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Lee KH, Yoo JY, Park CJ, Ahn KH. Development of Nano-Sized Copper-Deposited Antimicrobial Air Filters Using a Mixed Melt-Blown Process. Nanomaterials (Basel) 2023; 13:2071. [PMID: 37513082 PMCID: PMC10386529 DOI: 10.3390/nano13142071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 07/06/2023] [Accepted: 07/13/2023] [Indexed: 07/30/2023]
Abstract
Air purification devices, such as air purifiers, provide fresh air by filtering out airborne pollutants, dust, and other harmful substances using various filter systems. While air filters are generally effective in filtering pollutants such as dust, they encounter a challenge when filtering harmful microorganisms such as mites, bacteria, mold, and viruses. These microorganisms, which are present in public transport and public indoor spaces, tend to proliferate on the surface of the filter media, eventually reintroducing themselves into the air or causing unpleasant odors. To address this issue, herein, copper particles were prepared as one masterbatch and deposited on polypropylene (PP) pellets through plasma vacuum deposition to effectively filter dust and microorganisms and prevent their growth on the surface of the filter media. After adding 3-10 wt.% of the masterbatch to conventional PP pellets to fabricate a filter media, the distribution of copper on the surface of the filter media was observed through a scanning electron microscope. To verify the safety and effectiveness of the antimicrobial material, the filter media containing antimicrobial particles was tested using Escherichia coli (E. coli) and Staphylococcus aureus through a filter emission test.
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Affiliation(s)
- Kyung Hwan Lee
- Department of Mechanical Convergence Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gup, Seoul 04763, Republic of Korea
- Coway Environmental Technology Research Institute, Coway R&D Center, Seoul National University Research Park 1, Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Jun Young Yoo
- Coway Environmental Technology Research Institute, Coway R&D Center, Seoul National University Research Park 1, Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Chan Jung Park
- Coway Environmental Technology Research Institute, Coway R&D Center, Seoul National University Research Park 1, Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Kang Ho Ahn
- Department of Mechanical Convergence Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gup, Seoul 04763, Republic of Korea
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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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Kim YH, Jo MS, Kim JK, Shin JH, Baek JE, Park HS, An HJ, Lee JS, Kim BW, Kim HP, Ahn KH, Jeon K, Oh SM, Lee JH, Workman T, Faustman EM, Yu IJ. Short-term inhalation study of graphene oxide nanoplates. Nanotoxicology 2018; 12:224-238. [PMID: 29385887 DOI: 10.1080/17435390.2018.1431318] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Graphene oxides possess unique physicochemical properties with important potential applications in electronics, pharmaceuticals, and medicine. However, the toxicity following inhalation exposure to graphene oxide has not yet been clarified. Therefore, this study conducted a short-term graphene oxide inhalation toxicity analysis using a nose-only inhalation exposure system and male Sprague-Dawley rats. A total of four groups (15 rats per group) were exposed: (1) control (fresh air), (2) low concentration (0.76 ± 0.16 mg/m3), (3) moderate concentration (2.60 ± 0.19 mg/m3), and (4) high concentration (9.78 ± 0.29 mg/m3). The rats were exposed to graphene oxide for 6 h/day for 5 days, followed by recovery for 1, 3, and 21 days. No significant body or organ weight changes were noted after the short-term exposure or during the recovery period. Similarly, no significant systemic effects of toxicological importance were noted in the hematological assays, bronchoalveolar lavage fluid (BAL) inflammatory markers, BAL fluid cytokines, or blood biochemical assays following the graphene oxide exposure or during the post-exposure observation period. Moreover, no significant differences were observed in the BAL cell differentials, such as lymphocytes, macrophages, or polymorphonuclear cells. Graphene oxide-ingested alveolar macrophages as a spontaneous clearance reaction were observed in the lungs of all the concentration groups from post 1 day to post 21 days. Histopathological examination of the liver and kidneys did not reveal any significant test-article-relevant histopathological lesions. Importantly, similar to previously reported graphene inhalation data, this short-term nose-only inhalation study found only minimal or unnoticeable graphene oxide toxicity in the lungs and other organs.
