• Journal of the Korean Applied Science and Technology
• /
• v.34 no.2
• /
• pp.217-224
• /
• 2017

This is a study on the removal of nitrate nitrogen from wastewater by oxidation and reduction reaction of zinc in an acidic atmosphere. The optimum removal rate of nitrate nitrogen and the optimum pH were studied by controlling the amount of zinc and sulfamic acid. The oxidation efficiency was higher at pH 2.0 in the range of pH 2.0 ~ 4.0 because the reaction occurred more strongly in strong acidic atmosphere. It is advantageous to reduce the nitrate ion to the final nitrogen gas by adding the sulfamic acid to the sulfurous acid because it consumes less $H^+$ ion than when the sulfamic acid is not present. According to the same amount of zinc, nitrate nitrogen was removed by 46.0% while sulfamic acid was not added, whereas nitrite nitrogen was removed by 93.0% by adding sulfamic acid. In addition, In this experiment, zinc was prepared in powder form and its reactivity was larger than that of other common zinc metal, so the removal efficiency was very high, about 80.0%, within one minute after the reaction.

• The Journal of Engineering Geology
• /
• v.12 no.3
• /
• pp.285-294
• /
• 2002

The origin of nitrate in confined groundwater was studied using oxygen ($\delta$180), hydrogen ($\delta$D), and nitrogen ($\delta$15N) stable isotopes, along with chemical data of NO3-N. We analyzed groundwaters from more than sixty manufactories producing natural mineral waters around the country During the period of 1998-2001, an average value of nitrate was fair]y low (0.95 mg/$\ell$), however, groundwaters from six sites showed more than 2 mg/$\ell$ of nitrate. The stable isotope data of the groundwaters are -8.3~-11 $\textperthousand$ $\delta$8O, -60~-75 $\textperthousand$ $\delta$D, which lies in an average range of the groundwaters. The nitrogen isotope data with -11.8~-5.1$\textperthousand$ $\delta$15N suggest that manure, organic nitrate, and fertilizers can not be the origin of nitrate in the goundwaters.

• Asian-Australasian Journal of Animal Sciences
• /
• v.24 no.4
• /
• pp.471-478
• /
• 2011

The objectives were to compare the ability of various rumen microbial fractions to reduce nitrate and to assess the effect of nitrate on in vitro fermentation characteristics. Physical and chemical methods were used to differentiate the rumen microbial population into the following fractions: whole rumen fluid (WRF), protozoa (Pr), bacteria (Ba), and fungi (Fu). The three nitrogen substrate treatments were as follows: no supplemental nitrogen source, nitrate or urea, with the latter two being isonitrogenous additions. The results showed that during 24 h incubation, WRF, Pr and Ba fractions had an ability to reduce nitrate, and the rate of nitrate disappearance for the Pr fraction was similar to the WRF fraction, while the Ba fraction needed an adaptation period of 12 h before rapid nitrate disappearance. The WRF fraction had the greatest methane ($CH_4$) production and the Pr fraction had the greatest prevailing $H_2$ concentration (p<0.05). Compared to the urea treatment, nitrate diminished net gas and $CH_4$ production during incubation (p<0.05), and ammonia-N ($NH_3$-N) concentration (p<0.01). Nitrate also increased acetate, decreased propionate and decreased butyrate molar proportions (p<0.05). The Pr fraction had the highest acetate to propionate ratio (p<0.05). The Pr fraction as well as the Ba fraction appears to have an important role in nitrate reduction. Nitrate did not consistently alter total VFA concentration, but it did shift the VFA profile to higher acetate, lower propionate and lower butyrate molar proportions, consistent with less $CH_4$ production by all microbial fractions.

