• Microbiology and Biotechnology Letters
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• v.35 no.2
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• pp.150-157
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• 2007

The advanced bioremediation of diesel-contaminated soil through the exploration of bacterial interaction with plants was studied. A diesel-degrading rhizobacterium, Rhodococcus sp.412, and a plant species, Zea mays, having tolerant against diesel was selected. Zea mays was seeded in uncontaminated soil or diesel-contaminated soil with or without Rhodococcus sp. 412. After cultivating for 30 days, the growth of Zea mays in the contaminated soil inoculated with Rhodococcus sp. 412 was better than that in the contaminated soil without the bacterium. The residual diesel concentrations were lowered by seeding Zea mays or inoculating Rhodococctis sp. 412. These results Indicate that the simultaneous use of Zea mays and Rhodococcus sp. 412 can give beneficial effect to the remediation of oil-contaminated soil. Bacterial community was characterized using a 16S rDNA PCR and denaturing gradient gel electrophoresis (DGGE) fingerprinting method. The similarities of DGGE fingerprints were $20.8{\sim}39.9%$ between the uncontaminated soil and diesel contaminated soil. The similarities of DGGE fingerprints were $21.9%{\sim}53.6%$ between the uncontaminated soil samples, and $31.6%{\sim}50.0%$ between the diesel-contaminated soil samples. This results indicated that the structure of bacterial community was significantly influence by diesel contamination.

• Journal of Korea Soil Environment Society
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• v.1 no.2
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• pp.91-101
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• 1996

In recent years, phytoremediation, the use of plants to detoxify hydrocarbons, has been a promising new area of research, particularly in situ cleanup of large volumes of slightly contaminated soils. There is increasing need for a mathematical model that can be used as a predictive tool prior to actual field implementation of such a relatively new technique. Although a number of models exist for solute-plant interaction in the vegetated zone of soil, most of them have focused on ionic nutrients and some metals. In this study, we developed a mathematical model for simulation of bioremediation of hydrocarbons in soil, associated with plant root systems. The proposed model includes root interactions with soil-water and hydrocarbons in time and space, as well as advective and dispersive transport in unsaturated soil. The developed model considers gas phase diffusion and liquid-gas mass exchanges. For simulation of temporal and spatial changes in root behavior on soil-water and with hydrocarbons, time-specific distribution of root quantity through soil was incorporated into the simulation model. Hydrocarbon absorption and subsequent uptake into roots with water were simulated with empirical equations. In addition, microbial activity in the rhizosphere, a zone of unique interaction between roots and soil microorganisms, was modeled using a biofilm theory. This mathematical model for understanding and predicting fate and transport of compound in plant-aided remediation will assist effective application of plant-aided remediation to field contamination.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.363-367
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• 2003

Batch experiments were performed to determine optimum conditions for biopile. The batch experiments results showed that 12.5 to 17.9% of moisture content was effective to biodegradation of petroleum hydrocarbon regardless of soil texture. Total heterotrophic bacteria populations in the inoculum-treated soil were greater than of the control and nutrient-amended soil in the early stage, but the populations in the inoculum and nutrient-amended soil were not different significantly from those in the latter stage regardless of soil texture. The same trend was observed for petroleum hydrocarbon degrading bacteria populations. The results of the biodegradation capacity experiments showed that there was a decline in the TPH concentrations during the experiments and no significant difference on the biodegradation was observed by treatment in silt soil. Changes of n-C17/pristane and n-C18/phytane ratios in all treated soil were significantly more than those of control. This is a strong indication of biodegradation. The TPH removal rate was calculated at 60% in all treated soil.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.297-300
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• 2004

