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Jung KW, Choi BH, Lee SY, Ahn KH, Lee YJ. Green synthesis of aluminum-based metal organic framework for the removal of azo dye Acid Black 1 from aqueous media. J IND ENG CHEM 2018. [DOI: 10.1016/j.jiec.2018.07.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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2
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Jin H, Kang K, Ahn KH, Briels WJ, Dhont JKG. Non-local stresses in highly non-uniformly flowing suspensions: The shear-curvature viscosity. J Chem Phys 2018; 149:014903. [PMID: 29981556 DOI: 10.1063/1.5035268] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
For highly non-uniformly flowing fluids, there are contributions to the stress related to spatial variations of the shear rate, which are commonly referred to as non-local stresses. The standard expression for the shear stress, which states that the shear stress is proportional to the shear rate, is based on a formal expansion of the stress tensor with respect to spatial gradients in the flow velocity up to leading order. Such a leading order expansion is not able to describe fluids with very rapid spatial variations of the shear rate, like in micro-fluidics devices and in shear-banding suspensions. Spatial derivatives of the shear rate then significantly contribute to the stress. Such non-local stresses have so far been introduced on a phenomenological level. In particular, a formal gradient expansion of the stress tensor beyond the above mentioned leading order contribution leads to a phenomenological formulation of non-local stresses in terms of the so-called "shear-curvature viscosity". We derive an expression for the shear-curvature viscosity for dilute suspensions of spherical colloids and propose an effective-medium approach to extend this result to concentrated suspensions. The validity of the effective-medium prediction is confirmed by Brownian dynamics simulations on highly non-uniformly flowing fluids.
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Affiliation(s)
- H Jin
- School of Chemical and Biological Engineering, Institute of Chemical Process, Seoul National University, 151-744 Seoul, South Korea
| | - K Kang
- Institute of Complex Systems (ICS-3), Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - K H Ahn
- School of Chemical and Biological Engineering, Institute of Chemical Process, Seoul National University, 151-744 Seoul, South Korea
| | - W J Briels
- Institute of Complex Systems (ICS-3), Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - J K G Dhont
- Institute of Complex Systems (ICS-3), Forschungszentrum Jülich, D-52425 Jülich, Germany
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Jung KW, Jeong TU, Choi JW, Ahn KH, Lee SH. Adsorption of phosphate from aqueous solution using electrochemically modified biochar calcium-alginate beads: Batch and fixed-bed column performance. Bioresour Technol 2017; 244:23-32. [PMID: 28777987 DOI: 10.1016/j.biortech.2017.07.133] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 07/21/2017] [Accepted: 07/23/2017] [Indexed: 05/22/2023]
Abstract
Batch and continuous fixed-bed column studies were investigated using electrochemically modified biochar calcium-alginate beads (EMB-CABs) as an adsorbent for the removal of phosphate from aqueous solutions. Batch experiments revealed that the phosphate adsorption behavior of EMB-CABs and its structural characteristics were highly dependent on pH condition. Also, kinetics and equilibrium isotherms studies demonstrated that the experimental data correlated well with the pseudo-second-order and Sips isotherm models, respectively. The effects of different operating parameters such as bed height, initial phosphate concentration, and flow rate were investigated in a continuous fixed-bed column, and the experimental data were fitted to three different breakthrough models, the Adams-Bohart, Thomas, and Yoon-Nelson models. The results suggested that the Yoon-Nelson model showed better agreement with the breakthrough curves than other models. Lastly, the design parameters for a large-scale column were calculated via the scale-up approach using the breakthrough parameters obtained from lab-scale column tests.
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Affiliation(s)
- Kyung-Won Jung
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, 5 Hwarang-ro 14-gil, Seongbuk-gu, Seoul 02792, South Korea
| | - Tae-Un Jeong
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, 5 Hwarang-ro 14-gil, Seongbuk-gu, Seoul 02792, South Korea
| | - Jae-Woo Choi
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, 5 Hwarang-ro 14-gil, Seongbuk-gu, Seoul 02792, South Korea; Division of Energy and Environmental Engineering, KIST School, Korea University of Science and Technology, 5 Hwarang-ro 14-gil, Seongbuk-gu, Seoul 02792, South Korea
| | - Kyu-Hong Ahn
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, 5 Hwarang-ro 14-gil, Seongbuk-gu, Seoul 02792, South Korea
| | - Sang-Hyup Lee
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, 5 Hwarang-ro 14-gil, Seongbuk-gu, Seoul 02792, South Korea; Green School, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, South Korea.
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Moreno T, Querol X, Martins V, Minguillón MC, Reche C, Ku LH, Eun HR, Ahn KH, Capdevila M, de Miguel E. Formation and alteration of airborne particles in the subway environment. Environ Sci Process Impacts 2017; 19:59-64. [PMID: 28002504 DOI: 10.1039/c6em00576d] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Most particles in the rail subway environment are sub-micron sized ferruginous flakes and splinters generated mechanically by frictional wear of brake pads, wheels and rails. To better understand the mechanisms of formation and the alteration processes affecting inhalable particles in subways, PM samples (1-2.5 μm and 2.5-10 μm) were collected in the Barcelona Metro and then studied under a scanning electron microscope. Most particles in these samples are hematitic (up to 88%), with relatively minor amounts of mineral matter (up to 9%) and sulphates (up to 5%). Detailed microscopy (using back scattered and TEM-DRX imaging) reveals how many of the metallic particles comprise the metallic Fe nucleus surrounded by hematite (Fe2O3) and a coating of sulphate and chloride salts mixed with mineral matter (including Ca-carbonates, clay minerals and quartz). These observations record the emission of fine to ultrafine FePM by frictional wear at elevated temperatures that promote rapid partial (or complete) oxidation of the native metal. Water condensing on the PM surface during cooling leads to the adsorption of inorganic mineral particles that coat the iron oxide. The distinctively layered polymineralic structure that results from these processes is peculiar to particles generated in the subway environment and very different from PM typically inhaled outdoors.
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Affiliation(s)
- T Moreno
- Institute of Environmental Assessment and Water Research (IDÆA-CSIC), C/Jordi Girona 18-24, 08034 Barcelona, Spain.
| | - X Querol
- Institute of Environmental Assessment and Water Research (IDÆA-CSIC), C/Jordi Girona 18-24, 08034 Barcelona, Spain.
| | - V Martins
- Institute of Environmental Assessment and Water Research (IDÆA-CSIC), C/Jordi Girona 18-24, 08034 Barcelona, Spain.
| | - M C Minguillón
- Institute of Environmental Assessment and Water Research (IDÆA-CSIC), C/Jordi Girona 18-24, 08034 Barcelona, Spain.
| | - C Reche
- Institute of Environmental Assessment and Water Research (IDÆA-CSIC), C/Jordi Girona 18-24, 08034 Barcelona, Spain.
| | - L H Ku
- Department of Mechanical Engineering, Hanyang University, Ansan 425-791, Republic of Korea
| | - H R Eun
- Department of Mechanical Engineering, Hanyang University, Ansan 425-791, Republic of Korea
| | - K H Ahn
- Department of Mechanical Engineering, Hanyang University, Ansan 425-791, Republic of Korea
| | - M Capdevila
- Transports Metropolitans de Barcelona (TMB), Santa Eulalia, Av. del Metro s/n L'Hospitalet de Llobregat, 08902, Spain
| | - E de Miguel
- Transports Metropolitans de Barcelona (TMB), Santa Eulalia, Av. del Metro s/n L'Hospitalet de Llobregat, 08902, Spain
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Cho GJ, Ahn KH, Kim LY, Hwang SY, Hong SC, Oh MJ, Kim HJ. Effect of relative humidity on preeclampsia. CLIN EXP OBSTET GYN 2017; 44:264-267. [PMID: 29746035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
PURPOSE OF INVESTIGATION The authors aimed to determine the relationship between meteorological variables and hypertension in pregnancy by using data from a national weather database. MATERIALS AND METHODS For this population-based observational study, the database of the Korea National Health Insurance (KNHI) Claims of the Health Insurance Review and Assessment Service (HIRA) and Korea Meteorological Administration was used. The 48,275 women with preeclampsia among 2,495,383 women who gave birth were included. Monthly meteorological factors and preeclampsia prevalence for five years were statistically analyzed. RESULTS Among temperature, relative humidity, sunlight duration, and rainfall, only relative humidity had a significant inverse correlation with the preeclampsia prevalence (p < 0.001). The other meteorological factors were not associated with preeclampsia. CONCLUSION Relative humidity may be a significant factor for of the development of preeclampsia. Further monitoring of weather parameters during the entire pregnancy period may be the best method for verifying the present results in the development of preeclampsia.
