• Journal of Korea Soil Environment Society
• /
• v.3 no.3
• /
• pp.55-62
• /
• 1998

Soils contaminated with hydrocarbons and residual metals can be effectively treated by soil washing. In developing the soil washing process several major effects for separating contaminants from coarse soils progressively improved upon combinations of mining and chemical processing approaches. The pilot-scale soils washing process consists of the four major parts : 1) abrasive scouring, 2) scrubbing action using a washwater that is sometimes augmented by surfactants or other agents, 3) rinsing, and 4) regenerating the contaminated washwater. The plant was designed based upon the treatment capacity > 5 ton/hr on site. The lumpy contaminated soil fractions first experience deagglomeration and desliming passing through a rolling mill pipe. In the second unit the attrition scrubbing module equipped with paddles uses high-energy to remove contaminants from the soils. And a final rinsing system is assembled to separate the washwater containing the contaminants and very fine soils from the washed coarse soils. For recycling the contaminated washwater passes through a washwater clarifier specifically designed for flocculation, sedimentation and gravity separation of fine as well as flotation and separation of oils from the washwater. In order to more rapidly assess the applicability of soil washing at a potential site while minimizing the expense of mobilization and operation, a mobile-type soil washing process which is self-contained upon a trailer will be further developed.

• Journal of Soil and Groundwater Environment
• /
• v.9 no.4
• /
• pp.24-31
• /
• 2004

A cold mix asphalt (CMA) treatment process was proposed as a tool to recycle soils contaminated with petroleum hydrocarbons. Experimental studies were conducted to characterize performances of the CMA process in treating soils contaminated with diesel or diesel compounds. From the screening experiments, it was found that performances of five types of asphalt emulsions that contained a cationic or an anionic or a nonionic surfactant were not substantially different. In consideration of higher affinity for soils and higher sorption coefficients obtained, an emulsion containing Lauryl Dimethyl Benzyl Ammonium Chloride (LDBAC) was selected as a promising asphalt emulsion for treating diesel-contaminated soils. When the asphalt emulsion LDBAC was applied to treat three compounds that originated from diesel, the removal efficiencies obtained in the order of decreasing efficiencies were as follows: docosane > pentadecane > undecane. Leaching experiments on the specimen formulated by the emulsion LDBAC found that the selected treatment method could treat soils with diesel concentrations as high as 10,000 mg/kg. Leaching of the diesel from the specimen was controlled by diffusion for the first four days and then leaching rate diminished substantially. The latter behavior was characterized as depletion, which represents that the contaminant released amounts to more than $50\%$ of the total amount of the contaminant that can be leached. The amounts of three diesel compounds leached from the specimen in the order of decreasing amount were undecane, pentadecane, and docosane. The curing of the soil contaminated with pentadecane was relatively slow.

• Journal of Environmental Impact Assessment
• /
• v.16 no.1
• /
• pp.27-33
• /
• 2007

Hexavalent chromium-contaminated soils are encounted at many unregulated discharge and improper handling of wastes from electroplating, leather tanning, steelmaking, corrosion control, and wood preservation industries. Contamination of hexavalent chromium in the soil is a major concern because of its toxicity and threat to human life and environment. Current technologies for hexavalent chromium-contaminated soil remediation are usually costly and/or cannot permanently prohibit the toxic element from entering into the biosphere. Thus, as an alternative technique, immobilization is seen as a cost-effective and promising remediation technology that may reduce the leachable potential of hexavalent chromium. The purpose of this paper is to develope an immobilization technique for the formation of the geochemically stabilized hexavalent chromium-contaminated soil from the reactions of labile soil hexavalent chromium forms with the added soluble phosphate and chromium reducing agent. From the liquid phase experiment, reaction order of chromium reducing agent, soluble phosphate, alkali solution shows the best removal efficiency of 95%. In addition, actual soil phase experiment demonstrates up to 97.9% removal efficiency with 1:1 molar ratio of chromium reducing agent and soluble phosphate. These results provide evidence for the potential use of soluble phosphate and chromium reducing agent for the hexavalent chromium-contaminated soil remediation.

• Microbiology and Biotechnology Letters
• /
• v.48 no.4
• /
• pp.399-422
• /
• 2020

Remediating soils contaminated with heavy metals due to urbanization and industrialization is very important not only for human health but also for ecosystem sustainability. Of the available remediation technologies for heavy metal-contaminated soils, phytoremediation is a relatively low-cost environment-friendly technology which preserves biodiversity and soil fertility. The application of plant growth-promoting bacteria (PGPB) during the phytoremediation of heavy metal-contaminated soils can enhance plant growth against heavy metal toxicity and increase heavy metal removal efficiency. In this study, the sources of heavy metals that have adverse effects on microorganisms, plants, and humans, and the plant growth-promoting traits of PGPB are addressed and the research trends of PGPB-assisted phytoremediation over the last 10 years are summarized. In addition, the effects of environmental factors and PGPB inoculation methods on the performance of PGPB-assisted phytoremediation are discussed. For the innovation of PGPB-assisted phytoremediation, it is necessary to understand the behavior of PGPB and the interactions among plant, PGPB, and indigenous microorganisms in the field.