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Affiliation(s)
- Young Hun Kim
- a Department of Nanofusion Technology , Hoseo University , Asan , Korea
| | - Mi Seong Jo
- a Department of Nanofusion Technology , Hoseo University , Asan , Korea
| | - Jin Kwon Kim
- a Department of Nanofusion Technology , Hoseo University , Asan , Korea
| | - Jae Hoon Shin
- b Occupational Lung Diseases Institute, Korea Workers' Compensation and Welfare Service , Incheon , Korea
| | - Jin Ee Baek
- b Occupational Lung Diseases Institute, Korea Workers' Compensation and Welfare Service , Incheon , Korea
| | - Hye Seon Park
- a Department of Nanofusion Technology , Hoseo University , Asan , Korea
| | - Hyo Jin An
- a Department of Nanofusion Technology , Hoseo University , Asan , Korea
| | - Jong Seong Lee
- b Occupational Lung Diseases Institute, Korea Workers' Compensation and Welfare Service , Incheon , Korea
| | - Boo Wook Kim
- b Occupational Lung Diseases Institute, Korea Workers' Compensation and Welfare Service , Incheon , Korea
| | - Hoi Pin Kim
- a Department of Nanofusion Technology , Hoseo University , Asan , Korea
| | - Kang Ho Ahn
- c Department of Mechanical Engineering , Hanyang University , Ansan , Korea
| | | | - Seung Min Oh
- a Department of Nanofusion Technology , Hoseo University , Asan , Korea
| | - Ji Hyun Lee
- e Institute for Risk Analysis and Risk Communication , University of Washington , Seattle , WA , USA.,f Department of Environmental and Occupational Health Sciences , University of Washington , Seattle , WA , USA
| | - Tomomi Workman
- e Institute for Risk Analysis and Risk Communication , University of Washington , Seattle , WA , USA.,f Department of Environmental and Occupational Health Sciences , University of Washington , Seattle , WA , USA
| | - Elaine M Faustman
- e Institute for Risk Analysis and Risk Communication , University of Washington , Seattle , WA , USA.,f Department of Environmental and Occupational Health Sciences , University of Washington , Seattle , WA , USA
| | - Il Je Yu
- d HCTm, Co. Ltd. , Icheon , 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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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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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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Kim JS, Sung JH, Choi BG, Ryu HY, Song KS, Shin JH, Lee JS, Hwang JH, Lee JH, Lee GH, Jeon K, Ahn KH, Yu IJ. In vivo genotoxicity evaluation of lung cells from Fischer 344 rats following 28 days of inhalation exposure to MWCNTs, plus 28 days and 90 days post-exposure. Inhal Toxicol 2014; 26:222-34. [PMID: 24568578 DOI: 10.3109/08958378.2013.878006] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Despite their useful physico-chemical properties, carbon nanotubes (CNTs) continue to cause concern over occupational and human health due to their structural similarity to asbestos. Thus, to evaluate the toxic and genotoxic effect of multi-wall carbon nanotubes (MWCNTs) on lung cells in vivo, eight-week-old rats were divided into four groups (each group = 25 animals), a fresh air control (0 mg/m(3)), low (0.17 mg/m(3)), middle (0.49 mg/m(3)), and high (0.96 mg/m(3)) dose group, and exposed to MWCNTs via nose-only inhalation 6 h per day, 5 days per week for 28 days. The count median length and geometric standard deviation for the MWCNTs determined by TEM were 330.18 and 1.72 nm, respectively, and the MWCNT diameters ranged from 10 to 15 nm. Lung cells were isolated from five male and five female rats in each group on day 0, day 28 (only from males) and day 90 following the 28-day exposure. The total number of animals used was 15 male and 10 female rats for each concentration group. To determine the genotoxicity of the MWCNTs, a single cell gel electrophoresis assay (Comet assay) was conducted on the rat lung cells. As a result of the exposure, the olive tail moments were found to be significantly higher (p < 0.05) in the male and female rats from all the exposed groups when compared with the fresh air control. In addition, the high-dose exposed male and middle and high-dose exposed female rats retained DNA damage, even 90 days post-exposure (p < 0.05). To investigate the mode of genotoxicity, the intracellular reactive oxygen species (ROS) levels and inflammatory cytokine levels (TNF-α, TGF- β, IL-1, IL-2, IL-4, IL-5, IL-10, IL-12 and IFN-γ) were also measured. For the male rats, the H2O2 levels were significantly higher in the middle (0 days post-exposure) and high- (0 days and 28 days post-exposure) dose groups (p < 0.05). Conversely, the female rats showed no changes in the H2O2 levels. The inflammatory cytokine levels in the bronchoalveolar lavage (BAL) fluid did not show any statistically significant difference. Interestingly, the short-length MWCNTs deposited in the lung cells were persistent at 90 days post-exposure. Thus, exposing lung cells to MWCNTs with a short tube length may induce genotoxicity.
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Affiliation(s)
- Jin Sik Kim
- Bioconvergence Department, Korea Conformity Laboratories , Incheon , Korea
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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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Lee JH, Ahn KH, Yu IJ. Outbreak of bioaerosols with continuous use of humidifier in apartment room. Toxicol Res 2013; 28:103-6. [PMID: 24278596 PMCID: PMC3834414 DOI: 10.5487/tr.2012.28.2.103] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Revised: 06/21/2012] [Accepted: 06/26/2012] [Indexed: 11/20/2022] Open
Abstract
The effect of continuous humidifier use on the bioaerosol concentration in an indoor environment was investigated. An ultrasonic humidifier was operated for 10 hr per day for 15 days in an apartment room. During this time period, viable bioaerosol samples were taken using a single-stage Andersen sampler containing culture media plates for bacteria and fungi. The culture plates were then incubated at room temperature for 2~7 days depending on the media. The counts for the air sample plates were corrected for multiple impactions using the positive hole conversion method and are reported as the colony forming units per cubic meter of air (CFU/m(3)). While the bacterial concentration measured using the tryptic soy agar (TSA) did not show any significant change during the first 3 days, the concentration increased from the 6(th) day (6979 CFU/m(3)) and reached a maximum on the 9(th) day (46431 CFU/m(3)). The concentration then decreased to 2470 CFU/m(3) on the 12(th) day, at which point the fungal concentration increased rapidly to 14424~16038 CFU/m(3). Also, while the fungal concentration showed a significant change until the 9(th) day of humidifier use, fungal growth was observed on the wallpaper and increased rapidly from the 12(th) day. However, the bacterial concentration increased rapidly after the fungi were removed by remediation. The major fungal species identified in the samples were Penicillium representing 34%, Aspergillus representing 31%, Cladosporium representing 24%, and Alternaria representing 1%. The results also indicated that a relative humidity over 80% was easily achieved with continuous humidifier use. Yet, maintaining a high humidity in a room can cause a rapid outbreak of microbial growth.
