• Journal of the Korean GEO-environmental Society
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• v.8 no.2
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• pp.41-48
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• 2007

Zevo-valent iron (ZVI) has been widely used in permeable reactive barriers for reducing organic contaminants, such as trichloroethylene (TCE). The rapid reaction time, however, leads to decrease in reactivity and availability of ZVI. Shewanella algae BrY, a strain of dissimilatory iron reducing bacteria, can reduce the oxidized Fe (III) to Fe (II) and reduced Fe (II) can be reused to reduce the contaminant. The effect of Shewanella algae BrY on the reduction of the oxidized ZVI column and further TCE removal in the contaminated groundwater were studied at different flow rates and TCE input concentrations in this study. High input concentration of TCE and flow rate increase the amount of input contaminant and make to lower the effect of reduction by Shewanella algae BrY. Specially, the fast flow rate inhibits the direct contact and implantation on the surface of iron. The reduction of oxidized iron reactive barrier by Shewanella algae BrY can decrease the decreation of duration of PRBs by the precipitation of oxidized iron produced by dechlorination of TCE.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.8
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• pp.798-807
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• 2008

Due to economic impairment derived from metal corrosion of pumping station installed around coastal area, it was needed for related cause-effect to be investigated for understanding practical corrosion behavior and providing proper control. This research was thus carried out to determine whether the microbe can influence on metal corrosion along with its control in the laboratory. For this study, groundwater was sampled from the underground pump station(i.e. I Gas Station) where corrosion was observed. Microbial diversity on the samples were then obtained by 16S rDNA methods. From this, microbial populations showing corrosion behaviors against metals were reported as Leptothrix sp.(Iron oxidizing) and Desulfovibrio sp.(Sulfur reducing) Iron oxidizing bacteria were dominantly participating in the corrosion of iron, while sulfate reducing bacteria were more preferably producing precipitate of iron. In case of galvanized steel and stainless steel, iron oxidizing bacteria not only enhanced the corrosion, but also generated its scale of precipitate. Sulfate reducing bacteria had zinc steel corroded greater extent than that of iron oxidizing bacteria. In the inactivation test, chlorine or UV exposure could efficiently control bacterial growth. However as the inactivation intensity being increased beyond a threshold level, corrosion rate was unlikely escalated due to augmented chemical effect. It is decided that microbial corrosion could be differently taken place depending upon type of microbes or materials, although they were highly correlated. It could be efficiently retarded by given disinfection practices.

• Clean Technology
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• v.23 no.2
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• pp.172-180
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• 2017

Thermodynamic evaluation indicates that nearly 100% conversion of elemental mercury to oxidized mercury can be attained by HCl of several tens of ppm level at the temperature window of SCR reaction. Cu-, Fe-, Mn-chloride loaded $V_2O_5-WO_3/TiO_2$ catalysts revealed good NO removal activity at the operating temperature window of SCR process. The catalysts with high desorption temperature indicating adsorption strength of $NH_3$ revealed higher NO removal activity. The HCl fed to the reaction gases promoted the oxidation of mercury. However, the activity for the oxidation of elemental mercury to oxidized mercury by HCl was suppressed by $NH_3$ inhibiting the adsorption of HCl to catalyst surface under SCR reaction condition containing $NH_3$ for NO removal. Metal chloride loaded $V_2O_5-WO_3/TiO_2$ catalysts showed much higher activity for mercury oxidation than $V_2O_5-WO_3/TiO_2$ catalyst without metal chloride under SCR reaction condition. This is primarily attributed to the participation of chloride in metal chloride on the catalyst surface promoting the oxidation of elemental mercury.

• Clean Technology
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• v.27 no.2
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• pp.152-159
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• 2021

Volatile organic compounds (VOCs) occur in indoor and outdoor industrial and urban areas and cause environmental problems. Malodorous VOCs, along with aesthetic discomfort, can have a serious effect on the human body. Compared with the existing method of reducing malodorous VOCs, a wet scrubbing method using an electrolytic oxidant has the advantage of reducing pollutants and regenerating oxidants. This study investigated the optimal conditions for producing OCl^-, a chlorine-oxidant. Experiments were conducted by changing the type of anode and cathode electrode, the type of electrolyte, the concentration of electrolytes, and the current density. With Ti/IrO₂ as the anode electrode and Ti as the cathode electrode, OClproduction was highest and most stable. Although OCl^- production was similar with the use of KCl or NaCl, NaCl is preferable because it is cheap and easy to obtain. The effect of NaCl concentration and current density was examined, and the OCl^- production rate and concentration were highest at 0.75 M NaCl and 0.03 A cm^-2. However, considering the cost of electric power, OCl^- production under the conditions of 1.00 M NaCl and 0.01 A cm^-2 was most effective among the conditions examined. It is desirable to produce OCl^- by adjusting the current density in accordance with the concentration and characteristics of pollutants.