• Journal of Environmental Science International
• /
• v.17 no.1
• /
• pp.97-105
• /
• 2008

This study examined the contaminated soils with an indicator of TPH using SVE (Soil Vapor Extraction) and biological treatments. Their results are as follows. Water content in the polluted soils slowly decreased from 15% during the initial experimental condition to 10% during the final condition. Purification of polluted soils by Bioventing system is likely to hinder the microbial activity due to decrease of water content. Removal rate of TPH in the upper reaction chamber was a half of initial removal rate at the 25th day of the experiment. The removal rate in the lower reaction chamber was 45% with concentration of 995.4 mg/kg. When the Bioventing is used the removal rate at the 14th day of the experiment was 53%, showing 7 day shortenting. Since the Bioventing method control the microbial activity due to dewatering of the polluted soil, SVE method is likely to be preferable to remove in-situ TPH. The reactor that included microbes and nutrients showed somewhat higher removal rate of TPH than the reactor that included nurtients only during experimental period. In general, the concentration showed two times peaks and then decreased, followed by slight variation of the concentration in low concentration levels. Hence, in contrast to SVE treatment, the biological treatment tend to show continuous repetitive peaks of concentration followed by concentration decrease.

• Progress in Superconductivity and Cryogenics
• /
• v.22 no.2
• /
• pp.1-6
• /
• 2020

Large-scale civil engineering works discharge a large amount of soil suspension contaminated with natural heavy metals. Most of the heavy metal ions due to industrial activities and minings are accumulated in the soils and the sediments of lakes and inner bays through the rivers. It is necessary to remove heavy metals from the soils and the sediments, because some of these heavy metals, such as arsenic and cadmium, have significant biological effects even in small amounts. This study proposes a new volume reduction method of the contaminated soils and sediments by superconducting magnetic separation. Our process can remove the specific minute minerals selectively, which adsorbs heavy metals depending on pH. As a fundamental study, the adsorption behaviors of arsenic and cadmium on minute minerals as a function of pH were investigated, and the adsorption mechanism was discussed based on the crystal structure and pH dependence of surface potential in each minute minerals.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.10a
• /
• pp.268-276
• /
• 2008

The status of contaminated soils vary widely ; therefore, the techniques and equipment applicable to the soil concerned should be selected and used after careful consideration. Hyundai Soil Washing is physical-chemical separation based on mining and mineral processing principles for removing a broad range of organic and inorganic contaminants from soil. Mobile plant(capacity 15 tons./hr) was installed for this project. The goals of this project were 1) to verify the applicability of the washing process, which showed reliable results in the pilot plant with various kind of contaminated soils and 2) to promote recycling of the washed soil as a backfill on site. The results revealed that $F^-$ and $Pb^{2+}$ in the soil were effectively washed out to a certain level which washed soil was acceptable for recyeling.

• Proceedings of the IEEK Conference
• /
• 2001.10a
• /
• pp.91-96
• /
• 2001

Restoration of contaminated soils to an environmentally acceptable condition is important. One of the newer techniques in soil remediation is a method based on electrokinetic phenomena in soils. The technology uses electricity to affect chemical concentrations and water flow through the pores of soils. An important advantage of electrokinetic soil remediation over other in-situ processes such as soil flushing is the capability of control over the movement of the contaminants. Because the migration of the contaminants is confined by the electric field, there is little dispersion outside the treatment zone. Furthermore, the process is effective for soils with low and variable permeability. In the present study, the distributions of cadmium in the electrokinetic processing of kaolinite under the condition of constant applied voltage are investigated. Cadmium accumulates near the cathode without reducing the diffusion of hydroxide ion into the soil. In keeping the catholyte pH at neutrality, cadmium migrates toward the cathode without any accumulation of cadmium near the cathode and is successfully removed at the cathode reservoir. It was also found that the progress of electrokinetic processing of cadmium could be gasped to a certain extent by monitoring the local voltage and the current density.

• Journal of the Korean GEO-environmental Society
• /
• v.11 no.2
• /
• pp.5-11
• /
• 2010

Abandoned mines release acid mine drainage and cause the contamination of soil and crops around the mine area. The objective of current study is to evaluate effect of mine on the soil and crop contamination. Soils, water, and crops were collected and analyzed, and the heavy metal data were classified into types of the soil, types of crops, and distance from the minehead. Surface soils of the mine area were highly contaminated with heavy metals, especially with zinc and lead. Tailings and cultivated paddy soils were also highly contaminated. Heavy metal concentrations upon distance from minehead decrease steadily as the distance from the minehead increase. The correlation between heavy metals was extracted from soils and the content in the rice samples showed a positive relation for arsenic and cadmium but not a meaningful relation for other metals.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2003.09a
• /
• pp.314-317
• /
• 2003

Plants may enhance the remediation of munitions at contaminated soils using various natural processes. A computer model can be used as a valuable tool for assisting phytoremediation by predicting the transport and fate of target contaminants at remediation sites. For this research, modeling of phytoremediation and bioremediation of soil contaminated with 2, 4, 6-trinitrotoluene (TNT) was studied. Indian mallow (Abutilion avicennae) was grown in columns packed with 126mg TNT/kg contaminated soils for 50 days and a simulation model was developed to simulate the transport and fate of TNT and its breakdown products interacting with plant roots in a partially saturated soil. The column test showed the substantially enhanced reduction of TNT and greater soil microbial activity in Indian mallow planted soil compared to unplanted soil. The model successfully simulated the fate of TNT and by-products in phytoremediation. The results suggested that plants could provide favorable environments for reduction of TNT.