간행물
한국환경과학회지 KCI 등재 Journal of Environmental Science International
- 발행기관 한국환경과학회
- 자료유형 학술지
- 간기 월간
- ISSN 1225-4517 (Print)2287-3503 (Online)
- 수록기간 1992 ~ 2023
- 주제분류 자연과학 > 자연과학일반 자연과학 분류의 다른 간행물
- 십진분류KDC 539DDC 628
권호리스트/논문검색
제15권 제6호 (2006년 6월) 11건
1.
2006.06
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Airborne particles collected from a heavily industrialized site were analyzed by chemical speciation of seven trace metals: Pb, Cd, Cr, Cu, Ni, Zn, and As. The average concentrations were as follows: Zn, 502.0 ± 230.7; Pb, 176.5 ± 310.9; Cu, 111.9 ± 82.7; As, 38.0 ± 31.0; Cr, 21.5 ± 24.4; Cd, 20.8 ± 17.4; and Ni, 11.4 ± 8.4 ng/m3. The median enrichment factor (EF) values of Cd (7,280), As (1,030), Cu (215), Zn (214), and Pb (143), with respect to iron, were much larger than 100. We observed that Cd was found in the soluble and exchangeable form (56.9%), and that Pb and Cr were found in carbonates, oxides and the reducible form (69.8% and 61.1%, respectively). These two forms, which are the most easily absorbed into human body tissue, predominated in most of the trace metals investigated in this study.
2.
2006.06
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In recent decades, biofiltration has been widely accepted for the treatment of contaminated air stream containing low concentration of odorous compounds or volatile organic compounds (VOCs). In this study, conventional biofilters packed with flexible synthetic polyurethane (PU) foam carriers were operated to remove toluene from a contaminated air stream. PU foams containing various amounts of pulverized activated carbon (PAC) were synthesized for the biofilter media and tested for toluene removal. Four biofilter columns were operated for 60 days to remove gaseous toluene from a contaminated air stream. During the biofiltration experiment, inlet toluene concentration was in the range of 0-150 ppm and EBRT (i.e., empty bed residence time) was kept at 26-42 seconds. Pressure drop of the biofilter bed was less than 3 mm H2O/m filter bed. The maximum removal capacity of toluene in the biofilters packed with PU-PAC foam was in the order of column II (PAC = 7.08%) > column III (PAC = 8.97%) > column I (PAC = 4.95%) > column IV (PAC = 13.52%), while the complete removal capacity was in the order of column II > column I > column III > column IV. The better biofiltration performance in column II was attributed to higher porosity providing favorable conditions for microbial growth. The results of biodegradation kinetic analysis showed that PU-PAC foam with 7.08% of PAC content had higher maximum removal rate (Vm = 14.99 g toluene/kg dry material/day) than the other PU-PAC foams. In overall, the performance of biofiltration might be affected by the structure and physicochemical properties of PU foam induced by PAC content.
3.
2006.06
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The purpose of this study is to clarify the characteristic of urban heat island intensity in urban area formed at a basin. Thermal environments for basin-type cities are influenced by significant topographic relief winds. In this study, we analyzed the diurnal variations of the heat island intensity according to meteorological condition and season using AWS(Automatic Weather observation System) data in Daegu Metropolitan area for 1 year(3/April, 2003 ～ 2/April, 2004). In this study, we defined the urban heat island intensity as the air temperature difference between two points, the downtown and the suburban area. The suburban area is located at valley mouth around the western tip of Daegu.
The results are summarized as follows;
1. The maximum heat island intensity was recorded at early morning under the meteorological conditions, calm and clear
2. The heat island intensity was strong in the order of winter, fall, spring and summer.
3. The heat island intensity came out minus values in the afternoon. This phenomenon is known as a common for basin-type cities.
4. The heat island intensity was twice or more in clear and calm than not so.
4.