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Affiliation(s)
- Ji Hyun Lee
- Institute of Nanoproduct Safety Research, Hoseo University, Asan 336-795, Korea
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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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Kim JS, Sung JH, Song KS, Lee JH, Kim SM, Lee GH, Ahn KH, Lee JS, Shin JH, Park JD, Yu IJ. Persistent DNA damage measured by comet assay of Sprague Dawley rat lung cells after five days of inhalation exposure and 1 month post-exposure to dispersed multi-wall carbon nanotubes (MWCNTs) generated by new MWCNT aerosol generation system. Toxicol Sci 2012; 128:439-48. [PMID: 22543278 DOI: 10.1093/toxsci/kfs161] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Carbon nanotubes (CNTs) have specific physico-chemical properties that are useful for the electronics, automotive, and construction industries. Yet, despite their many advantages, there is a current lack of available information on the human health and environmental hazards of CNTs. For this reason, the current study investigated the inhalation toxicity potential of multiwall CNTs (MWCNTs). Eight-week-old rats were divided into four groups (10 rats in each group), the fresh-air control (0mg/m(3)), low-concentration group (0.16mg/m(3)), middle-concentration group (0.34mg/m(3)), and high-concentration group (0.94mg/m(3)), and the whole body was exposed to MWCNTs for 5 days (6h/day). Lung cells were then isolated from five rats in each group on day 0 and 1 month after the 5-day exposure, respectively. The MWCNTs were generated by a newly designed generation system, and the MWCNT concentrations in the exposure chambers monitored in accordance with National Institute for Occupational Safety and Health (NIOSH) 0500 using a membrane filter. The MWCNTs were also sampled for an elemental carbon concentration analysis using a glass filter. The animals exhibited no significant body weight changes, abnormal clinical signs, or mortality during the experiment. A single-cell gel electrophoresis assay (Comet assay) was conducted to determine the DNA damage in lung cells obtained from the right lung. As a result, the Olive tail moments were 23.00±1.76, 30.39±1.96, 22.96±1.26, and 33.98±2.21 for the control, low-, middle-, and high-concentration groups, respectively, on day 0 postexposure. Meanwhile, 1 month postexposure, the Olive tail moments were 25.00±2.71, 28.39±3.55, 22.56±1.36, and 31.97±3.16 for the control, low-, middle-, and high-concentration groups, respectively. Thus, the MWCNTs caused a statistically significant increase in lung DNA damage at high concentration (0.94mg/m(3)) when compared with the negative control group on day 0 and 1 month postexposure.
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Affiliation(s)
- Jin Sik Kim
- Bioconvergence Department, Korea Conformity Laboratories, 7-44, Songdo-dong, Yeonsu-gu, Incheon, 406-840, Korea
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Lee JH, Kwon M, Ji JH, Kang CS, Ahn KH, Han JH, Yu IJ. Exposure assessment of workplaces manufacturing nanosized TiO2and silver. Inhal Toxicol 2011; 23:226-36. [DOI: 10.3109/08958378.2011.562567] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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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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16
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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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17
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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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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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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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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, 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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Lee SH, Iamchaturapatr J, Polprasert C, Ahn KH. Application of chemical precipitation for piggery wastewater treatment. Water Sci Technol 2004; 49:381-388. [PMID: 15137448] [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: 05/24/2023]
Abstract
Several series of experiments were conducted to investigate the treatment of piggery wastewater using chemical precipitation (CP) where various types of coagulants such as aluminium sulfate (Al2(SO4)3), poly aluminium chloride (PAC), ferric chloride (FeCl3), ferric sulfate (Fe2(SO4)3), ferrous sulfate (FeSO4) and ferrous chloride (FeCl2) were used. Throughout the experiments, CP was found to achieve high removal efficiencies for organic compounds and nutrients (nitrogen and phosphorus) from the piggery wastewater. Experimental results showed the optimal doses of FeCl3, Fe2(SO4)3, FeCl2 and FeSO4 was 2.0 g/L, while 0.31 g/L and 2.5 g/L were the optimum dose for PAC and Al2(SO4)3, respectively. The pH range 4-5 resulted in the best performance to all coagulants except FeCl2 and FeSO4, whose optimum pH were more than 6. Percentage removal efficiencies for COD were in the ranges of 70-80%, 90-95% for SS, 80-90% for organic-N and TP. Those removal efficiencies were achieved within 5 min of operation. Three times of repetition in CP resulted in higher removal efficiencies for COD, SS and colour up to 74%, 99% and 94% respectively, in which Al2(SO4)3 was used as the coagulant. Removal efficiencies of various water quality parameters in a continuously operated reactor were similar to those of the batch experiments. Biodegradable ratios (BOD5/COD) increased up to 65% after the application of CP.
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Affiliation(s)
- S H Lee
- School of Civil and Environmental Engineering, Kumoh National Institute of Technology, Gumi 730-701, Korea.
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Wichitsathian B, Sindhuja S, Visvanathan C, Ahn KH. Landfill leachate treatment by yeast and bacteria based membrane bioreactors. J Environ Sci Health A Tox Hazard Subst Environ Eng 2004; 39:2391-2404. [PMID: 15478931 DOI: 10.1081/ese-200026295] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [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
Biological treatment of medium-age landfill leachate was investigated on a membrane bioreactor. The experiments were conducted in two 5-L reactors with immersed hollow fiber microfiltration membranes. One reactor was operated with a mixed bacterial culture termed as bacteria based membrane bioreactor (BMBR) while the other with mixed yeast culture termed as yeast based membrane bioreactor (YMBR). The leachate was characterized with a chemical oxygen demand (COD) concentration of 7000-9000mg/L, biochemical oxygen demand (5 days) to chemical oxygen demand ratio (BOD5/COD) of 0.35-0.45 and total Kjeldahl nitrogen (TKN) of 1800-2000mg/L. The performance was assessed with and without ammonia stripping. In both the reactors, the average COD and TKN removal efficiency without ammonia stripping ranged between 52-66 and 14-28%, respectively. The performance of both the membrane bioreactors improved with ammonia stripping in terms of both COD (72-76%) and TKN (82-89%) removal efficiency. Though, the difference in the performance of the BMBR and YMBR was not significant in terms of COD removal, the YMBR showed better removal efficiency in terms of BOD5. The molecular weight cut-off showed that the degradation pathway of the leachate by bacterial and yeast are different. In regard to membrane fouling, the YMBR showed better performance with lower trans-membrane pressure as well as longer operating time. This superior performance of the YMBR could be due to the structure of yeast cells which are larger in size as well as reduced soluble extracellular polymeric substances (EPS) production, which are the main cause of membrane biofouling.
