• Korean Chemical Engineering Research
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• v.52 no.1
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• pp.92-97
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• 2014

Perchlorate ($ClO_4^-$) is an emerging contaminant of soil/groundwater and surface water. $ClO_4^-$ has been shown to inhibit iodide uptake into the thyroid gland and cause a reduction in thyroid hormone production. $ClO_4^-$ is highly soluble and very stable in water. Biodegradation by $ClO_4^-$-reducing bacteria (PRB) is considered the most important factor in natural attenuation of $ClO_4^-$. Rivers in an industrial complex have potential to be contaminated with $ClO_4^-$ discharged from point or non-point sources. In this study, water samples were taken from the rivers running through the Gumi industrial complexes and used for batch test to analyze $ClO_4^-$-degradation potential of river microorganisms. The results of 83-h batch culture showed that $ClO_4^-$-removal efficiency of all samples was 0.77% or less without addition of an external electron ($e^-$) donor. However $ClO_4^-$-removal efficiency was higher when an $e^-$ donor (acetate, thiosulfate, $S^0$, or $F^0$) was added into the batch culture, showing up to 100% removal efficiency. The removal efficiency was various depending on type of $e^-$ donor and site of sampling. When acetate was used as an $e^-$ donor, the highest $ClO_4^-$-removal efficiency was observed among the $e^-$ donors used in this study, suggesting that activity of heterotrophic PRB was dominant. The results of this study provide basic information on natural attenuation of $ClO_4^-$ by river microorganisms. The information can be useful to prepare a strategy to enhance efficiency of $ClO_4^-$ biodegradation for in situ bioremediation.

• Clean Technology
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• v.23 no.2
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• pp.133-139
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• 2017

Bio-based plastics containing the biomass content higher than 25 wt% have been considered as environment-friendly materials due to their effects on the reduction in the $CO_2$ emission and petroleum consumption as well as biodegradability after use. In this study, poly vinyl chloride, plant-derived plasticizers, by adding a biodegradable catalyst was observed a change in the biodegradability and physical properties. To produce the oxidative decomposition transparent bio film, which is broken down in the initial percent elongation and physical properties such as tensile strength, it was to test the safety of the product as a food packaging material. Poly vinyl chloride, primary plasticizer, secondary plasticizer, anti fogging agent, the combined stabilizer were mixed in a high speed mixer, then extruded using an extrusion molding machine, after cooling, winding, to produce a oxidative decomposition transparent bio film and the control film, with a thickness of $12{\mu}m$ through winder role. Mechanical properties tensile strength, elongation, and the maximum load elongation and biodegradation test. Transparent bio film produced by biodegradation catalyst is compared with the control film. Tensile strength and elongation of films were found to be no significant difference. Further, as a result of the biodegradation test for 45 days based on the ASTM D6954-04 method, biodegrability of film is 61.4%.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.4
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• pp.619-627
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• 2000

Biodegradation of the C. I. Reactive Blue 114 was investigated in an upflow anaerobic sludge blanket (UASB) reactor. Important parameters studied include dye concentration, the kind and concentration of carbon source, hydraulic retention time (HRT), and influent pH. Glucose was found to be a better co-substrate than the mixture of volatile fatty acids (VFAs), although its concentration did not affect dye removal efficiency in the range of $1000{\sim}3000mg/{\ell}$. When HRT increased from 6 hr to 24 hr, dye removal efficiency increased up to 12 hr and remained almost constant thereafter at about 40%. When influent pH was varied in the range of 6.0~8.0, the effluent pH was varied in the range of 6.8~7.5 with maximum efficiency at pH 7.0. The highest dye removal rate obtained was $52mg/{\ell}{\cdot}day$, while the maximum dye load to meet the discharge limit of color intensity was estimated to be $46mg/{\ell}{\cdot}day$ at HRT of 12 hr and an influent glucose concentration of $2200mg/{\ell}$.

