• Journal of Soil and Groundwater Environment
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• v.10 no.3
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• pp.38-45
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• 2005

The feasibility of stimulating in situ aerobic cometabolic activity of indigenous microorganisms was investigated in a trichloroethylene (TCE)-contaminated aquifer. A series of single-well natural drift tests (SWNDTs) was conducted by injecting site groundwater amended with a bromide tracer and combinations of toluene, oxygen, nitrate, ethylene and TCE into an existing monitoring well and by sampling the same well over time. Three field tests, Push-pull Transport Test, Drift Biostimulation Test, and Drift Surrogate Activity Test, were performed in sequence. Initial rate of toluene degradation was much faster than the rate of bromide dilution resulting from natural groundwater drift, indicating stimulation of indigenous toluene-oxidizing microorganisms. Transformation of ethylene, a surrogate probing overall activity of TCE transformation, was also observed, and its transformation results in the production of ethylene oxide, suggesting that some tolueneoxidizing microorganisms stimulated may express a orthomonooxygenase enzyme. Also in situ transformation of TCE was confirmed by greater retardation of TCE than bromide after the stimulation of toluene-oxidizing microorganisms. These results indicate that, in this environment, toluene and oxygen additions stimulated the growth and aerobic cometabolic activity of indigenous microorganisms expressing orthomonooxygenase enzymes. The simple, low-cost field test method presented in this study provides an effective method for conducting rapid field assessments and pilot testing of aerobic cometabolism, which has previously hindered application of this technology to groundwater remediation.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.29 no.4
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• pp.477-487
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• 2019

Objectives: Firefighters are known to be exposed to a variety of toxic substances, but little information is available on the exposure profile of firefighting activities. The aims of this study were to conduct exposure monitoring of toxic chemicals at fire scenes, to compare the concentrations of respective chemicals among firefighting tasks, and to assess the main factors influencing the concentrations of chemicals. Methods: Researchers performed sampling at firefighting scenes during four weeks in 2013. At the scene, we collected samples based on firefighters' own activities and examined the situation and scale of the accident. Collected samples were classified into three categories, including fire extinguishing and overhaul, and were analyzed in the laboratory according to respective analysis methods. Results: A total of fourteen fire activity events were surveyed: five fire extinguishing, six overhaul, and three fire investigations. Although no substance exceeded the ACGIH TLV, PAHs were detected in every sample. Naphthalene ranged from 0.24 to 279.13 mg/㎥ (median 49.6 mg/㎥) and benzo(a)pyrene was detected in one overhaul case at 10.85 ㎍/㎥. Benzene (0.01-12.2 ppm) was detected in every task and exceeded the ACGIH TLV. No significant difference in concentrations between tasks was shown. Conclusions: These results indicate that all firefighting tasks generated various hazardous combustion products, including possible carcinogens.

• Applied Chemistry for Engineering
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• v.7 no.6
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• pp.1034-1042
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• 1996

Various $TiO_2-SiO_2$ composite powders were prepared by the modified sol-gel method using 1-dodecanol as DCCA (Dryng Control Chemical Additive ). Their characterizations were carried out and their photocatalytic catalysis was examined on the evolution reaction of hydrogen. The weight losses at $500^{\circ}C$ of only $TiO_2$ and $SiO_2$ powders were 33. 0wt% and 42.5wt%, respectively, and those of the $TiO_2/SiO_2$ powders ($TiO_2/SiO_2=25/75$, 50/50 and 75/25) were about $70.0{\pm}3.0wt%$. The released substances from the powders were almost organic matters. The as-prepared powders except only $TiO_2$ powder were amorphous. Transformation of anatase to rutil was hindered by $SiO_2$ component and the crystallinity of anatase was decreased with increasing $SiO_2$ contents. The as-prepared powders were bulky states. By heating at $600^{\circ}C$ for 1 hr $TiO_2-SiO_2$ powders ($TiO_2=100%$, $TiO_2/SiO_2=75/25,\;50/50$) showed agglomerates consisted of particles in submicron, but those of $TiO_2/SiO_2=25/75$ and $SiO_2=100%$ were still bulky states. Specific surface area of the powders heat-treated at $600^{\circ}C$ for 1hr was increased with $SiO_2$ concents and their pore sizes were also depended on $SiO_2$ contents. The photocatalytic activity of $TiO_2/SiO_2=75/25$ heat-treated at $600^{\circ}C$ for 1hr was 0.240mo1/h.g-cat as $H_2$ evolution rate. This value was about 2.0 times that of P-25(Degussa P-25) as a standard photocatalyst.

