• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.179-182
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• 2000

Toluene-degrading bacterium, Microbacterium esteraromaticum CS3-1 was isolated from the biofilter for the removal of BTEX. Microbacterium esteraromaticum CS3-1 was shown to utilize toluene as a primary carbon and energy source. Effect of mixed BTEX gases on toluene degradation rate by M. esteraromaticum CS3-1 was investigated in this study. Toluene degradation rate was 2.26(only toluene), 2.06(toluene+benzene), 2.57(toluene+ethylbenzene), and 4.74(toluene+xylene) mmole $toluene\;{\cdot}\;g-DCW^{-1}\;{\cdot}\;h^{-1}$. Toluene degradation rate was 2.26(only toluene), 1.23(toluene+benzene+ethylbenzene), 1.52 (toluene+ethylbenzene+xylene), and 1.76(toluene+benzene+ethylbenzene+xylene) mmole $toluene\;{\cdot}\;g-DCW^{-1}\;{\cdot}\;h^{-1}$. The presence of BTEX compounds over three mixtures had a negative effect on toluene degradation rate. Toluene degradation rates were enhanced by the presence of ethylbenzene or xylene, whereas the presence of benzene had a negative effect on toluene degradation rate in comparison with toluene degradation rate when only toluene is existent.

• Journal of Urban Science
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• v.8 no.2
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• pp.13-18
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• 2019

Using self-made coil dielectric barrier discharge reactor, the removal efficiency of ethyl acetate under simulated experimental parameters such as initial concentration of waste gas, total flow rate, relative humidity and voltage was investigated. The results show that the degradation rate of ethyl acetate increases with the increase of output voltage. When other conditions remain unchanged, the degradation rate decreases with the increase of initial concentration of ethyl acetate; with the increase of total flow rate, the degradation rate of ethyl acetate decreases; with the increase of relative humidity, the degradation rate first increases and then decreases, and when the relative humidity is 64%, the degradation efficiency is the highest.

• Journal of Environmental Science International
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• v.11 no.10
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• pp.1103-1108
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• 2002

In order to evaluate the degradation organophosphorus pesticide, EPN, in water environment, the effects of water temp.(10$^{circ}C,\;30^{\circ}C$), pH(3-11) and sunlight on its degradation were investigated during 10 days. The degradation rate of EPN(200 rpm) was faster at higher water temp. and higher pH, i.e., its degradation rate at pH 3, 5, 7, 9, 11 was 57, 63, 66, 69, 75%(1$0^{\circ}C$), and 70, 74, 79, 91, 97%(3$0^{\circ}C$) after 10 days, respectively. The effect of water temp. on its degradation was little in acidic condition, but was rather great in alkaline condition, with time. EPN was degraded fast at the alkaline condition by photolysis. At the condition of pH 11, EPN was degraded fast at the early stage in the first 2 days, but after that the degradation rate was weakened.

• Journal of Korean Institute of Industrial Engineers
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• v.34 no.1
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• pp.23-31
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• 2008

This paper presents accelerated degradation test plans considering adoption of tightened critical values. Under arandom coefficient degradation rate and log-linear acceleration models, the asymptotic variance of an estimatorfor a lifetime quantile at the use condition as the optimization criterion is derived where the degradation ratefollows a lognormal and Reciprocal Weibull distributions, respectively and then the low stress level andproportions ofunits allocated to each stress level are determined. We also show that the developed test plans canbe applied to the multiplicative model with measurement error.

• Korean Journal of Environmental Agriculture
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• v.16 no.4
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• pp.341-346
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• 1997

The degradation of fungicide oxadixyl in soil amended with manure, chemical fertilizers, heavy metals and detergent was studied. The degradation of oxadixyl in the soil was slow, but became to be fast after the lag phase of about 14 days. The half-life was 10.5 days. The degradation rate was accelerated largely by the amendment of manure. Potassium also promoted the degradation rate but nitrogen and phosphate did not. The heavy metals inhibited the degradation rate, in order of Ni, Cd, Cr, Cu, and Zn. The degradation rate was declined greatly with the addition of synthetic detergent. The microbial biomass and the respiration rate in the soil were increased by the amendment of manure and chemical fertilizers, but decreased by the addition of heavy metals and cleaner. The degradation rate of oxadixyl was positively correlated with the microbial biomass and the respiration rate.

• Journal of Korean Society on Water Environment
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• v.21 no.4
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• pp.347-352
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• 2005

The isolated microorganisms, Pseudomonas stutzeri, Raoultella planticola (Klebsiella), Serratia fonticola from petroleum contaminated soil were enriched on benzene, toluene, ethylbenzene, o-xylene as carbon and energy sources, respectively. And the degradation characteristics of BTEX was observed in the mixed BTEX substrates. We found that the BTEX in mixed substrates were degraded more than 50% by three isolated microorganisms. Among three isolated microorganisms, the highest degradation rate was observed in Pseudomonas stutzeri, but the degradation rate was different according to microorganisms. In order to increase the degradation efficiency, we applied the co-culture of isolated three microorganisms. The mixture rate of pseudomonas stutzeri : Raoultella planticola (Klebsiella) : Serratia fonticola was follows ; 1:2:1, 1:1:2, and 2:1:1, respectively. In two co-culture of 1:2:1 and 1:1:2, degradation rate was lower than isolated microorganisms. However, degradation rate became higher than isolated microorganisms and the degradation rate of benzene, toluene, and ethylene was more than 95% in co-culture of 2:1:1. The degradation rate increased through the co-culture of isolated microorganisms, however, the growth rate decreased. This was resulted from the substrate competition between microorganisms. The co-culture of microorganisms is a effective method to increase the degradation efficiency of BTEX and the co-culture mixing rate is a important factor for determination of degradation efficiency.