• Journal of the Korean Society of Industry Convergence
• /
• v.2 no.2
• /
• pp.83-90
• /
• 1999

A cellulose acetate membrane containing silver nitrate was prepared by gelatinizing in water at $2^{\circ}C$ after evaporating solvent from the casting solution on a glass plate. Permeation experiments for oxygen and nitrogen were conducted in the ranges of temperature, $5-40^{\circ}C$ and pressure difference, $1-5kg/cm^2$ in order to investigate the effects of temperature and pressure difference on permeation characteristics of the membrane. When the evaporation time was increased, the permeability of oxygen decreased but the separation factor of oxygen against nitrogen increased since a more dense layer was formed on the membrane surface. When the silver nitrate was added, the permeation flux was doubled and the separation factor was improved from 3.0 to 3.3. This implies that silver nitrate acts as an oxygen carrier in the membrane.

• The Korean Journal of Ecology
• /
• v.27 no.3
• /
• pp.155-159
• /
• 2004

In order to gain a better understanding of how forests participate in the cycling of carbon, effects of nitrogen addition on soil respiration were investigated on the oak forest in Kongju, Korea. Study site was divided into control, treatment f and treatment 2 plots, with 5 replication in each plot. In each replicate of treatment 1 and treatment 2 were fertilized with ammonium nitrate (NH$_4$NO$_3$), 30 g/$m^2$ and 60 g/$m^2$, respectively. Soil respiration, soil temperature, ammonium-N and nitrate-N were measured during the experimental period. Ammonium-N and nitrate-N in Ta were higher than those in control and T$_1$. Ammonium-N and nitrate-N in top-soil and sub-soil decreased sharply in August after bi9 rainfall in July in T$_1$ and T$_2$, however, those in control plot increased. Soil respiration in T$_2$ Plot showed consistently higher than those in control and T$_1$ until the end of July. However, soil respiration was similar among the control, T$_1$ and T$_2$ in mid-August and September The amount of Co$_2$ released from soil respiration in control, T$_1$ and T$_2$ in mid-August was 8.0$\pm$0.4, 9.3$\pm$0.6 and 10.2$\pm$0.5 $\mu$mol$^{-1}$ ㆍm$^{-2}$ ㆍs$^{-1}$ , respectively. However, those in control, T$_1$ and T$_2$in mid-August was 13.0$\pm$0.4, 13.5$\pm$0.5, 13.3$\pm$0.6 $\mu$mol$^{-1}$ ㆍm$^{-2}$ ㆍ$^{-1}$ , respectively. The results suggest that nitrogen addition in this oak forest has a positive effect on soil respiration.

• Journal of Korean Society of Water and Wastewater
• /
• v.21 no.1
• /
• pp.139-147
• /
• 2007

For environmental remediation of a contaminated groundwater plume, the use of zero-valent metal represents one of the latest innovative technologies. In this study, the effects of denitrification by zero-valent iron adsorbed in mesoporous silicas have been studied for groundwater contaminant degradation. The mesoporous silica was functionalized with 3-mercaptopropyltrimethoxysilane (MPTS) ligands and the zero-valent iron precipitated in the mesopore of granular silica was made by $FeCl_2$ and $NaBH_4$. Hydrogen was exchanged with $Fe^{2+}$ ions in the granular silicas. And then the ions were reduced by sodium borohydride in the mesoporous silicas. The surface area of the silica determined via the BET method ranged from 858 to $1275m^2/g$. The reductive reaction of nitrate-nitrogen indicated that the degradation of nitrate-nitrogen appeared to be pseudo first-order with the observed reaction rate constant kobs ($0.1619h^{-1}$) and to be directly proportional to the specific surface area. Therefore, the mesoporous silica with nano zero-valent iron proposed as a novel treatment strategy for contaminated groundwater was successfully implemented herein for the removal of nitrate-nitrogen.

• Advances in environmental research
• /
• v.5 no.1
• /
• pp.51-59
• /
• 2016

In this study, nitrate reduction of real groundwater sample by 2.2%Cu-1.6%Pd-hematite catalyst was evaluated at different nitrate concentrations, catalyst concentrations, and recycling. Results show that the nitrate reduction is improved by increasing the catalyst concentration. Specific nitrate removal by 2.2%Cu-1.6%Pd-hematite increased linearly with the increase of nitrate concentration showing that the catalyst possesses significantly higher reduction capacity. More than 95% nitrate reduction was observed over five recycles by 2.2%Cu-1.6%Pd-hematite with ~56% nitrogen selectivity in all recycling batches. The results from this study indicate that stable reduction of nitrate in groundwater can be achieved by 2.2%Cu-1.6%Pd-hematite over the wide range of initial nitrate inputs.

