• Journal of Soil and Groundwater Environment
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• v.10 no.1
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• pp.6-12
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• 2005

Contamination of soils and groundwater by leakage of petroleum compounds from underground storage tanks (USTs) has become great environmental issues. Conventional methods such as soil vapor extraction (SVE) used for the remediation of unsaturated soils contaminated with volatile organic compounds might not be applied for the removal of semi-volatile organic compounds such as diesel fuels and PCBs, which have low volatility and high hydrophobicity. The objective of this study is to develop a hot air injection method to remove semi-volatile compounds. Additionally, operation parameters such as temperature, air flow rate, and water content are evaluated. Experimental results show that diesel ranged organics (DROs) are removed in the order of volatility of organic compounds. As expected, removal efficiency of organics is highly dependent on the temperature. It is considered that more than $90\%$ of organic contaminants whose carbon numbers range between 17 and 22 can be removed efficiently by the hot air injection-extraction method (modified SVE) over the $100^{\circ}C$. It is also found that increased air flow rate resulted in high removal rate of contaminants. However, air flow rate over 40 cc/min is not effective for the operation aspects, due to mass transfer limitation on the volatilization rate of the contaminants. The effect of the water content on the decane removal is minimal, but some components show large dependence on the removal efficiency with increasing water content.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.44-52
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• 2002

Low temperature thermal desorption (LTTD) has become one of the cornerstone technologies used for the treatment of contaminated soils and sediments in the United States. LTTD technology was first used in the mid-1980s for soil treatment on sites managed under the Comprehensive Environmental Respones, Compensation and Liability Act (CERCLA) or Superfund. Implementation was facilitated by CERCLA regulations that require only that spplicable regulations shall be met thus avoiding the need for protracted and expensive permit applications for thermal treatment equipment. The initial equipment designs used typically came from technology transfer sources. Asphalt manufacturing plants were converted to direct-fired LTTD systems, and conventional calciners were adapted for use as indirect-fired LTTD systems. Other innovative designs included hot sand recycle technology (initially developed for synfuels production from tar sand and oil shale), recycle sweep gas, travelling belts and batch-charged vacuum chambers, among others. These systems were used to treat soil contaminated with total petroleum hydrocarbons (TPH), polycyclic aromatic hydrocarbons (PAHs), pesticides, polychlorinated biphenyls (PCBs) and dioxin with varying degrees of success. Ultimately, performance and cost considerations established the suite of systems that are used for LTTD soil treatment applications today. This paper briefly reviews the develpoment of LTTD systems and summarizes the design, performance and cost characteristics of the equipment in use today. Designs reviewed include continuous feed direct-fired and indirect-fired equipment, batch feed systems and in-situ equipment. Performance is compared in terms of before-and-after contaminant levels in the soil and permissible emissions levels in the stack gas vented to the atmosphere. The review of air emissions standards includes a review of regulations in the U.S. and the European Union (EU). Key cost centers for the mobilization and operation of LTTD equipment are identified and compared for the different types of LTTD systems in use today. A work chart is provided for the selection of the optmum LTTD system for site-specific applications. LTTD technology continues to be a cornerstone technology for soil treatment in the U.S. and elsewhere. Examples of leading-edge LTTD technologies developed in the U.S. that are now being delivered locally in global projects are described.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.6
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• pp.199-206
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• 2016

The aim of this study was to establish the optimal conditions to design a shoe rack that could effectively sterilize and deodorize shoes contaminated by various bacteria. The manufacture and evaluation of a shoe rock was conducted for one year from October 2014 to September 2015. The antibacterial efficacies were evaluated using Escherichia coli and Staphylococcus aureus by JIS Z 2801:2010. The deodorization efficiency was identified by the standard method for deodorization efficiency evaluation of an indoor air cleaner established by Korea Air Cleaning Association, SPS-KACA002-132:2006. The results showed that antibacterial evaluation showed more than 99.9% of the sterilization effects on Escherichia coli and Staphylococcus aureus after exposure to ultraviolet (UV) light for 30 seconds. The average deodorization efficiency for the test gases was 42.5%. The temperature in the shoes and in the shoe rack was lower than $40^{\circ}C$ and $25^{\circ}C$, respectively, when the UV lamp was turned on for 5 minutes and off for 25 minutes repeatedly. This was controlled by turning the UV lamp on and off to maintain the appropriate temperature in the shoes. In conclusion, the real deodorization efficiency is expected to be higher than the measured value because the internal volume of the shoe rack was smaller than the test chamber used to measure the deodorization efficiency. The deodorization effect could be increased further by the sterilization of bacteria causing bad odors in shoes. Further studies will be needed to determine the temperature deviations within the shoe rack to provide constant conditions.