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Jung KW, Choi BH, Jeong TU, Ahn KH. Facile synthesis of magnetic biochar/Fe3O4 nanocomposites using electro-magnetization technique and its application on the removal of acid orange 7 from aqueous media. Bioresour Technol 2016; 220:672-676. [PMID: 27638463 DOI: 10.1016/j.biortech.2016.09.035] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 09/05/2016] [Accepted: 09/08/2016] [Indexed: 06/06/2023]
Abstract
This study introduces a new methodology to synthesize magnetic biochar/Fe3O4 nanocomposites (M-BC) from marine macroalgae using a facile electro-magnetization technique. M-BC was prepared by stainless steel electrode-based electrochemical system, followed by pyrolysis. Physical and chemical analyses revealed that the porosity and magnetic properties were simultaneously improved via the electro-magnetization process, which enabled not only higher adsorption performance, but also easier separation/recovery from aqueous media at post-adsorption stage using a bar magnet. The adsorption equilibrium studies reveal that the Sips model satisfactorily predicts the adsorption capacity, which found to be 190, 297, and 382mgg(-1) at 10, 20, and 30°C, respectively. The overall findings indicate that one-step electro-magnetization technique can be effectively utilized for the fabrication of biochar with concurrent acquisition of porosity and magnetism, which can bring about new directions in the practical use of adsorption process in environment remediation and mitigate crises originating from it.
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Affiliation(s)
- Kyung-Won Jung
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, 5 Hwarang-ro 14-gil, Seongbuk-gu, Seoul 02792, South Korea
| | - Brian Hyun Choi
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, 5 Hwarang-ro 14-gil, Seongbuk-gu, Seoul 02792, South Korea; Department of Energy and Environmental Engineering, Korea University of Science and Technology, 217, Gajeong-ro, Yuseong-gu, Daejeon 34113, South Korea
| | - Tae-Un Jeong
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, 5 Hwarang-ro 14-gil, Seongbuk-gu, Seoul 02792, South Korea
| | - Kyu-Hong Ahn
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, 5 Hwarang-ro 14-gil, Seongbuk-gu, Seoul 02792, South Korea.
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Jung KW, Choi BH, Hwang MJ, Jeong TU, Ahn KH. Fabrication of granular activated carbons derived from spent coffee grounds by entrapment in calcium alginate beads for adsorption of acid orange 7 and methylene blue. Bioresour Technol 2016; 219:185-195. [PMID: 27494099 DOI: 10.1016/j.biortech.2016.07.098] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Revised: 07/21/2016] [Accepted: 07/22/2016] [Indexed: 05/27/2023]
Abstract
Biomass-based granular activated carbon was successfully prepared by entrapping activated carbon powder derived from spent coffee grounds into calcium-alginate beads (SCG-GAC) for the removal of acid orange 7 (AO7) and methylene blue (MB) from aqueous media. The dye adsorption process is highly pH-dependent and essentially independent of ionic effects. The adsorption kinetics was satisfactorily described by the pore diffusion model, which revealed that pore diffusion was the rate-limiting step during the adsorption process. The equilibrium isotherm and isosteric heat of adsorption indicate that SCG-GAC possesses an energetically heterogeneous surface and operates via endothermic process in nature. The maximum adsorption capacities of SCG-GAC for AO7 (pH 3.0) and MB (pH 11.0) adsorption were found to be 665.9 and 986.8mg/g at 30°C, respectively. Lastly, regeneration tests further confirmed that SCG-GAC has promising potential in its reusability, showing removal efficiency of more than 80% even after seven consecutive cycles.
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Affiliation(s)
- Kyung-Won Jung
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, 5 Hwarang-ro 14-gil, Seongbuk-gu, Seoul 02792, South Korea
| | - Brian Hyun Choi
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, 5 Hwarang-ro 14-gil, Seongbuk-gu, Seoul 02792, South Korea
| | - Min-Jin Hwang
- Future Environmental Research Center, Korea Institute of Toxicology, 17 Jeigok-gil, Munsan, Jinju, Gyeongsangnam-do 52834, South Korea
| | - Tae-Un Jeong
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, 5 Hwarang-ro 14-gil, Seongbuk-gu, Seoul 02792, South Korea
| | - Kyu-Hong Ahn
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, 5 Hwarang-ro 14-gil, Seongbuk-gu, Seoul 02792, South Korea.
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Jung KW, Hwang MJ, Park DS, Ahn KH. Comprehensive reuse of drinking water treatment residuals in coagulation and adsorption processes. J Environ Manage 2016; 181:425-434. [PMID: 27420166 DOI: 10.1016/j.jenvman.2016.06.041] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Revised: 05/27/2016] [Accepted: 06/22/2016] [Indexed: 06/06/2023]
Abstract
While drinking water treatment residuals (DWTRs) inevitably lead to serious problems due to their huge amount of generation and limitation of landfill sites, their unique properties of containing Al or Fe contents make it possible to reuse them as a beneficial material for coagulant recovery and adsorbent. Hence, in the present study, to comprehensively handle and recycle DWTRs, coagulant recovery from DWTRs and reuse of coagulant recovered residuals (CRs) were investigated. In the first step, coagulant recovery from DWTRs was conducted using response surface methodology (RSM) for statistical optimization of independent variables (pH, solid content, and reaction time) on response variable (Al recovery). As a result, a highly acceptable Al recovery of 97.5 ± 0.4% was recorded, which corresponds to 99.5% of the predicted Al recovery. Comparison study of recovered and commercial coagulant from textile wastewater treatment indicated that recovered coagulant has reasonable potential for use in wastewater treatment, in which the performance efficiencies were 68.5 ± 2.1% COD, 97.2 ± 1.9% turbidity, and 64.3 ± 1.0% color removals at 50 mg Al/L. Subsequently, in a similar manner, RSM was also applied to optimize coagulation conditions (Al dosage, initial pH, and reaction time) for the maximization of real cotton textile wastewater treatment in terms of COD, turbidity, and color removal. Overall performance revealed that the initial pH had a remarkable effect on the removal performance compared to the effects of other independent variables. This is mainly due to the transformation of metal species form with increasing or decreasing pH conditions. Finally, a feasibility test of CRs as adsorbent for phosphate adsorption from aqueous solution was conducted. Adsorption equilibrium of phosphate at different temperatures (10-30 °C) and initial levels of pH (3-11) indicated that the main mechanisms of phosphate adsorption onto CRs are endothermic and chemical precipitation; the surfaces are energetically heterogeneous for adsorbing phosphate.
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Affiliation(s)
- Kyung-Won Jung
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul, 130-650, South Korea
| | - Min-Jin Hwang
- Future Environmental Research Center, Korea Institute of Toxicology, 17 Jeigok-gil, Munsan, Jinju, Gyeongsangnam-do, 660-844, South Korea
| | - Dae-Seon Park
- Department of Civil and Environmental Engineering, KAIST, 291, Daehak-ro, Yuseong-gu, Daejeon, 341-141, South Korea
| | - Kyu-Hong Ahn
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul, 130-650, South Korea.
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Jung KW, Jeong TU, Kang HJ, Chang JS, Ahn KH. Preparation of modified-biochar from Laminaria japonica: Simultaneous optimization of aluminum electrode-based electro-modification and pyrolysis processes and its application for phosphate removal. Bioresour Technol 2016; 214:548-557. [PMID: 27179950 DOI: 10.1016/j.biortech.2016.05.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Revised: 05/01/2016] [Accepted: 05/03/2016] [Indexed: 06/05/2023]
Abstract
The preparation conditions of electro-modification (current density) and pyrolysis (pyrolysis temperature and heating rate) processes were simultaneously optimized using response surface methodology with the quadratic regression model associated with Box-Behnken design. By numerical optimization, the phosphate adsorption capacity of 245.06mg/g was achieved, corresponding to 99.9% of the predicted values under statistically optimized conditions (current density: 38.78mA/cm(2), pyrolysis temperature: 584.1°C, heating rate: 6.91°C/min). By considering R(2) and three error functions values, the experimental results of adsorption kinetics, and the equilibrium isotherms at different temperatures (10-30°C) showed that predictive pseudo-second-order and Sips isotherm models could adequately interpret the phosphate adsorption process for 'statistically optimized electrically modified'-biochar (SOEM-biochar). The maximum phosphate adsorption capacities of SOEM-biochar were found to be 273.9, 345.1, and 460.3mg/g at 10, 20, and 30°C, respectively, which are higher than that of other adsorbents reported in the literature.
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Affiliation(s)
- Kyung-Won Jung
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, 5 Hwarang-ro 14-gil, Seongbuk-gu, Seoul 02792, South Korea
| | - Tae-Un Jeong
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, 5 Hwarang-ro 14-gil, Seongbuk-gu, Seoul 02792, South Korea
| | - Ho-Jeong Kang
- Civil and Environmental Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, South Korea
| | - Jae-Soo Chang
- Department of Environmental Engineering, Korea maritime and Ocean University, 727 Taejong-ro, Yeongdo-gu, Busan 49112, South Korea
| | - Kyu-Hong Ahn
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, 5 Hwarang-ro 14-gil, Seongbuk-gu, Seoul 02792, South Korea.
