• Title, Summary, Keyword: 영가철

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Decolorization and organic removal characteristics of a SBR process combined with zero-valent iron column (ZVI (Zero-Valent Iron)를 조합한 SBR 공정의 색도 및 유기물 제거 특성)

  • Choi, YoungGyun;Park, ByungJu;Kim, SeongHong
    • Journal of Korean Society of Water and Wastewater
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    • v.23 no.4
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    • pp.431-438
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    • 2009
  • The purpose of this study was to evaluate the performances of zero-valent iron (ZVI) combined SBR (Z-SBR) process in decolorization and organic removal of synthetic dye wastewater. The batch test for optimizing the operation parameters of ZVI column showed that the appropriate EBCT was around 11 min and the pH of the dye wastewater was below 7.0. During the step increase of influent color unit from 300 to 1,000cu, about 53 to 79% decolorization efficiency could be achieved in control SBR (C-SBR, without ZVI column), which resulted from destroying azo bond of synthetic dye in anaerobic condition. For the same influent color loading, Z-SBR showed always higher decolorization efficiency than C-SBR with an aid of ZVI reducing power. The TCOD concentration in Z-SBR effluent was 20-30mg/L lower than C-SBR effluent although the TCOD before and after ZVI column was nearly same. It means that breakdown of azo bond by ZVI reducing power could increase biodegradability of synthetic dye wastewater.

Optimization of Zero-valent Iron Technology for Color Removal from Real Dye Wastewater (염색폐수 색도 제거를 위한 영가철 기술 최적화)

  • Lee, Jae Woo;Oh, Young Khee;Cha, Daniel K.;Lee, Taewon;Ko, Kwang Baik
    • Journal of Korean Society on Water Environment
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    • v.25 no.5
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    • pp.758-763
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    • 2009
  • This study presents the optimal conditions of zero-valent iron (ZVI) pretreatment for color removal from real dye wastewater. Removal of color by ZVI was strongly subject to the acidity of the wastewater buffering the pH increased after ZVI reduction. The real dye wastewater did not contain a sufficient amount of acidity and thus it was necessary to supplement acid to the dye wastewater before treatment. In continuous operation of iron column, the empty bed contact time (EBCT) and initial pH were varied to find the optimal conditions. A non-linear regression model fitted well the experimental result predicting that the optimal EBCT and pH for 80% removal efficiency was present in the range of 57~90 and 5~5.9, respectively. Color of column effluents could be further removed in the following biological oxidation step and the biodegradability of wastewater was also enhanced after iron pretreatment.

Electrochemical Reduction of Perchlorate Ion on Porous Carbon Electrodes Deposited with Iron Nanoparticles (영가철 나노 입자가 전착된 다공성 탄소전극을 이용한 과염소산 이온의 전기화학적 환원)

  • Rhee, Insook;Kim, Eun Yong;Lee, Bokyoung;Paeng, Ki-Jung
    • Journal of the Korean Electrochemical Society
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    • v.18 no.2
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    • pp.81-85
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    • 2015
  • A method for degradation of the perchlorate anion ($ClO{_4}^-$) has been studied using electrochemically generated zero-valent iron (ZVI) deposited on a porous carbon electrode. The first strategy of this study is to produce the ZVI via the electrochemical reduction of iron (II) on a porous carbon electrode coated with a conducting polymer, instead of employing expensive $NaBH_4$. The present method produced well distributed ZVI on conducting polymer (polypyrrole thin film) and increased surface area. ZVI surface can be regenerated easily for successive reduction. The second strategy is to apply a mild reducing condition (-0.3 V) to enhance the efficiency of the degradation of perchlorate with ZVI without the evolution of hydrogen. The electrochemically generated ZVI nanoparticles may offer an alternative means for the complete destruction perchlorate without evolution of hydrogen in water with high efficiency and at low cost.

A Study on Enhancement of Nitrate Removal Efficiency using Surface-Modified Zero-Valent Iron Nanoparticles (표면개질된 영가철 나노입자를 이용한 질산성 질소 제거율 향상에 대한 연구)

  • Lim, Taesook;Cho, Yunchul;Cho, Changhwan;Choi, Sangil
    • Journal of Environmental Science International
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    • v.25 no.4
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    • pp.517-524
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    • 2016
  • In order to treat groundwater containing high levels of nitrate, nitrate reduction by nano sized zero-valent iron (nZVI) was studied using batch experiments. Compared to nitrate removal efficiencies at different mass ratios of $nitrate/Fe^0$, the removal efficiency at the mass ratio of 0.02% was the highest(54.59%). To enhance nitrate removal efficiency, surface modification of nZVI was performed using metallic catalysis such as Pd, Ni and Cu. Nitrate removal efficiency by Cu-nZVI (at $catalyst/Fe^0$ mass ratio of 0.1%) was 66.34%. It showed that the removal efficiency of Cu-nZVI was greater than that of the other catalysts. The observed rate constant ($k_{obs}$) of nitrate reduction by Cu-nZVI was estimated to $0.7501min^{-1}$ at the Cu/Fe mass ratio of 0.1%. On the other hand, TEM images showed that the average particle sizes of synthetic nZVI and Cu-nZVI were 40~60 and 80~100 nm, respectively. The results imply that catalyst effects may be more important than particle size effects in the enhancement of nitrate reduction by nZVI.

