• Journal of the Korean GEO-environmental Society
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• v.11 no.10
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• pp.49-55
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• 2010

The oil spill occurred frequently due to probably the increased consumption of oil as the energy source and the raw materials of various chemicals. For the treatment of oil contaminated groundwater, DAF(Dissolved Air Flotation) is being used but the removal efficiency is low. Therefore it is necessary to reduce the free phase oil, oil-in water type or water-in oil type emulsified oil, and soluble oil which are the main sources of contaminated groundwater. In this study, treatment of contaminated groundwater was performed using the Fenton oxidation process. The optimum conditions for the removal of THP(Total Petroleum Hydrocarbon) were 3 of pH, 25mM of $H_2O_2$ concentration and 25mM of $Fe^{2+}$ concentration. THP and COD(Chemical Oxygen Demand) concentrations decreased less than 1.5mg/L and 40.0mg/L in 7 minutes using DAF and Fenton oxidation process. However it is necessary to install the settling basin as the sludge concentration increased approximately 5 times.

• Journal of Microbiology and Biotechnology
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• v.18 no.12
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• pp.1966-1974
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• 2008

A typical tropical soil from the northeast of Brazil, where an important terrestrial oil field is located, was accidentally contaminated with a mixture of oil and saline production water. To study the bioremediation potential in this area, molecular methods based on PCR-DGGE were used to determine the diversity of the bacterial communities in bulk and in contaminated soils. Bacterial fingerprints revealed that the bacterial communities were affected by the presence of the mixture of oil and production water, and different profiles were observed when the contaminated soils were compared with the control. Halotolerant strains capable of degrading crude oil were also isolated from enrichment cultures obtained from the contaminated soil samples. Twenty-two strains showing these features were characterized genetically by amplified ribosomal DNA restriction analysis (ARDRA) and phenotypically by their colonial morphology and tolerance to high NaCl concentrations. Fifteen ARDRA groups were formed. Selected strains were analyzed by 16S rDNA sequencing, and Actinobacteria was identified as the main group found. Strains were also tested for their growth capability in the presence of different oil derivatives (hexane, dodecane, hexadecane, diesel, gasoline, toluene, naphthalene, o-xylene, and p-xylene) and different degradation profiles were observed. PCR products were obtained from 12 of the 15 ARDRA representatives when they were screened for the presence of the alkane hydroxylase gene (alkB). Members of the genera Rhodococcus and Gordonia were identified as predominant in the soil studied. These genera are usually implicated in oil degradation processes and, as such, the potential for bioremediation in this area can be considered as feasible.

• Journal of Soil and Groundwater Environment
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• v.22 no.6
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• pp.48-56
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• 2017

Although various methods have been investigated for treatment of crude oil contaminated soil, more researches are still required to preserve soil environment. This study investigated the potential utility of subcritical water in remediation of crude oil contaminated soil under various experimental conditions including temperature ($150-300^{\circ}C$), flow rate (1.0-2.0 mL/min) and extraction time (60-120 min). The removal rate of crude oil gradually increased with increasing temperature and time. After treatment at $200^{\circ}C$ and $300^{\circ}C$ for 60 min, the remaining concentration of crude oil met the Kuwait standard clean-up level (10,000 mg/kg) and the Korean standard level (2,000 mg/kg), respectively. The removal efficiency of crude oil increased from 77.8% to 88.4% with increasing extraction time from 60 to 120 min at $250^{\circ}C$. A decreasing rate of oil removal was observed as flow rate increased, possibly due to channeling flow occurred within the soil body at higher flow rate condition. Overall, the results revealed that subcritical water extraction process could be feasible for remediation of crude oil contaminated soil, and the relative effect of parameters on the oil removal was in the order of temperature > time > flow rate.

