태 질소의 형태로 존재하며 특히 질소의 농도가 낮은 저농도 액비의 경우 질산태 질소의 농도에 따라 총 질소 함량이 달라질 수 있다. 이를 개선하기 위한 방법으로 가축분뇨 액비 총 질소의 분석 시 액비의 황산 분해 후에 devarda's alloy를 첨가하면 액비에 포함되어있는 질산태 질소까지 정량할 수 있기 때문에 총 질소 정량을 효과적으로 할 수 있는 장점이 있다.