• Journal of Microbiology
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• 제43권4호
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• pp.319-324
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• 2005

Estuarine sediments are frequently polluted with hydrocarbons from fuel spills and industrial wastes. Polycyclic aromatic hydrocarbons (PAHs) are components of these contaminants that tend to accumulate in the sediment due to their low aqueous solubility, low volatility, and high affinity for particulate matter. The toxic, recalcitrant, mutagenic, and carcinogenic nature of these compounds may require aggressive treatment to remediate polluted sites effectively. In petroleum-contaminated sediments near a petrochemical industry in Gwangyang Bay, Korea, in situ PAH concentrations ranged from 10 to 2,900 ${\mu}g/kg$ dry sediment. To enhance the biodegradation rate of PAHs under anaerobic conditions, sediment samples were amended with biostimulating agents alone or in combination: nitrogen and phosphorus in the form of slow-release fertilizer (SRF), lactate, yeast extract (YE), and Tween 80. When added to the sediment individually, all tested agents enhanced the degradation of PAHs, including naphthalene, acenaphthene, anthracene, fluorene, phenanthrene, fluoranthene, pyrene, chrysene, and benzo [a] pyrene. Moreover, the combination of SRF, Tween 80, and lactate increased the PAH degradation rate 1.2-8.2 times above that of untreated sediment (0.01-10 ${\mu}g$ PAH/ kg dry sediment/day). Our results indicated that in situ contaminant PAHs in anoxic sediment, including high molecular weight PAHs, were degraded biologically and that the addition of stimulators increased the biodegradation potential of the intrinsic microbial populations. Our results will contribute to the development of new strategies for in situ treatment of PAH-contaminated anoxic sediments.

• 한국지하수토양환경학회지:지하수토양환경
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• 제21권1호
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• pp.94-103
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• 2016

Landfarming that supplies aerobic biodegradation condition to indigenous microbes in soils is a biological remediation technology. In this research, volatilization and biodegradation rate by indigenous microbes in the soil contaminated with total petroleum hydrocarbons (TPH) were measured. Soils were contaminated with diesel artificially and divided into two parts. One was sterilized by autoclave to remove indigenous microorganism and the other was used as it was. Various moisture contents and number of tillings were applied to the soil to find out proper condition to minimize volatilization and enhance bioremediation. Volatilization of TPH was inhibited and biodegradation was enhanced by increase on moisture content. Tilling was usually used to supply air for microbes, but tillings did not affect the growth of microbes in our study. Enough moisture content and proper aeration are important to control volatilization in landfarming. Also, TPH degradation was a function of the microbe counts (x₁), numbers of tilling (x₂), and moisture content (x₃) from the application of the response surface methodology. Statistical results showed the order of significance of the independent variables to be microbe counts > numbers of tilling > moisture content.

• Journal of Microbiology and Biotechnology
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• 제11권4호
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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.

• Environmental Engineering Research
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• 제13권1호
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• pp.8-13
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• 2008

The extent of solubility enhancement by biosurfactant was examined at various pHs prior to the biodegradation experiments. The molar solubilization ratio (MSR) was calculated from the batch solubilization experiments and the highest MSR was detected at pH 5. The effect of the biosurfactant, rhamnolipids, on the phenanthrene mineralization in soil-water system was investigated. The strain 3Y was selected for the mineralization assay and large amounts of phenanthrene were degraded at neutral pH in soil-water system without the biosurfactant. The addition of 150 mg/L rhamnolipids showed no effect on mineralization of phenanthrene in soil-water system, and total mineralization rates after 6 weeks incubation at each pH showed no differences in presence and absence of rhamnolipids. Our result indicated that the toxic effect of rhamnolipids can disappear when soil particles exist, and also the enhanced solubility of phenanthrene does not work for mineralization enhancement in this soil-water system.

• 한국환경과학회지
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• 제4권5호
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• pp.115-115
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• 1995

Reuse of industrial effluents through the cooling systems in a petrochemical complex was described. The partial oxidation of the effluents from the biological treatment plant was examined, using Fenton''s reagent as a pretreatment step prior to a next treatment of the effluents. Next tertiary treatment using fixed-film reactor resulted in marked reductions in COD and suspended solids. The continuous fixed-film process with Fenton oxidation pretreatment showed a 23% increase in the COD removal efficiency when compared to that without pretreatment of Fenton oxidation under the volumetric organic loading rate of 0.1 kg COD/m3/day. The Fenton oxidation treatment seemed to be a possible method for tertiary biological treatment to reduce the residual toxicity with the enhanced biodegradation of the effluents.

• 한국환경과학회지
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• 제4권5호
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• pp.501-508
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• 1995

Reuse of industrial effluents through the cooling systems in a petrochemical complex was described. The partial oxidation of the effluents from the biological treatment plant was examined, using Fenton's reagent as a pretreatment step prior to a next treatment of the effluents. Next tertiary treatment using fixed-film reactor resulted in marked reductions in COD and suspended solids. The continuous fixed-film process with Fenton oxidation pretreatment showed a 23% increase in the COD removal efficiency when compared to that without pretreatment of Fenton oxidation under the volumetric organic loading rate of 0.1 kg COD/m3/day. The Fenton oxidation treatment seemed to be a possible method for tertiary biological treatment to reduce the residual toxicity with the enhanced biodegradation of the effluents.