• Journal of Food Hygiene and Safety
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• v.25 no.2
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• pp.153-161
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• 2010

The purpose of this study was to examine the appearance of norovirus in the water for food in food service institutions and the influence of physicochemical and microbial factors of norovirus in order to work out basic data to predict the detection of norovirus. Among 82 samples of water for food in food service institutions, norovirus appeared in 7 samples and the rate of appearance was 8.5%. As for the type of norovirus, one samples contained GI type (genotype GI-6) and six samples contained GII type (genotype GII-2, GII-4, GII-12). In the regression model of prediction of norovirus, the rate of appearance was correlated with $NH_3$-N, total solids and the consumption of $KMnO_4$, out of such variables as $NH_3$-N, total solids, the consumption of $KMnO_4$, depth, chloride and total colony counts, and its contribution rate for effectiveness was 78.60%. In order to examine the influential factor of environment upon the detection of norovirus, Pearson's correlation analysis was carried out. The predictable regression formula for appearance rate of norovirus was expressed as -1.818 + 42.677 [$NH_3$-N] + 0.023 [total solids] + 0.762 [consumption of $KMnO_4$] -0.009 [depth] -0.146 [chloride] + 0.007 [total colony counts] (R = 0.904, $R^2$ = 0.818, adjusted $R^2$ = 0.786, p < 0.05). The most influential factors upon the detection of norovirus were $NH_3$-N, total solids and the consumption of $KMnO_4$. In other words, when the measured values of $NH_3$-N, total solids and the consumption of $KMnO_4$ were higher, the possibility of appearance of norovirus increased.

• 보존과학연구
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• s.33
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• pp.45-55
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• 2012

A beeswax-treated paper has no air permeability but has the water repellency compared with a general Hanji. Because of these properties, the differences of the aging factors and mechanisms between the outer partition of beeswax-treated paper that is affected by the surrounding conservation environment and the inner partition of it that is not affected are bigger than general books. In this research, we analyzed and compared the aging characteristics through the accelerated aging of the beeswax-treated paper by some air and humidity conditions. The results of the physical and optical analysis after the artificial aging, it was shown that the oxygen accelerates the aging of the beeswax-treated paper and the condition with the humidity 50% RH is more stable than the condition with the humidity 0% RH. The results of the CG/MS analysis that was conducted to figure out the decomposition charateristics of the beeswax according to the air quality and the humidity, a low molecular weight compound that the number of carbon is C9-C20 including a fatty acid such as a palmitic acid was increased as the aging was progressed. However, under the same environment, a compound that the number of carbon is C21-C36 including a hydrocarbon and a aliphatic alcohol and a high molecular weight compound that the number of carbon is more than C34 including a wax ester were decreased. A rate of change according to the air quality and the humidity was similar to the beeswax-treated papers.

• Microbiology and Biotechnology Letters
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• v.35 no.3
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• pp.196-202
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• 2007

Mutations in the cystathionine ${\beta}$-synthase (CBS) gene cause homocystinuria, the most frequent inherited disorder in sulfur metabolism. CBS is the unique enzyme using both heme and pyridoxal 5-phosphate (PLP) for activity. Among the reported 140 mutations, one of the most common disease-causing alterations in human CBS is G307S mutation. To investigate the pathogenic mechanism of G307S by spectroscopic methods, we engineered the full length and the truncated G247S mutation of yeast CBS that is corresponding mutation to human G307S. Yeast CBS does not contain heme and thus gives a merit to study the spectroscopic properties. The UV-visible spectra of the purified full length and the truncated G247S yeast CBSs showed the total absence of PLP in the protein. The absence of PLP in G247S mutation was also confirmed by the PLP-cyanide adduct formation experiment, which was conducted by the incubation of the purified enzyme with KCN. The adducts were detected using a circular dichroism (CD) and a spectrofluorimeter. Radio isotope activity assay of full length and truncated G247S proteins also gave no activity. Our yeast G247S mutation data suggested that G307S might make the distortion of the active site so that cofactor PLP and substrate can not fit inside the active site. Our yeast CBS study addressed the reason why the G307S mutation in human CBS makes the enzyme inactive that consequently leads to severe clinical phenotype.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.6
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• pp.1572-1578
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• 2007

The specified wastes consist of waste acid, waste alkali, waste oil, waste organic solvent, waste resin, dust, sludge, infectious waste, and others. Among these specified wastes, a great portion is liquid phase wastes. The purpose of this study is to develop the high temperature and high pressure (HTHP) treatment system for decomposition of the liquid phase specified waste (LPSW). For this, we analyzed the physical and chemical properties of the LPSW such as density, proximate analysis, ultimate analysis, heating values, and designed 0.3 ton/day HTHP treatment system. The LPSW tested in this experiment were prepared by adding TCE(trichloroethylene) and toluene to liquid phase waste which was brought into the commercial waste treatment company. The average density of waste oil (25 samples), waste resin (5 samples), and waste solvent (12 samples) was 0.99 g/mL, 0.91 g/mL, and 0.93 g/mL, respectively. And the average lower heating value of waste oil, waste resin, and waste solvent was 8,294 kcal/kg, 5,809 kcal/kg, and 7,462 kcal/kg, respectively. The DRE (Destruction & Removal Efficiency) of TCE and toluene were 99.95% and 99.73% at atmospheric pressure conditions and that were 99.99% and 99.82% at pressurized conditions, respectively. These results showed that TCE/toluene mixtures were properly decomposed over about 99.73% of DRE by the HTHP treatment system and pressurized conditions were more effective to destroy those pollutants than atmospheric pressure conditions. Also these systems could be directly applied to industries which try to treat the liquid phase specified waste within the regulation limit.