• Asian Journal of Turfgrass Science
• /
• v.10 no.2
• /
• pp.125-142
• /
• 1996

Crassulacean acid metaholism (CAM) was investigated in leaves and stems of the succulent $C_4$dicot Portulaca oleracea L. Under 14-hour days, stem tissues showed much greater fluctuation of acidity than leaf tissues. But leaf and stem tissues showed almost same CAM-like pattern of acid fluctuation under 8-hour days. Stem tissues of R oleracea grown under the naturai environment showed high CAM activity, but no CAM activity was seen in leaves of those plants. In the naturally growing plants, the rapid acidification was seen in intact stems at dawn, but defoliated stems showed only a gradual increase. RuBP carlboxylase activity was very high at 2:00 P.M. in both leaves and stems. However, its activity at 1:00 A.M. and 5:30 AM. was hardly detected. particularly, activity of PEP carboxylase in leaves was very high in the early morning, though that in stem tissues was little. These results indicate that $CO_2$ passed through open stomata at dawn may be assimilated by PEP carboxylase in leaves, and then $C_4$ products move to stems. The levels of nitrate concentration and of nitrate reductase were higher in stems than in leaves. The levels were also higher in the light than in the dark. It would be suggested that considerable amount of nitrate absorbed from roots ho assimilated in stems, and nitrate transferred to leaves via stem tissues be reduced there. Key words: Portalaca oleracea, Cactus, Photosynthesis, Nitrogen assimilation, Crassulacean acid metabolism (CAM).

• Journal of Korean Society of Water and Wastewater
• /
• v.22 no.3
• /
• pp.307-314
• /
• 2008

In this study, the effects of applied voltage, solution pH and coexistence of other ions such as sulfate ion (${SO_4}^{2-}$) and chloride ion ($Cl^-$) were investigated on the removal of nitrate-nitrogen ($NO_3{^-}-N$) from ground water by electrodialysis. The examined operating conditions were evaluated for optimizing the removal efficiency of $NO_3{^-}-N$. Real ground water samples taken from a rural area of Yongin city and artificial ones with components similar to the real ground water were tested for the study, which contained $NO_3{^-}-N$ concentration of 17mg/L that exceeds current drinking water quality standard of 10 mg/L. The increase in the removal rate of $NO_3{^-}-N$ was observed as the applied voltage increased from 5V to 30V, while no significant increase in the removal rate appeared at the applied voltage beyond 20V during a given operating time. The removal rate appeared to get lower at both acidic and basic condition, compared to neutral pH. Coexistence of of ${SO_4}^{2-}$and $Cl^-$ demanded much longer operating time to achieve a given removal rate or to meet a certain level of treated water concentration. When nitrate ion was combined with ${SO_4}^{2-}$and $Cl^-$, the removal rate was reduced by 4.29% and 10.83%, respectively.

• Journal of Korean Society on Water Environment
• /
• v.31 no.3
• /
• pp.253-261
• /
• 2015

The purpose of this study is the efficient biological treatment of highly concentrated nitrate nitrogen by calcium ion control present within the pickling wastewater. In laboratory scale's experiments research was performed using a sequencing batch reactor and the evaluation of denitrification reaction in accordance with the injection condition of calcium ions, the surface properties of microorganisms, and the evaluation of sludge precipitability were performed. Results of the study showed that the denitrification reaction was delayed when injecting more than 600 mg/L of the calcium ion within the denitrification process. In addition, we observed the absorption form of calcium ions absorbed on the surface of microorganisms following an increase in the calcium ion dose. It was found that as the calcium ion dose increased the sludge precipitability also increased continuously and it is judged that a smooth denitrification induction is possible when treating the nitrate nitrogen by the calcium ion control of pickling waste water and the shortening of precipitation time enables a liquid operation to increase the reaction time.