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Affiliation(s)
- B Wichitsathian
- Environmental Engineering and Management Program, School of Environment, Resources and Development, Asian Institute of Technology, Pathumthani, Thailand
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Cho ES, Ahn KH, Molof AH. Improvement of denitrification by denitrifying phosphorus removing bacteria using sequentially combined carbon. Water Sci Technol 2004; 50:33-40. [PMID: 15566184] [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: 05/24/2023]
Abstract
The effects of sequentially combined carbon (SCC) using a symbiotic relationship of methanol and acetic acid on biological nutrient removal were investigated in both the continuous bench scale process consisting of an anoxic, an aerobic and a final settling tank and intensive batch tests. Compared to the use of respective sole carbon sources, methanol and acetic acid, the use of SCC showed superior removal efficiency of nitrogen (98.3%) and phosphorus (approximately 100%). Furthermore, the use of SCC enhanced simultaneous denitrification and phosphorus uptake by denitrifying phosphorus removal bacteria (DPB), resulting in the highest specific denitrification rate (SDNR) of 0.252 g NO3-N/g VSS/d achieved from the first anoxic zone with methanol of 30 mg COD/I. From batch tests performed under carbon limited anoxic conditions, 1 g of nitrate was used by DPB for P-uptake of 1.19 g. According to this result, 0.205 g NO3-N/g VSS/d was accomplished by normal denitrifiers using methanol, and 0.047 g NO3-N/g VSS/d was achieved by DPB. This research also demonstrated that the increase of poly-beta-hydroxybutyrate (PHB) stored by phosphorus accumulating organisms (PAOs) could be of importance in improving aerobic denitrification. The use of SCC produced the highest P-release in the anoxic zone, indicating the amount of PHB would be higher compared to the use of other sole carbons. Therefore, the SCC could be a very effective carbon source for the enhancement of aerobic denitrification as well.
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Affiliation(s)
- E S Cho
- Institute of Science and Technology, Cheongryang, Seoul 130-630, Korea.
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Cho ES, Ahn KH, Molof AH. Comparison of sequentially combined carbon with sole carbon in denitrification and biological phosphorus removal. Water Sci Technol 2004; 49:251-256. [PMID: 15137431] [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: 05/24/2023]
Abstract
The sequentially combined carbon (SCC) of methanol and acetic acid was used for the biological nutrient removal (BNR). Its BNR performance was compared with methanol or acetic acid as a sole carbon substrate. Compared to the sole carbon substrate, the use of SCC demonstrated the highest overall TIN removal of 98.3% at a COD ratio of 30 mg COD/l of methanol/50 mg CDO/l of acetic acid. Furthermore, denitrification was more enhanced when methanol was used as one of the SCC, rather than as a sole carbon source. Complete phosphorus removal was accomplished with a non-detectable o-P concentration when SCC was added. This research also showed that aerobic denitrifiers appear to prefer acetic acid to methanol, and the amount of poly-beta-hydroxybutyrate (PHB) stored by P accumulating organisms (PAOs) using acetic acid in the anoxic zone could be another important factor in improving the aerobic denitrification. The SCC was a very favorable carbon source for the aerobic denitrification since acetic acid was utilized more efficiently for P-release in accordance with increase of PHB stored in the cell of PAOs by removing nitrogen first using methanol.
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Affiliation(s)
- E S Cho
- Environment and Process Division, Korea Institute of Science and Technology, P.O. Box 131 Cheongryang Seoul, 130-630 Korea.
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Lee S, Ahn KH. Monitoring of COD as an organic indicator in waste water and treated effluent by fluorescence excitation-emission (FEEM) matrix characterization. Water Sci Technol 2004; 50:57-63. [PMID: 15566187] [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: 05/24/2023]
Abstract
The fluorescence excitation-emission matrices (FEEM) of domestic waste water, treated effluent of a waste water treatment plant and receiving river water were analyzed to select wavelengths for the monitoring of organic contents as COD. Excitation/emission wavelengths of 220/350 nm and 270/350 nm for protein-like fluorescence and 240/450 nm and 340/450 nm for humic-like fluorescence were suggested as fluorescence peak emitting wavelength pairs, respectively. Without any pre-treatment, the protein-like fluorescence peaks showed better correlation between COD values and fluorescence intensities than the humic-like fluorescence peaks. No enhanced correlation was observed by removing the suspended solids from the samples using filtration. However, statistical multiple regression methods, using the fluorescence intensities from each peak and the light scattering intensity at 633 nm as variables, resulted in an enhanced correlation, with r2 > 0.9 for the measured and predicted COD values.
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Affiliation(s)
- S Lee
- Water Environment & Remediation Res Center, Korea Institute of Science and Technology, Cheongryang, Seoul, Korea.
