• Journal of the Korean Applied Science and Technology
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• v.34 no.3
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• pp.487-494
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• 2017

Since nitrate nitrogen is quite stable in aqueous solution, considerable skill is required to remove it. Low concentrations of nitrate nitrogen are easily removed, while high concentrations of nitrate nitrogen are difficult to remove. This study is to show that nitrate nitrogen in the form of gaseous nitrogen can be removed by using zinc ball with a diameter of about 3mm and to test the removal characteristics of nitrate nitrogen under various reaction conditions. As a result of this study, the treatment efficiency of nitrate nitrogen by continuous treatment with zinc ball was about 80%. However, there is a problem that the wastewater must be maintained in an acidic atmosphere of about pH 2, and the treated wastewater must be neutralized and discharged.

• Journal of Soil and Groundwater Environment
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• v.10 no.2
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• pp.20-27
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• 2005

The seasonal variation of water quality was studied in the Hwabongcheon. It runs though a small catchment where shallow groundwater was contaminated with $NO_3-N$ by intensive livestock facilities. A direct inflow of animal waste and incoming of contaminated groundwater affected its water quality. In the dry season, an important factor of water quality in the Hwabongcheon was direct inflow of animal waste. In the wet season, concentrations of $NO_3-N$ in the Hwabongcheon were elevated in spite of being diluted by precipitation. It could be explained by the effect of increased incoming of contaminated groundwater and showed by oxygen and hydrogen isotope values. $NO_3-N$ concentration in the Cheongmicheon was lower than that in the Hwabongcheon, so it increased next a junction. This effect was intense in wet season because $NO_3-N$ concentration in the Hwabongcheon was high.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.459-462
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• 2003

충청북도 증평에 위치한 문화마을 인근의 19개 지하수 관측정에서 시료를 채취하여 질산성질소 농도와 $\delta$$^{15}$ N 값, 암모니아성질소 농도와 $\delta$$^{15}$ N 값을 정량하였다. 그 결과 질산성질소에 의한 심각한 오염은 관찰되지 않으며, 질산성질소내 $\delta$$^{15}$ N이 +9.4~+36.8%0의 범위를 갖는 것으로 보아 계분이나 생활하수 혹은 두 가지 이상의 오염원이 동시에 작용함을 나타낸다. 연구지역의 $^{15}$ N 부화지수($\varepsilon$)은 -6.697%0로 탈질에 의한 범위를 만족한다. 암모늄의 질산화가 주요한 반응기작일 경우에 나타나는 암모늄 농도 감소에 따른 $^{15}$ N의 부화는 관찰할 수 없다.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2003.10a
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• pp.246-251
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• 2003

전기분해법을 이용하여 수용액 중의 질산성 질소의 환원거동에 대한 연구를 통하여 수용액중의 질산 함량을 제어하는 연구를 수행하였다. 촉매전극을 채택한 복극전해조에서 30분의 조업에 질산 100ppm 이하의 저농도 용액은 70%, 300ppm 이상의 고농도의 경우는 90%까지 질소를 용이하게 제거할 수 있었다. 초기 질소농도가 증가하면서 한계전류밀도도 크게 증가하였으며, pH가 감소할수록 환원전류가 증가하였다. 그리고 수용액의 pH는 질소 환원반응기구에 큰 영향을 주는 것으로 판명되었으며, 산성에서는 질소형태로 중성 혹은 염기성에서는 암모니아 형태로 환원되는 것으로 추정된다.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2001.11a
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• pp.71-73
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• 2001

W3와 W4는 질산성 질소의 농도가 자연 토양의 농도 범위에 있고 질산성 질소의 기여율도 토양이 각각 찔.8과 75%로 질산성 질소에 의한 오염이 없다고 볼 수 있다. Sl의 경우 토지 이용이 주거지와 상류에 밭 경작지가 있어서 생활 하수와 화학비료의 영향을 받고 있음을 알 수 있다. S2와 W6의 경우는 생활 하수와 화학비료의 영향이 48.1%와 48.2%로 거의 유사하게 영향을 주고 있음을 알 수 있다. Wl, W2 그리고 W7은 각각 73.2%, 82.7% 그리고 48.8%의 화학비료의 기여율로 보아 주로 화학비료의 영향을 받고 있다고 사료된다.

• Clean Technology
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• v.15 no.4
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• pp.280-286
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• 2009

To evaluate the feasibility of electrodialysis for nitrate-nitrogen removal from wastewater, the effect of operating parameters on the removal of nitrate-nitrogen was experimentally estimated. The limiting current density (LCD) linearly increased with the nitrate concentration and the flow rate. The time when the nitrate concentration of diluate reached at 20 mg/L was linearly proportional to concentration of diluate, and the concentration of concentrate did not affect the removal rate. Increase in the flow rate gave a positive effect on the removal rate and became insignificant at How rates greater than 1.6 L/min. The removal rate increased with the applied voltage, but the increment in the removal rate decreased as the applied voltage approached the LCD. From the operation of the electrodialysis module used in this research, the flow rate of 1.6 L/min and the voltage corresponding to the 80~90% of LCD were found be the optimum operating condition for the nitrate removal from highly concentrated nitrate-nitrogen solutions.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.1
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• pp.29-34
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• 2009

