• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.467-470
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• 2003

Leaking underground storage tanks are a major source of groundwater contamination by petroleum hydrocarbons. Aerobic bioremediation has been highly effective in the remediation of many fuel releases. However, Bioremediation of aromatic hydrocarbons in groundwater and sediments is ofen limited by the inability to provide sufficient oxygen to the contaminated zones due to the low water solubility of oxygen. Nitrate can also serve as an electron acceptor and results in anaerobic biodegradation of organic compounds via the processes of nitrate reduction and denitrification. Because nitrate is less expensive and more soluble than oxygen. it may be more economical to restore fuel-contaminated aquifers using nitrate rather than oxygen. And denitrifying bacteria are commonly found in the subsurface and in association with contaminated aquifer materials. These studies have shown that BTEX and MTBE can be degraded by the nitrate-amended microcosms under aerobic and anaerobic conditons. Biodegradation of the toluene and ethylbenzne compounds occurred very quickly under denitrifying conditions. MTBE, benzene and p-xylene were recalcitrant under denitrifying conditions in this study, But finally Biodegradaton was observed for all of the test compounds.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.368-371
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• 2003

Leaking underground storage tanks are a major source of groundwater contamination by petroleum hydrocarbons. Bioremediation of aromatic hydrocarbons in groundwater and sediments is often limited by dissolved oxygen. Aerobic bioremediation has been highly effective in the remediation of many fuel releases, but Many aromatic hydrocarbons degrade very slowly under anaerobic conditions. Nitrate is a good alternative electron acceptor to oxygen and denitrifying bacteria are commonly found in the subsurface and in association with contaminated aquifer materials. Because nitrate is less expensive and more soluble than oxygen. it may be more economical to restore fuel-contaminated aquifers using nitrate rather than oxygen. This study show that biodegradation of BTEX and MTBE is enhanced by the nitrate-amended microcosms under aerobic/anaerobic conditons. Although aromatic hydrocarbons degrade very slowly under anaerobic conditions. Biodegradaton was observed for all of the test compounds.

• Journal of Korea Soil Environment Society
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• v.4 no.2
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• pp.193-201
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• 1999

This study was conducted to check the applicability of pilot-scale co-composting for the remediation of diesel contaminated soil during the winter. Nutrients and microbes were added to enhance the efficiency of bioremediation and fermenting composts were also added to stimulate the microbial activities. As a result. the soil pile was kept at adequate temperature for the bioremediation during the test period of 30∼40 days and initial concentration(2,340mg TPH/kg dry soil) was reduced to 216mg TPH/kg dry soil (approximately 91% removal). During the initial 10∼30 days, it was found that the TPH concentration and the microbial population were rapidly reduced and increased. respectively. The co-composting technology studied can be effectively applied to remediate the diesel contaminated soil during the winter.

• Journal of Soil and Groundwater Environment
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• v.14 no.3
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• pp.57-67
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• 2009

In soil and sediment environment, microorganisms play major roles in biochemical cycles of ecological significant elements. Because of its ecological significance, microbial diversity and community structure information are useful as indexes for assessing the quality of subsurface ecological environment and bioremediation. To achieve more accurate assessment, it is requested to gain sufficient yield and purity of DNA extracted from various soil and sediment samples. Although there have been a large number of basic researches regarding soil and sediment DNA extraction methods, little guideline information is given in literature when choosing optimal DNA extraction methods for various purposes such as environmental ecology impact assessment and bioremediation capability evaluation. In this study, we performed a thorough literature review to compare the characteristics of the current DNA extraction methods from soil and sediment samples, and discussed about considerations when selecting and applying DNA extraction methods for environmental impact assessment and bioremediation capability evaluation. This review suggested that one approach is not enough to gain the suitable quantity and yield of DNA for assessing microbial diversity, community structure and population dynamics, and that a careful attention has to be paid for selecting an optimal method for individual environmental purpose.

• Microbiology and Biotechnology Letters
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• v.39 no.1
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• pp.86-92
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• 2011

Three bioremediation methods, natural attenuation (NA), biostimulation (BS) and bioaugmentation (BA) were applied to remediate diesel-contaminated soil, with their remediation efficiencies and soil microbial activities compared both with and without surfactant (Tween 80). BA treatment employing Rhodococcus sp. EH831 was the most effective for the remediation of diesel-contaminated soil at initial remediation stage. On the addition of surfactant, no significant effect on the remediation performance was observed. A negative correlation was found between the dehydrogenase activity (DHA) and residual concentration of total petroleum hydrocarbons (TPHs) at below 20,000 mg-$TPHs{\cdot}kg$-dry $soil^{-1}$, as follows: DHA (${\mu}g$-TPF(Triphenylformazan)${\cdot}g$-dry $soil^{-1}\;d^{-1}$) = -0.02 ${\times}$ TPHs concentration (mg-$TPHs{\cdot}kg$-dry $soil^{-1}$) + 425.76 (2500 ${\leq}$ TPHs concentration ${\leq}$ 20000, p < 0.01).