2006.06
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Removal of NOx on CaO/TiO2 photocatalyst manufactured by the addition of Ca(OH)2 was measured in relation with the amount of Ca(OH)2 and calcination temperature. In case of pure TiO2, the NOx removal decreased greatly with the increase of calcination temperature from 500oC to 700oC, whereas in the photocatalyst added with Ca(OH)2, the removed amount of NOx was high and constant regardless of calcination temperature. Considering NOx removal patterns depending on the amount of Ca(OH)2 added(50, 30, 10wt%), high removal rate showed at the photocatalysts containing less than 30wt% of Ca(OH)2, and it was about 30% higher than that of pure TiO2. From the XRD patterns, it is seen that the addition of Ca(OH)2 contributes to maintaining the anatase structure that is favourable to photocatalysis. It also indicates that the possibility of the formation of calcium titanate(CaTiO3) by reacting with TiO2 above 700oC. Apart from the favourable crystalline structure, the addition of Ca(OH)2 helped increase the alkalinity of photocatalyst surface, thus promoting the photooxidation reaction of NOx.
5.
2006.06
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The clarification of spatial-temporal patterns of phytoplankton from southern coastal waters during the period of March to November in 2004 was carried out. Total cell numbers were shown in 5,286 cells ml−1 on March and reached to encounter a peak of 27,775 cells ml−1 on July. Mean cell number was also shown in maximum of 1,587 cells ml−1 on July, which recorded approximately two times higher than on June. The cell number of phytoplankton from southmiddle waters attained an abundance of ≥35 regardless of months, which was the highest the abundance of phytoplankton in 2004 than any other waters in this study. Southwestern waters were lower the cell number of 2-5 times than those of southmiddle and southeastern waters. In particular, Prorocentrum occurred in southeastern waters on June and the highest cell number of 8,200 cells ml−1 around Tongyeong region on July, which was recorded to occupy the value of 60.9% in southeast waters. The abundance of Skeletonema costatum as a dominant taxa in southwest was shown in ≥60 on March, July, September, and October, whereas was also recorded to achieve the abundance of above 80% in southmiddle waters on March, July, and September. The majority of the taxa in southeastern waters was diatom: Eucampia zoodiacus, and Chaetoceros spp.. They occupied above 45%. On November, most of southern waters were abundant to Chaetoceros spp. On the basis of cluster analysis using SPSS ver 10.0, phytoplankton occurring on March showed somewhat no correlation with all of southern waters. In contrast to on March, the relationship between southwestern and southmiddle waters was shown on August and November, indicating a distinction from southeastern waters. However, the distance between southwestern/middle and southeastern waters appeared to be less than 5. Consequently, the abundance of phytoplankton in southern waters showed much fluctuations in temporal and spatial assays. In particular, southwestern and southmiddle waters during the periods of summer and winter appeared to be a similar to environmental characteristics.
6.
2006.06
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It was compared the reduction effect of contaminants and odor according to DO change and EM (effective microorganisms) addition in maturation process of piggery slurry. The maturation processes were divided into three cases as follows: R-1 was operated at 2.5 mg/ℓ of DO without the addition of EM, R-2 was operated at 7.5 mg/ℓ of DO without the addition of EM and R-3 was operated at 2.5 mg/ℓ of DO with the addition of EM. The addition of EM was more effective than the increase of DO for the reduction of CODcr, NH3-N and T-N in the maturation of piggery slurry. In addition, the reducing effect of odor intensity appeared high even in the short-term maturation period in case of adding EM and one could not even smell the stimulating odor of piggery slurry.
7.
2006.06
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This study make a comparison between the phosphorus removal performance of FNR(Ferrous Nutrient Removal) process and A/O process by the laboratory experiments. For simultaneous removal of phosphorus, iron electrolysis was combined with oxic tank. Iron precipitation reactor on the electrochemical behaviors of phosphorus in the iron bed. The phosphorus removal in FNR process was more than A/O process. Iron salts produced by iron electrolysis might help to remove COD and nitrogen. And the demanded longer SRT is the more removes the removes COD, nitrogen, and phosphorus. Also, FNR process of sludge quantity more reduce than A/O process to input cohesive agents.
