• Journal of Korean Society of Water and Wastewater
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• v.25 no.5
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• pp.767-775
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• 2011

In this study we verified if the electro-coagulation process can treat properly the nitrate and fluoride that are not removed well in the conventional small water treatment plants which usually employ chlorination and filtration only. As we gave a change of electrode material and gap-distance between electrodes, removal efficiency of the nitrate and fluoride was determined by electro-coagulation process which were equipped with aluminum and stainless steel (SUS304) electrodes. In addition, electrode durability was investigated by determination of electrodes mass change during the repetitive experiments. Removal efficiency was great when aluminum was used as an anode material. Nitrate removals increased as electric density and number of electrodes increased, but fluoride removal was less sensitive to both parameters than nitrate. After 10 minutes of contact time with the current density from $1{\times}10^{-3}$ to $3{\times}10^{-3}A/cm^{2}$, nitrate and fluoride concentration ranged from 9.2 to 1.2mg/L and from 0.02 to 0.01mg/L, which satisfied the regulation limits. Regardless of the repeating number of experiments, removal efficiency of both ions were almost similar and the change of electrode mass ranged within ${\pm}$0.5%, indicating that the loss of the electrode mass is not so much great under the limited circumstances.

• Nuclear Engineering and Technology
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• v.48 no.3
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• pp.727-732
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• 2016

A simple and rapid spectrophotometric method has been developed to enable the determination of plutonium concentration in an irradiated fuel solution in the presence of all fission products. An excess of ceric ammonium nitrate solution was employed to oxidize all the valence states of plutonium to +6 oxidation state. Interference due to the presence of fission products such as ruthenium and zirconium, and corrosion products such as iron in the envisaged concentration range, as in the irradiated fuel solution, was studied in the determination of plutonium concentration by the direct spectrophotometric method. The stability of plutonium in +6 oxidation state was monitored under experimental conditions as a function of time. Results obtained are reproducible, and this method is applicable to radioactive samples resulting before the solvent extraction process during the reprocessing of fast reactor spent fuel. An analysis of the concentration of plutonium shows a relative standard deviation of <1.2% in standard as well as in simulated conditions. This reflects the fast reactor fuel composition with respect to uranium, plutonium, fission products such as ruthenium and zirconium, and corrosion products such as iron.

• Journal of the Korean Chemical Society
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• v.31 no.3
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• pp.271-279
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• 1987

A nitrate ion-selective PVC membrane electrode based on ammonia modified bakelite A-Ni$(NO_3)_2$ complex as ion exchanger was prepared. The electrode gave a linear response with a Nernstian slope of 60mV per decade within the concentration range $1{\sim}10^{-4}$ M $KNO_3$ but nonresponse to hydrogen ion and multivalent anions. The selectivity, response time and life time of the electrode were investigated and it was found that the electrode exhibited good selectivity for four univalent anions ($Cl^-,\;Br^-,\;I^-,\;{ClO_4}^-$). Analytical application to the determination of nitrate were also studied.

• Korean Journal of Soil Science and Fertilizer
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• v.30 no.4
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• pp.361-369
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• 1997

A microbiological nitrate determination method by E. coli is modified in Korea, using K12 wildtype, KCTC 1116, for the quantitative reduction of $NO_3{^-}$ to $NO_2{^-}$. The nitrate in plant, soil or water sample is determined spectrophotometrically after being diazotized with sulfaniamide and N-(1-naphthl)-ethlenediamine. The modified E. coli cell method and principle for nitrate determination using Korean wildtype E. coli strain is described, and cell culture and preparation of stock suspension for E. coli as well. This modified E. coli cell method can be managed simply and fast, it is suitable for the investigation of the large serials, it can be also automated and has a high degree of sensitivity up to 0.01ppm $NO_3{^-}-N$ in the sample solution. The applicability of the modified E. coli cell method has been tested for plant, soil and water analysis on a wide range of different samples. Recovery rates of added nitrate have been determined and comparisons with other standard nitrate analytical procedures have been carried out. The results with the modified E. coli cell method show high correlation ($r^2=0.98$) with those gained by the standard analytical procedures. The advantages and disadvantages of the method are also discussed to other nitrate determination methods.

• Journal of the Korean Society of Safety
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• v.5 no.2
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• pp.40-49
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• 1990

For the determination of polluant NOx in ambient air, nitrate ion-selective electrode(ISE) was made. To comparison of NOx in each method, the nitrate-ISE, NEBA, Orion electrode were used to determinee NOx in ambient air. In this work, the concentration of NOx in ambient air was average 0.06ppm. The results were good agreement with those obtained by each method within a relative error of 3％, Absorbing efficiency of nitrogen oxides in ambient air was good for Alkali solution. The determination of nitrogen oxides in ambient air using the Aliquat 336N-PVC membrane electrode was one of the useful method. The best characteristics of the Aliquat 336N-PVC me,mbrane electrode were obtained with the ion-exchanger concentration level of 6.5-9.1 percent by weight. The optimal membrane composition, was 9.09wt.％ of ion-exchanger, 30.95wt.％ of PVC, 60.6wt.％ of plasticizer (DBP), and 0.5mm of thickness. Under the above condition, the electrode approached the Nernstian slope most closely, and the linear response ranges produced the best results.