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Jung KW, Hwang MJ, Jeong TU, Chau DM, Kim K, Ahn KH. Entrapment of powdered drinking water treatment residues in calcium-alginate beads for fluoride removal from actual industrial wastewater. J IND ENG CHEM 2016. [DOI: 10.1016/j.jiec.2016.05.017] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Jung KW, Jeong TU, Kang HJ, Ahn KH. Characteristics of biochar derived from marine macroalgae and fabrication of granular biochar by entrapment in calcium-alginate beads for phosphate removal from aqueous solution. Bioresour Technol 2016; 211:108-16. [PMID: 27010340 DOI: 10.1016/j.biortech.2016.03.066] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 03/11/2016] [Accepted: 03/13/2016] [Indexed: 06/05/2023]
Abstract
In this work, granular biochar, Laminaria japonica-derived biochar (LB)-calcium alginate beads (LB-CAB), was successfully prepared by dropping a mixture of powder biochar and alginate solution into a calcium chloride solution for phosphate adsorption. Among different marine macroalgae derived biochars, LB exhibited the best performance, showing a phosphate removal rate of 97.02%, which was attributed to its high Ca/P and Mg/P ratios. With increasing pyrolysis temperature up to 600°C, the physicochemical properties of LB became suitable for adsorbing phosphate. Experimental results of kinetics and equilibrium isotherms at different temperatures (10-30°C) showed that the phosphate adsorption process is endothermic and is mainly controlled by external mass transfer and the intraparticle diffusion rate. The maximum adsorption capacity was found to be 157.7mgg(-1) at 30°C, as fitted by the Langmuir-Freundlich model, which is higher than capacities of other powder form of biochars.
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Affiliation(s)
- Kyung-Won Jung
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, 5 Hwarang-ro 14-gil, Seongbuk-gu, Seoul 02792, South Korea
| | - Tae-Un Jeong
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, 5 Hwarang-ro 14-gil, Seongbuk-gu, Seoul 02792, South Korea
| | - Ho-Jeong Kang
- Civil and Environmental Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, South Korea
| | - Kyu-Hong Ahn
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, 5 Hwarang-ro 14-gil, Seongbuk-gu, Seoul 02792, South Korea.
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Wu T, Chen H, Gao P, Yu T, Chen Z, Liu Z, Ahn KH, Wang X, Cheong SW, Tyson TA. Pressure dependent structural changes and predicted electrical polarization in perovskite RMnO₃. J Phys Condens Matter 2016; 28:056005. [PMID: 26760118 DOI: 10.1088/0953-8984/28/5/056005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
High pressure x-ray diffraction measurements on perovskite RMnO3 (R = Dy, Ho and Lu) reveal that varying structural changes occur for different R ions. Large lattice changes (orthorhombic strain) occur in DyMnO3 and HoMnO3 while the Jahn-Teller (JT) distortion remains stable. Conversely, in the small R-ion system LuMnO3, Mn-O bond distortions are observed between 4 and 8 GPa with a broad minimum in the JT distortion. High pressure infrared measurements indicate that a phonon near 390 cm(-1) corresponding to the complex motion of the Mn and O ions changes anomalously for LuMnO3. It softens in the 4-8 GPa region, which is consistent with the structural change in Mn-O bonds and then hardens at higher pressures. By contrast, the phonons continuously harden with increasing pressure for DyMnO3 and HoMnO3. Density functional theory methods show that E-phase LuMnO3 is the most stable phase up to the 10 GPa pressure examined. Simulations indicate that the distinct structural change under pressure in LuMnO3 can possibly be used to optimize the electric polarization by pressure/strain.
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Affiliation(s)
- T Wu
- Department of Physics, New Jersey Institute of Technology, Newark, NJ 07102, USA
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Jung KW, Ahn KH. Fabrication of porosity-enhanced MgO/biochar for removal of phosphate from aqueous solution: Application of a novel combined electrochemical modification method. Bioresour Technol 2016; 200:1029-32. [PMID: 26476871 DOI: 10.1016/j.biortech.2015.10.008] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 10/02/2015] [Accepted: 10/06/2015] [Indexed: 05/28/2023]
Abstract
A novel combined electrochemical modification (CEM) method, using a graphite electrode-based electric field and MgCl2 as electrolyte, was newly developed to prepare porosity-enhanced biochar containing periclase (MgO) nanocomposites (PE-MgO/biochar). During the CEM method, the dried marine macroalgae was immersed in the MgCl2 solution, and a voltage of 20V was then applied for 10min prior to pyrolysis. Morphological and chemical analyses results showed that nano-sized MgO particles with a highly crystalline structure were dispersed and enriched on the surface of the PE-MgO/biochar, which enabled higher phosphate adsorption capability. In an adsorption equilibrium test, among various biochars, PE-MgO/biochar exhibited the highest phosphate adsorption capacity from aqueous solution with a Langmuir-Freundlich maximum adsorption capacity as high as 620mg-Pg(-1). It can be concluded that the newly introduced CEM method is a potent additional technique to effectively prepare modified-biochar in terms of a simple and time-saving modification method.
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Affiliation(s)
- Kyung-Won Jung
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650, South Korea
| | - Kyu-Hong Ahn
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650, South Korea.
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14
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Jung KW, Kim K, Jeong TU, Ahn KH. Influence of pyrolysis temperature on characteristics and phosphate adsorption capability of biochar derived from waste-marine macroalgae (Undaria pinnatifida roots). Bioresour Technol 2016; 200:1024-8. [PMID: 26482944 DOI: 10.1016/j.biortech.2015.10.016] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Revised: 09/30/2015] [Accepted: 10/01/2015] [Indexed: 06/05/2023]
Abstract
The collected roots of Undaria pinnatifida, the main waste in farming sites, accounting for 40-60% of annual production, was pyrolyzed under temperature ranging from 200 to 800°C to evaluate the influence of pyrolysis temperature on biochar properties and phosphate adsorption capacity. It was confirmed that an increase in the pyrolysis temperature led to a decrease of the yield of biochar, while ash content remained almost due to carbonization followed by mineralization. Elemental analysis results indicated an increase in aromaticity and decreased polarity at a high pyrolysis temperature. When the pyrolysis temperature was increased up to 400°C, the phosphate adsorption capacity was enhanced, while a further increase in the pyrolysis temperature lowered the adsorption capacity due to blocked pores in the biochar during pyrolysis. Finally, a pot experiment revealed that biochar derived from waste-marine macroalgae is a potent and eco-friendly alternative material for fertilizer after phosphate adsorption.
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Affiliation(s)
- Kyung-Won Jung
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650, South Korea
| | - Kipal Kim
- Environmental Business Team, R&D Division, KG Chemical, Sihwa Industrial Complex 1Da 106, 5, Somanggongwon-ro, Siheung-si, Gyeonggi-do 429-848, South Korea
| | - Tae-Un Jeong
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650, South Korea
| | - Kyu-Hong Ahn
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650, South Korea.
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Jung KW, Ahn KH. Dual purpose recovered coagulant from drinking water treatment residuals for adjustment of initial pH and coagulation aid in electrocoagulation process. Environ Technol 2015; 37:1605-1617. [PMID: 26593378 DOI: 10.1080/09593330.2015.1122096] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 11/15/2015] [Indexed: 06/05/2023]
Abstract
The present study is focused on the application of recovered coagulant (RC) by acidification from drinking water treatment residuals for both adjusting the initial pH and aiding coagulant in electrocoagulation. To do this, real cotton textile wastewater was used as a target pollutant, and decolorization and chemical oxygen demand (COD) removal efficiency were monitored. A preliminary test indicated that a stainless steel electrode combined with RC significantly accelerated decolorization and COD removal efficiencies, by about 52% and 56%, respectively, even at an operating time of 5 min. A single electrocoagulation system meanwhile requires at least 40 min to attain the similar removal performances. Subsequently, the interactive effect of three independent variables (applied voltage, initial pH, and reaction time) on the response variables (decolorization and COD removal) was evaluated, and these parameters were statistically optimized using the response surface methodology. Analysis of variance showed a high coefficient of determination values (decolorization, R(2) = 0.9925 and COD removal, R(2) = 0.9973) and satisfactory prediction second-order polynomial quadratic regression models. Average decolorization and COD removal of 89.52% and 94.14%, respectively, were achieved, corresponding to 97.8% and 98.1% of the predicted values under statistically optimized conditions. The results suggest that the RC effectively played a dual role of both adjusting the initial pH and aiding coagulant in the electrocoagulation process.
