• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제10권S_3호
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• pp.127-137
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• 2001

The sonochemical Process has been applied as a treatment method and was investigated its effect on the decomposition of humic substances(HS). The reaction kinetics and mechanisms in the Process of sonochemical treatment for humic substances(HS) in wastewater have also been discussed. It was observed that the metal ions such as Fe(II) and Mn(II) showed catalytic effects, while Al(III), Ca(II), and Mg(II) had inhibitory effects on the decomposition of humic substances in sonochemical reaction with hydrogen peroxide. Experimental results also showed factors such as hydrogen peroxide dose affected the formation of disinfection by-products. Two trihalomethanes, chloroform and dichlorobromomethane were formed as major disinfection by-products during chlorination. The mechanism of radical reaction is controlled by an oxidation process. The radicals are so reactive that most of them are consumed by HS radicals and hydroxyl radicals can be acted on organic solutes by hydroxyl addition, hydrogen abstraction, and electron transfer. The depolymerization and the radical reaction of HS radicals appear to occur simultaneously. The final steps of the reaction are the conversion of organic acids to carbon dioxide.

• 환경위생공학
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• 제14권4호
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• pp.41-49
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• 1999

The water treatment by was performed to remove VOC and organic substances in the multi-stage ozone contactor. Ozone is mainly utilized to change the chemical structures of organic substance, of which finally has the purpose to degrad them. The removal efficiency of VOC has 20~60% at the ozone concentration of 3 ppm, in case of trichloroethylene, its efficiency is reduced by 85% at the ozone contact time of 8 min. Design factors such as the number of stage, ozone concentration, zone contact time are determined for optimal treatment in the multi-stage contactor.

• 한국물환경학회지
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• 제25권3호
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• pp.419-424
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• 2009

Characteristics of humic substances on the changes in dissolved organic matter (DOM) characteristics by biodegradation was investigated using three types of the artificial water samples composed of glucose and Suwannee River fulvic acid (SRFA). Some selected DOM characteristics including the specific UV absorbance (SUVA), the synchronous fluorescence spectra and the molecular weight (MW) were compared for the artificial water samples before and after 28-day microbial incubation. The changes of the DOM characteristics were minimal for SRFA during the incubation whereas they were significant for glucose. SUVA, dissolved organic carbon (DOC)-normalized fluorescence intensity, and MW values of glucose increased, suggesting that such labile organic compounds could be exclusively transformed into more humidified materials by biodegradation. For glucose-SRFA mixture, the selected DOM characteristics were greater than those estimated using the assumption that the individual changes of either glucose or SRFA are conservative for the mixture of the two materials. Our results suggest that the presence of humic substances (HS) may lead to the enhancement of the formation of refractory organic materials during biodegradation of labile compounds. Detailed analyses of size exclusion chromatography (SEC) revealed that the enhancement occurred for the DOM mixture with a MW range between 500 Da to 4000 Da.

• 공업화학
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• 제17권2호
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• pp.119-124
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• 2006

물 속에 존재하는 자연 유기물의 성분은 계절과 장소에 따라 다양하게 변하므로 이들 성분에 대한 고찰과 이들이 환경에 미치는 영향을 고찰할 필요가 있다. 본 총설에서는 물 속에 존재하는 휴믹 물질, 탄수화물, 단백질(아미노산), hexosamine, 유지, 오일, 그리스 및 미량 유기물질(내분비교란화학물질과 의약품) 등의 자연 유기물의 특성을 정리하였다.

• 한국산업보건학회지
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• 제10권1호
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• pp.179-207
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• 2000

Hazardous organic solvents management as prescribed by presidential decree in Korea is reviewed. The status of import, manufacture, and circulation of organic solvents was investigated. Problems inherent in the management of organic solvents in the electroplating, metal degreasing, and dry cleaning industries were discussed. The chemical substance management system in Korea was compared to those of foreign organizations. A walk-through check list was developed and then used to assess the actual conditions and potential hazards of chemical substances in these industries. The questionnaire could be used to develop a chemical management system and protect workers from hazardous substances. Based on the results of the site survey, MSDSs were not integrated appropriately into the workers education and were not readily accessible to employees. In the case of the dry cleaning industry, the new dry cleaning solvent used as a substitute includes a lot of potentially hazardous organic solvents. This research is preliminary. It is recommended that a national survey be performed to better identify the current situation. Because chemical substances are regulated by thirteen laws in seven executive branches, management systems often overlap, resulting in ineffective control. Using the above results, a model for managing chemical substances was developed. This will more efficiently provide MSDS information to workers covered by the presidential decree and allow the construction of a management system database for better cooperation with the executive branches in Korea.

• 한국산업보건학회지
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• 제32권4호
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• pp.371-380
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• 2022

Objectives: To ensure that employers handling petroleum compounds understand whether petroleum-based UVCB (unknown or variable composition, complex reaction products, or biological materials) substances contain hazardous substances and comply with the Occupational Safety and Health Act, petroleum-based UVCB substances were analyzed and the results from samples were compared with MSDS (Material Safety Data Sheet) contents. Methods: Twenty-one petroleum samples were analyzed using GC-MS (Gas Chromatography-Mass Spectrometry), targeting ten volatile organic compounds regulated by the Occupational Safety and Health Act. Results: The target chemicals were detected in 13 out of 21 samples. All 13 samples were in the naphtha (low boiling point naphthas (gasolines)) group. There were also naphtha group samples containing 2% benzene. Some naphtha samples used as solvents contained about 1% benzene. Conclusions: This study shows that naphtha group petroleum substances contain hazardous chemicals in many cases. In particular, if benzene, n-hexane, and toluene with low occupational exposure limits are contained above the limit concentration. Such information should be delivered in the article on MSDS legal regulations.