The various microbial tests were performed to determine bioremediation agent capacity for eight strains isolated from the oil contaminated regions. Two tests for isolated strains were conducted such as cell hydrophobicity and emulsifying activity. The biodegradation of SHM (saturated hydrocarbon mixture) and AHM (aromatic hydrocarbon mixture) with the strains also was carried out. The strains having higher cell hydrophobicity and emulsifying activity degraded petroleum oil effectively. The degradation capacity for SHM was represented more than 90% in YS-7 and WLH-1 of isolated strains, and KH3-2 were capable of degrading AHM. Especially, WLH-1 as yeast was shown more than two or three times in the degradation capacity of automobile engine lubricants and the biomonitoring results of contaminated soil for residual oil degrading test showed that the hydrocarbon biodegradation was increased in the second treatment by this strain.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.91-94
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• 2003

A field pilot-scale demonstration of an enhanced SVE using hot air injection and extraction was conducted to remove diesel range compounds from subsurface soils at a site in J-city, Korea. The objective of demonstration was to evaluate field ISR by intrinsic microorganism after an application study of hot air-SVE technology and to calculate each first-order kinetic with soil temperature. TPH concentration of contaminated soil at the site was approximately 2, 000~11, 000 mg/kg (average 6, 900 mg/kg) with depths greater than 5 m bgs. The 1st-order reaction rate constants, k were 0.0438(@about5$0^{\circ}C$), 0.0564(@4$0^{\circ}C$), and 0.0685(@33$^{\circ}C$) d-1 respectively.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.347-350
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• 2002

Arsenic speciation changes between As(V) and As(III) are subject to changes in accordance with redox conditions in the environment. It is common to find contaminated sites associated with mixed wastes including both organic pollutants and heavy metals. We conducted microcosm experiment under hypothesis that the co-disposed organic pollutants would influence on the arsenic forms and concentrations, via degradation of the organic pollutants and the consequent impact on the redox conditions in soil. Artificially contaminated soil samples were run for 40 days with control samples without artificial contamination. We noticed arsenic in the contaminated soil showed different behaviour compared with the arsenic in the control soil. The findings indicate degradation of organic pollutants in the contaminated soil influenced on the arsenic speciation and concentrations. A further work is needed to understand the process quantitatively. However, we could confirm that degradation of organic pollutants can influence on the abiotic processes associated with geochemical reactions in contaminated soil. Degradation of organic pollutants can increase the mobility and toxicity of arsenic in soil and sediment by changing redox conditions in the geological media and subsequently from As(V) to As(III).

• Journal of Soil and Groundwater Environment
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• v.20 no.3
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• pp.83-91
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• 2015

Mine soil contamination by high levels of metal ions that prevents the successful vegetation poses a serious problem. In the study presented here, we used the microbial biocatalyst of urease producing bacterium Sporosarcina pasteurii or plant extract based BioNeutro-GEM (BNG) agent. The ability of the biocatalysts to bioremediate contaminated soil from abandoned mine was examined by solid-state composting vegetation under field conditions. Treatment of mine soil with the 2 biocatalysts for 5 months resulted in pH increase and electric conductivity reduction compared to untreated control. Further analyses revealed that the microbial catalysts also promoted the root and shoot growth to the untreated control during the vegetation treatments. After the Sporosarcina pasteurii or plant extract based BNG treatment, the microbial community change was monitored by culture-independent pyrosequencing. These results demonstrate that the microbial biocatalysts could potentially be used in the soil bioremediation from mine-impacted area.

• Journal of Microbiology and Biotechnology
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• v.21 no.1
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• pp.71-80
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• 2011

