• Journal of Korea Soil Environment Society
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• v.1 no.2
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• pp.35-42
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• 1996

Seawater samples were collected from P'ohang coastal area during April 1995 - January 1996. The distribution of total heterotrophic bacteria and crude oil-degrading bacteria (CDB) were studied. In addition, biodegradation of crude oil was investigated through mono and mixed culture. The heterotrophic bacterial distribution was in the range of 4.1 $\times$ $10^4$- 1.2 $\times$ $10^5$ CFU/$m\ell$, respectively. The percent of crude oil-degrading bacteria against total heterotrophic bacteria was 0.05-0.54% which was lower than other marine samples reported. Therefore it could be suggested that the distribution of crude oil-degrading bacteria in the seawater of P'ohang coastal area was highly affected by presence of petroleum hydrocarbon. Taxonomical characteristics of 26 isolates were investigated. The results of identification were showed 7 genera which were Acinetobacter spp., Bacillus spp., Citrobacter spp., Micrococcus spp., Moraxella spp., Rhodococcus spp., and Serratia spp. Appearance of Enterobacteriaceae indicated that the seawater was polluted with wastewater. Also genus of Bacillus had predominant in CDB on P'ohang coastal area. In flask culture, biodegradation of crude oil was enhanced by addition of mixed culture of CDB.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.6
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• pp.318-324
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• 2017

We evaluated geosmin and MIB biodegradation and adsorption mechanism of biological activated carbon (BAC) and anthracite biofilter. In steady state of BAC process, the geosmin and MIB were completely removed at the 30 min empty bed contact time (EBCT) even though low water temperature ($9^{\circ}C$) in which the activity of attached bacteria decreased. When the water temperature was $26^{\circ}C$, the microbial biomass and activity were higher at the upper layer of the biofilm than at $9^{\circ}C$, and the microbial biomass and activity decreased as the depth was deeper. This is because when the water temperature is high, the biodegradable organic matter (BOM) removal rate in the upper layer is high and the BOM amount that can't be supplied to the lower layer. The Removal rate of geosmin and MIB by BAC process did not show a significant difference compare to activity-inhibited BAC by treated with azide and the biofilter also removed the geosmin and MIB by biological action. It means geosmin and MIB could be removed by competitive relationship between adsorption and biodegradation.

• Applied Chemistry for Engineering
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• v.10 no.3
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• pp.349-353
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• 1999

A study was carried out to see the effects of phenol on the biological degradation of a wastewater containing 2,4-dichlorophenol and 2,4-dinitrophenol and the biodegradation kinetic coefficients of Eckenfelder's modified model for the activated sludge process. The system containing base mix (BM) which was formulated with essential energy sources and nutrients was run down and washed out when 2,4-dichlorophenol and 2,4-dinitrophenol was introduced into the base mix unit without acclimation to phenol. Whereas for the system acclimated to phenol, the treatment efficiency was 91.9% in terms of $BOD_5$ and treatability for each chemical of phenol, 2,4-dichlorophenol, and 2,4-dinitrophenol was 99.8%, 43.3% and 62.5% based on concentration, respectively. Additional BM was added into the combined unit containing phenol, 2,4-dichlorophenol, 2,4-dinitrophenol so that the better treatment efficiency was achieved for each compound. The biokinetic coefficient of Eckenfelder's modified model without phenol acclimation was not estimated because the system did not reach the steady state. Thc coefficient for the phenol acclimation was 12.44 /day, however it was changed as 46.91 /day in addition of both of phenol acclimation and 47 mg/l of BM. The results presented above could be useful for the process design and further study in the field of biodegradation of benzene derivatives.

• Journal of the Korean Wood Science and Technology
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• v.38 no.6
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• pp.568-578
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• 2010

In this study, the possibility of biodegradation of polychlorinated biphenyls (PCBs) by various white rot fungi was evaluated, and outstanding white rot fungi for the degradation of PCBs were selected. Seven white rot fungi were used to degrade Aroclor 1254 and 1260, which are widely considered to be toxic and difficult to degrade. And the degradation rates of Aroclors by selected white rot fungi were performed by GC analysis. Through the resistance test of white rot fungi on different concentrations of PCBs, the inhibition of mycelial growth of Cystidodontia isubellina was much less than that of others, and this fungus grew faster than others, relatively. Based on this result, it was considered that C. isubellina was selected as degrading fungus for Aroclors. As a result of biodegradation rate of Aroclors by Cystidodontia isubellina, the degradation rate of Arolor 1254 was reached to 57.57% in 13 days, which showed very high degradation rate. Also the degradation rate of Aroclor 1260 by C. isubellina had a tendency of increasing along with increasing incubation day. Maximal degradation rate of Aroclor 1260 was 49.43% at 13 days. Based on this results, it indicated that in comparison with a previous study, high degradation rate was obtained by C. isubellina.