• Journal of the Korean GEO-environmental Society
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• v.15 no.5
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• pp.39-46
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• 2014

The objectives of this study were to determine biodegradation and characteristics of BTEX and MTBE under aerovic-anaerobic conditions and evaluate the potential of natural attenuation method in denitrifying condition.. In the single-substrate experiments, all of the BTEX compounds were degraded under all the conditions. but, lower degradation of benzene and p-xylene were observed under aerobic condition due to the lack of oxygen initially supplied. In the mixed-substrate experiments, BTEX degradation was delayed compared to that in the single-substrate experiments due to a competition of the substrates. Biodegradation of MTBE was observed only under denitrifying conditions and we expected that MTBE mineralized to $CO_2$ without the accumulation of TBA. We also conducted to determine the effect of initial nitrate concentration on BTEX and MTBE degradation. At low nitrate concentration (<50 mg/L), BTEX degradations were limited by the lack of electron acceptor and BTEX degradation was inhibited at high nitrate concentration (>200 mg/L). The results in this study indicated that biotransformation could be applied to the gasoline-contaminated region under aerovic-anaerobic.

• Microbiology and Biotechnology Letters
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• v.31 no.4
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• pp.408-412
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• 2003

The purpose of this study was to evaluate the Influence of oil concentration and inoculum size on petroleum biodegradation in soil by Nocardia sp. H17-1, isolated from oil-contaminated soil. To investigate the effect of initial oil concentration on total petroleum hydrocarbon (TPH) degradation, the soil was artificially contaminated with 10, 50 or 100 g of Arabian light oil per kg of soil, respectively. After 50 days, Nocardia sp. H17-1 degraded 78,94 and 53% of the each initial TPH concentration, respectively. Also, it produced 1.35, 4.21, and 5.91 mmol of $CO_2$ per g of soil, respectively. The degradation rate constant (k) of TPH was decreased in proportion to the initial oil concentrations while $CO_2$ production was increased with the concentration. The growth of Nocardia sp. H17-1 was remarkably inhibited when it was inoculated into soil containing 100 g of oil per kg of soil. To evaluate the effect of the inoculum size, the soil was artificially contaminated with 50 g of Arabian light oil per kg of soil, and inoculated with $3${\times}$10^{6}$ , $5${\times}$10^{7}$ , $2${\times}$10^{8}$ cells per g of soil, respectively. After 50 days, the degradation of TPH was remained with similar in all treatment but degradation rate constant (k) and evolved $CO_2$ was increased with increasing the inoculum size.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.8
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• pp.754-760
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• 2010

Geosmin removal by biodegradation was investigated in lab-scale slow sand filtration column with different empty bed contact times (EBCTs) and water temperature. Schmutzdecke layer was built up after 30 days operation and biomass and activity were $4.5{\times}10^6\;CFU/g$ and $3.42\;mg{\cdot}C/m^3{\cdot}hr$, respectively. The attached bio-film microorganisms in schmutzdecke layer were isolated and identified. The dominant species was Pseudomonas sp. that had occupied 56%. Removal efficiencies of dissolved organic carbon (DOC) and geosmin were 27% and 95% after 30 days operation. In lab-scale slow sand filtration column, geosmin and DOC removal efficiencies were 62% and 10% at $5^{\circ}C$, respectively. And increasing water temperature ($15^{\circ}C$ and $25^{\circ}C$) increased the geosmin and DOC removal efficiencies (88~100% and 25~42%) in lab-scale slow sand filtration column. Geosmin and DOC biodegradation rates (k) in the schmutzdecke layer (in the upper 5 cm filter bed) were $1.842{\sim}15.965\;hr^{-1}$1 and $0.253{\sim}1.123\;hr^{-1}$, respectively. It were about 18~32 times and 20~51 times of the rates in the deeper filter bed (5~60 cm).

• Journal of Soil and Groundwater Environment
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• v.9 no.3
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• pp.38-48
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• 2004

Natural attenuation of petroleum hydrocarbon was investigated at an industrial complex about 45 Km away from Seoul. The three-years monitoring results indicated that the concentrations of DO, nitrate, and sulfate in the contaminated area were significantly lower than the background monitoring groundwater under the non-contaminated area. The results also showed a higher ferrous iron concentration, a lower redox potential, and a higher (neutral) pH in the contaminated groundwater, suggesting that biodegradation of TEX(Toluene, Ethylbenzene, Xylene) is the major on-going process in the contaminated area. Groundwater in the contaminated area is anaerobic, and sulfate reduction is the dominant terminal electron accepting process in the area. The total attenuation rate was about 0.0017∼0.0224day$^{-1}$ and the estimated first-order degradation rate constant(λ) was 0.0008∼0.0106day$^{-1}$ . However, the reduction of TEX concentration in the groundwater was resulted from not only biodegradation but also dilution and reaeration through recharge of uncotaminated surface and groundwater. The natural attenuation was, therefore, found to be an effective, on-going remedial process at the site.