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Affiliation(s)
- Kyung-Won Jung
- a Center for Water Resources Cycle Research , Korea Institute of Science and Technology , Seoul , South Korea
| | - Kyu-Hong Ahn
- a Center for Water Resources Cycle Research , Korea Institute of Science and Technology , Seoul , South Korea
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Jung KW, Jeong TU, Hwang MJ, Kim K, Ahn KH. Phosphate adsorption ability of biochar/Mg-Al assembled nanocomposites prepared by aluminum-electrode based electro-assisted modification method with MgCl₂ as electrolyte. Bioresour Technol 2015; 198:603-610. [PMID: 26433157 DOI: 10.1016/j.biortech.2015.09.068] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Revised: 09/15/2015] [Accepted: 09/19/2015] [Indexed: 06/05/2023]
Abstract
In this work, the textural properties and phosphate adsorption capability of modified-biochar containing Mg-Al assembled nanocomposites prepared by an effective electro-assisted modification method with MgCl2 as an electrolyte have been determined. Structure and chemical analyses of the modified-biochar showed that nano-sized stonelike or flowerlike Mg-Al assembled composites, MgO, spinel MgAl2O4, AlOOH, and Al2O3, were densely grown and uniformly dispersed on the biochar surface. The adsorption isotherm and kinetics data suggested that the biochar/Mg-Al assembled nanocomposites have an energetically heterogeneous surface and that phosphate adsorption could be controlled by multiple processes. The maximum phosphate adsorption capacity was as high as 887 mg g(-1), as fitted by the Langmuir-Freundlich model, and is the highest value ever reported. It was concluded that this novel electro-assisted modification is a very attractive method and the biochar/Mg-Al assembled nanocomposites provide an excellent adsorbent that can effectively remove phosphate from aqueous solutions.
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Affiliation(s)
- Kyung-Won Jung
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650, South Korea
| | - Tae-Un Jeong
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650, South Korea
| | - Min-Jin Hwang
- Future Environmental Research Center, Korea Institute of Toxicology, 17 Jeigok-gil, Munsan, Jinju, Gyeongsangnam-do 660-844, South Korea
| | - Kipal Kim
- Environmental Business Team, R&D Division, KG Chemical, Sihwa Industrial Complex 1Da 106, 5, Somanggongwon-ro, Siheung-si, Gyeonggi-do 429-848, South Korea
| | - Kyu-Hong Ahn
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650, South Korea.
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17
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Jung KW, Hwang MJ, Jeong TU, Ahn KH. A novel approach for preparation of modified-biochar derived from marine macroalgae: Dual purpose electro-modification for improvement of surface area and metal impregnation. Bioresour Technol 2015; 191:342-345. [PMID: 26008889 DOI: 10.1016/j.biortech.2015.05.052] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Revised: 05/13/2015] [Accepted: 05/15/2015] [Indexed: 06/04/2023]
Abstract
In the present study, an aluminum electrode-based electrochemical process was newly adopted as a modification method for fabricating physically and chemically modified biochar derived from marine macroalgae. Specifically, a current density of 93.96 mA cm(-2) was applied for 5 min at pH 3.0. Subsequently, the mixture was stirred continuously for 30 min without electric field, and the dried sample was then pyrolyzed at 450 °C under a N2 environment for 2 h. SEM-EDS and XRD analyses clearly indicated that nano-sized aluminum crystals (beohemite, AlOOH) were uniformly present on the EM-biochar surface. Adsorption equilibrium tests showed that the phosphate adsorption onto EM-biochar agreed well with the Langmuir-Freundlich adsorption isotherm model, with a maximum adsorption capacity of 31.28 mg-P g(-1). These findings suggest that this novel and simple electro-modification method is a reasonable and effective option for simultaneously upgrading both the surface area and chemical properties of biochar.
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Affiliation(s)
- Kyung-Won Jung
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650, South Korea
| | - Min-Jin Hwang
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650, South Korea
| | - Tae-Un Jeong
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650, South Korea
| | - Kyu-Hong Ahn
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650, South Korea.
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Jung KW, Park DS, Hwang MJ, Ahn KH. Decolorization of Acid Orange 7 by an electric field-assisted modified orifice plate hydrodynamic cavitation system: Optimization of operational parameters. Ultrason Sonochem 2015; 26:22-29. [PMID: 25753312 DOI: 10.1016/j.ultsonch.2015.02.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 01/10/2015] [Accepted: 02/25/2015] [Indexed: 05/13/2023]
Abstract
In this study, the decolorization of Acid Orange 7 (AO-7) with intensified performance was obtained using hydrodynamic cavitation (HC) combined with an electric field (graphite electrodes). As a preliminary step, various HC systems were compared in terms of decolorization, and, among them, the electric field-assisted modified orifice plate HC (EFM-HC) system exhibited perfect decolorization performance within 40 min of reaction time. Interestingly, when H2O2 was injected into the EFM-HC system as an additional oxidant, the reactor performance gradually decreased as the dosing ratio increased; thus, the remaining experiments were performed without H2O2. Subsequently, an optimization process was conducted using response surface methodology with a Box-Behnken design. The inlet pressure, initial pH, applied voltage, and reaction time were chosen as operational key factors, while decolorization was selected as the response variable. The overall performance revealed that the selected parameters were either slightly interdependent, or had significant interactive effects on the decolorization. In the verification test, complete decolorization was observed under statistically optimized conditions. This study suggests that EFM-HC is a useful method for pretreatment of dye wastewater with positive economic and commercial benefits.
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Affiliation(s)
- Kyung-Won Jung
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650, South Korea
| | - Dae-Seon Park
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650, South Korea
| | - Min-Jin Hwang
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650, South Korea
| | - Kyu-Hong Ahn
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650, South Korea.
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Lee CG, Jeon JW, Hwang MJ, Ahn KH, Park C, Choi JW, Lee SH. Lead and copper removal from aqueous solutions using carbon foam derived from phenol resin. Chemosphere 2015; 130:59-65. [PMID: 25819762 DOI: 10.1016/j.chemosphere.2015.02.055] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Revised: 02/23/2015] [Accepted: 02/23/2015] [Indexed: 05/15/2023]
Abstract
Phenolic resin-based carbon foam was prepared as an adsorbent for removing heavy metals from aqueous solutions. The surface of the produced carbon foam had a well-developed open cell structure and the specific surface area according to the BET model was 458.59m(2)g(-1). Batch experiments showed that removal ratio increased in the order of copper (19.83%), zinc (34.35%), cadmium (59.82%), and lead (73.99%) in mixed solutions with the same initial concentration (50mgL(-1)). The results indicated that the Sips isotherm model was the most suitable for describing the experimental data of lead and copper. The maximum adsorption capacity of lead and copper determined to Sips model were 491mgg(-1) and 247mgg(-1). The obtained pore diffusion coefficients for lead and copper were found to be 1.02×10(-6) and 2.42×10(-7)m(2)s(-1), respectively. Post-sorption characteristics indicated that surface precipitation was the primary mechanism of lead and copper removal by the carbon foam, while the functional groups on the surface of the foam did not affect metal adsorption.
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Affiliation(s)
- Chang-Gu Lee
- Center for Water Resource Cycle Research, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791, Republic of Korea
| | - Jun-Woo Jeon
- Center for Water Resource Cycle Research, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791, Republic of Korea
| | - Min-Jin Hwang
- Center for Water Resource Cycle Research, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791, Republic of Korea
| | - Kyu-Hong Ahn
- Center for Water Resource Cycle Research, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791, Republic of Korea
| | - Chanhyuk Park
- Center for Water Resource Cycle Research, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791, Republic of Korea
| | - Jae-Woo Choi
- Center for Water Resource Cycle Research, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791, Republic of Korea; Department of Energy and Environmental Engineering, University of Science and Technology (UST), Daejeon 305-350, Republic of Korea.
| | - Sang-Hyup Lee
- Center for Water Resource Cycle Research, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791, Republic of Korea; Green School, Korea University, 145, Anam-ro, Seongbuk-gu, Seoul 136-701, Republic of Korea.
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Jung KW, Hwang MJ, Park DS, Ahn KH. Combining fluidized metal-impregnated granular activated carbon in three-dimensional electrocoagulation system: Feasibility and optimization test of color and COD removal from real cotton textile wastewater. Sep Purif Technol 2015. [DOI: 10.1016/j.seppur.2015.03.043] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Jung KW, Hwang MJ, Cha MJ, Ahn KH. Application and optimization of electric field-assisted ultrasonication for disintegration of waste activated sludge using response surface methodology with a Box-Behnken design. Ultrason Sonochem 2015; 22:437-445. [PMID: 25023828 DOI: 10.1016/j.ultsonch.2014.06.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 06/16/2014] [Accepted: 06/16/2014] [Indexed: 06/03/2023]
Abstract
In the present study, an electric field is applied in order to disintegrate waste activated sludge (WAS). As a preliminary step, feasibility tests are investigated using different applied voltages of 10-100V for 60min. As the applied voltage increases, the disintegration degrees (DD) are gradually enhanced, and thereby the soluble N, P, and carbohydrate concentrations increase simultaneously due to the WAS decomposition. Subsequently, an optimization process is conducted using a response surface methodology with a Box-Behnken design (BBD). The total solid concentration, applied voltage, and reaction time are selected as independent variables, while the DD is selected as the response variable. The overall results demonstrate that the BBD with an experimental design can be used effectively in the optimization of the electric field treatment of WAS. In the confirmation test, a DD of 10.26±0.14% is recorded, which corresponds to 99.1% of the predicted response value under the statistically optimized conditions. Finally, the statistic optimization of the combined treatment (electric field+ultrasonication) demonstrated that even though this method is limited to highly disintegrated WAS when it is applied individually, a high DD of 47.28±0.20% was recorded where the TS concentration was 6780mg/l, the strength of ultrasonication was 8.0W, the applied voltage was 68.4V, and the reaction time was 44min. E-SEM images clearly revealed that the application of the electric field is a significant alternative method for the combined treatment of WAS. This study was the first attempt to increase disintegration using the electric field for a combined treatment with ultrasonication.
