• Environmental Engineering Research
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• v.22 no.2
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• pp.141-148
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• 2017

Globalization, industrialization, mining, and uncontrolled population growth have fostered a shortage of potable water. Therefore, it has become imperative to understand an effective and reasonable water purification technique. A renewed interest in electrocoagulation (EC) has been spurred by the search for reliable, cost-effective, water-treatment processes. This paper has elucidated a technical approach for getting rid of heavy metals and total suspended solids (TSS) from synthetic water using an aluminum electrode. The effect of operational parameters, such as current density, inter-electrode distance, operating time, and pH, were studied and evaluated for maximum efficiency. This study corroborates the correlation between current density and removal efficiency. Neutral pH and a low electrode gap have been found to aid the efficacy of the EC setup. The outcome indicates that a maximum TSS removal efficiency of 76.6% occurred at a current density of $5.3mA/cm^2$ during a contact time of 30 min. In the case of heavy metals remediation, 40 min of process time exhibited extremely reduced rates of 99%, 59.2%, and 82.1%, for Cu, Cr, and Zn, respectively. Moreover, kinetic study has also demonstrated that pollutants removal follows first-and second-order model with current density and EC time being dependent.

• Microbiology and Biotechnology Letters
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• v.48 no.2
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• pp.223-229
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• 2020

The application of plant-growth-promoting rhizobacteria (PGPR) supports the growth of plants in contaminated soil while ureolytic bacteria can immobilise heavy metals by carbonate precipitation. Thus, dual treatment with such bacteria may be beneficial for plant growth and bioremediation in contaminated soil. This study aimed to determine whether the PGPR Pseudomonas fluorescens could work in synergy with ureolytic bacteria to assist with the remediation of cadmium (Cd)- and lead (Pb)-contaminated soils. Pot experiments were conducted to grow radish plants in Cd- and Pb-contaminated soils treated with PGPR P. fluorescens and the results were compared with dual inoculation of P. fluorescens combined with ureolytic Staphylococcus epidermidis HJ2. The removal rate of the metals from the soil was more than 83% for Cd and Pb by the combined treatment compared to 17% by PGPR alone. Further, the dual treatment reduced the metal accumulation in the roots by more than 80%. The translocation factors for Cd and Pb in plant tissues in both treatments remained the same, suggesting that PGPR combined with the carbonate precipitation process does not hamper the transfer of essential metal ions into plant tissues from the soil.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.2
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• pp.146-152
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• 2015

Heavy metal pollution has been a critical problem in agricultural field near at the abandoned metal mines and chemical amendments are applied for remediation purpose. However, biological activity can be changed depending on chemical amendments affecting crop productivity. Main purpose of this research was to evaluate biological parameters after applying chemical amendments in heavy metal polluted agricultural field. Result showed that soil respiration (SR) and microbial biomass carbon (MBC) were changed after chemical amendments were applied. Among three different amendments, lime stone (LS), steel slag (SS), and acid mine drainage sludge(AMDS), AMDS had an effect to increase SR in paddy soil. Comparing to control ($93.98-170.33mg\;kg^{-1}day^{-1}$), average of 30% increased SR was observed. In terms of MBC, SS had an increased effect in paddy soil. However, no significant difference of SR and MBC was observed in upland soil after chemical amendment application. Overall, SR can be used as an indicator of heavy metal remediation in paddy soil.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.984-999
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• 2010

A long-term field demonstration experiment of selected stabilization method to reduce the heavy metal mobility in farmland soil contaminated by heavy metals around abandoned mine site was conducted. Field demonstration experiments were established on the contaminated farmland with the wooden plate(thickness=1cm) which dimension were width=200cm, Length=200cm, height=80cm and filled with treated soil, which was mixed with lime stone and steel refining slag except on control plot. Soil samples in the plots were collected and analyzed during the experiment period(2008. 2~2008. 8) after the installation of the plots. Field demonstration experiments results showed that the application ratio of lime stone 5% was effective for immobilizing heavy metal components in contaminated farmland soil.

