• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.203-206
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• 2002

토양 오염의 주된 원인인 디젤은 휘발성과 용해도가 낮아 생물학적 처리법이 많이 이용된다. 생물학적 처리에서 Bioavailability 는 생분해의 속도에 영향을 미치며 유효성평가에 있어 중요하다. 디젤로 오염된 토양의 생분해 특성 및 Bioavailability를 평가하기 위하여 생분해 실험과 mass transfer 실험을 수행하였다. 생분해 속도와 mass transfer 속도의 비교를 통해 생분해 초기에는 mass transfer에 의해 그 속도가 부분적으로 제한을 받으나, 일정시간 후에는 mass transfer 속도에 의해 생분해 속도가 결정되어짐을 알 수 있었다. Multi -component 인 디젤 성분에서의 mass transfer 의 영향을 알기 위해 각 성분별에 따라 조사한 결과, linear H.C 성분과 고 휘발성 성분은 생분해 속도가 초기에는 mass transfer 에 의해 부분적으로 제한되고 후에 mass transfer 에 의해 결정되어지나, tracked H.C 성분과 저휘발성 성분은 전체적으로 mass transfer 에 의해 생분해 속도가 제한되고 있음을 알 수 있었다.

• Journal of the Korea Organic Resources Recycling Association
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• v.14 no.3
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• pp.110-116
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• 2006

In this study, the biodegradation rate of paraoxon, that is an organophosphate pesticide, was enhanced by recombinant Escherichia coli harboring organophosphorus hydrolase (OPH). The optimum conditions were 8.5 of initial pH and 5.0% of acetone for the enhancement of specific whole cell OPH activity. When the OPH was produced to 498 Unit/L, 98% of 275mg/L paraoxon was degraded within 10 minutes, and thus the biodegradation rate was enhanced to $29.2mg/g{\cdot}min$. The results implied that practical bioremediation technology developed in this study was an effective method to degrade residual organophosphate pesticide in ground water or soils in a short time.

• Journal of Soil and Groundwater Environment
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• v.10 no.4
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• pp.45-53
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• 2005

The objective of this study is to evaluate the effects of changes in soil temperature on biodegradation rate of diesel compounds from a field pilot test using hot air injection process. Total remediation time was estimated from in-situ biodegradation rate and temperature for optimum biodegradation. All tests were conducted by measuring in-situ respiration rates every about 10 days on highly contaminated area where an accidental diesel release occurred. The applied remediation methods were hot air injection/extraction process to volatilize and extract diesel compounds followed by a bioremediation process to degrade residual diesels in soils. Oxygen consumption rate varied from 2.2 to 46.3%/day in the range of 26 to $60^{\circ}C$, and maximum $O_2$ consumption rate was observed at $32.0^{\circ}C$. Zero-order biodegradation rate estimated on the basis of oxygen consumption rates varied from 6.5 to 21.3 mg/kg-day, and the maximum biodegradation rate was observed at $32^{\circ}C$ as well. In other temperature range, the values were in the decreasing trend. The first-order kinetic constants (k) estimated from in-situ respiration rates measured periodically were 0.0027, 0.0013, and $0.0006d^{-1}$ at 32.8, 41.1, and $52.7^{\circ}C$, respectively. The estimated remediation time was from 2 to 9 years, provided that final TPH concentration in soils was set to 870 mg/kg.

• Journal of Food Hygiene and Safety
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• v.14 no.3
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• pp.249-254
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• 1999

The present study was performed to investigate biodegradation rate of BPMC(2-sec-butylphenyl methyl carbamate) and chlorothalonil. In the biodegradation test of two pesticides by the modified river die-away method from June 17 to August 22, 1998, the biodegradation rate constants and half-life were determined in Nakdong(A) and Kumho River(B). Bio- degradation rate of BPMC was 27% in A sampling point, 40% in B sampling point after 7 days. Biodegradation rate constants and half-life of BPMC were 0.0460 and 15.1 days in A sampling point, 0.0749 and 9.3 days in B sampling point, respectively. Biodegradation rate of chlorothalonil was 100% in A and B sampling points after 7 days. Biodegradation rate constants and half-life of chlorothalonil were 0.1416 and 4.9 hours in A sampling point, 0.1803 and 3.8 hours in B sampling point, respectively. Biodegradation rate of chlorothalonil was faster than that of BPMC. Correlation analysis between biodegradation rate constants of pesticides and water quality(DO, BOD, SS, ABS, $NH_3-N\;and\;NO_3-N$) showed significant correlation with BOD, SS and $NH_3-N$. Furthermore, regression analysis with BOD, SS and $NH_3-N$ as independent variable and biodegradation rate constant as independent variable showed a significant linear equation. These results suggested that BPMC and chlorothalonil were mainly degraded by biodegradation, and the difference in biodegradation of two pesticides was due to difference of water quality.