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Affiliation(s)
- Kyung-Won Jung
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650, South Korea.
| | - Min-Jin Hwang
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650, South Korea
| | - Min-Jung Cha
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650, South Korea
| | - Kyu-Hong Ahn
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650, South Korea
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22
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Han SY, Ryu KJ, Ahn KH, Cho SB, Lee CH, Hong SC. Conservative treatment of uterine fistula with abdominal abscess after caesarean section. J OBSTET GYNAECOL 2014; 35:650-1. [PMID: 25496617 DOI: 10.3109/01443615.2014.987115] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- S Y Han
- a Department of Obstetrics and Gynecology , College of Medicine, Korea University , Seoul , Republic of Korea
| | - K J Ryu
- a Department of Obstetrics and Gynecology , College of Medicine, Korea University , Seoul , Republic of Korea
| | - K H Ahn
- a Department of Obstetrics and Gynecology , College of Medicine, Korea University , Seoul , Republic of Korea
| | - S B Cho
- b Department of Radiology , College of Medicine, Korea University , Seoul , Republic of Korea
| | - C H Lee
- c Department of Science , University of Manitoba , Winnipeg , MB , Canada
| | - S C Hong
- a Department of Obstetrics and Gynecology , College of Medicine, Korea University , Seoul , Republic of Korea
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Yu T, Tyson TA, Chen HY, Abeykoon AMM, Chen YS, Ahn KH. Absence of significant structural changes near the magnetic ordering temperature in small-ion rare earth perovskite RMnO3. J Phys Condens Matter 2014; 26:495402. [PMID: 25396338 DOI: 10.1088/0953-8984/26/49/495402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Detailed structural measurements on multiple length scales were conducted on a new perovskite phase of ScMnO3, and on orthorhombic LuMnO3 as a benchmark. Complementary density functional theory (DFT) calculations were carried out, and predict that ScMnO3 possesses E-phase magnetic order at low temperature with displacements of the Mn sites (relative to the high temperature state) of ∼0.07 Å, compared to ∼0.04 Å predicted for LuMnO3. However, detailed local, intermediate and long-range structural measurements by x-ray pair distribution function analysis, single crystal x-ray diffraction and x-ray absorption spectroscopy, find no local or long-range distortions on crossing into the low temperature E-phase of the magnetically ordered state. The measurements place upper limits on any structural changes to be at most one order of magnitude lower than DFT predictions and suggest that this theoretical approach does not properly account for the spin-lattice coupling in these oxides and may possibly predict the incorrect magnetic order at low temperatures. The results suggest that the electronic contribution to the electrical polarization dominates and should be more accurately treated in theoretical models.
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Affiliation(s)
- T Yu
- Department of Physics, New Jersey Institute of Technology, Newark, NJ 07102, USA
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24
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Han SY, Ahn KH, Lee CH, Hong SC, Oh MJ, Kim HJ. Concomitant therapy with hysterectomy and arterial embolisation for postpartum uterine haemorrhage. J OBSTET GYNAECOL 2014; 35:424-5. [PMID: 25207796 DOI: 10.3109/01443615.2014.954100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- S Y Han
- Department of Obstetrics and Gynaecology, Korea University Medical Center, College of Medicine, Korea University , Seoul , South Korea
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25
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Jung KW, Hwang MJ, Yun YM, Cha MJ, Ahn KH. Development of a novel electric field-assisted modified hydrodynamic cavitation system for disintegration of waste activated sludge. Ultrason Sonochem 2014; 21:1635-40. [PMID: 24798225 DOI: 10.1016/j.ultsonch.2014.04.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 04/15/2014] [Accepted: 04/15/2014] [Indexed: 05/07/2023]
Abstract
In this current study, we present a modified hydrodynamic cavitation device that combines an electric field to substitute for the chemical addition. A modified HC system is basically an orifice plate and crisscross pipe assembly, in which the crisscross pipe imparts some turbulence, which creates collision events. This study shows that for maximizing disintegration, combining HC system, which called electric field-assisted modified orifice plate hydrodynamic cavitation (EFM-HC) in this study, with an electric field is important. Various HC systems were compared in terms of disintegration of WAS, and, among them, the EFM-HC system exhibited the best performance with the highest disintegration efficiency of 47.0±2.0% as well as the destruction of WAS morphological characteristics. The experimental results clearly show that a conventional HC system was successfully modified. In addition, electric field has a great potential for efficient disintegration of WAS for as a additional option in a combination treatment. This study suggests continued research in this field may lead to an appropriate design for commercial use.
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Affiliation(s)
- Kyung-Won Jung
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seonbuk-gu, Seoul 136-791, Republic of Korea.
| | - Min-Jin Hwang
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seonbuk-gu, Seoul 136-791, Republic of Korea
| | - Yeo-Myeong Yun
- Department of Civil and Environmental Engineering, KAIST, 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701, Republic of Korea
| | - Min-Jung Cha
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seonbuk-gu, Seoul 136-791, Republic of Korea
| | - Kyu-Hong Ahn
- Center for Water Resources Cycle Research, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seonbuk-gu, Seoul 136-791, Republic of Korea
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26
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Park KY, Maeng SK, Ahn KH, Lee K, Choi OK, Lee JW. Carbon dioxide injection method for enhancing hydrogenotrophic denitrification of secondary wastewater effluent in fixed bed reactor. BIOTECHNOL BIOPROC E 2013. [DOI: 10.1007/s12257-012-0537-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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27
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Lee JY, Choi BK, Maeng SK, Ahn KH, Song KG. Performance of a Coagulant-Membrane Bioreactor for the Removal of Dissolved Organic Matter and Phosphorus. J Chem Eng Japan / JCEJ 2013. [DOI: 10.1252/jcej.12we134] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Jung-Yeol Lee
- Center for Water Resource Cycle, Korea Institute of Science and Technology
| | - Bo-Kyung Choi
- Center for Water Resource Cycle, Korea Institute of Science and Technology
| | - Sung Kyu Maeng
- Department of Civil and Environmental Engineering, Sejong University
| | - Kyu-Hong Ahn
- Center for Water Resource Cycle, Korea Institute of Science and Technology
| | - Kyung-Guen Song
- Center for Water Resource Cycle, Korea Institute of Science and Technology
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28
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Bae HS, Ahn KH, Oh MJ, Kim HJ, Hong SC. Postpartum uterine involution: sonographic changes in the endometrium between 2 and 6 weeks postpartum related to delivery mode and gestational age at delivery. Ultrasound Obstet Gynecol 2012; 39:727-728. [PMID: 22223478 DOI: 10.1002/uog.11069] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
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29
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Cho KW, Yoon MH, Song KG, Ahn KH. The effects of antecedent dry days on the nitrogen removal in layered soil infiltration systems for storm run-off control. Environ Technol 2011; 32:747-755. [PMID: 21879550 DOI: 10.1080/09593330.2010.511278] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The effects of antecedent dry days (ADD) on nitrogen removal efficiency were investigated in soil infiltration systems, with three distinguishable layers: mulch layer (ML), coarse soil layer (CSL) and fine soil layer (FSL). Two sets of lab-scale columns with loamy CSL (C1) and sandy CSL (C2) were dosed with synthetic run-off, carrying chemical oxygen demand of 100 mg L(-1) and total nitrogen of 13 mg L(-1). The intermittent dosing cycle was stepwise adjusted for 5, 10 and 20 days. The influent ammonium and organic nitrogen were adsorbed to the entire depth in C1, while dominantly to the FSL in C2. In both columns, the effluent ammonium concentration increased while the organic nitrogen concentration decreased, as ADD increased from 5 to 20 days. The effluent of C1 always showed nitrate concentration exceeding influent, caused by nitrification, by increasing amounts as ADD increased. However, the wash-out of nitrate in C1 was not distinct in terms of mass since the effluent flow rate was only 25% of the influent. In contrast, efficient reduction (>95%) of nitrate loading was observed in C2 under ADD of 5 and 10 days, because of insignificant nitrification in the CSL and denitrification in the FSL. However, for the ADD of 20 days, a significant nitrate wash-out appeared in C2 as well, possibly because of the re-aeration by the decreasing water content in the FSL. Consequently, the total nitrogen load escaping with the effluent was always smaller in C2, supporting the effectiveness of sandy CSL over loamy FSL for nitrogen removal under various ADDs.