• Horticultural Science & Technology
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• v.30 no.4
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• pp.442-448
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• 2012

Many outbreaks of food-borne illnesses have been associated with the consumption of fresh vegetables and fruits contaminated with food-borne pathogens. Contaminated medium, manure and irrigation water are probable vehicles for the pathogen in many outbreaks. The aim of this study was to determine the potential transfer of Escherichia coli and Bacillus cereus from medium and soil fertilized with contaminated compost or irrigation with contaminated water to the edible parts of lettuce. Moreover, survivals of the two pathogens on lettuce contaminated medium, soil and irrigation water were estimated. Lettuce seeds were planted in medium contaminated with 7.5 log colony forming unit (CFU)/g of E. coli and B. cereus. Seedlings grown in the contaminated medium were transplanted in soil fertilized with contaminated pig manure compost or uncontaminated soil. Contaminated irrigation water with E. coli and B. cereus at 8.0 log CFU/mL was applied only once on the plant by sprinkle irrigation and surface irrigation. Although E. coli and B. cereus in medium and sprouted lettuce after planting seeds were reduced as time passed, these pathogens survived in seedling raising stage for extended periods. The numbers of E. coli and B. cereus in lettuce grown on contaminated soil were detected over 4.0 log CFU/g for 21 days. The numbers of E. coli and B. cereus in lettuce applied by sprinkle irrigation were higher than those of surface irrigation by 5.0 log CFU/g. Our results indicated that contaminated medium, soil and irrigation water can play an important role in the presence of food-borne pathogens on vegetables.

• Environmental Engineering Research
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• v.15 no.4
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• pp.225-230
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• 2010

In order to treat soil contaminated with high percentages of water and petroleum, the combined microwave and thermal desorption process was studied, which was composed of the consecutive connection of two pre-treatment processes. For the thickness of the contaminated soil layer on the transfer conveyor belt, the optimal total petroleum hydrocarbon (TPH) removal rate was studied with respect to the duration of microwave exposure in the consecutive process combined with thermal desorption. The TPH removal rate when the contaminated soil layer thickness was 1 cm at 6 kW of microwave power was 80%. The removals rates for 2 and 3 cm soil layer thicknesses were both 70%. Under identical experimental conditions, the TPH removal rate for the microwave pre-treatment, when considering the soil particle size, was over 70%. The lowest TPH removal rate was achieved with a particle diameter of 2.35 mm. For contaminated soil with 30% water content, 6 kW and a thermal desorption temperature of $600^{\circ}C$ were the optimal operational conditions for the removal of THP. However, considering the fuel consumption cost, 4 kW and a thermal desorption temperature of $300^{\circ}C$ would be the most economic conditions.

• Journal of Environmental Science International
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• v.18 no.4
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• pp.473-478
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• 2009

The removal characteristics of total petroleum hydrocarbons (TPHs) and heavy metals in contaminated soils with ultrasonic washing have been studied. The ultrasonic washing was evaluated on a laboratory scale. In this investigation, the effects of factors such as ultrasonic frequency, power intensity, duration of irradiation, contents of the TPHs and heavy metals and mixing ratios between the contaminated soils and water, were considered. Experimental results suggested that the rates for contaminant extraction of the TPHs and heavy metals in the contaminated soil increased considerably with the ultrasonic washing. Therefore, the ultrasonic washing has previously been to be an effective method to remediate the contaminated soils with the TPHs and heavy metals.

• Journal of Korean Society on Water Environment
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• v.21 no.4
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• pp.403-409
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• 2005