Four diazinon-degrading bacteria were isolated from agricultural soil by using an enrichment technique. The biochemical analysis and molecular method including RFLP indicated that these isolates were identical, and one strain designated DI101 was selected for further study. Phylogenetic analysis based on 16S rDNA sequencing indicated that the strain DI101 clearly belongs to the Serratia marcescens group. The ability of the strain to utilize diazinon as a source of carbon and phosphorus was investigated under different culture conditions. The DI101 strain was able to completely degrade 50 mg/l diazinon in MSM within 11 days with a degradation rate of 0.226 $day^{-1}$. The inoculation of sterilized soil treated with 100 mg/kg of diazinon with $10^6$ CFU/g DI101 resulted in a faster degradation rate than was recorded in non-sterilized soil. The diazinon degradation rate by DI101 was efficient at temperatures from 25 to $30^{\circ}C$ and at pHs from 7.0 to 8.0. The degradation rate of diazinon was not affected by the absence of a phosphorus supplement, and addition of other carbon sources (glucose or succinate) resulted in the slowing down of the degradation rate. The maximum degradation rate ($V_{max}$) of diazinon was 0.292 $day^{-1}$ and its saturation constant ($K_s$) was 11 mg/l, as determined by a Michaelis-Menten curve. The strain was able to degrade diethylthiophosphate-containing organophosphates such as chlorpyrifos, coumaphos, parathion, and isazofos when provided as a source of carbon and phosphorus, but not ethoprophos, cadusafos, and fenamiphos. These results propose useful information for the potential application of the DI101 strain in bioremediation of pesticide-contaminated environments.

• Journal of Soil and Groundwater Environment
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• v.6 no.2
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• pp.39-47
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• 2001

According to a series of batch-scale washing tests, SDS+$POE_5$ and $POE_5$+$POE_14$ were determined for the applicable mixed surfactants. Because SDS+$POE_5$ showed slightly negative effects on the microbes in the toxicity tests, $POE_5$+$POE_14$((1:1) 1%) was chosen for this study. In the in-situ flushing experiments, the removal rate of endosulfan was 67% for the injection rate of 1.5L/min/$\textrm{km}^2$. And when methanol and ethanol were added as cosolvent, 75% and 81% removal efficiencies were achieved, respectively. In the tests of bioremediation after the application of in-situ flushing, the removal rates of contaminated soils having 13mg/kg dry soil and 3mg/kg dry soil as initial concentrations were 86% and 81%, respectively. There were no significant degradation after 24 hours. The major rate-limiting factor for the biodegradation of endosulfan might be the mass transfer from soil phase to liquid phase after 24 hours. With the addition of surfactant, 89% removal was achieved after 120 hours. Because the surfactant improved the mass transfer rate, the biodegradation of endosulfan was enhanced. When surfactant and cosolvent were added together, the adaptation period of microorganisms to the surfactant became longer and the removal rates were 84% and 83% for methanol and ethanol, respectively.

• Korean Journal of Environmental Agriculture
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• v.34 no.4
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• pp.268-273
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• 2015

BACKGROUND: Petroleum-contaminated soil from leaking above- and underground storage tanks and spillage during transport of petroleum products is widespread environmental problem in recent years. Application of compost may be the most promising, cost-effective, and eco-friendly technology for soil bioremediation because of its advantages over physical and chemical technology. The objective of this study was to evaluate effect of compost application on degradation of total petroleum hydrocarbon (TPH) in petroleum hydrocarbon-contaminated soil.METHOD AND RESULTS: An arable soil was artificially contaminated by diesel, and compost was applied at the different rate of 0, 10, 30, and 50 Mg/ha. Concentration of TPH in the soil decreased as application rate of compost increased. Degradation efficiency was highest at compost 30 Mg/ha; however, it slightly decreased with compost 50 Mg/ha. Kinetic modeling was performed to estimate the rates of chemical reaction. The correlation coefficient (R2) values for the linear plots using the second-order model were higher than those using the first-oder model. Compost 30 and 50 Mg/ha had the fastest TPH degradation rate in the second-order model. Change of microbial population in soil with compost application was similar to that of TPH. Microbial population in the soil increased as application rate of compost increased. Increasing microbial population in the contaminated soil corresponded to decreased in TPH concentration.CONCLUSION: Conclusively, compost application for soil bioremediation could be an effective response to petroleum hydrocarbon-contaminated soil. The increase in microbial population with compost suggested that compost application at an optimum rate might enhance degradation of TPH in soil.