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Affiliation(s)
- Kang-Woo Cho
- Water Environment Centre, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650, Korea
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30
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Park KY, Lee JW, Song KG, Ahn KH. Ozonolysate of excess sludge as a carbon source in an enhanced biological phosphorus removal for low strength wastewater. Bioresour Technol 2011; 102:2462-2467. [PMID: 21109429 DOI: 10.1016/j.biortech.2010.11.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2010] [Revised: 10/28/2010] [Accepted: 11/01/2010] [Indexed: 05/30/2023]
Abstract
Potential use of the municipal sludge ozonolysate as a carbon source was examined for phosphorus removal from low strength wastewater in a modified intermittently decanted extended aeration (IDEA) process. At ozone dosage of 0.2 g O(3)/g solids, readily biodegradable COD accounted for about 36% of COD from sludge ozonolysate. The denitrification potential of ozonolysate as a carbon source was comparable to that of acetate. Although, the first order constant for phosphorus release with the ozonolysate was half that of acetate, it was much higher than that of wastewater. Continuous operation of the modified IDEA process showed that the removals of nitrogen and phosphorus were simultaneously enhanced by addition of the ozonolysate. Phosphorus release was significantly induced after complete denitrification indicating that phosphorus release was strongly depended on nitrate concentration. Effectiveness of the ozonolysate as a carbon source for EBPR was also confirmed in a track study of the modified IDEA.
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Affiliation(s)
- K Y Park
- Department of Civil and Environmental System Engineering, Konkuk University, Seoul, South Korea
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31
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Kim KP, Ahmed Z, Song KG, Magram SF, Daoud MHH, Ahn KH, Paeng KJ. Adsorption of Aluminum Ion from Water on Alginate-Modified Polyurethane. J Chem Eng Japan / JCEJ 2011. [DOI: 10.1252/jcej.10we154] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Ki-Pal Kim
- Center for Environmental Technology Research, Energy and Environment Research Division, Korea Institute of Science and Technology
| | - Zubair Ahmed
- Department of Civil Engineering, King Abdul Aziz University
| | - Kyung-Guen Song
- Center for Environmental Technology Research, Energy and Environment Research Division, Korea Institute of Science and Technology
| | | | | | - Kyu-Hong Ahn
- Center for Environmental Technology Research, Energy and Environment Research Division, Korea Institute of Science and Technology
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Kiso Y, Jung YJ, Yamamoto H, Oguchi T, Kuzawa K, Yamada T, Kim SS, Ahn KH. The effect of co-existing solutes on arsenate removal with hydrotalcite compound. Water Sci Technol 2010; 61:1183-1188. [PMID: 20220240 DOI: 10.2166/wst.2010.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Hydrotalcite (HTAL-Cl), an inorganic anion exchanger, is of use as an adsorbent for the removal of arsenate (As(V)) in water systems. The adsorption properties of HTAL-Cl for As(V) and the effects of co-existing anions on the As(V) removal performance were investigated in this work. Under the conditions of pH>or=4, the adsorption capacity for As(V) gradually decreased with an increase of pH, but As(V) was removed effectively within the range of pH = 5-8. Co-existing anions interfered As(V) removal, and the effect decreased in the order of HPO(4)(2-) > HCO(3)(-) > SO(4)(2-) > Cl(-). In binary solute systems containing phosphate and As(V), the maximum adsorption capacity of HTAL-Cl was 0.95 mmol g(-1) for phosphate and 0.65 mmol g(-1) for As(V): the total of these values corresponded to the maximum adsorption capacity for As(V) in single solute systems. The adsorption isotherms in these binary solute systems were approximated by the following modified Langmuir equations:As(V): q(As) = 18.7 radicalC(As)/(1 + 21.5 radicalC(P) + 12.8 radicalC(As)), phosphate : q(P) = 33.1 radicalC(P)/(1 + 21.5 radicalC(P) + 12.8 radicalC(As)). The column adsorption experiments showed that the adsorbed As(V) was released by the phosphate adsorption, because phosphate was adsorbed more strongly on HTAL-CL than As(V).
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Affiliation(s)
- Y Kiso
- Department of Ecological Engineering, Toyohashi University of Technology, Toyohashi, Japan
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Park KY, Maeng SK, Song KG, Ahn KH. Ozone treatment of wastewater sludge for reduction and stabilization. J Environ Sci Health A Tox Hazard Subst Environ Eng 2008; 43:1546-1550. [PMID: 18821242 DOI: 10.1080/10934520802293719] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Ozonation was applied to wastewater sludge for reduction and stabilization. Ozone was found to be very effective at reducing sludge and producing a useful carbon source. An ozone dose of 0.3 g/gDS fulfilled the criteria for the disinfection of class A type biosolids. The sludge treated with 0.5 gO(3)/gDS produced no hydrogen sulfide for a month at 29 degrees C. Ozonation resulted in low pH conditions, which might facilitate the mobilization of heavy metals from sludge. The results of a geotechnical investigation proved that the residuals of ozone-treated sludge did not meet the required properties required for landfill cover without the addition of quick lime.
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Affiliation(s)
- K Y Park
- Department of Civil and Environmental System Engineering, Konkuk University, Seoul, Korea.
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Lee JW, Cha DK, Kim I, Son A, Ahn KH. Fatty acid methyl ester (FAME) technology for monitoring biological foaming in activated sludge: full scale plant verification. Environ Technol 2008; 29:199-206. [PMID: 18613618 DOI: 10.1080/09593330802028808] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Fatty acid methyl ester (FAME) technology was evaluated as a monitoring tool for quantification of Gordonia amarae in activated sludge systems. The fatty acid, 19:1 alcohol, which was identified as a unique fatty acid in G. amarae was not only confirmed to be present in foaming plant samples, but the quantity of the signature peak correlated closely with the degree of foaming. Foaming potential experiment provided a range of critical foaming levels that corresponded to G. amarae population. This range of critical Gordonia levels was correlated to the threshold signature FAME amount. Six full-scale wastewater treatment plants were selected based on a survey to participate in our full-scale study to evaluate the potential application of the FAME technique as the Gordonia monitoring tool. Greater amounts of signature FAME were extracted from the mixed liquor samples obtained from treatment plants experiencing Gordonia foaming problems. The amounts of signature FAME correlated well with the conventional filamentous counting technique. These results demonstrated that the relative abundance of the signature FAMEs can be used to quantitatively monitor the abundance of foam-causing microorganism in activated sludge.
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Affiliation(s)
- J W Lee
- Department of Environmental Engineering, Korea University, ChoongNam 339-800, Korea
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35
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Kim KP, Song KG, Ahmed Z, Paeng KJ, Ahn KH. Enhancement of Phosphorus Removal in a Polyurethane Compressible Media Filtration System with Coagulation. J Chem Eng Japan 2008. [DOI: 10.1252/jcej.08we013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Ki-Pal Kim
- Center for Environmental Technology Research, Korea Institute of Science and Technology
| | - Kyung-Guen Song
- Center for Environmental Technology Research, Korea Institute of Science and Technology
| | - Zubair Ahmed
- Center for Environmental Technology Research, Korea Institute of Science and Technology
| | | | - Kyu-Hong Ahn
- Center for Environmental Technology Research, Korea Institute of Science and Technology
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Ahmed Z, Lim BR, Cho J, Song KG, Kim KP, Ahn KH. Biological nitrogen and phosphorus removal and changes in microbial community structure in a membrane bioreactor: effect of different carbon sources. Water Res 2008; 42:198-210. [PMID: 17640701 DOI: 10.1016/j.watres.2007.06.062] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2007] [Revised: 06/15/2007] [Accepted: 06/24/2007] [Indexed: 05/16/2023]
Abstract
Bacterial community structures in four sequencing anoxic/anaerobic-aerobic membrane bioreactors (SAMs) that were fed with synthetic medium composed of different organic compounds in substrate as carbon source; acetate-dominant (acetate/propionate = 4/1), propionate-dominant (acetate/propionate = 1/4), glucose-dominant (glucose/acetate = 4/1) and methanol-dominant (methanol/acetate/propionate = 6/3/1) were analyzed by respiratory quinone profile and fluorescent in situ hybridization (FISH) techniques. The SAMs were operated at controlled pH range 7-8.5 and at constant temperature 25 degrees C. Total nitrogen (TN), total phosphorus (TP) and COD removal performances were also evaluated and compared. In addition, trans-membrane pressure was monitored to observe the impact of substrate composition on membrane fouling. The dominance of the mole fraction of ubiquinone (UQ-8) in the SAMs indicated dominance of the beta-subclass of Proteobacteria; however, its population comparatively decreased when the substrate was glucose dominant or methanol dominant. A relatively higher and stable enhanced biological phosphorus removal performance was observed when methanol-dominant substrate was used concurrently with an increase in the gamma-subclass of Proteobacteria. The population of the alpha-subclass of Proteobacteria slightly increased along with a decrease in phosphate removal activity when the substrate was glucose-dominant. Results from FISH analysis also supported the findings of the quinone profile. The trans-membrane pressure variation in the SAMs indicated that fouling was relatively rapid when propionate-dominant or methanol-dominant substrate was used and most stable when glucose-dominant substrate was used. A combination of methanol and acetate would be a better choice as an external carbon source when nutrients removals, as well as fouling, are considered in the membrane bioreactor- (MBR-) coupled biological nutrients removing (BNR) process.