A Study for Recoverability of Iron Resource in Red Mud (레드머드 내 철 자원 회수 가능성 고찰)

  • Kim, Bong-Ju;Kwon, Jang-Soon;Koh, Yong-Kwon;Park, Cheon-Young
    • Economic and Environmental Geology
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    • v.53 no.3
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    • pp.297-306
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    • 2020
  • The red mud generated from bauxite during the Bayer alumina production process has been regarded as an industrial waste due to the high alkaline property and high content of Na. Despite of its environmental problem, various studies for recovery of the valuable resources from red mud has been also carried out because of high content (25.7 wt.% as Fe2O3 in this study) of iron in red mud. In order to recover the iron resource in the red mud, microwave heating experiments were performed with adding of activated carbon and elemental sulfur to the red mud. Through the microwave heating the powdered red mud mixtures converted to porous and vitrified solid aggregates. The vitrified aggregates produced by microwave heating are composed of goethite, zero valent iron (Fe0), pyrrhotite and pyrite. And then, the microwave heating samples were dissolved in the aqua regia solution, and Fe precipitates were obtained as a Fe-chlorides by adding of NaCl salt in the aqua regia solution. The Fe recovery rates in the Fe-chloride precipitates showed differences depending on the experimental mixture conditions, and Fe grades of the end products are 49.0 wt.%, 58.0 wt.% and 59.5 wt.% under mixture conditions of red mud, red mud + activated carbon, and red mud + activated carbon + elemental S, respectively. The Fe content of 56.0 wt.% is generally known as the grade value of Fe in a iron ore for iron production, and the Fe grades of microwave heating samples with adding activated carbon and elemental S in this study are higher than the grade value of 56.0 wt.%.

Removal of Nitrate by modified Nanoscale Zero-Valent Iron (개질된 Nanoscale Zero-Valent Iron을 이용한 질산성질소 처리)

  • Kim, Hong-Seok;Ahn, Jun-Young;Hwang, Kyung-Yup;Park, Joo-Yang;Hwang, Inseong
    • Journal of Korean Society of Water and Wastewater
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    • v.23 no.4
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    • pp.471-479
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    • 2009
  • A Nanoscale Zero-Valent Iron(NZVI) was modified to build a reactor system to treat nitrate. Shell layer of the NZVI was modified by slow exposure of the iron surface to air flow, which produced NZVI particles that are resistant to aerial oxidation. A XANES (X-ray Absorption Near-Edge Structure) analysis revealed that the shell consists of magnetite ($Fe_3O_4$) dominantly. The shell-modified NZVI(0.5 g NZVI/ 120 mL) was able to degrade more than 95% of 30 mg/L of nitrate within $30 hr^{-1}$ ( pseudo first-order rate constant($k_{SA}$) normalzed to NZVI surface area ($17.96m^2/g$) : $0.0050L{\cdot}m^{-2}{\cdot}hr^{-1}$). Ammonia occupied about 90% of degradation products of nitrate. Nitrate degradation efficiencies increased with the increase of NZVI dose generally. Initial pH values of the reactor systems at 4, 7, and 10 did not affect nitrate removal rate and final pH values of all experiments were near 12. Nitrate removal experiments by using the shell-modified NZVI immobilized on a cellulose acetate (CA) membrane were also conducted. The nitrate removal efficiency of the CA membrane supported NZVI ($k_{SA}=0.0036L{\cdot}m^{-2}{\cdot}hr^{-1}$) was less than that of the NZVI slurries($k_{SA}=0.0050L{\cdot}m^{-2}{\cdot}hr^{-1}$), which is probably due to less surface area available for reduction and to kinetic retardation by nitrate transport through the CA membrane. The detachment of the NZVI from the CA membrane was minimal and impregnation of up to 1 g of NZVI onto 1 g of the CA membrane was found feasible.

Dechlorination of the Fungicide Chlorothalonil by Zerovalent Iron and Manganese Oxides (Zerovalent Iron 및 Manganese Oxide에 의한 살균제 Chlorothalonil의 탈염소화)

  • Yun, Jong-Kuk;Kim, Tae-Hwa;Kim, Jang-Eok
    • The Korean Journal of Pesticide Science
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    • v.12 no.1
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    • pp.43-49
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    • 2008
  • This study is conducted to determine the potential of zerovalent iron (ZVI), pyrolusite and birnessite to remediate water contaminated with chlorothalonil. The degradation rate of chlorothalonil by treatment of ZVI, pyrolusite and birnessite was much higher in low condition of pH. Mixing an aqueous solution of chlorothalonil with 1.0% (w/v) ZVI, pyrolusite and birnessite resulted in 4.7, 13.46 and 21.38 hours degradation half-life of chlorothalonil, respectively. Dechlorination number of chlorothalonil by treaonent of ZVI, pyrolusite and birnessite exhibited 2.85, 1.12 and 1.09, respectively. Degradation products of chlorothalonil by teartment of pyrolusite and birnessite were confirmed as trichloro-1,3-dicyanobenzene and dichloro-1,3-dicyanobenzene which were dechlorinated one and two chlorine atoms from parent chlorothalonil by GC-mass. Degradation products of chlorothalonil by ZVI were identified not only as those by pyrolusite and birnessite but as further reduced chloro-1,3-dicyanobenzene and chlorocyanobenzene.