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Kwon JH, Park KY, Park JH, Lee SH, Ahn KH. Acidic and hydrogen peroxide treatment of polyaluminum chloride (PACL) sludge from water treatment. Water Sci Technol 2004; 50:99-105. [PMID: 15581000] [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: 05/24/2023]
Abstract
The water treatment sludge including coagulants cannot be easily removed by conventional dewatering methods. The possibility of hydrogen peroxide (H2O2) oxidation as a pretreatment to enhance the dewaterability of polyaluminum chloride (PACl) sludge from water works was investigated. H2O2 treatment alone was not effective but H2O2 treatment under acidic condition significantly reduced both the cake water content and specific resistance to filtration (SRF), indicating the enhancement of dewaterability and filterability. The filterability after acid/H2O2 treatment was comparable to polymer conditioning and even more dewatered cake than polymer conditioning was produced. By H202 combined with sulfuric acid (H2SO4), leached iron caused Fenton's reaction, which showed a potential to significantly reduce the amount of solids mass and to produce more compact cake with higher filterability.
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Affiliation(s)
- J H Kwon
- School of Environmental Science and Engineering, Inje University, 607 Obang-Dong, Kimhae 621-749, Korea
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Songprasert P, Lim BR, Ahn KH. Change of microbial community structure by respiratory quinone profile at intermittently aerated membrane bioreactor. Water Sci Technol 2004; 49:459-465. [PMID: 15137458] [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: 05/24/2023]
Abstract
In the present study, the microbial community structure in an intermittently aerated submerged membrane bioreactor treating domestic wastewater was observed using the respiratory quinone profiles. The effects of different time interval for the aerobic and anoxic period on microbial community structure were examined with 60/90 min (Step 1) and 90/60 min (Step 2) as anoxic/aerobic periods. There was an observable slight difference in microbial community structure between Step 1 and Step 2 in the submerged membrane bioreactor. The dominant quinone types for Step 1 at both anoxic and aerobic conditions were UQ-8 followed by UQ-10 and MK-6, but those for Step 2 were UQ-8, MK-6 and MK-10(H4). The microbial diversity of Step 1 and Step 2 based on the composition of all quinones was 10.6-11.7 and 13.3-13.0 for anoxic and aerobic conditions, respectively. The present results suggest that the introduction of intermittent aeration into the submerged membrane bioreactor has little influence on the bacterial community structure.
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Affiliation(s)
- P Songprasert
- School of Environment, Resources and Development, Asian Institute of Technology, P.O. Box 4 Klong Luang Pathumthani 12120 Thailand.
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Cho JW, Ahn KH, Lee YH, Lim BR, Kim JY. Investigation of biological and fouling characteristics of submerged membrane bioreactor process for wastewater treatment by model sensitivity analysis. Water Sci Technol 2004; 49:245-254. [PMID: 14982187] [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: 05/24/2023]
Abstract
In this study, a mathematical model for the submerged membrane bioreactor (SMBR) was developed. The activated sludge model No. 1 (ASM1) was modified to be suitable for describing the characteristics of the SMBR, and the resistance-in-series model was integrated into the ASM1 to describe membrane fouling. Using the newly developed model, the biological and fouling characteristics of the submerged membrane bioreactor process for wastewater treatment was investigated by sensitivity analysis. The sensitivity of effluent COD and nitrogen, TSS in the reactor and membrane flux with respect to each parameter (K(h), mu(H), K(S), K(NHH), K(NOH), b(H), Y(H), mu(A), K(NHA), b(A), Y(A), K(m) and alpha) was investigated by model simulation. As a result, the most important factors affecting membrane fouling were hydrolysis rate constant (K(h)) and cross-flow effect coefficient (K(m)). Heterotrophic yield coefficient (Y(H)) had a great influence on effluent quality. Effluent quality was also somewhat sensitive to K(h). Peculiar operating conditions of the SMBR such as long solids retention time (SRT), absolute retention of solids by membrane and high biomass concentration in bioreactor could explain these model simulation results. The model developed in this study would be very helpful to optimize operating conditions as well as design parameters for a SMBR system.
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Affiliation(s)
- J W Cho
- Korea Institute of Science and Technology, P.O. Box 131, Cheongyang, Seoul 130-650, Korea.
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36
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Bae JH, Lee IS, Jang MS, Ahn KH, Lee SH. Treatment of landfill leachate by a pilot-scale modified Ludzack-Ettinger and sulfur-utilizing denitrification process. Water Sci Technol 2004; 50:141-148. [PMID: 15537001] [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: 05/24/2023]
Abstract
Nitrogen removal efficiency of a pilot-scale system consisted of Modified Ludzack-Ettinger (MLE) followed by sulfur-utilizing denitrification (SUDNR) process was evaluated with a landfill leachate. For SUDNR, a down-flow mode sulfur packed bed reactor (SPBR) filled with sulfur and limestone particles was used. Although total nitrogen removal efficiency of the MLE process was about 80% at the recycle ratio of 4, effluent contained 350-450 mg/L NO(3-)-N. Up to a loading rate of 1.2 kg NO(3-)-N/m3-day, the SPBR could achieve complete removal of nitrate, and nitrate removal rate was kept to that level even at higher loading rate. When a COD/N ratio of MLE process was maintained at 2 instead of 4, more organics with molecular weight less than 500 were utilized for heterotrophic denitrification although denitrification was not complete with the lack of electron donors. Clogging in the SPBR, mainly by the accumulation of nitrogen gas in the pores, could easily be removed by introducing the effluent in an upward direction for 1 min at 1 hr intervals. The proposed treatment system could achieve nitrate free effluent with a slight increase in chemical cost. Furthermore, depending on further COD removal requirement after biological treatment, the proposed treatment system can be an economical solution.
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Affiliation(s)
- J H Bae
- Dept of Civil and Environmental Eng Inha Univ Inchon, Korea.