• KSBB Journal
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• v.16 no.6
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• pp.603-608
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• 2001

In this study, we studied on the remeval of toluene vapors in a lab-scale biofilter. Biofiltration was performed in a column fed downflow with contaminated air at ambient conditions. The column was packed with mixture of Peat and Calstene(5:3 vol. Ratio), Synthesized media, Bark and Wood chip, which were inoculated with microbial population of selected stains(Pseudomonas. putida, KCCM 11343, ATCC 12633). The microorganisms were immobilized on the bed medium and then biofilm were formed. The biofilter was operated under the conditions of various inlet toluene concentrations for 180 days and treated up to the elimination capacity of maximum 40 g/㎥hr at the inlet load of 30 g/㎥ hr with percentage removals of 20∼90% and gas retention times between 1 and 2 min. The pressure drop was very negligible through the biofilter columps because its value of 0.054 cmH$_2$O/m was much less than others. The effect of operating conditions such as flow rate, inlet toluene concentration and moisture contents on the performance of the biofilter was sequentially investigated in this study.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.3
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• pp.228-234
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• 2008

The purpose of this study was to predict environmental distribution of anthracene, benzene, benzo[a]pyrene, 1-methylphenanthrene and phenanthrene in a four phase biopile system - air, water, soil and non aqueous phase liquid (NAPL) phase using level I fugacity model. Soil samples used for this study were collected from three sites in the United Kingdom which were historically contaminated with petroleum hydrocarbons. The level I fugacities (f) for the five contaminants were markedly different, however, the fugacities of each contaminant in three soil samples did not show significant difference. NAPL and soil were the dominant phases for all five contaminants. Results of this study indicated that difference in percentage of organic carbon strongly influenced the partitioning behavior of the cntaminants. The presence of benzene calls for an urgent need for risk-based management of air and water phase. Whereas insignificant amount of chemicals leached in the water phase for other organic contaminants showing greatly reduced potential of groundwater contamination. Furthermore, this study helped us to confirm the association of risk critical contaminants with the residual saturation in treated soils. They also can be used to emphasize the importance of accounting for the partitioning behavior of both NAPL and soil phases in the process of the risk assessment of the sites contaminated with petroleum hydrocarbons.

• Journal of Environmental Impact Assessment
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• v.28 no.3
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• pp.332-345
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• 2019

The purpose of the study is to evaluate the treatability of contaminated groundwater with TPH and (or) $Cr^{6+}$. Laboratory scale tests were performed for oil/water separation, dissolved air flotation (DAF), coagulation and precipitation, and filtration with sand and activated carbon respectively. Two times of oil/water separation tests for total 40 minutes of separation or separating time shows 90.2 % of TPH removal rate. In case of DAF test for high TPH sample, the TPH removal rates were not varied significantly by the variation of microbubble size. However, tests for low TPH samples show that TPH removal rate increases as microbubbles are smaller. When coagulant was added to sample for DAF test, TPH removal rate was increased 12.3 %. SS removal rate by DAF was 97.9 % at $16-40{\mu}m$ and it was increased as the size of microbubble is reduced. Tests for coagulation and precipitation were performed to evaluate the removal of $Cr^{6+}$ in groundwater. The increase of $FeSO_4$ dosage increased $Cr^{6+}$ removal rate in the coagulation and precipitation process. As the amount of activated carbon in the filter media increased TPH removal rate in the filtration process. SS removal rate by the filtration was 96.7 % similar to the results of DAF process tests. The filtration process treats TPH and SS. Best design parameters are determined as the size of sand is $425-850{\mu}m$ and the ratio of activated carbon and sand is 50:50.

• Journal of Food Hygiene and Safety
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• v.36 no.6
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• pp.520-527
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• 2021

In this study, toxin gene and antibiotic resistance of food poisoning strains isolated from indoor air in the cafeteria were analyzed to prevent food poisoning. Staphylococcus aureus (16 strains) and Bacillus cereus (37 strains) isolated from indoor air in child care center were tested. The toxin genes of S. aureus and B. cereus were detected by PCR assay. The antimicrobial susceptibility test followed the disc diffusion method described by the Clinical and Laboratory Standard Institute. The seg and sei toxin genes were detected in 11 of 16 S. aureus strains (68.6%). The nheA and nheB toxin genes were detected in 37 B. cereus strains. In this study, a total of 12 toxin gene patterns of B. cereus were found, among which the nheA-nheB-nheC toxin gene was found to be the most frequent pattern. The result of the antimicrobial susceptibility test of S. aureus revealed 93.8% and 87.5% resistance to ampicillin and penicillin antibiotics, but methicillin resistance S. aureus and vancomycin resistance S. aureus were not detected. All 37 B. cereus tested in this study were resistant to ampicillin and penicillin antibiotics. Based on the result of this study, it was judged that regular ventilation and air quality management were necessary to prevent food poisoning caused by S. aureus and B. cereus contaminated in the indoor air of child care centers.