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Affiliation(s)
- Zubair Ahmed
- Center for Environmental Technology Research, Energy & Environment Research Division, Korea Institute of Science and Technology, Seoul 130-650, Republic of Korea.
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Ko KB, Park CG, Moon TH, Ahn YH, Lee JK, Ahn KH, Park JH, Yeom IT. Advanced H2O2 oxidation for diethyl phthalate degradation in treated effluents: effect of nitrate on oxidation and a pilot-scale AOP operation. Water Sci Technol 2008; 58:1031-1037. [PMID: 18824801 DOI: 10.2166/wst.2008.461] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
One of the objectives of this study was to delineate the effect of nitrate on diethyl phthalate (DEP) oxidation by conducting a bench-scale ultraviolet (UV)/H2O2 and O3/H2O2 operations as suggested in a previous study. We also aim to investigate DEP oxidation at various UV doses and H2O2 concentrations by performing a pilot-scale advanced oxidation processes (AOP) system, into which a portion of the effluent from a pilot-scale membrane bioreactor (MBR) plant was pumped. In the bench-scale AOP operation, the O3 oxidation alone as well as the UV irradiation without H2O2 addition could be among the desirable alternatives for the efficient removal of DEP dissolved in aqueous solutions at a low DEP concentration range of 85+/-15 microg/L. The adverse effect in the UV/H2O2 process was significantly greater than that in the UV oxidation alone, and its oxidation was almost halved by the nitrate. However, the nitrate clearly enhanced the DEP oxidation in the O3 oxidation and O3/H2O2 process. Especially, the addition of nitrate almost doubled the DEP oxidation efficiency in the O3/H2O2 process. The series of pilot-scale AOP operations confirmed that about 30-50% of DEP dissolved in the treated MBR effluent streams was, at least, oxidized by the O3 oxidation alone as well as the UV irradiation without H2O2 addition. The UV photolysis of H2O2 was most effective for DEP degradation with an H2O2 concentration of 40 mg/L at a UV dose of 500 mJ/cm2.
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Affiliation(s)
- K B Ko
- School of Civil & Environmental Engineering, Yonsei University, 134 Shinchondong, Seoul 120-749, Republic of Korea.
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Doh H, Kim YB, Ahn KH. Nematic domains and resistivity in an itinerant metamagnet coupled to a lattice. Phys Rev Lett 2007; 98:126407. [PMID: 17501144 DOI: 10.1103/physrevlett.98.126407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2006] [Indexed: 05/15/2023]
Abstract
The nature of the emergent phase near a putative quantum critical point in the bilayer ruthenate Sr3Ru2O7 has been a recent subject of intensive research. It has been suggested that this phase may possess electronic nematic order (ENO). In this work, we investigate the possibility of nematic domain formation in the emergent phase, using a phenomenological model of electrons with ENO and its coupling to lattice degrees of freedom. The resistivity due to the scattering off the domain walls is shown to closely follow the ENO parameter. Our results provide qualitative explanations for the dependence of the resistivity on external magnetic fields in Sr3Ru2O7.
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Affiliation(s)
- Hyeonjin Doh
- Department of Physics, University of Toronto, Toronto, Ontario M5S 1A7, Canada
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Ahmed Z, Cho J, Lim BR, Song KG, Ahn KH. Effects of sludge retention time on membrane fouling and microbial community structure in a membrane bioreactor. J Memb Sci 2007. [DOI: 10.1016/j.memsci.2006.10.036] [Citation(s) in RCA: 175] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Ahmed Z, Lim BR, Cho J, Ahn KH. Effects of the internal recycling rate on biological nutrient removal and microbial community structure in a sequential anoxic/anaerobic membrane bioreactor. Bioprocess Biosyst Eng 2006; 30:61-9. [PMID: 17120059 DOI: 10.1007/s00449-006-0098-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2006] [Accepted: 10/31/2006] [Indexed: 10/23/2022]
Abstract
This study investigated the effects of the internal recycling rate on nutrients removal in a sequential anoxic/anaerobic membrane bioreactor (SAM). Microbial community structure in sludge from the SAM was studied using quinone profile method. Above 98% COD, 68% nitrogen, and 55% phosphorus removal efficiencies were achieved when the internal recycling rate was 2.5 times influent flow. At that rate, the optimum specific nitrate loading rate and COD/NO(3)-N ratio were found to be 2.24 mgNO(3)-N g(-1) MLSS h(-1) and 9.13, respectively. Batch tests demonstrated that anoxic condition suppressed phosphorus release, and that denitrification was also influenced by initial substrate concentration. Denitrification appeared to have some priority over phosphorus release for substrate uptake. Microbial community analysis revealed a predominance of the subclass beta-Proteobacteria. Furthermore, it was found that Rhodocyclus-related bacteria were efficient at phosphorus removal than Actinobacteria.
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Affiliation(s)
- Zubair Ahmed
- Environment System Research Center, Korea Institute of Science and Technology, PO Box 131, Cheongryang, Seoul 130-650, Republic of Korea.
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Kim WJ, Lee JI, Lee S, Ahn KH, Park JW. UV spectroscopic monitoring of vaporized monoaromatic hydrocarbons from petroleum-contaminated soils. Environ Monit Assess 2006; 120:527-36. [PMID: 16763743 DOI: 10.1007/s10661-005-9101-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2004] [Accepted: 10/11/2005] [Indexed: 05/10/2023]
Abstract
Fast and simple systems using ultraviolet (UV) absorbance were examined for on-line monitoring of monoaromatic hydrocarbons from petroleum-contaminated soils in this research. Since soil particles hinder the UV light transmittance, the absorbance measurement of vaporized monoaromatic hydrocarbons in soil gas extracted from petroleum-contaminated soils was proposed. In the fixed system that exhibited higher sensitivity than the portable one, the absorbance intensity of benzene, toluene, ethylbenzene, and xylene increased in proportion to the concentration of the contaminants. The portable system, however, was suitable for screening purpose, while it exhibited faster response. There was no interference from water, which helps the applicability of the proposed systems to the actual fields.
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Affiliation(s)
- Woo Jin Kim
- Department of Environmental Science and Engineering, Ewha Womans University, Seoul, Korea
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Park KY, Maeng SK, Kim K, Kweon JH, Ahn KH. A high filtration system with synthetic permeable media for wastewater reclamation. Water Sci Technol 2006; 53:185-90. [PMID: 16752780 DOI: 10.2166/wst.2006.223] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
A novel filtration process with synthetic permeable media was investigated for secondary effluent reclamation. Polyurethane was chosen as the filter medium among three tested media. Compressibility and up-flow velocity were changed to determine the optimum operation for the system. An equation was introduced to express the relationship between the removal efficiency and up-flow velocity. In a pilot study, the synthetic medium filtration with compression showed very stable effluent quality without clogging trouble, though the system operated with three times higher filtration rate and much longer backwashing interval than conventional systems.
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Affiliation(s)
- K Y Park
- Dept of Civil and Environmental System Engineering, and Innovative Environmental Technology Center, Konkuk University, Seoul, Korea.
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43
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Lee SS, Kim NJ, Sun K, Dobbe JG, Hardeman MR, Antaki JF, Ahn KH, Lee SJ. Association between arterial stiffness and the deformability of red blood cells (RBCs). Clin Hemorheol Microcirc 2006; 34:475-81. [PMID: 16687787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The relationship between the flexibility of atherosclerotic vessels and RBC deformability has been investigated. A significant difference of RBC deformability was found among the arterial stiffness groups classified by oscillometric measurement of blood pressure. The deformability was determined by direct microscopic observation of RBCs subjected to shear stress of 0.3 to 40.0 Pa with a rotating rheoscope. The deformability of stiffen group - abnormal pulse wave pattern group or moderate cardiovascular risk group - was found to be much higher than that of normal groups in wide shear stress region (3.0, 10.0, 30.0, and 40.0 Pa). We postulate that the body adapts high shear stress in vivo by making RBCs more distensible, and therefore less likely to rupture under strain or microcirculatory alterations.