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Lim BR, Hu HY, Ahn KH, Fujie K. Oxidative treatment characteristics of biotreated textile-dyeing wastewater and chemical agents used in a textile-dyeing process by advanced oxidation process. Water Sci Technol 2004; 49:137-143. [PMID: 15137417] [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: 05/24/2023]
Abstract
The oxidative treatment characteristics of biotreated textile-dyeing wastewater and typical chemicals such as desizing, scouring, dispersing and swelling agents used in the textile-dyeing process by advanced oxidation process were experimentally studied. The refractory organic matters remained in the effluent of biological treatment process without degradation may be suitable for the improvement of biodegradability and mineralized to CO2 by combined ozonation with and without hydrogen peroxide. On the other hand, the refractory chemicals contained in the scouring agent A and swelling agent may not be mineralized and their biodegradability may not be improved by ozonation. However, the BOD/DOC ratio of scouring agent B increased from 0.3 to 0.45 after ozonation. Based on the results described above, advanced treatment process involving the ozonation without and with the addition of hydrogen peroxide, followed by biological treatment was proposed for the treatment of refractory wastewater discharged from the textile-dyeing process.
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Affiliation(s)
- B R Lim
- Water Environment Research Center, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650, Korea.
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Lim BR, Ahn KH, Songprasert P, Cho JW, Lee SH. Microbial community structure of membrane fouling film in an intermittently and continuously aerated submerged membrane bioreactor treating domestic wastewater. Water Sci Technol 2004; 49:255-261. [PMID: 14982188] [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: 05/24/2023]
Abstract
There was an observable difference in microbial community structure between suspended microorganisms and membrane biofouling film in intermittently and continuously aerated SMBRs. The dominant quinone type of membrane biofouling film in an intermittently aerated SMBR was ubiquinone (UQs)-8, -10 followed by menaquinone (MKs)-8(H4) and -8(H2). But that of the continuously aerated SMBR was UQs-10, -8 followed by MKs-6 and -8(H4). The experimental results also showed that the conditions of an intermittently aerated SMBR may contribute to biofouling by Pseudomonas, Moraxella, Vibrio (quinone type UQ-8), Staphylococcus warneri (quinone type MK-7), Micrococcus sp. (quinone type MK-8(H2)) and Nocardia sp. (quinone type MK-8(H4)), but biofouling in a continuously aerated SMBR may be due to Paracoccus sp. (quinone type: UQ-10) and Flavobacterium species (quinone type: MK-6). The microbial diversities in the intermittently aerated SMBR were 10.9 and 9.4 for biofouling film and suspended microorganisms, respectively. For the continuously aerated SMBR, the results were 10.4 and 10.5 for biofouling film and suspended microorganisms, respectively.
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Affiliation(s)
- B R Lim
- Future Technology Research Division, Korean Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul, 130-650 Korea.
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Zhu JX, Ahn KH, Nussinov Z, Lookman T, Balatsky AV, Bishop AR. Elasticity-driven nanoscale electronic structure in superconductors. Phys Rev Lett 2003; 91:057004. [PMID: 12906626 DOI: 10.1103/physrevlett.91.057004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2003] [Indexed: 05/24/2023]
Abstract
The effects of long-range anisotropic elastic deformations on electronic structure in superconductors are analyzed within the framework of the Bogoliubov-de Gennes equations. Cases of twin boundaries and isolated defects are considered as illustrations. We find that the superconducting order parameter is depressed in the regions where pronounced lattice-deformation occurs. The calculated local density of states suggests that the electronic structure is strongly modulated in response to lattice deformations, and propagates to longer distances. In particular, this allows the trapping of low-lying quasiparticle states around defects. Some of our predictions can be directly tested by scanning tunneling microscopy experiments.
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Affiliation(s)
- Jian-Xin Zhu
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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Demsar J, Averitt RD, Ahn KH, Graf MJ, Trugman SA, Kabanov VV, Sarrao JL, Taylor AJ. Quasiparticle relaxation dynamics in heavy fermion compounds. Phys Rev Lett 2003; 91:027401. [PMID: 12906507 DOI: 10.1103/physrevlett.91.027401] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2003] [Indexed: 05/24/2023]
Abstract
We present the first femtosecond studies of electron-phonon (e-ph) thermalization in heavy-fermion compounds. The e-ph thermalization time tau(ep) increases below the Kondo temperature by more than 2 orders of magnitude as T=0 K is approached. Analysis using the two-temperature model and numerical simulations based on Boltzmann's equations suggest that this anomalous slowing down of the e-ph thermalization derives from the large electronic specific heat and the suppression of scattering between heavy electrons and phonons.
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Affiliation(s)
- J Demsar
- Los Alamos National Laboratory, Mail Stop K764, Los Alamos, New Mexico 87545, USA
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Cho J, Ahn KH, Seo Y, Lee Y. Modification of ASM No.1 for a submerged membrane bioreactor system: including the effects of soluble microbial products on membrane fouling. Water Sci Technol 2003; 47:177-181. [PMID: 12926686] [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: 05/24/2023]
Abstract
In this study, a mathematical model for the submerged membrane bioreactor (SMBR) was developed by combining the activated sludge model (ASM) with a membrane resistance-in-series model. Some modifications were introduced to make ASM to be suitable for describing the characteristics of SMBR. A set of the 1st-order differential equations was established for 13 dependent variables relevant to particles and soluble matters. Performing model simulations for various conditions, the time when a membrane would be fouled could be predicted as well as the effluent quality. From simulation results, F/M ratio and SRT can be considered as major factors of the soluble microbial products (SMP) concentration in a reactor and it is clear that SMP can play an important role in membrane fouling and water quality simultaneously. The model would be very helpful in optimizing operation conditions as well as in designing an optimal SMBR system.
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Affiliation(s)
- J Cho
- KIST, P.O. Box 131, Cheongyang, Seoul 130-650, Korea.