• Journal of Environmental Science International
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• v.4 no.3
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• pp.229-237
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• 1995

This study was investigated with denitrification of wastewater containing nitrate using upflow sludge blanket process. Contents of this study were the NO3--N removal efficiency by various hydrogen donor addition, determination of optimum COD/$NO_3^--N$ ratio and characteristics of granular sludge.

• Journal of Environmental Science International
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• v.4 no.3
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• pp.77-77
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• 1995

This study was investigated with denitrification of wastewater containing nitrate using upflow sludge blanket process. Contents of this study were the NO3--N removal efficiency by various hydrogen donor addition, determination of optimum COD/$NO_3^--N$ ratio and characteristics of granular sludge.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.175-178
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• 2004

Little study has been published specifically addressing the dynamics of nitrate reducing bacteria (NBR) during the bioremediation of nitrate-contaminated aquifer. In our previous study we successfully quantified fumarate-enhanced microbial nitrate reduction rate in a nitrate-contaminated aquifer by using a series of single-well push-pull tests (PPTs). In this study we analyzed the suspended population during PPTs. To monitor changes in the microbial community, PCR amplification of 16S rDNA genes and denaturing gradient gel electrophoresis (DGGE) were used to study the dynamics of the bacterial community in detail. Before the stimulation of NBR, the dominant DGGE bands obtained by PCR were affiliated with V-Proteobacteria consisting of Acinetobacter spp. and Pseudomonas fluorescens. However, as NBR biostimulation proceeded, the dominant patterns of DGGE bands changed, and they were affiliated with Azoarcus denitrificans Td-3 and Flavobacterium xanthum. Azoarcus denitrificans Td-3 is known to completely reduce nitrate to nitrogen gas. The series of single-well push-pull tests in this study should prove useful for conducting rapid, low-cost feasibility assessments for in situ denitrification and provide important information about which microorganisms play a key role in bioremediation of a nitrate contaminated aquifer.

• Journal of Biosystems Engineering
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• v.31 no.6 s.119
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• pp.463-473
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• 2006

Automated sensing of soil macronutrients would allow more efficient mapping of soil nutrient spatial variability for variable-rate nutrient management. The capabilities of ion-selective electrodes for sensing macronutrients in soil extracts can be affected by the presence of other ions in the soil itself as well as by high concentrations of ions in soil extractants. Adoption of automated, on-the-go sensing of soil nutrients would be enhanced if a single extracting solution could be used for the concurrent extraction of multiple soil macronutrients. This paper reports on the ability of the Kelowna extractant to extract macronutrients (N, P, and K) from US Corn Belt soils and whether previously developed PVC-based nitrate and potassium ion-selective electrodes could determine the nitrate and potassium concentrations in soil extracts obtained using the Kelowna extractant. The extraction efficiencies of nitrate-N and phosphorus obtained with the Kelowna solution for seven US Corn Belt soils were comparable to those obtained with IM KCI and Mehlich III solutions when measured with automated ion and ICP analyzers, respectively. However, the potassium levels extracted with the Kelowna extractant were, on average, 42% less than those obtained with the Mehlich III solution. Nevertheless, it was expected that Kelowna could extract proportional amounts of potassium ion due to a strong linear relationship ($r^2$ = 0.96). Use of the PVC-based nitrate and potassium ion-selective electrodes proved to be feasible in measuring nitrate-N and potassium ions in Kelowna - soil extracts with almost 1 : 1 relationships and high coefficients of determination ($r^2$ > 0.9) between the levels of nitrate-N and potassium obtained with the ion-selective electrodes and standard analytical instruments.

• Korean Journal of Agricultural Science
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• v.41 no.4
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• pp.399-404
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• 2014

Soil moisture is an important factor for the availability and circulation of nutrients in arable soil. The purpose of this study was to set thresholds moisture content on soil nitrate concentration in the solution for real-time diagnosis. Sandy loam, silt loam, and sandy loam was filled with $1.2g\;cm^{-3}$ at Wagner pots, 0, 100, and $200mg\;L^{-1}$ of $KNO_3$ was saturated. Nitrate in standard solution was recovered about 95% by passing the porous cup. Nitrate concentrations in sampling of soil solution were examined by using a porous cup. The soil solution was higher in accordance with sandy loam> silt loam> clay loam, limited water filled pore space for sampling soil solution was 33.7, 56.4, and 62.2%, respectively. Nitrate concentration in the soil solution was negligible at sandy loam and silt loam during sampling periods, which was decreased about 50~82% in clay loam compared to the initial $NO_3$-N concentration in the saturated $KNO_3$ solution. Over limitation of soil solution sampling, soil EC and $NO_3$-N content were increased with the saturated $NO_3$-N concentration, regardless of soil texture (p<0.05). Conclusively, soil solution by using a porous cup was possible, regardless of the soil texture, which was useful for the diagnosis in nitrate concentration of soil solution. However, because nitrate concentration of soil solution in a clay loam changes, it was necessary for careful attention in order to take advantage for the real-time diagnosis of nitrogen management in soil.