• Journal of Food Hygiene and Safety
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• v.22 no.4
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• pp.288-293
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• 2007

To evaluate effects of airborne microorganisms in fresh cut processing plant, microorganisms in air, equipments, raw material, water and final product were isolated and identified using Vitek (R)2 compact system. Airborne microorganisms were isolated from 1000L air using air sampler for floating microorganisms and plate count agar for falling microorganisms. And contaminated microorganisms of equipment, water, and product were isolated from plate count agar plate. Total plate counts for floating and falling, raw material, equipments and final product were $10^2-10^3CFU/m^3,{\sim}10^1CFU/plate,\;10^3CFU/g,{\sim}10^4CFU/cm^2\;and\;10^4CFU/g$, respectively. From the result of isolated microorganism identification from raw material to final product, airborne microorganisms could affect the flora of final product.

• Journal of Korean Academy of Nursing
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• v.9 no.2
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• pp.17-26
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• 1979

This research is to prevent the infection of maternity in the hospital by examining the microbes contaminations in maternity through airbone microbes and those who are engaged in the ward of O.B. ＆ G.Y. and to furnish the basic data available to hospital management. The bacterial growth of airbone microbes contaminations in nosocomial air and who thor the nasal cavity of passers by (doctors, nurses, parturient women) who went to the ward of O.B. ＆ G.Y. contaminated or not were examined in“E”Univ. Hospital from July to August, 1979 by using thioglycollate broths and agar plates. The following results were obtained: 1. The average colony number of airborne microbes revealed as follows the pediatric ward (36 colonies), the internal ward (33 colonies), the ward of O.B. ＆ G.Y. (30 colonies), the ward of surgery (24 colonies), delivery-waiting room (11 colonies), and the delivery room (3 colonies). 2. The bacterial growth beforenoon differed from that of afternoon. Namely, the latter (24 colonies) was higher than the former (21 colonies). 3. The type of strains isolated from the air of the ward revealed staphylococci (82%), Gram negative bacilli (18%), fungi (17%), Gram positive diplococci (13%), and Bacillus subtilis (2.8%). 4. The strains isolated in the delivery-waiting room revealed staphylococci (66.7%), Gram negative bacilli (33.6%), and revealed staphylococci (75%), Gram positive diplococci (8.3%), and fungi (8.3%), in delivery room. 5. Most of strains isolated in the ward of O.B. & G.Y. revealed staphylococci (100.0%), Gram positive diplococci (8.3%), and Gram negative bacilli (6.7%). 6. The strain isolated in the surgical ward revealed staphylococci (91.7%), fungi (33.3%), Gram positive diplococci (25%), Gram negative bacilli (25%) and Bacillus subtilis (8.3%). 7. The strain isolated in the pediatric ward revealed staphylococci (75%), fungi (25%), Gram positive diplococci (8.3%), Bacillus subtilis (8.3%), and Gram negative bacilli (8.3%). 8. The strain isolated in the internal ward revealed staphylococci (91.7%), fungi (33.3%), Gram positive diplococci (25%), and negative bacilli (16.7%). The strains isolated from the nasal cavity of those doctors and nurses who and enaged in the ward of O.B. & G.Y. revealed staphylococci (80%), Bacillus subtilis (10%), and Gram negative bacilli (10%), from doctors and Gram positive diplococci (10%), instead of Gram negative bacilli (10％), from nurses. 10. The strain isolated from nasal cavity of parturient women on admission revealed staphylococci (90%), and Gram negative bacilli (10%), but after admission revealed staphylococci (70％), Gram positive diplococci (10%), and Gram negative bacilli (10%). 11. Of the total 91 staphylococci isolated from the air of the ward, the Coagulase pastive was 36 (39.6%), and the negative 55 (60.4%), As a result of the coagulase experiment of the staphylococci isolated from the nasal cavity of those who are engaged in the ward of O.B. ＆ G.Y. all were revealed as negative that belonged to non-pathogenic. 12. Consequence of the biochemic examination of the gram negative bacilli isolated from the air of the ward the aerobacter aerogens revealed was (16.7%) E-coli 5％ in the nasal cavity of those came and went to the of O.B. ＆ G.Y. and Aerobacter aerogens 7.5%.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.5
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• pp.454-460
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• 2012

The purpose of the present work is to investigate the removal characteristics of positively charged filters for capturing negatively charged particles such as bacteria and virus in water. In order to reduce the pressure drop and increase the filtration efficiency, the filter media, modified by charge modifier having positive functional groups, is developed and evaluated. Improved liquid filters have been developed with the modified surface charge to capture and adsorb particles by electrokinetic interaction between the filter surface and particles contained in an aqueous liquid. The positively charged filter media is composed of glass fiber, cellulose and poly-ethylenimine resin for positively charging with the variation of volume ratio. The zeta potential value of the positively charged filter is +37.92 mV at the glass fiber and cellulose content ratio of 50 : 50 with resin content of 100%, while that of the PSL test particle is -23.5 mV at pH 7. The removal efficiency of the electro-positively charged filter is 98% for PSL particles of 0.11 ${\mu}m$, while that of the negatively charged filter is 7%. The positively charged filter media showed the potential to be an effective method for removing fine particles from the contaminated water for liquid filtration.