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Cho JH, Ahn KH, Chung WJ, Gwon EM. Waste load allocation for water quality management of a heavily polluted river using linear programming. Water Sci Technol 2003; 48:185-190. [PMID: 15137169] [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: 05/24/2023]
Abstract
A waste load allocation model using linear programming has been developed for economic water quality management. A modified Qual2e model was used for water quality calculations and transfer coefficients were derived from the calculated water quality. This allocation model was applied to the heavily polluted Gyungan River, located in South Korea. For water quality management of the river, two scenarios were proposed. Scenario 1 proposed to minimise the total waste load reduction in the river basin. Scenario 2 proposed to minimise waste load reduction considering regional equity. Waste loads, which have to be reduced at each sub-basin and WWTP, were determined to meet the water quality goal of the river. Application results of the allocation model indicate that advanced treatment is required for most of the existing WWTPs in the river basin and construction of new WWTPs and capacity expansion of existing plants are necessary. Distribution characteristics of pollution sources and pollutant loads in the river basin was analysed using Arc/View GIS.
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Affiliation(s)
- J H Cho
- Department of Environmental Engineering, Kwandong University, Yangyang-Up, Yangyang-Gun, Gangwon-Do 215-800, Korea.
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Park JS, Choi H, Ahn KH. The reaction mechanism of catalytic oxidation with hydrogen peroxide and ozone in aqueous solution. Water Sci Technol 2003; 47:179-184. [PMID: 12578192] [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: 05/24/2023]
Abstract
The sorption and catalytic oxidation of model compounds (pCBA and phenanthrene) and NOM on FeOOH were investigated using hydrogen peroxide and ozone, respectively. After oxidation with ozone, the hydrophobic, transphilic, and hydrophilic NOM fractions were isolated using XAD-8 and -4 resins to analyze the reaction characteristics. The sorption of pCBA was strongly dependent upon the pH, but phenanthrene exhibited a sorption behavior that was independent of the pH. In the case of NOM, the hydrophobic portion showed higher sorption affinity than hydrophilic and transphilic at pH 7.2. The concentrations of model compounds and oxidants were measured during the oxidations and the efficiency was compared for tests done with ozone alone and those using catalytic ozonation. Through the comparison of the sorption and decomposition of the model compounds, along with the effects of bicarbonate addition, mechanisms for catalytic oxidation with hydrogen peroxide or ozone were proposed, respectively.
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Affiliation(s)
- J S Park
- Department of Environment Science and Engineering, Kwangju Institute of Science and Technology (K-JIST), Oryong-dong, Puk-gu, Kwangju 500-712, South Korea
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Ahn KH, Yeom IT, Park KY, Maeng SK, Lee Y, Song KG, Hwang JH. Reduction of sludge by ozone treatment and production of carbon source for denitrification. Water Sci Technol 2002; 46:121-125. [PMID: 12523742] [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: 05/24/2023]
Abstract
The feasibility of ozone treatment of municipal sludge for sludge reduction and carbon source production has been investigated. Significant accumulation of solubilized organics and unsettlable micro-solids (UMS) was observed at relatively low ozone dosages while mineralization became dominant at higher dosages. Batch denitrification experiments showed that the solubilized organics and the UMS could be utilized as carbon sources for nitrogen removal. In terms of overall sludge reduction, 54% reduction of the total sludge mass could be achieved by ozone treatment at 0.2 g-O3/g-MLSS.
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Affiliation(s)
- K H Ahn
- Korea Institute of Science and Technology P.O. Box 131, Cheongryang, Seoul, 136-791, Korea
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Ahn KH, Park KY, Maeng SK, Hwang JH, Lee JW, Song KG, Choi S. Ozonation of wastewater sludge for reduction and recycling. Water Sci Technol 2002; 46:71-77. [PMID: 12479455] [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: 05/24/2023]
Abstract
An ozone treatment system was introduced as an alternative method for municipal sludge treatment and disposal. A pilot-scale facility was built to investigate the feasibility of the ozonation for sludge reduction and recycle. The system consists of three main parts; advanced wastewater treatment, sludge ozone treatment and belt press dewatering. Ozonation of wastewater sludge resulted in mass reduction by mineralization as well as volume reduction by improvement of dewatering characteristics. The supernatant of the ozonated sludge, consisting of solubilized organics and micro-particles, proved to be an effective carbon source for denitrification. A simple economic assessment reveals that the ozonation process can be more economical than incineration for sludge treatment and disposal at small- and medium-sized wastewater treatment plants.
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Affiliation(s)
- K H Ahn
- Future Technology Research Division, Korea Institute of Science and Technology P.O. Box 131, Cheongryang, Seoul, 136-791, Korea
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46
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Yeom IT, Lee KR, Ahn KH, Lee SH. Effects of ozone treatment on the biodegradability of sludge from municipal wastewater treatment plants. Water Sci Technol 2002; 46:421-425. [PMID: 12361042] [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: 05/23/2023]
Abstract
The effects of ozone pretreatment on the biodegradability of municipal wastewater sludge were determined. Three types of experiments were conducted: anaerobic digestion, aerobic biodegradation, and denitrification using ozone-treated sludge as a carbon source. For 5 days, ozonated sludge at 0.1 gO3/g-SS showed about 2-3 times greater biodegradation compared to the raw sludge in both aerobic and anaerobic conditions. In anaerobic experiments, biodegradation increased with ozone dosage up to 0.2 gO3/g-SS. Further increase of ozone dosage did not improve the biodegradation. In aerobic condition, about 77% of the ozonated sludge at 0.1 gO3/g-SS could be biodegraded after 15 days and is compared with 36% degradation of the untreated sludge. Most of the biodegradation of the ozonated sludge occurred within 5 days while the raw sludge was biodegraded steadily throughout the experimental period. The biodegradation enhancement of ozonated sludge was confirmed in batch denitrification experiments.