• 상하수도학회지
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• 제21권1호
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• pp.37-46
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• 2007

A feasibility test was conducted to evaluate the addition of turbidity substance in a coagulation process to remove natural organic matters (NOM), the precursor of disinfection by-products (DBPs). The experimental water sources were synthetic water containing 5 mg/L of humic acid and 50 mg/L of NaHCO3 and drinking water resource of Ulsan city (S Dam water, D Dam water and Nak-Dong raw water). The examined turbidity substances were kaolin, acid clay, and modified clay (0.38 meq $NH_4{^+}-N/g$ clay). In Jar tests at different concentrations of the turbidity substances (5, 10, 15, 20, 30 mg/L) using the synthetic water, the turbidity substances improved the removal of turbidity, UV-254 absorbance and dissolved organic carbon (DOC) by 23.8-38.1%, 17.0-24.5% and 2.5-44.5%, respectively. The modified clay showed higher removal efficiencies than other substances. In Jar tests using the drinking water, 10 and 20 mg/L of modified clay enhanced the removal efficiencies of turbidity, UV-254 absorbance, DOC, trihalomethane formation potential (THMFP), and haloacetic acid formation potential (HAAFP) by 3.0~4.3%, 19.1~29.0%, 12~34.9%, 4.9~36.7%, and 1.6~30.2%, respectively.

• 환경위생공학
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• 제14권3호
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• pp.139-149
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• 1999

This study was performed to investigate components of organic solvents and present statues of environmental measurements with official records of working environmental measurements of 4,181 workplaces in 3,280 workshops used airborne organic solvents. 1. The mean working hour of 4,181 workplace producing airborne organic solvents in 3,280 workshops was 437±28.7min, but the mean sampling time for measurement of airborne organic solvents was identified to be 254±28.8min. In 73.0% of 4,181 samples the sampling frequencys were Full-period, single sample measurement. 2. The total 54 components of organic solvents were measured in total airborne samples of 4,181 workplace in 3,280 workshops in both of first and second half-year. These were divided into 38 components, Group 1 substances (5 components), Group 2 substances (31 components) and Group 3 substances (2 components), regulated by the Industrial Safety and Health Law, and other 16 components without legal duty of working environment measurement. The most common component in each half-year was Toluene (84.8%, 88.2%), which was followed by Xylene (464.4%, 51.7%), Methyl ethyl ketone (31.1%, 34.4%), n-Hexane (22.7%, 27.8%) and Benzene (20.4%, 21.5%) in frequency. Of legal duty free components, Ethyl benzen, Trimethyl benzene and Pentane were frequently detected. In conclusion, these results show that the present legal classification system of organic solvents needs to revise. Also these results suggest that it must be necessary to analyze the component of airborne organic solvents mixture and to evaluate their effects on workers' health for the effective management of working environment in workshops treating with organic solvents.

• 한국물환경학회지
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• 제21권2호
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• pp.125-131
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• 2005

Natural organic matter(NOM) is defined as the complex matrix of organic material and abundant in natural waters. It affects the performance of unit operations for water purification. Several kinds of analytical indicators such as DOC, specific ultraviolet absorbance(SUVA), apparent molecular weight (AMW), fractionation and high performance size exclusive chromatography(HPSEC) have been used to understand characteristics and variations of NOM. This study aims to evaluate the characteristics of NOM in the Geum River system comprising with stream flows and reservoirs. It was identified that SUVA denoting the portion of humic substance in water ranged within 1.60~3.36. Using resin adsorbents, dissolved organic carbon(DOC) was fractionated into three classes: hydrophobic bases(HOB), hydrophobic acids(HOA) and hydrophilic substances(HI). HI dominates in all samples, collectively accounting for more than 62% of the DOC. HOA was the second dominated fraction and it varied considerably but accounted for about 30% of the DOC. The distribution of high molecular weight(HMW) measured by HPSEC being used to determine the molecular weight distribution of aquatic humic substances was 40.1% and 38.7% in reservoir and stream flow, respectively. The distribution of low molecular weight(LMW) in stream flow was 13.2% higher than that in reservoir. And apparent molecular weight less than 1KDa, which include the molecular weight of hydrophilic organic matter, occupied with 69.2% and 68.2% in stream flow and reservoir, respectively. While the molecular weight of 1 to 100 KDa including humic substances ranged with 18.6% and 21.6% in stream flow and reservoir, respectively. Seasonal variation of refractory dissolved organic carbon was similar to that of SUVA.

• 환경위생공학
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• 제10권1호
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• pp.76-84
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• 1995

This study was performed to examine the factors influenced on the decomposition of nondegradable organic pollutants( Tricholoroethylene,Benzene ) in aqueous by ultrasonic irradiation. The TCE( Tricholoroethylene ) and Benzene are major hazard compounds causing environmental Pollution and not decomposable substances by conventional treatment. The results shows that the oxidation and reduction reaction of ultrasonic Irradiation was formed the H$_{2}$O$_{2}$ , H$^{+}$ and OH$^{-}$ radical, and then theses was decomposed pollutants of TCE and Benzene in aqueous. We were conformed that the ultrasonic irradiation was excellent in removal efficiency of the nondegradable organic substances any other than processes and utilized the treatment of organic compounds in the industrial wastewater. Conclusively, these results suggest that ultrasonic irradiation may be extremely useful for the treatment of wastewater contaminated organic pollutants, which is difficult to treat economically by conventional treatment.