• 한국지하수토양환경학회지:지하수토양환경
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• 제19권3호
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• pp.56-65
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• 2014

Contamination of explosive compounds in the soils of military shooting range may pose risks to human and ecosystems. As shooting ranges are located at remote places, active remediation processes with hardwares and equipments are less practical to implement than natural solutions such as bioremediaton. In this study, a series of experiments was conducted to select a suitable carbon source and to optimize dosing rate for the enhanced bioremediation of explosive compounds in surface soils and sediments of shooting ranges with indigenous microorganisms activated by external carbon source. Treatability study using slurry phase reactors showed that the presence of indigenous microbial community capable of explosive compounds degradation in the shooting range soils, and starch was a more effective carbon source than glucose and acetic acid in the removal of TNT. However, at higher starch/soil ratio, i.e., 2.0, the acute toxicity of the liquid phase increased possibly due to transformation products of TNT. RDX degradation by indigenous microorganisms was also stimulated by the addition of starch but the acute toxicity of the liquid phase decreased with the increase of starch/soil ratio. Taken together, the optimum range of starch/soil ratio for the degradation of explosive compounds without significant increase in acute toxicity was found to be 0.2 of starch/soil.

• Advances in environmental research
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• 제1권3호
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• pp.201-210
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• 2012

The bioavailability of sorbed organic contaminants is one of the most important factors used to determine their fate in the environment. This study was conducted to evaluate the bioavailability of slow-desorbable naphthalene in soils. An air sparging system was utilized to remove dissolved (or desorbed) naphthalene continuously and to limit the bacterial utilization of dissolved naphthalene. A biological air sparging system (air sparging system with bacteria) was developed to evaluate the bioavailability of the slow-desorption fraction in soils. Three different strains (Pseudomonas putida G7, Pseudomonas sp. CZ6 and Burkholderia sp. KM1) and two soils were used. Slow-desorbable naphthalene continuously decreased under air sparging; however, a greater decrease was observed in response to the biological air sparging system. Enhanced bioavailability was not observed in the Jangseong soil. Overall, the results of this study suggests that the removal rate of slow-desorbable contaminants may be enhanced by inoculation of degrading bacteria into an air sparging system during the remediation of contaminated soils. However, the enhanced bioavailability was found to depend more on the soil properties than the bacterial characteristics.

• 대한환경공학회지
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• 제30권9호
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• pp.893-899
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• 2008

본 연구에서는 낙엽과 토양에서 추출한 용존 자연유기물질(DOM)을 대상으로 생분해 과정 중 변화하는 분광특성과 pyrene 결합 반응성을 조사하였다. 유기물질 특성 변화 분석을 위해 용존 유기탄소(DOC), 용존 자연유기물질 내 방향족 탄소성분을 나타내는 고유흡광도(Specific UV absorbance: SUVA), synchronous 형광 스펙트럼과 유기탄소결합계수(pyrene organic carbon-normalized binding coefficient: K$_{oc}$) 분석을 실시하였다. 3주간의 배양기간 동안 낙엽 추출 DOM과 토양 DOM의 DOC는 각각 61%, 51% 감소하였다. 배양 전과 후의 분광특성을 비교해 보면 단백질/아미노산 계 형광특징(PLF)은 점차 감소된 반면 SUVA, 펄빅산계 형광 특징(FLF)과 휴믹산 계 형광 특징(HLF)은 점차 증가하였다. 이러한 자연유기물질의 분광특성 변화는 생분해 과정을 통해 휴믹화가 진행되며 자연유기물질 내 비방향족 생분해성 탄소성분이 단단한 구조의 방향족 탄소구조로 변화됨을 시사한다. SUVA 값과 유기오염물질과의 결합정도를 나타내는 K$_{oc}$ 값 사이에서는 시료의 종류와 상관없이 1차 상관관계(r = 0.97)를 보여 주어 생분해가 진행되는 동안 방향족 탄소구조 분포가 자연유기물질의 소수성 오염물질과의 결합 정도에 큰 영향을 미침을 보여주었다. 또한 형광특징 중 FLF와 HLF가 K$_{oc}$ 값과 높은 상관관계를 보였으며 자연유기물질의 기원에 따라 다른 상관관계식을 보여주었다. 본 연구를 통해 생분해가 진행되는 동안 자연유기물질 성분변화 및 소수성 유기오염물질의 거동 예측에 자연유기물질의 분광특성이 좋은 모니터링 지표로 사용될 수 있음을 보여 주었다.

• 한국토양환경학회지
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• 제1권2호
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• pp.35-42
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• 1996

포항근해의 정점을 대상으로 1995년 4월부터 1996년 1월까지 3개월 간격으로 종속영양세균과 원유분해세균의 분포를 조사하였다. 또한, 분리된 원유분해세균의 단일 및 혼합배양을 통하여 원유분해능도 조사하였다. 종속영양세균의 분포는 4.1 $\times$ $10^4$ - 1.2 $\times$ $10^5$ CFU/$m\ell$ 이었으며 종속영양세균에 대한 원유분해세균의 분포비는 0.05 -0.54%로서 지금까지 보필된 타지역보다 낮은 수치였다. 이 결과에서 포항근해의 원유분해세균의 분포는 육지로부터 유입되는 석유계 탄화수소에 의하여 크게 영향을 받는것으로 사료된다. 원유분해능이 우수한 26 균주를 분리.동정한 결과 Acinetobacter spp., Bacillus spp., Citrobacter spp., Micrococcus spp., Moraxella spp., Rhodococcus spp., 그리고 Berratia spp. 등의 7개 속이 나타났고, 장내세균의 출현은 해수내 오수의 유입을 반영하고 있었다. 또한 Bacillus 속 균주가 포항근해의 원유분해세균의 우점종으로 밝혀졌다. 원유분해세균을 이용한 플라스크 배양에서 원유분해는 혼합배양에 의해 증가하였다.