This study was performed under four operational conditions for nitrogen removal in metal finishing wastewater. The conditions include electrode gap, reducing agent, the recycling of treated wastewater in 1st step and the simultaneous treatment of nitrate and other materials. Result showed that the removal efficiency of $NO_3{^-}-N$ was highest at the electrode gap of 10 mm. As the electrode gap was shorter than 10 mm, the removal efficiency of $NO_3{^-}-N$ decreased due to increasing in concentration polarization on electrode. And, in case that the electrode gap was longer than 10 mm, the removal efficiency of $NO_3{^-}-N$ increased with an increase in energy consumption. Because hydrogen ions are consumed when nitrate is reduced, reducing reaction of nitrate was effected more in acid solution. As 1.2 excess amount of zinc was injected, the removal efficiency of $NO_3{^-}-N$ increased due to increasing in amount of reaction with nitrate. As the effluent from 1st step in the reactor was recycled into the 1st step, the removal efficiency of $NO_3{^-}-N$ increased. Because the zinc were detached from the cathode and concentration-polarization was decreased due to formation of turbulence in the reactor. The presence of $NH_4{^+}-N$ did not affect the removal efficiency of $NO_3{^-}-N$ but the addition of heavy metal decreased the removal efficiency of $NO_3{^-}-N$. As chlorine is enough in wastewater, the simultaneous treatment of nitrate and ammonia nitrogen may be possible. The problem that heavy metal decrease the removal efficiency of $NO_3{^-}-N$ may be solved by increasing current density or using front step of electrochemical process for heavy metal removal.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.93-96
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• 2004

국내 대부분의 경작지를 차지하고 있는 논농사 지역에서의 질산성 질소의 자연저감을 고찰하기 위하여, 세 유형의 수조 환경을 조성하고 mesocosm 실험 연구를 수행하였다. 두개의 mesocosm에는 논토양을, 그리고 비교를 위하여 다른 하나에는 밭토양(황토)을 사용하였으며, 하나의 논토양 mesocosm과 밭토양(황토) mesocosm에는 벼를 재배하였다. 인위적으로 질산성 질소 성분을 용해한 지하수를 주입수로 사용하였으며, mesocosm을 통과한 물 시료를 41일 동안 12시간 또는 24시간 간격으로 채취하고 화학분석을 실시하였다. 실험 결과, 논토양에서는 실험 시작과 동시에 급격한 환원환경이 형성되었으며, 그 결과 탈질반응에 의해 질산성 질소의 농도가 현저히 저감되었다. 분석 자료의 해석 결과, 논토양 mesocosm에서는 유기물이, 밭토양 mesocosm에서는 철이온(Fe2+)이 질산성 질소의 탈질 반응에 중요한 역할을 수행하는 것으로 판단된다.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.4
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• pp.355-361
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• 2006

In this study, effects of influent C/N(COD/Nitrate) ratio and dissolved oxygen(DO) concentration on biological nitrate removal from groundwater were investigated in the fixed-type biofilter. Influent nitrate of 30 mg/L was removed completely by biological denitrification at the C/N ratio of 10 and 4.0, while residual nitrate of 5 mg/L occurred at the C/N ratio of 2.0, which resulted from deficiency of organic electron donor. Furthermore, nitrite was accumulated up to about 5 mg/L as the C/N ratio decreased to 2.0. Increase in DO concentration also inhibited denitrification activity at the relatively high C/N ratio of 5.0, which decreased the nitrate removal efficiency. Although the influent DO concentration was reduced as low as 0.3 mg/L using sodium sulfite($Na_2SO_3$), effluent nitrite was up to 3.6 mg/L. On the other hand, nitrate was completely removed without detection of nitrite at the DO concentration of 0.3 mg/L using nitrogen gas($N_2$) sparging. The organic matter for denitrification in biofilter were in the range from 3.0 to $3.5gSCOD/g{NO_3}^--N$, while utilized these values increased at the high DO concentration of 5.5 mg/L. In addition to the high DO concentration and the low influent C/N ratio, DO control by chemical such as sodium sulfite affected on biological denitrification, which resulted in the reduction of nitrate removal efficiency and nitrite build-up in a biofilter.

• Korean Chemical Engineering Research
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• v.45 no.2
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• pp.190-196
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• 2007

This study examined the nitrate removal efficiency which uses an electrowinning, and also analyzed the nitrate removal efficiency under a variety of operating conditions such as nitrate concentrations, pH, current densities, electrodes, reducing agents in order to determine optimal conditions. In addition, the multi-step electro-chemical process test has been also analyzed. During the electrowinning, the identical Zn-Zn and Pt-Ti electrodes in the insoluble oxidation electrode(Pt) has shown the highest nitrate removal efficiency in the 100 mg $NO_3^{-}$ -N/L concentration. In the concentration of 150 mg $NO_3^{-}$ -N/L, the efficiency of the Zn-Zn electrode were 70~85%, and that of Pt-Ti electrode were 40~50% without any change of pH. In the high concentration of 500 and 1,000 mg $NO_3^{-}$ -N/L, the higher the concentration, the more decrease of its nitrate removal efficiency decreased. However, the energy consumed for nitrogen removal increased when the nitrate concentration was high. As a result of the multi-step electro-chemical process test, We chose the Test 4. Because the first, most of the zinc consumed from 1 step was recovered from over the 2 step. The second, amount of consumption anode decreased with insoluble anode Pt from over the 2 step. And the third, Zn cathode increased the possibility of reusing Zn deposited. In view of the results so far achieved, the multi-step electro-chemical process would be applied to treat nitrogen involved in metal finishing wastewater.