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Affiliation(s)
- S S Lee
- School of Chemical and Biological Engineering, Seoul National University, Korea
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Lee S, Kweon JH, Choi YH, Ahn KH. Effects of flocculent aggregates on microfiltration with coagulation pretreatment of high turbidity waters. Water Sci Technol 2006; 53:191-7. [PMID: 16752781 DOI: 10.2166/wst.2006.224] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Immersed membrane systems, and those with in-line coagulation, have been extensively applied in drinking water systems. Sedimentation is usually replaced by membrane processes in both systems. In these systems, voluminous flocculent aggregates formed during coagulation could be potential foulants. When raw waters with high turbidity are introduced, particle loadings to membrane due to coagulation pretreatment are enormous and thus could increase fouling. In general, during the rainy season, the turbidity of the Han River water, which supplies drinking water for the City of Seoul, Korea, is more than a hundred times higher than usual. Therefore, effects of floc on membrane fouling were investigated with highly turbid waters. Two turbidity concentrations, 40 and 200 NTU, were formulated by the addition of kaolin (used as a natural particle surrogate) to the Han River raw water. The results showed that the flux decline behaviours of the highly turbid waters were different from those of natural raw water. Coagulation pretreatment was very effective at reducing membrane fouling. Flocculent aggregates showed a negative effect on the flux decline but a positive effect on the membrane cleaning efficiency.
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Affiliation(s)
- S Lee
- Water Environment and Remediation Center, Cheonryang, Seoul, Korea.
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Lim BR, Hu HY, Ahn KH, Fujie K. Effect of biodegradable substrates on the removal rate of concentrated p-phenol sulphonic acid in the solid phase aerobic biological treatment process. Process Biochem 2005. [DOI: 10.1016/j.procbio.2004.06.059] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Lim BR, Ahn KH, Song KG, Cho JW. Microbial community in biofilm on membrane surface of submerged MBR: effect of in-line cleaning chemical agent. Water Sci Technol 2005; 51:201-7. [PMID: 16003979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The objective of this study was to investigate the change in microbial community pattern with the effect of cleaning agent using a quinone profile that is used for membrane in-line chemical cleaning in SMBR. The dominant quinone types of biofilm were ubiquinone (UQs)-8, -10, followed by menaquinone (MKs)-8(H4), -7 and UQ-9, but those of suspended microorganisms were UQ-8, UQ-10 followed by MKs-8(H4), -7 and -11. Both UQ and MK contents decreased with increasing NaCIO dosage and it seems that there is more resistance from UQ compared to MK. In addition, COD and DOC concentrations increased with increasing NaClO dosage up to 0.05 g-NaCIO/g-SS. The organic degradation performance of the microbial community in the presence of NaClO was impaired. The present study suggested that larger added amounts of NaClO caused an inhibition of organic degradation and cell lysis.
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Affiliation(s)
- B R Lim
- Water Environment and Remediation Research Center, Korea Institute of Science and Technology, PO BOX 131, Cheongryang, Seoul 130-650, Korea.
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Abstract
Ozonation of leachate effluent obtained from a Membrane Bioreactor (MBR) process treating a medium-aged landfill leachate was investigated. The sequence of ammonia stripping, membrane bioreactor, and ozonation was used in the experiment. Ozonation of the MBR effluent showed reduction in Chemical Oxygen Demand (COD) and Total Organic Carbon (TOC) with an increase in five days Biochemical Oxygen Demand (BOD5) concentration. About 73% of COD could be removed at an ozone (O3) dosage of 4.2 mg O3 mg COD(-1). The biodegradability indicated by BOD5/COD ratio increased from 0.03 to 0.08 after ozonation at optimum ozone condition. While analyzing the molecular weight distribution, the fraction of molecular weight (MW) greater than 50 kDa of MBR effluent was transferred to MW 10-50 kDa (38%) at an ozone dosage of 810 mg O3. When O3 dosage was increased to 2,025 mg O3, a rapid change occurred in MW > 50 kDa fraction. This fraction was completely broken down into lower molecular weight fractions. This indicates partial degradation of landfill leachate by ozonation. The colour removal from the leachate was found to be greater than 95%. When the ozonated leachate was recirculated into the MBR system, along with an improvement in the performance of MBR, overall COD removal increased from 78% to 83%. Further, the ozone consumption decreased from 6.1 to 3.4 mg O3 mg COD(-1) removed, thus reducing the ozone requirement.
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Affiliation(s)
- A Chaturapruek
- Environmental Engineering and Management Program, School of Environment, Resources and Development, Asian Institute of Technology, PO Box 4, Klong Luang, Pathumthani, 12120, Thailand
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Cho J, Song KG, Yun H, Ahn KH, Kim JY, Chung TH. Quantitative analysis of biological effect on membrane fouling in submerged membrane bioreactor. Water Sci Technol 2005; 51:9-18. [PMID: 16003956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The objective of this study is to investigate solids concentration and extracellular polymeric substance (EPS) effects on the membrane fouling in the submerged membrane bioreactor. The relationship between the solids retention time (SRT) and the amount of EPS is observed in three lab-scale MBRs. Additionally, the EPS effect on membrane fouling is quantified by calculating the specific cake resistance (alpha) using an unstirred batch cell test. By observing the sludge over a long period under various SRT scenarios, a wide range of EPS and membrane fouling data is obtained. These observations provide sufficient evidence of the functional relationship between SRT, EPS and alpha. As SRT decreases, the amount of EPS bound in sludge floc becomes higher in the high MLSS condition (> 5,000 mg/L). The amount of EPS in the sludge floc has positive influence on alpha. A sigmoid trend between EPS and alpha is observed and the functional relationship obtained by dimensional analysis is consistent with the experimental results.
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Affiliation(s)
- J Cho
- Korea Institute of Science and Technology, Environmental Process and Technology.
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Ahn KH, Lookman T, Bishop AR. Strain-induced metal–insulator phase coexistence in perovskite manganites. Nature 2004; 428:401-4. [PMID: 15042083 DOI: 10.1038/nature02364] [Citation(s) in RCA: 513] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2003] [Accepted: 01/23/2004] [Indexed: 11/09/2022]
Abstract
The coexistence of distinct metallic and insulating electronic phases within the same sample of a perovskite manganite, such as La(1-x-y)Pr(y)Ca(x)MnO3, presents researchers with a tool for tuning the electronic properties in materials. In particular, colossal magnetoresistance in these materials--the dramatic reduction of resistivity in a magnetic field--is closely related to the observed texture owing to nanometre- and micrometre-scale inhomogeneities. Despite accumulated data from various high-resolution probes, a theoretical understanding for the existence of such inhomogeneities has been lacking. Mechanisms invoked so far, usually based on electronic mechanisms and chemical disorder, have been inadequate to describe the multiscale, multiphase coexistence within a unified picture. Moreover, lattice distortions and long-range strains are known to be important in the manganites. Here we show that the texturing can be due to the intrinsic complexity of a system with strong coupling between the electronic and elastic degrees of freedom. This leads to local energetically favourable configurations and provides a natural mechanism for the self-organized inhomogeneities over both nanometre and micrometre scales. The framework provides a physical understanding of various experimental results and a basis for engineering nanoscale patterns of metallic and insulating phases.
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Affiliation(s)
- K H Ahn
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
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50
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Park KY, Lee JW, Ahn KH, Maeng SK, Hwang JH, Song KG. Ozone disintegration of excess biomass and application to nitrogen removal. Water Environ Res 2004; 76:162-167. [PMID: 15168848 DOI: 10.2175/106143004x141690] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A pilot-scale facility integrated with an ozonation unit was built to investigate the feasibility of using ozone-disintegration byproducts of wasted biomass as a carbon source for denitrification. Ozonation of biomass resulted in mass reduction by mineralization as well as by ozone-disintegrated biosolids recycling. Approximately 50% of wasted solids were recovered as available organic matter (ozonolysate), which included nonsettleable microparticles and soluble fractions. Microparticles were observed in abundance at relatively low levels of ozone doses, while soluble fractions became dominant at higher levels of ozone doses in ozone-disintegrated organics. Batch denitrification experiments showed that the ozonolysate could be used as a carbon source with a maximum denitrification rate of 3.66 mg nitrogen (N)/g volatile suspended solids (VSS) x h. Ozonolysate was also proven to enhance total nitrogen removal efficiency in the pilot-scale treatment facility. An optimal chemical oxygen demand (COD)-to-nitrogen ratio for complete denitrification was estimated as 5.13 g COD/g N. The nitrogen-removal performance of the modified intermittently decanted extended aeration process dependent on an external carbon supply could be described as a function of solids retention time.
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Affiliation(s)
- Ki Young Park
- Ecotechnology Research Group, Korea Institute of Science and Technology, Seoul, Cheongryang, South Korea.
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