• Journal of Life Science
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• v.21 no.11
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• pp.1599-1606
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• 2011

To evaluate the effects of microorganism agents on oil biodegradation, treatability and microcosm studies were conducted. Petroleum oil degrading bacteria were isolated from enriched cultures of oil-contaminated sediment samples using a mineral salts medium (MSM) containing 0.5% Arabian heavy crude oil as the sole carbon source. After a 5 day-incubation period using MSM, mixed microorganisms of three species (strains BS1, BS2 and BS4) degraded 48.4% of aliphatic hydrocarbons and 30.5% of aromatic hydrocarbons. Treatability and microcosm tests were performed in the three different treatment conditions (AO: Arabian heavy crude oil, AO+IN: Arabian heavy crude oil+inorganic nutrient, AO+IN+MM: Arabian heavy crude oil+inorganic nutrient+mixed microorganism agents). Among these, significantly enhanced biodegradation of aliphatic hydrocarbons were observed in AO+IN and AO+IN+MM conditions, without showing any different biodegradation rates in either condition. However, the degradation rates of aromatic hydrocarbons in an AO+IN+MM condition were increased by 50% in the treatability test and by 13% in the microcosm test compared to those in an AO+IN condition. Taken together, it can be concluded that mixed microorganism agents enhance the biodegradation of aliphatic and aromatic hydrocarbons in laboratory, a treatability test, and a microcosm test. This agent could especially be a useful tool in the application of bioremediation for removal of aromatic hydrocarbons.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.7
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• pp.757-763
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• 2006

In our previous studies, we have isolated bacteria from BTEX-contaminated sediment, which utilized BTEX as a sole carbon source and $NO_3$-N as an electron acceptor. For the possibility of field application, we have applied co-culture of those isolates in the BTEX-contaminated soil and evaluated their biodegradation efficiencies. To investigate the relationship between the isolates and indigenous microorganism in soil, changes of microbial community structure in soil samples with respect to time were monitored. To examine this, soil samples were artificially contaminated with benzene, toluene, ethylbenzene and o-xylene. BTEX-degrading bacteria such as Pseudomonas stutzeri strain 15(DQ 202712), Klebsiells sp. strain 20(DQ 202715) and Citrobacter sp. strain A(DQ 202713) were injected into the soil samples in the ratio of 2:1:1. Our results showed that the highest BTEX biodegradation efficiency was achieved when both BTEX and $NO_3-N$ existed simultaneously. The change in soil microbial community structure was characterized by PCR-DGGE analysis comparing the relative DGGE band intensities. The band intensities of indigenous microorganisms in the soil were reduced by injecting co-culture of the three isolates. On the contrary, the relative band intensities of the isolates were increased. Among the three isolates, Pseudomonas stutzeri strain 15 rendered the highest band intensity. This indicates that the Pseudomonas stutzeri was the dominant microbial species found in the soil samples.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.3
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• pp.195-203
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• 2012

In this study, The effects of three different biological activated carbon (BAC) materials (each coal, coconut and wood based activated carbons) and anthracite, empty bed contact time (EBCT) and water temperature on the removal of MK, HHCB and AHTN in BAC filters were investigated. Experiments were conducted at three water temperatures (5, 15 and $25^{\circ}C$) and four EBCTs (5, 10, 15 and 20 min). The results indicated that coal based BAC retained more attached bacterial biomass on the surface of the activated carbon than the other BAC, increasing EBCT or increasing water temperature increased the synthetic musk compounds (SMCs) removal in BAC columns. The kinetic analysis suggested a first-order reaction model for MK, HHCB and AHTN removal at various water temperatures (5, 15 and $25^{\circ}C$). The pseudo-first-order biodegradation rate constants and half-lives were also calculated for MK, HHCB and AHTN removal at 5, 15 and $25^{\circ}C$. The pseudo-first-order biodegradation rate constants and half-lives of MK, HHCB and AHTN ranging from 0.0082 $min^{-1}$ to 0.4452 $min^{-1}$ and from 1.56 min to 84.51 min could be used to assist water utilities in designing and operating BAC filters for SMCs removal.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.6B
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• pp.695-701
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• 2006

A toluene-degrading bacterial strain was isolated from a mixed culture that was maintained using toluene as a sole carbon and energy source. The isolated bacterium was classified as Pseudomonas sp. TBD4 based on the close relationship to bacteria belonging to this genus. A bottle study to determine biodegradation rates of individual aromatic compounds showed that the biodegradation was faster in the order of toluene, benzene, styrene, and p-xylene. However, when various mixtures were subjected to TDB4, styrene was degraded at the highest rate, indicating that both toluene and p-xylene could stimulate the degradation of other substrates whereas styrene played as an inhibitor. In addition, the mixed culture and TDB4 were inoculated to the bioactive foam reactor (BFR), and the reactor performance and the corresponding change of microbial community were monitored using the fluorescent in situ hybridization (FISH) method. When an inlet concentration of the VOC mixture increased to greater than 250 ppm, the overall removal efficiency dropped significantly. The FISH measurement demonstrated that the ratio of TDB4 to the total bacteria also decreased to less than 20% along with the decline in removal efficiency in the BFR. As a result, the periodic addition of the pre-grown TDB4 might have been beneficial to achieve a stable performance in the BFR operated over an extended period.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.6B
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• pp.689-694
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• 2006

The system performance of a bioactive foam reactor (BFR), that consists of a foam column using a surfactant and a biodegradation basin containing suspended bacteria, was investigated for the treatment of gaseous toluene or a mixture of four volatile organic compounds (VOCs, benzene, toluene, p-xylene, and styrene). Overall, the BFR achieved stable VOC removal efficiencies, indicating that it can be used as a potential alternative over conventional packed-bed biofilters. Furthermore, a dynamic loading test showed that relatively constant removal was maintained at the elevated loading due to a high mass transfer rate in the foam column. However, as the inlet concentration of VOCs increased, a portion of the VOCs mass-transferred to the liquid phase was stripped out from the biodegradation basin, resulting in a decrease in the overall removal efficiency. In the BFR, the removal efficiency of the individual VOC was mainly determined depending on the biodegradation rate (styrene > toluene > benzene > p-xylene), rather than the mass transfer rate. Consequently, increases in the microbial activity and the volume of the basin could improve the overall performance of the BFR system. Further investigation on microbial activity and community dynamics is required for the BFR when subjected to high loadings of VOC mixtures.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.420-420
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• 2003