8.
2006.06
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The purposes of this paper were to monitor the temperature rising courses and spark discharge of the modified granular activated carbon (GAC) by microwave (MW) irradiation and to evaluate absorption of benzene. The GAC coated on SiO2, boron, talc, ferrite was named as the modified GAC. Thermal and spark discharge measurement of virgin GAC and modifed GAC has been carried out using a MW device operating at 2450 MHz under various energy conditions. The results of this paper as follows. First, the modified GAC is more efficient than the virgin GAC in temperature control. Temperature gradient of the modified GAC is more lower than that of virgin GAC. The temperature gradient of GAC was observed in the following order : virgin GAC, Mn-Zn ferrite/GAC, Ni-Zn ferrite,/GAC, SiO2/GAC, Boron/GAC, Talc/GAC. Second, the spark discharge of the modified GAC was diminished, compared with that of virgin GAC. Because of its excellent electrical insulating properties, the coating material prevents the spark discharge. Finally, the benzene adsorption capacity of the modified GAC decreased due to diminishing of adsorption site by the coating material. Considering the temperature gradient and spark discharge of GAC, the GAC coated SiO2 would be appropriate absorbent under irradiation of MW.
9.
2006.06
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The advantage of CFBC(Circulating fluidized bed combustor) is that it can apply to various fuel sources including the lower rank fuel and remove SOx by means of direct supply of limestone to the combustor without additional desulfation facility.
In this paper, we denote characteristics of fly and bed ash to reuse finer limestone usually abandoned(used spec[Coarse LS] 0.1mm under 25%, new spec[Fine LS] 0.1mm under 50%).
According to the results, the chemical composition of fly ash was as follows; SiO2 40.8%, Al2O3 31.9%, CaO 10.7%, K2O 4.46% in the case of coarse limestone and SiO2 41.1%, Al2O3 31.3%, CaO 10.9%, K2O 4.66% in the case of fine limestone. The chemical composition of bed ash was as follows; SiO2 54.2%, Al2O3 33.1%, CaO 1.56%, K20 4.34% in the case of coarse limestone and SiO2 53.8%, Al2O3 32.6%, CaO 2.21%, K2O 4.45% in the case of fine limestone. It showed that there was no significant change in chemical composition. And it is conformed that there was no significant change in particle size and shapes.
10.
2006.06
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SIS triblock copolymers, one of the major raw materials of oil gelling agent, were synthesized by living anionic polymerization and the resultant copolymers formed with various shapes and sizes were used to examine their oil gelling capacities. Coupling method was adapted to form final triblock products from diblock living polymers. Prior to polymerization, the impurities in monomers and solvents were throughly removed by killing technique. We experimentally investigated the effects of operating parameters of synthesis and forming of SIS triblock copolymers on oil gelling capacity. The photocatalytic decomposition of SIS triblock copolymer under ultraviolet circumstance was also investigated and it is found that the addition of P-25 enhances the photocatalytic decomposition.
11.
2006.06
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The coal gasification fuel is important to replace petroleum fuel. Also they have many benefits for reducing the air pollution. Measurements on the combustion characteristics of synthetic gas from coal gasification have been conducted as compared with LPG in constant volume combustion chamber. The fuel is low caloric synthetic gas containing carbon monoxide 30%, hydrogen 20%, carbon dioxide 5%, and nitrogen 45%. To elucidate the combustion characteristics of the coal gasification fuel, the combustion pressures, combustion durations, and pollutants(NOx, CO2, CO) are measured with equivalence ratios(ø), and initial pressures of fuel-air mixture in constant volume chamber. In the case of the coal gasification fuel, maximum combustion pressure and NOx concentration are lower rather than LPG fuel. However CO and CO2 emission concentration are similar to that of LPG fuel.