Methyl tert-butyl ether (MTBE) contamination in groundwater often coexists with benzene, toluene, ethylbenzene, and xylene (BTEX) near the source of the plume. Then, groundwater contamination problems have been developed in areas where the chemical is used. Common sources of water contamination by BTEX and MTBE include leaking underground gasoline storage tanks and leaks and spills from above ground fuel storage tanks, etc. In oil-contaminated environments, anaerobic biodegradation of BTEX and MTBE depended on the concentration and distribution of terminal electron acceptor. In this study, effect of electron acceptor on the anaerobic biodegradation for BTEX and MTBE-contaminated soil was investigated. This study showed the anaerobic biodegradation of BTEX and MTBE in two different soils by using nitrate reduction, ferric iron reduction and sulfate reduction. The soil samples from the two fields were enriched for 65 days by providing BTEX and MTBE as a sole carbon source and nitrate, sulfate or iron as a terminal electron acceptor. This study clearly shows that degradation rate of BTEX and MTBE with electron acceptors is higher than that without electron acceptors. Degradation rate of Ethylbenzene and Xylene is higher than that of Benxene, Toluene, and MTBE. In case of Benzene, Ethylbenzene, and MTBE, nitrate has more activation. In case of Toluene and Xylene, sulfate has more activation.

• Journal of Soil and Groundwater Environment
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• v.10 no.2
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• pp.20-27
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• 2005

The seasonal variation of water quality was studied in the Hwabongcheon. It runs though a small catchment where shallow groundwater was contaminated with $NO_3-N$ by intensive livestock facilities. A direct inflow of animal waste and incoming of contaminated groundwater affected its water quality. In the dry season, an important factor of water quality in the Hwabongcheon was direct inflow of animal waste. In the wet season, concentrations of $NO_3-N$ in the Hwabongcheon were elevated in spite of being diluted by precipitation. It could be explained by the effect of increased incoming of contaminated groundwater and showed by oxygen and hydrogen isotope values. $NO_3-N$ concentration in the Cheongmicheon was lower than that in the Hwabongcheon, so it increased next a junction. This effect was intense in wet season because $NO_3-N$ concentration in the Hwabongcheon was high.

• Journal of Soil and Groundwater Environment
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• v.19 no.6
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• pp.13-17
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• 2014

Subcritical water acts like an organic solvent at elevated temperature in terms of its physicochemical properties. Taking into account this advantage, the remediation experiments of benzo[a]pyrene contaminated soil (8.45 mg/kg of initial concentration) were conducted using subcritical water extraction apparatus. The effect of operating factors on the removal efficiency was studied at the varying the conditions of the water temperature ranging $200{\sim}300^{\circ}C$, extraction time 30~90 min, and flow rate 0.3~2.0 mL/min. 12 g of benzo[a]pyrene contaminated soil was inserted into the extraction cell and placed into the reactor and then the subcritical water was driven through the cell. In this study, the removal efficiency of benzo[a]pyrene was increased from 55.1 to 98.1% when the temperature increased from 200 to $300^{\circ}C$. The removal efficiency was decreased from 97.0 to 77.0% when the flow rate increased from 0.3 to 2.0 mL/min, suggesting that the extraction is limited by intra-particle diffusion. The 30 min reaction time was determined as an effective treatment time at $250^{\circ}C$. Based on the results, the optimum condition for the remediation of benzo[a]pyrene contaminated soil was suggested to be $250^{\circ}C$, 30 min, and 0.3 mL/min.

• Environmental Engineering Research
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• v.23 no.2
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• pp.175-180
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• 2018

Box-Behnken Design (BBD) under response surface methodology (RSM) was implemented to optimization the operating parameters and assess the removal and recovery efficiencies of crude oil from contaminated soil using subcritical water extraction. The effects of temperature, extraction time and water flow rate were explored, and the results indicate that temperature has a great impact on crude oil removal and recovery. The correlation coefficients for oil removal ($R^2=0.74$) and recovery ($R^2=0.98$) suggest that the proposed quadratic model is useful. When setting the target removal and recovery (>99%), BBD-RSM determined the optimum condition to be a temperature of $250^{\circ}C$, extraction time of 120 min, and water flow rate of 1 mL/min. An experiment was carried out to confirm the results, with removal and recovery efficiencies of 99.69% and 87.33%, respectively. This result indicates that BBD is a suitable method to optimize the process variables for crude oil removal and recovery from contaminated soil.