• Journal of the Korean Society for Marine Environment & Energy
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• v.13 no.1
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• pp.18-29
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• 2010

Offshore subsurface storage of $CO_2$ is regarded as one of the most promising options to response severe climate change. Marine geological storage of $CO_2$ is to capture $CO_2$ from major point sources, to transport to the storage sites and to store $CO_2$ into the offshore subsurface geological structure such as the depleted gas reservoir and deep sea saline aquifer. Since 2005, we have developed relevant technologies for marine geological storage of $CO_2$. Those technologies include possible storage site surveys and basic designs for $CO_2$ transport and storage processes. To design a reliable $CO_2$ marine geological storage system, we devised a hypothetical scenario and used a numerical simulation tool to study its detailed processes. The process of transport $CO_2$ from the onshore capture sites to the offshore storage sites can be simulated with a thermodynamic equation of state. Before going to main calculation of process design, we compared and analyzed the relevant equation of states. To evaluate the predictive accuracies of the examined equation of states, we compare the results of numerical calculations with experimental reference data. Up to now, process design for this $CO_2$ marine geological storage has been carried out mainly on pure $CO_2$. Unfortunately the captured $CO_2$ mixture contains many impurities such as $N_2$, $O_2$, Ar, $H_{2}O$, $SO_{\chi}$, $H_{2}S$. A small amount of impurities can change the thermodynamic properties and then significantly affect the compression, purification and transport processes. This paper analyzes the major design parameters that are useful for constructing onshore and offshore $CO_2$ transport systems. On the basis of a parametric study of the hypothetical scenario, we suggest relevant variation ranges for the design parameters, particularly the flow rate, diameter, temperature, and pressure.

• Korean Journal of Microbiology
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• v.47 no.4
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• pp.356-363
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• 2011

The accidental releases of total petroleum hydrocarbons (TPH) due to oil spills frequently ended up with soil and ground water pollution. TPH may be degraded through physicochemical and biological processes in the environment but with relatively slow rates. In this study an attempt has been made to develop an integrated chemical and biological treatment technology in order to establish an efficient and environment-friendly restoration technology for the TPH contaminated soils. A Fenton-like reaction was employed as a preceding chemical treatment process and a bioaugmentation process utilizing a diesel fuel degrader consortium was subsequently applied as a biological treatment process. An efficient chemical removal of TPH from soils occurred when the surfactant OP-10S (0.05%) and oxidants ($FeSO_4$ 4%, and $H_2O_2$ 5%) were used. Bioaugmentation of the degrader consortium into the soil slurry led to an increase in their population density at least two orders of magnitude, indicating a good survival of the degradative populations in the contaminated soils ($10^8-10^9$ CFU/g slurry). TPH removal efficiencies for the Fenton-treated soils increased by at least 57% when the soils were subjected to bioaugmentation of the degradative consortium. However, relatively lower TPH treatment efficiencies (79-83%) have been observed in the soils treated with Fenton and the degraders as opposed to the control (95%) that was left with no treatment. This appeared to be due to the presence of free radicals and other oxidative products generated during the Fenton treatment which might inhibit their degradation activity. The findings in this study will contribute to development of efficient bioremediation treatment technologies for TPH-contaminated soils and sediments in the environment.

• Journal of agriculture & life science
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• v.51 no.5
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• pp.91-101
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• 2017

The in vitro experiment was conducted to ensure the supplemental level of spent Flammulina velutipes mushroom substrates(SMS) as an energy source in manufacturing of rye silage. Rye harvested at heading stage was ensiled with spent mushroom substrates of 0%(Control), 20%(R-20), 40%(R-40) and 60%(R-60) as fresh matter basis for 6week. The rumen fluid for preparation of in vitro solution was collected from two cannulated Holstein bulls fed a 40:60 concentrate:timothy diet. The experiment was conducted by 3, 6, 9, 12, 24, and 48 hrs of ncubation time with 3 replications. The silages were evaluated fermentation characteristics and dry matter digestibility(DMD) in vitro. The pH of in vitro solution was inclined to decrease with elapsing the incubation time, and that of the R-60 was significantly(p<0.05) lower than the other treatment at 48 hr of incubation. The microbial growth in vitro was inclined to increase with elapsing the incubation time, and that of the R-20 was significantly(p<0.05) greater than the Control at 48 hr of incubation. Gas production was greater(p<0.05) in the Control than the other treatments at 48 hr of incubation. In vitro dry matter digestibility(IVDMD) was higher with increasing the supplemental level of SMS, and was significantly(p<0.05) lower in the Control compared with other treatments throughout whole incubation time. The IVDMD for R-60 was the highest(p<0.05) among treatments at 24 hr and 48 hr of incubation. Considering of above results and the availability of SMS, SMS could be supplemented by 60% in fresh matter basis for rye silage fermentation.