• Applied Chemistry for Engineering
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• v.7 no.2
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• pp.326-333
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• 1996

Dehydrogenation of 4-vinylcyclohexene(4-VCH) to ethylbenzene is elucidated via catalytic transfer hydrogenation with the heterogeneous catalyst of Pd/C. Hydrogen-donor solvent is ethanol or water. Oxidizers of the catalytic dehydrogenation reaction are mono- or dinitro compounds, $H_2O_2$, NaClOn (n=1~4), or oxygen at $70{\sim}110^{\circ}C$. The ratio of 4-VCH/Nitro compounds is 1:0.02 to 1:0.5 and 4-VCH vs. $H_2O_2$ or NaClOn (n=1~4) is 1:0.1 to 1:3.

• The Korean Journal of Food And Nutrition
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• v.14 no.5
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• pp.446-456
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• 2001

This study was carried out for the dietry safely based on the level of pesticide residues In 13 kinds of agricultural products consumed in Kyonggi-Do. Korea. From June to October 2000, sixteen organochlorine pesticides in 397 samples were analyzed by using GC/ECD and GC/MSD. According to the results, endosulfan were detected in 27(7.8%) samples and chlorothalonil were detected in 4(1.0%) samples. Detection ranges of endosulfan were 3.7437∼ 0.0488ppm for lettuce, 2.1902 ∼0.1423ppm for spinach, 2.4909 ∼0.0786ppm for mallow and 3.2333∼0.3997ppm for mustard leaf, respectively Chlorothalonil were 5.8097 for lettuce and 0.8962ppm for spinach. Consequently, six agricutural products were detected more than the maximum residue limits in Korea Endosulfan were detected In 5(1.8%) samples and cholrothalonil were detected in 1(0.3%) sample. Detection rates of endosulfan sulfate(45.9%) of agricultural products were more than $\alpha$-endosulfan(28.5% ) and $\beta$-endosulfan (23.9% ) .

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.4
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• pp.41-47
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• 2020

This study aims to develop eco-friendly propellant that reduce the generation of harmful gases such as HCl gas and increase the emmision of nitrogen gas emissions. For this purpose, GUDN(N-Guanylurea dinitramide) and BTATz(3,6-bis(1H-1,2,3,4-tetrazol-5-ylamino)-1,2,4,5-tetrazine), which are low carbon high nitrogen materials, were used instead of AP(Ammonium Perchlorate) and Al(Aluminium), which are gernerally used in solid propellant. The prepared propellants were analyzed for mechanical properties and combustion characteristics, performance and AGARD smoke classification. Compared with AP/Al propellant, GUDN/BTATz propellant tended to decrease mechanical and combustion rate. Also, as a result of the static test after the production of the 4-inch motor, the performance of combustion of the GUDN/BTATz propellant decreased, but it was confirmed that the secondary smoke was improved by reducing harmful gases such as HCl gas.

• Clean Technology
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• v.18 no.4
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• pp.446-450
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• 2012

Strong alkaline electrolyzed water which is produced in cathode by electrolyzing the solution where electrolytes (NaCl, $K_2CO_3$ etc.) are added in diaphragm electrolytic cell, is eco-friendly and has cleaning effects. So, it is viewed as a substitution of chemical cleaner. In addition, strong alkaline electrolyzed water is being used by some Japanese automobile and precision parts manufacturing industries. When strong alkaline electrolyzed water is produced by using diaphragm electrolytic cell, it is necessarily produced at the anode side. Since strong acidic electrolyzed water produced is discarded when its utilization cannot be found, production efficiency of electrolyzed water is consequently decreased. Also, there is a weakness electrolytic efficiency is decreasing due to the pollution of diaphragm. In order to overcome this, non-diaphragm all-in-one electrolytic cell integrated with electrode reaction chamber and dilution chamber was applied. Strong alkaline electrolyzed water was produced for different composition of electrolytes, and their properties and characteristics were identified. In comparing the properties between strong alkaline electrolyzed water produced in diaphragm electrolytic cell and that produced in all-in-one electrolytic cell, the differences in ORP and chlorine concentration were found. In emulsification test to confirm surface-active capability, similar results were obtained and strong alkaline electrolyzed water produced in non-diaphragm all-in-one electrolytic cell was identified to be useable as a cleaner like strong alkaline electrolyzed water produced in diaphragm electrolytic cell. Strong alkaline electrolyzed water produced in non-diaphragm all-in-one electrolytic cell is thought to have sterilizing power because it has active chlorine which is different from strong alkaline electrolyzed water produced in diaphragm electrolytic cell.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.137-137
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• 2011