Investigation of Stabilization Effect on Arsenic Contamination Soils using Zerovalent Iron and Industrial by-products (영가철 및 산업폐기물을 활용한 비소오염토양의 안정화 효과조사)

  • Yu, Chan;Yun, Sung-Wook;Baek, Seung-Hwan;Park, Jin-Chul;Lee, Jung-Hoon;Lim, Young-Cheol;Choi, Seung-Jin;Jang, Min
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.229-241
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    • 2008
  • In order to investigate stabilization effect on As-contaminated soils treated by zero-valent iron(ZVI) and industrial by-products, batch tests and column tests were carried out with As-contaminated soils collected from farmland around the abandoned mine site. In batch tests, ZVI and industrial by-products(blast furnace slag, steel refining slag and oyster shell powder) were used as treatment materials to reduce As. Industrial by-products were mixed with As-contaminated soils, in the ratio of 1%, 3%, 5% and 7% on the weight base of dried soil. After incubation, all samples showed the reduction of As concentration and it was expected that ZVI and steel refining slag were effective treatment materials to remove As among treatment materials used in batch test. In column tests, columns were made by acrylic with the dimension of diameter=10cm, height=100cm, thickness=1cm and these columns were filled with untreated soils and treated soils mixed with ZVI and steel refining slag(mixing ratio=3%). Distilled water was discharged into the columns with the velocity of 1 pore-volume/day. During test, pH, EC, Eh and As concentration were measured in the regular term(1 pore-volume). As a result, ZVI and steel refining slag were shown 93%, 62% reduction of As concentration respectively by comparison with untreated soils. Therefore, if ZVI and steel refining slag are used as treatment materials in As-contaminated soils, it is expected that the As concentration in soils is reduced effectively.

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Oxidative Degradation of Phenol Using Zero-Valent Iron-Based Fenton-Like Systems (영가철 기반 펜톤 시스템을 활용한 페놀의 산화분해)

  • Kim, Hak-Hyeon;Lee, Hye-Jin;Kim, Hyung-Eun;Lee, Hongshin;Lee, Byeong-Dae;Lee, Changha
    • Journal of Soil and Groundwater Environment
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    • v.18 no.4
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    • pp.50-57
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    • 2013
  • For the last couple of decades, the Fenton (-like) systems have been extensively studied for oxidation of organic contaminants in water. Recently, zero-valent iron (ZVI) has received attention as a Fenton catalyst as well as a reducing agent capable of producing reactive oxidants from oxygen. In this study, the ZVI-based Fenton reaction was assessed for the oxidative degradation of phenol using $ZVI/O_2$, $ZVI/H_2O_2$, ZVI/Oxalate/$O_2$ and hv/ZVI/Oxalate/$O_2$ systems. Reaction parameters such as pH and reagent dose (e.g., ZVI, $H_2O_2$, and oxalate) were examined. In the presence of oxalate (ZVI/Oxalate/$O_2$ and hv/ZVI/Oxalate/$O_2$ systems), the degradation of phenol was greatly enhanced at neutral pH values. It was found that ZVI accelerates the Fenton reaction by reducing Fe(III) into Fe(II). The conversion of Fe(III) into Fe(II) by ZVI was more stimulated at acidic pH than at near-neutral pH values.

Remediation of Soil Contaminated with Persistent Organic Pollutants through Subcritical Water Degradation (아임계수 분해를 이용한 난분해성 물질로 오염된 토양의 정화 연구)

  • Choi, Jae-Heon;Lee, Hwan;Lee, Cheol-Hyo;Kim, Ju-Yup;Oh, Seok-Young
    • Journal of Korean Society of Environmental Engineers
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    • v.37 no.2
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    • pp.113-119
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    • 2015
  • This study examined remediation of soil contaminated with polychlorinated biphenyls (PCBs) and other persistent organic pollutants by using subcritical water. Our results showed that removal efficiency of PCBs from soil and treatment temperature were linearly proportional under subcritical conditions. The removal efficiency as increased as reacting period increased. PCBs contaminating fine particles in soil were less effectively removed than those in entire contaminated soil. Reaction of the zero-valent iron and PCBs under subcritical condition produced dechlorinated product, where most of the PCBs were oxidised while little remained as dechlorinated. Other organic pollutants, such as TPH, BTEX, TCE/PCE, and chlorpyrifos, were removed by more than 90% at $300^{\circ}C$. Considering removal efficiency and identification of by-products, we suggest that subcritical water treatment may be effectively applied to soils contaminated with various persistent organic pollutants.