• The Korean Journal of Mycology
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• v.23 no.4 s.75
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• pp.348-353
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• 1995

Biodegradability of poly (3-hydroxybutyrate) (PHB) by Penicillium pinophilum was investigated by the modified Sturm Test. The biodegradability measurement by this method was more reproducible than other conventional activated sludge methods. Optimum inoculum size for the PHB biodegradation was 1% (v/v). The degradation appeared to occur not only on the sample surface but also inside the sample because the biodegradation did not increase quite proportionally with the sample surface area. The biodegradation rate increased to an asymptotic value as the nitrogen content in the test medium increased, indicating the nitrogen source was needed for the synthesis of the PHB depolymerase.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.2
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• pp.144-149
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• 2006

As a strain EH741, having an excellent hexane degradability, was isolated from bacterial consortium using hexane as a sole carbon and energy source. EH741 was identified as a Rhodococcus sp. and the addition of a surfactant Pluronic F68(PF68), for increasing hexane solubility couldn't enhance the specific growth rate of the isolate EH741 n the mineral salt medium supplemented with hexane as a sole carbon source(hexane-BH medium). In the hexane-BH medium, the maximum specific growth rate(${\mu}_{max}$) of this strain was $0.04h^{-1}$, and the maximum hexane degradation rate($V_{max}$) and saturation constant($K_s$) were$161{\mu}mol{\cdot}g-DCW^{-1}{\cdot}h^{-1}$ and 10.5 mM, respectively. Rhodococcus sp. EH741 was one of excellent microorgamisms for hexane biodegradation processes.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.35-38
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• 2004

부틸알데히드로 오염된 대상 부지에 Biosparging 공법의 현장 적용을 위해 적정 공기 주입 압력 조건을 도출한 결과, 주 오염층인 자갈질 모래층에 공기주입 가능 파괴압력(Pe)는 약 300mmAq로 측정되었으며 4,500mmAq 압력 조건에서는 용존 산소농도의 영향 반경이 약 3 m로 나타났다. 위의 조건을 적용하여 약 150일간 운전한 결과, 영양물질을 투입하지 않은 초기 90일 동안 최고농도 대비 약 90%가 저감되었으며 그 이후에 영양물질을 투입하여 초기 최고 농도 대비 96%가 저감되어 복원목표치인 50ppm을 모든 지역에서 만족시켰다. 또한 생분해 반응속도가 k=0.03/day로 나타나 휘발성이 낮고 생분 해도가 뛰어난 부틸알데히드로 오염된 자갈질 모래층에 Biosparging공법이 성공적으로 적용된 사례이다.

• The monthly packaging world
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• s.354
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• pp.91-97
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• 2022

바이오플라스틱의 니즈는 계속 증가 중이며 생분해 바이오플라스틱이 실제 현장에 사용되기 위해서는 물성개선이 필요한 실정이다. 본 연구에서는 바이오플라스틱에 과산화물 첨가제를 농도별로 첨가하여 생산한 복합화 필름의 신장률, morphology, TGA 변화를 조사하였다. 신장률과 TGA는 과산화물 상용화제 첨가구가 대조구보다 더 우수한 것으로 나타났다. 상용화제 첨가량에 따라서 압출성형 공정의 생산성에 영향을 미치며, 과산화물은 적정량을 첨가하는 것이 중요한 것으로 나타났다. 복합화 필름의 morphology를 분석한 결과 수지별로 결정화 속도가 달라 이형분산배열을 관찰할 수 있었고, 표면물성은 4%의 과산화물 첨가구에서 가장 좋은 것으로 나타났다. 이상의 결과로부터 복합화 생분해 필름 제조 방법으로 과산화물 상용화 제를 4% 첨가한 시험구가 우수한 것으로 사료되었다.

• Journal of the Korean GEO-environmental Society
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• v.11 no.4
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• pp.43-50
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• 2010

In this study, we have isolated MTBE utilizing bacteria at the gasoline contaminated soil and also MTBE degradation patterns were characterized. The 18 bacterial mono-cultures isolated from enrichment cultures were screened for MTBE degradation. Of the 18 strains, the 3 strains (Flavobacterium, Pseudomonas, and Achromobacter) have shown effective MTBE degradation. Experimental parameters affecting the growth conditions (such as temperature, pH, initial cell mass) were optimized. Experimental parameters such as temperature $30^{\circ}C$, pH 7, and initial cell mass 0.6 g/mL in optimal growth conditions for MTBE degradation. The optimal growth conditions of the isolated stains were temperature $30^{\circ}C$, pH 7, and initial cell mass 0.6 g/mL in our experiment, respectively. The first order degradation coefficients of Achromobacter, Mixed culture, Pseudomonas, and Flavobacterium were 0.072, 0.066, 0.047, and $0.032hr^{-1}$, respectively. and also, it could be expressed as a degradation rate considering cell mass (1.302, 1.019, 0.523, and 0.352 mg/TSS g/hr for each microorganism). Although Achromobacter has shown highest MTBE degradation rate, degradation rate for BTEX was relatively lower than other strains. and Mixed culture and Flavobacterium have shown similar degradation pattern for MTBE and BTEX biodegradation.

• Composites Research
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• v.22 no.3
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• pp.18-28
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• 2009

Blends of poly(lactic acid) (PLA) and poly(butylene terephthalate) (PBT) were prepared by reaction extrusion with para-phenylene diisocyanate (PPDI). The crystallization behavior and biodegradability were investigated by using a differential scanning calorimeter (DSC), a wide angle X-ray diffractometer (WAXD), a contact angle goniometer, and a buffer solution containing esterase. The addition of PBT into PLA polymer matrix induced the cold crystallization of PLA phase, and the crystallization rate of PLA phase was significantly accelerated when both PBT and PPDI participated in the reaction with PLA simultaneously. But the chain extension caused by PPDI decreased the crystallinity and hydrophilicity of PLA and PBT phases. The crystallinity and hydrophilicity did not affect the biodegradability of PLA/PBT blends. However, phase separation between PLA and PBT in PLA/PBT blends increased the interfacial area exposed to the hydrolysis of enzyme, resulting in the improved degradability rate of PLA phase. In contrast, the improved interfacial adhesion between PLA and PBT matrices by the reaction with PPDI reduced the area exposed to the enzyme to decrease the degradation rate of PLA phase.