• Journal of Soil and Groundwater Environment
• /
• v.7 no.3
• /
• pp.61-70
• /
• 2002

Direct electron beam irradiation experiments on artificially contaminated soil by polynuclear aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) were performed to evaluate applicability of direct electron beam irradiation process for contaminated soil remediation. The removal efficiency of PAHs was about 97 % at 600 kGy and PCBs about 70 % at 800 kGy. PAHs were removed 27 % more, compared to PCBs although the absorbed dose was as low as 200 kGy. The contaminants decomposition was due predominantly to direct interaction of high-energy electrons and the target compounds rather than due to oxidation/reduction reaction by reactive intermediates. Radiolysis of electron beam may be able to decontaminate contaminated soil by toxic and recalcitrant organic compounds like as PAHs and PCBs effectively, but it may be economically uncompetitive. Thus, developments of post-treatment process of conventional site remediation technologies may be more practical and economical than direct radiolysis.

• Journal of Korea Soil Environment Society
• /
• v.4 no.1
• /
• pp.49-55
• /
• 1999

The treatment of petroleum contaminated soil requires various physico-chemical remediation technologies which are efficient in time and can reduce the possibility of secondary contamination by themselves In this study, an innovated soil washing process was proposed to treat the diesel-contaminated soil. Micro-bubbles, which were generated by hydrogen peroxide, deserted and floated the contaminants. Soils less than #60(0.25mm) were artificially contaminated by 6,500mg TPH/kg dry soil initially. The process was examined for pH, the soil to water mixing ratio, concentration of $H_2O$$_2$, and contacting times. In the case of less than #60 soil, maximum removal efficiency(60%) was obtained at pH 12. 1.0% hydrogen peroxide, and 1 : 5 soil to water mixing ratio for 1 hour.

• Journal of Radiation Protection and Research
• /
• v.48 no.2
• /
• pp.77-83
• /
• 2023

Background: The purpose of this study is to purify uranium (U[VI])-contaminated soil-flushing effluent using the precipitation-distillation process for clearance. Precipitation and distillation are commonly used techniques for water treatment. We propose using a combination of these methods for the simple and effective removal of U(VI) ions from soil-flushing effluents. In addition, the U concentration (Bq/g) of solid waste generated in the proposed treatment process was analyzed to confirm whether it satisfies the clearance level. Materials and Methods: Uranium-contaminated soil was decontaminated by soil-flushing using 0.5 M sulfuric acid. The soil-flushing effluent was treated with sodium hydroxide powder to precipitate U(VI) ions, and the remaining U(VI) ions were removed by phosphate addition. The effluent from which U(VI) ions were removed was distilled for reuse as a soil-flushing eluent. Results and Discussion: The purification method using the precipitation-distillation process proposed in this study effectively removes U(VI) ions from U-contaminated soil-flushing effluent. In addition, most of the solid waste generated in the purification process satisfied the clearance level. Conclusion: The proposed purification process is considered to have potential as a soil-flushing effluent treatment method to reduce the amount of radioactive waste generated.

• Journal of the Korean GEO-environmental Society
• /
• v.13 no.12
• /
• pp.59-66
• /
• 2012

In this study, it was sampling from heavy metal-contaminated soil with the waste in railroad workshop. And, the pollution concentration and analysis of particle-size distribution were conducted to design efficient purification process that it was aimed at high contaminated area, low contaminated area and samples containing waste foundry sand. But, it was the other signs of general soil contamination, as construction waste of waste concrete and waste wood, waste foundry sand, incinerator ash, etc is overall buried on the grounds. Thus, the common heavy metal purification technology has not decreased the pollution. However, heavy-metal contamination was reduced by magnetic separation utilizing the magnetic component of the mixed waste.

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

• Korean Journal of Soil Science and Fertilizer
• /
• v.45 no.5
• /
• pp.798-804
• /
• 2012

Although siderophores are induced primarily in response to iron deficiency, soil and other ecological factors can affect on this process. This study was to evaluate the production of siderophores by different fungal species isolated from heavy metal contaminated and uncontaminated soils. More than thirty fungal strains were isolated from heavy metal contaminated and rhizosphere uncontaminated soils. Chrome azurol sulfonate (CAS) was used for both quantitative and qualitative evaluation of siderophores production. No significant correlations were observed between the tested variables such as ultraviolet (UV) irradiation method and CAS-agar plate and heavy metal concentration in both soils. The production of siderophores in rhizosphere fungi was higher than those isolated from the contaminated soil; however, the difference was not significant. The siderophore production (%) by fungi isolated from heavy metal contaminated soil using UV irradiation method was positively correlated with the qualitative values using CAS-plate method (P<0.05). Pearson correlation test indicated a positive correlation between the quantitative and qualitative methods of detection for fungi isolated from rhizosphere and also those isolated from heavy metal contaminated soil.