• Journal of the Korean Wood Science and Technology
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• v.33 no.1 s.129
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• pp.48-57
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• 2005

Phthalate esters are known as plasticizers and some of them suspected as endocrine disrupting chemicals. In this study, in order to identify the mechanism of phthalate esters degradation by white rot fungus, phthalic acid, which is major metabolite in the biodegradation of phthalate esters, was used. Phthalic acid 50 ppm was treated in culture medium with Polyporus brumalis. The availability of ABTS oxidation was different from control and phthalic acid treated group after 4 days of incubation. The activity was gradually increased in control group, but not in phthalic acid treated group. Especially, esterase activity of control group was maximized at 10 days of incubation, and then decreased while the activity of phthalic acid treated group was increased. Glucose was used as a carbon source, and the difference of glucose consumption by control and phthalic acid treated group was not significant. However, after 6 days of incubation the residual glucose in culture medium was rapidly decreased. The consumption rate of phthalic acid treated group was lower than control. These results might indicate that the absorption of phthalic acid in culture medium was occurred by mycelium and metabolized through some pathways as that of glucose was. To clearify the chemical modification of phthalic acid in culture medium, phthalic acid was reacted under in vitro condition which mycelium was excluded. The metabolites were analyzed by GC/MS. The results showed that phthalic acid was converted to phthalic acid anhydride by the extracellular enzymes of P. brumalis.

• Journal of the Korean Society of Radiology
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• v.17 no.6
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• pp.993-999
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• 2023

Bio materials of fibrinogen and collagen are widely used in tissue regeneration engineering. In this study, I aim to create a new dual-structure support using these two materials. Strategically, tissue regeneration takes priority over blood vessel regeneration, so by forming a fibrinogen support that helps blood vessel formation on the outside of the double support and placing collagen, which is more effective in tissue regeneration, in the center, a synergistic effect in new tissue regeneration is expected. Although these two materials have been used interchangeably in previous studies, there has been no report yet on making a support through the formation of a support structure for the core system. Therefore, the core of this study, the double scaffold, is to propose a method for manufacturing a core structure with a collagen scaffold on the inside and fibrinogen on the outside. The experimental results showed that the fibrinogen located on the outside of the scaffold resulted in rapid biodegradation and drug release due to strategic biodegradation of the dual structure scaffold. On the other hand, collagen scaffolds were found to be able to maintain drug release time relatively longer than fibrinogen scaffolds. In conclusion, it is believed that applying the method of creating a double scaffold will have a synergistic effect on defective tissue regeneration.

• Journal of Mushroom
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• v.22 no.1
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• pp.31-36
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• 2024

Plastics are widely used in industries in human society and because of their structural stability, degradation is a serious global issue. To estimate the degradation of plastic, 31 edible mushrooms were cultured with the selected plastic films (polyethylene [PE], polystyrene [PS], and poly(ethylene terephthalate) [PET]) for 3 months at 25 ℃. Measuring the weight of the films showed that four species of mushrooms, namely Porostereum spadiceum, Ganoderma lucidum, Coprinellus micaceus, and Pleurotus ostreatus, exhibited the highest degrees of plastic degradation. In addition, the mushrooms and fungi that exhibited the most significant plastic degradation were cross-cultured to promote this degradation. As a result, cross-cultivation of G. lucidum and Aspergillus niger showed a weight loss of 2.49% for the PET film. For the PS film, Aspergillus nidulans showed a weight loss of 4.06%. Cross-cultivation of A. nidulans and C. micaceus, which showed a weight loss of 2.95%, was noted as an alternative for PS biodegradation, but is harmful to humans. These bio-degradation effects of edible mushroom will contribute to the development of alternatives for eco-friendly plastic degradation.