급격한 세계인구의 증가에 의해 물 부족지역이 세계 각지로 확산되고 있다. 이에 따라, 건전한 수자원으로써 하수처리수의 재이용이 주목을 받고 있다. 하수처리수의 재이용시에는 특히, 재이용수의 미생물학적 안전성과 더불어 화학물질 등으로부터 기인할 수 있는 인체 및 생태계에의 리스크를 고려해야 한다. 미국 EPA는 병원성 미생물 뿐만 아니라 화학물질에 대한 안전성을 확보 차원에자외선/과산화수소 등의 고도산화처리법을 검토하였다. 1일 $10m^3$ 처리규모의 연속실험장치를 이용, 검토된 공정별 실제 하수 2차 처리수중에 존재하는 의약품류의 제거효과, 에너지 소비량 및 생태리스크 저감효과 등을 비교, 평가하였다. 에너지 소비량에 있어서는 공정별로 다소 차이가 있었으나, 본 실험동안 검출된 38종의 의약품류 제거에는 각 공정 모두 매우 효과적이었다. 에너지 소비측면에서는 오존 단독공정이 가장 적은 에너지 소비량에서 타 공정과 동일한 수준의 의약품류 서 막처리나 자외선 처리 등의 고도처리시설에 대한 정보를 재이용수 가이드라인에 제시하고 있는 반면, 우리나라에서는 재이용수중에 일정농도 이상의 염소가 잔류하도록 함으로써, 재이용수의 미생물학적 안전성 확보만을 고려하고 있다. 최근, 수환경분야에서는 의약품류라는 화학물질이 유럽, 미국 및 일본 등지를 중심으로 주목을 받아오고 있으며, 이들은 ng/L-${\mu}g$/L 수준으로 수환경중에서 검출되고 있다. 이들의 주요 발생원으로 하수처리시설이 지목되고 있으며, 따라서 하수처리수의 재이용시 잔류 의약품류에 의한 리스크 발생 가능성이 우려되고 있다. 이를 배경으로, 하수처리시설에서 의약품류를 효과적으로 제거할 수 있는 공정으로 오존 및 오존/자외선, 제거효과가 얻어졌다. 한편, 오존처리시 발암성 물질인 브로메이트($BrO_3^-$) 등과 같은 부생성물 생성 가능성을 고려하면, 오존 단독공정보다 상대적으로 많은 에너지를 소비하는 오존/자외선, 자외선/과산화수소 등의 고도산화처리법이 높은 적용성을 갖는 것으로 나타났다. 향후, 수자원 부족문제로 재이용수의 용도가 훨씬 다양해 질 것으로 예상된다. 그에 따라, 재이용수의 안전성 확보를 위해 보다 폭넓은 검토가 예상되지만, 현 단계에서는 오존을 포함, 다소 많은 에너지 소비가 예상되는 자외선을 이용한 고도산화처리법이 다양한 미량 화학물질의 제거에 유효한 공정으로 판단된다.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.6
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• pp.329-333
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• 2016

Disinfection by electrolysis would be useful for small wastewater treatment plant, combined sewer overflow, ballast water, swimming pool, and fish farming, where the transport, storage, and the use of chlorine gas is limited. This study investigated the feasibility of the electrolysis of dilute hydrochloric acid (HCl) for disinfection. The effects of HCl concentration, voltage and reaction time on the generation of oxidizing agents, HOCl, $O_3$, and $H_2O_2$, were examined in a series of batch test. The highest current efficiency was 99.3% which was found at 2.2%, 3 V, and 5 min of HCl concentration, voltage, and reaction time, respectively. Continuous electrolysis at 2.2% HCl, 3 V, and 5 min of the hydraulic retention time showed 97.4% of the current efficiency. Addition of sodium chloride up to 20 g/L linearly increased the oxidizing agents production. 92.2% of total coliforms were removed by the contact with the electrolyzed water.