• Korean Journal of Materials Research
• /
• v.9 no.5
• /
• pp.491-495
• /
• 1999

In this study, we focus on Ca contaminant which affects on the roughness Si substrate after thermal process. The initial Si substrates were contaminated intentionally by using a standard Ca solution. The contamination levels of Ca impurity were measured by TXRF and the chemical composition of that was analyzed by AES. Then we gre the thermal oxide to investigate the effect of Ca contaminants. The microroughness of the Si surface, the thermal oxide surface, and the surface after removing the thermal oxide were measured to examine the electrical characteristics. The initial substrates that were contaminated with the standard solution of Ca exhibited the contamination levels of 10\ulcorner~10\ulcorneratoms/$\textrm{cm}^2$ which was measured by TXRF. The Ca contaminants were detected by AES and exhibited the peaks of Ca, SI, C and O.After intentional contamination, the surface microroughness of this initial substrate was increased from $1.5\AA$ to 4$\AA$ as contamination levels became higher. The microroughness of the thermal oxide surfaces of both contaminated and bare Si substrates exhibits similar values. But the microroughness of the contaminated$ Si/SiO_2$ interface was increased as contamination increased. The thermal oxide of contaminated substrate exhibited the small minority carrier diffusion length, low breakdown voltage, and slightly high leakage current.

• Journal of Microbiology and Biotechnology
• /
• v.33 no.4
• /
• pp.471-484
• /
• 2023

Compost is widely used as an organic additive to improve the bioremediation of diesel-contaminated soil. In this study, the effects of compost amendment on the remediation performance, functional genes, and bacterial community are evaluated during the bioremediation of diesel-contaminated soils with various ratios of compost (0-20%, w/w). The study reveals that the diesel removal efficiency, soil enzyme (dehydrogenase and urease) activity, soil CH₄ oxidation potential, and soil N₂O reduction potential have a positive correlation with the compost amendment (p < 0.05). The ratios of denitrifying genes (nosZI, cnorB and qnorB) to 16S rRNA genes each show a positive correlation with compost amendment, whereas the ratio of the CH₄-oxidizing gene (pmoA) to the 16S rRNA genes shows a negative correlation. Interestingly, the genera Acidibacter, Blastochloris, Erythrobacter, Hyphomicrobium, Marinobacter, Parvibaculum, Pseudoxanthomonas, and Terrimonas are strongly associated with diesel degradation, and have a strong positive correlation with soil CH₄ oxidation potential. Meanwhile, the genera Atopostipes, Bacillus, Halomonas, Oblitimonas, Pusillimonas, Truepera, and Wenahouziangella are found to be strongly associated with soil N₂O reduction potential. These results provide useful data for developing technologies that improve diesel removal efficiency while minimizing greenhouse gas emissions in the bioremediation process of diesel-contaminated soil.

• Journal of Environmental Science International
• /
• v.12 no.4
• /
• pp.447-459
• /
• 2003

This study was carried out to develop an efficient process far the elimination of phenol pollutant from soils. An microwave-assisted process (MAP) and a conventional Soxhlet extraction method (SEM) were employed to extract phenol from two types of soils. The effects of extraction methods, aged time of the spiked soil samples, extraction solvent and extraction time on the extraction performance were compared. Our results demonstrate that the recoveries from standard soil spiked were at least 10% higher fer MAP than these f3r the conventional Soxhlet. The extraction time by MAP requires significantly shelter time (1 min) than 15 h of the conventional Soxhlet. The recoveries from non-contaminated soil spiked with phenol were also almost identical f3r above results. The reduction of the extraction times with efficiency higher than that afforded by the conventional Soxhlet technique supports the suitability of the MAP method.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.45 no.6
• /
• pp.144-152
• /
• 2003

Laboratory experiments were carried out to investigate the influence of pore water contamination on the treatment effect of sandy soil which was solidified by Portland cement. In the experiments, setting time of hydraulic cement that was mixed with contaminated mixing water was measured using Vicat equipment and observed the tendency of setting process with the kind of contaminants, organic or inorganic components. It was shown that organic contaminants of the mixing water affect largely on the initial setting process of hydraulic cement and inorganics, expecially heavy metals, did not affect on the initial setting process, otherwise it was appeared that setting time of the sandy soil that was contaminated with inorganic components was apparently faster than the sandy soil that did not include inorganic components even though organic concentrations was relatively low level (COD=200∼300) in the mixing water. The results of unconfined compression strength test (UCST) were well consistent with the results of Vicat equipment test.