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Affiliation(s)
- I T Yeom
- Department of Civil and Environmental Engr, Sungkyunkwan University, Suwon, Korea.
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Choi S, Yang JD, Ji M, Choi H, Kee M, Ahn KH, Byeon SH, Baik W, Koo S. Selective oxidation of allylic sulfides by hydrogen peroxide with the trirutile-type solid oxide catalyst LiNbMoO(6). J Org Chem 2001; 66:8192-8. [PMID: 11722224 DOI: 10.1021/jo016013s] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Chemoselective sulfur oxidation of allylic sulfides containing double bonds of high electron density due to multiple alkyl substituents or extended conjugation was developed using the composite metal oxide catalyst, LiNbMoO(6), without any epoxidation of the electron-rich double bond(s). Selective oxidation to either the corresponding sulfoxides or the sulfones was realized by controlling the stoichiometry of the quantitative oxidant, H(2)O(2). This new oxidant system had general applicability for chemoselective oxidation of various allylic, benzylic, or propargylic sulfides containing unsaturated carbon-carbon bonds with different electron properties. Various functional groups including hydroxy, formyl, and ethers of THP or TBDMS are compatible under this mild oxidation reaction condition.
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Affiliation(s)
- S Choi
- Department of Chemistry, Kyung Hee University, Yongin, Kyunggi-Do, 449-701, Korea
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48
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Lee SH, Yeom IT, Ahn KH, Khim J. Nonequilibrium mass transfer of multi-component NAPL in a soil column venting. Environ Technol 2001; 22:741-748. [PMID: 11482395 DOI: 10.1080/09593332208618250] [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] [Indexed: 05/23/2023]
Abstract
This study was conducted to investigate the mass transfer behavior for a multi-component system in the soil venting process. Soil venting experiments were conducted using gasoline-contaminated soil and models of local equilibrium assumption (LEA) and the first-order kinetic approach were used to descnbe the gasoline volatilization process. However, the focus was on the application of the kinetic model. In both models, thirteen major components of gasoline were selected for the model input and the rest of the gasoline was divided into 11 groups based on the retention times in the gas chromatography of gasoline. The LEA model had the tendency of underestimating the gas concentration at the initial phase and overestimating at the later phase due to the different volatilities of multi-components. n the kinetic model, the estimation of mass transfer coefficient values were carried out by adopting the relationship developed in the single-components system and choosing the appropriate modified Sherwood number. This method resulted in the good agreement with the simulation and the experimental results.
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Affiliation(s)
- S H Lee
- Department of Environmental Management, Korea University, Seoul
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49
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Jung MW, Ahn KH, Lee Y, Kim KP, Paeng IR, Rhee JS, Park JT, Paeng KJ. Evaluation on the adsorption capabilities of new chemically modified polymeric adsorbents with protoporphyrin IX. J Chromatogr A 2001; 917:87-93. [PMID: 11403495 DOI: 10.1016/s0021-9673(01)00673-2] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
A chemically modified polymeric adsorbent was synthesized to evaluate the availability as an adsorbent for solid-phase extraction (SPE) of phenol and chlorophenols. Commercially available Amberlite XAD-2 and XAD-4 resins were modified with macrocyclic protoporphyrin IX (PPIX) through the ketone linkage. Adsorption isotherms were obtained by batch experiments and the data were fitted to the Freundlich equation to calculate the adsorption parameters. Breakthrough volumes were measured by column experiments. Physical properties such as surface area, average pore diameter and micropore volume of resins were measured to correlate with the adsorption characteristics. As a result, adsorption capacity was increased for the chemically modified resins and it can be concluded that the increase of pi-pi interaction due to the introduction of the porphyrin molecule is the major factor for the increase of the adsorption capacity.
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Affiliation(s)
- M W Jung
- Environment and Process Technology Division, Korea Institute of Sciene and Technology, Cheongryang, Seoul, South Korea
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50
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Park KY, Lee JW, Inamori Y, Mizuochi M, Ahn KH. Effects of fill modes on N2O emission from the SBR treating domestic wastewater. Water Sci Technol 2001; 43:147-150. [PMID: 11381898] [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: 05/23/2023]
Abstract
Nitrous oxide (N2O) gas is emitted as an intermediate in the biological nitrogen removal process. A track study was performed to investigate the characteristics of N2O emission depending on the cyclic mode of a sequencing batch reactor (SBR). A major emission of N2O took place at the aerobic phase, while N2O emission at the anoxic phase was insignificant. Especially, the highest N2O emission rate was observed at the initial stage of aerobic phase under the limited dissolved oxygen (DO) condition. Under such a condition, nitrite (NO2-) was transiently accumulated along with significant N2O emission due to incomplete nitrification. In addition, N2O production at the aerobic phase was strongly related with incomplete denitrification by nitrifiers. N2O emission could be reduced by change in fill modes in the SBR. A significant conversion to N2O took place in the SBR with the anoxic fill mode, while only small amount of N2O was conversed in the SBR with the aerobic fill mode. Relatively high concentration of ammonia nitrogen (NH4+) accelerated N2O production at the aerobic phase in the SBR with the anoxic fill compared to the aerobic fill. For control of N2O emission in the SBR, the aerobic fill mode could be an effective method even if denitrification efficiency may be reduced at the anoxic phase.
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Affiliation(s)
- K Y Park
- Environment and Process Technology Division, KIST, 39-1 Hawolgok-dong, Songbuk-gu, Seoul 136-791, Korea
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