• Journal of Microbiology and Biotechnology
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• v.13 no.1
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• pp.29-34
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• 2003

A Pseudomonas sp. strain NGK1 (NCIM 5120) capable of utilizing salicylate was immobilized in alginate and polyurethane foam (PUF). The degradation rate of salicylate by freely suspended cells was compared with the degradation rate by immobilized cells. In an initial 20 and 40 mM salicylate, free cells ($2{\times}10^{11}\;cfu\;ml^{-1}$) degraded to 16 and 14 mM, alginate-entrapped cells degraded to 18 and 26 mM, and PUF-entrapped cells degraded to 20 and 32 mM salicylate, respectively, in batch cultures. The alginate-and PUF-entrapped cells were used in repeated batch and continuous culture systems. The efficiency of both the immobilized systems f3r the degradation of salicylate was compared. It has been observed that the PUF-entrapped cells could be reused for more than 20 cycles whereas alginate-entrapped cells could be reused for a maximum of only 12 cycles, after which a decrease in degradation rat was observed with the initial 20 and 40 mM salicylate. The continuous degradation of sallcylate by freely suspended cells showed a negligible degradation rate of salicylate when compared with immobilized cells. With the immobilized cells in both alginate and polyurethane foam, the degradation rate increased with an increase in the dilution rate up to $2\;h^{-1}$ for 20 mM, and $1.5\;h^{-1}$ for 40 mM salicylate. The results revealed that PUF-entrapped cells were more efficient for the degradation of salicylate than alginate-entrapped cells and freely suspended cells.

• KSBB Journal
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• v.15 no.3
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• pp.247-253
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• 2000

This study was aimed to enhance polycyclic aromatic hydrocarbon(PAHS) biodegradation rate by repeated-batch treatment using immobilized cells of Phanerochaete chrysosporium. In the repeated-batch operations with 30 mg/L of pyrene the maximum degradation rate was 6.58 mg/L day. As the number of batches increased the concentration of immobilized cells significantly decreased and the degradation rate and specific acitivity gradually increased to a maximum value and then decreased. To have PAH degradation activity and cell mass recovered one batch of cultivation using the growth medium instead of the PAH-degrading medium was carried in the course of repeated-batch operations. This maximum degradation rates of pyrene and anthracene were 4.29 and 4.46 mg/L$.$day respectively. Overall the rate of PAH degradation could be enhanced 2.5-30 folds by using immobilized cells compared to the case of using suspended cells.

• Journal of Microbiology and Biotechnology
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• v.11 no.4
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• pp.607-613
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• 2001

The biodegradation rates of diesel oil by a selected diesel-degrading bacterium, Pseudomonas stutzeri strain Y2G1, and microbial consortia composed of combinations of 5 selected diesel-degrading bacterial were determined in liquid and soil systems. The diesel degradation rate by strain Y2G1 linearly increased $(R^2=0.98)$ as the diesel concentration increased up to 12%, and a degradation rate as high as 5.64 g/l/day was obtained. The diesel degradation by strain Y2G1 was significantly affected by several environmental factors, and the optimal conditions for pH, temperature, and moisture content were at pH8, $25^{\circ}C$, and 10%, respectively. In the batch soil microcosm tests, inoculation, especially in the form of a consortium, and the addition of nutrients both significantly enhanced the diesel degradation by a factor of 1.5 and 4, respectively. Aeration of the soil columns effectively accelerated the diesel degradation, and the initial degradation rate was obviously stimulated with the addition of inorganic nutrients. Based on these results, it was concluded that the major rate-limiting factors in the tested diesel-contaminated soil were the presence of inorganic nutrients, oxygen, and diesel-degrading microorganisms. To resolve these limiting parameters, bioremediation strategies were specifically designed for the tested soil, and the successful mitigation of the limiting parameters resulted in an enhancement of the bioremediation efficiency by a factor of 11.

• Journal of Environmental Health Sciences
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• v.20 no.3
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• pp.78-84
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• 1994

The effects of heavy metal, Cd on the degradation of the herbicide butachlor (N-Butoxymethyl-2-chlor-2',6'-diethylacetanilide) in soils were examined the laboratory. The degradation of the herbicide in soil was greatly inhibited by the amendment of the heavy metal, Cd. The inhibited rate of Cd concentration was high in the order of 30 ppm>20 ppm> 10 ppm>0 ppm. And tile degradation rate of butachlor was high in order of 80 $\mu$M>40 $\mu$M>20 $\mu$M. The effects of Cd on the degradation of the butachlor in soil varied with concentration of heavy metal and butachlor.