• KSBB Journal
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• v.24 no.1
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• pp.53-58
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• 2009

This study was focused on the investigation of the characteristics of TPH and BTEX removal in oil-contaminated sandy soil and fine soil with injection of microorganisms, nutrients, and surfactants. As the result of the experiments maintained moisture contents by 10${\sim}$20%, the TPH removal efficiency in oil-contaminated sandy soil was the highest in C-1 (microorganisms+nutrients), and the efficiency in C-2 (microorganisms+nutrients+surfactants) was higher than the efficiency in C-0(microorganisms). In 81 days, TPH removal efficiency in case of C-0, C-1 and C-2 showed 51%, 83%, 63% respectively. The results of D group with fine soil showed similar trends as C group, but the TPH removal efficiency of D group was lower than that of C group. Those of both C and D group were the highest in 1 group (microganisms+nutrients). The pH of fine soil was some lower than that of sandy soil or was similar to sandy soil. In 14 days, BTEX removal efficiency in case of C-0, C-1, C-2, D-0, D-1 and D-2 showed 99.8%, 99.4%, 96.0%, 99.5%, 99.2%, 96.3% respectively. Those of both C and D group were the highest in 0 group (microganisms).

• Journal of Microbiology and Biotechnology
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• v.16 no.5
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• pp.704-715
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• 2006

Oil spill was found in 1999 from a diesel storage facility located near the top of Baekun Mountain in Uiwang City. Application of bioremediation techniques was very relevant in removing oil spills in this site, because the geological condition was not amenable for other onsite remediation techniques. For efficient bioremediation, bacterial communities of the contaminated site and the uncontaminated control site were compared using both molecular and cultivation techniques. Soil bacterial populations were observed to be stimulated to grow in the soils contaminated with diesel hydrocarbon, whereas fungal and actinomycetes populations were decreased by diesel contamination. Most of the dieseldegrading bacteria isolated from contaminated forest soils were strains of Pseudomonas, Ralstonia, and Rhodococcus species. Denaturing gradient gel electrophoresis (DGGE) analysis revealed that the profiles were different among the three contaminated sites, whereas those of the control sites were identical to each other. Analysis of 16S rDNA sequences of dominant isolates and clones showed that the bacterial community was less diverse in the oil-contaminated site than at the control site. Sequence analysis of the alkane hydroxylase genes cloned from soil microbial DNAs indicated that their diversity and distribution were different between the contaminated site and the control site. The results indicated that diesel contamination exerted a strong selection on the indigenous microbial community in the contaminated site, leading to predominance of well-adapted microorganisms in concurrence with decrease of microbial diversity.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.4
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• pp.593-601
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• 2012

Heavy metals and metalloids removal can be considered as one of the most important world challenges because of their toxicity and direct impact on human health. Many processes have been introduced but biological processes of remediation seem to offer the most suitable solution in terms of efficiency and low cost. Actinobacteria constitute one of the major microbial populations in soil, and this can be attributed to their adaptive morphological structure as well as their exceptional metabolic power. Among microbes, actinobacteria are morphologic intermediate between fungi and bacteria. Studies on microbial diversities in metal contaminated lands have shown that actinobacteria may constitute a dominantly active microbiota in addition to ${\alpha}$ Proteobacteria. Furthermore, isolation studies have shown metal removal mechanisms which are reminiscent of notable multiresistant strains, such as Cupriavidus metallidurans. Apart from members of genus Streptomyces, which produce more than 90% of commercialized antibiotics, and the nitrogen fixing Frankia, little attention has been given to other members of this phylum. This is because of difficult culture condition requirements and maintenance. In this review, we focused on specific isolation of actinobacteria and their potential applications in metal bioremediation and plant growth promotion.

• Journal of Environmental Health Sciences
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• v.28 no.5
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• pp.65-70
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• 2002

Recently, surfactants were frequently used in order to desorb the hydrophobic organic compounds (HOCs) from soil and to enhance the bioavailability. Among them, -cyclodextrin ($\beta$-CD) is one of those. This study was performed to investigate the binding characteristics between benzene and $\beta$-CD and to examine the bioavailability of benzene. First, we investigated binding characteristics between benzene and $\beta$-CD in water and water/soil system. Then, we examined the effect of $\beta$-CD on the biodegradation of benzene in water and water/soil system. Experimental results on the binding characteristics showed that $\beta$-CD resulted in an efficient complex formation with benzene. As -CD concentration increased, the benzene concentration complexed with $\beta$-CD rapidly increased to 30-40% initial benzene added, and reached the equilibrium. We also investigated the effect of $\beta$-CD on the desorption of benzene from soil in the water/soil system. As $\beta$-CD concentration increased, benzene concentration desorbed into water increased up to 90%. How-ever, in its application to biodegradation of benzene in water and water/soil system, the biodegradation rate of benzene did not improved in the presence of $\beta$-CD compared with in the absense of $\beta$-CD. This result indicated that $\beta$-CD was more preferentially used as a carbon source than benzene. Therefore, for remediation of benzene contaminated soils, $\beta$-CD can be used as a surfactant to desert benzene from soil, and then ex-situ chemical treatment can be applied for the remediation.

• KSBB Journal
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• v.23 no.6
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• pp.479-483
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• 2008

The environmental contamination by organic pollutants is a widespread problem. The most widely distributed pollution can be attributed to oil contamination. Bioremediation, the use of microorganism or microbial processes to degrade environmental contaminant, is one of the new technologies. The objective of the present study is to study the degradation of JP-8 in soil by microorganism. The degradation of JP-8 was analysed by TPH using gas chromatography. Rhodococcus fascians isolated from the petroleum contaminated site was applied for the degradation of JP-8 in the soil column system. Air flow rate of 30 ml/min was sufficient to degrade JP-8 in the soil column as much as 70% of JP-8 in the soil column. The addition of nitrogen source resulted in the increase in JP-8 degradability to 75% of JP-8 and the C:N ratio for JP-8 degradation was 100:10.