• Economic and Environmental Geology
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• v.55 no.6
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• pp.717-726
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• 2022

This study was conducted to assess the geochemical contamination degree of As, Cd, Cu, Pb, Sb, and Zn in the soil and water samples from an abandoned gold mine. Enrichment Factor (EF), Geoaccumulation Index (Igeo), and Pollution Load Index (PLI) were carried out to assess the geochemical contamination degree of the soil samples. Variations of sulfate and heavy metals concentration in water samples were determined to identify the geochemical distribution with respect to the distance from the mine tailing dam. Geochemical pollution indices indicated significant contaminated with As, Cd, Pb, and Zn in the soil samples that areas close to the mine tailing dam, while, Sb showed similar indices in all soil samples. These results indicated that the As, Cd, Pb, and Zn dispersion has occurred via anthropogenic sources, such as mining activities. In terms of water samples, anomalies in the concentrations of As, Cd, Zn, and SO₄^2- was determined at specific area, in addition, the concentrations of the elements gradually decreased with distance. This result implies the heavy metals distribution in water has carried out by the weathering of sulfide minerals in the mine tailing and soil. The study area has been conducted the remediation of contaminated soil in the past, however, the geochemical dispersion of heavy metals was supposed to be occurred from the potential contamination source. Therefore, continuous monitoring of the soil and water is necessary after the completion of remediation.

• Journal of Soil and Groundwater Environment
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• v.20 no.7
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• pp.103-111
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• 2015

Soil washing with ethylenediaminetetraacetic acid (EDTA) is highly effective in the remediation of soils contaminated with heavy metals. The EDTA recycling process is a requisite for reducing the operating cost. The applicability of Na₂S addition on the precipitation of heavy metals from the spent soil washing solution and thereby recycling of EDTA was investigated. Addition of Na₂S into the single metal-EDTA and the mixed metal-EDTA solutions ([Na₂S]/[metal-EDTA] ratio = 30, reaction time = 30 min and pH = 7~9) was highly effective in the separation of Cu and Pb from metal-EDTA complexes, but not for Ni. The Zn removal efficiency varied with pH and slightly increased upto 40% as the reaction time increased from 0 to 240 min which was longer than those for Cu and Pb. Ca(OH)₂ was subsequently added to induce further precipitation of Zn and Ni and to reduce the Na₂S dose. At the [Na₂S]/[metal-EDTA] ratio of 10, the removal efficiencies of all heavy metals excluding Ni were above 98% with the dose of Ca(OH)₂ at 0.002, 0.006 and 0.008 g into 100 mL of Cu-, Pb- and Zn-EDTA solutions, respectively. However, Ca(OH)₂ addition was not effective for Ni-EDTA solution. A further research is needed to improve metal removal efficiency and subsequent EDTA recycling for the real application in field-contaminated soils.

• Applied Chemistry for Engineering
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• v.27 no.6
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• pp.606-611
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• 2016

In this work, the treatment of heavy metals and phenol in the contaminated soil was investigated by applying direct current (DC) and pulse voltage. When the DC was used, the removal efficiencies for Cu, Zn, As, and Pb were 73, 88, 10, and 10%, respectively, and more than 95% for phenol was removed. Furthermore, when a pulse voltage was employed the removal efficiencies for Cu, Zn, As, and Pb were 88, 92, 40, and 40%, respectively, and 87% of phenol was removed. The results indicate that the application of a pulse voltage for the treatment of contaminated soil reduced electro-osmosis, but increased the rate of electric current movement of heavy metals. In addition, the removal efficiencies for As and Pb have been improved due to the enhanced adsorption capacity of clay components in the soil. Therefore, these experimental results could be effectively applied in remediation technology for the treatment of various heavy metals and phenol.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.819-835
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• 2009

In order to investigate the field application of selected stabilization methods(cover soil method, surface and total interval treatment of embankment method) on rice paddies contaminated by heavy metals, column test was carried out with heavy metal-contaminated soils collected from rice paddies around abandoned mine site. Columns were made by acrylic and filled with untreated soil, treated soil mixed with amendments(lime stone and steel refining slag) and uncontaminated cover soil according to the design report. Distilled water was discharged into the columns with the velocity of 1 pore volume/day. During test, pH, EC, and heavy metal concentration were measured in the regular term. The column test result showed that the selected stabilization methods were effective remediation method to stabilize heavy metals in paddy soils, but it was also expected that application of surface treatment methods was required the careful observation on pH variation due to the lowest increment.

• Applied Chemistry for Engineering
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• v.33 no.5
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• pp.502-522
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• 2022

Clay minerals are natural materials that show widespread applications in various branches of science, including environmental sciences, in particular the remediation of water contaminated with various water pollutants. Modified clays and minerals have attracted the attention of researchers in the recent past since the modified materials are seemingly more useful and efficient for removing emerging water contaminants. Therefore, modified engineered materials having multi-functionalities have received greater interest from researchers. The advanced clay-based materials are highly effective in the remediation of water contaminated with organic and inorganic contaminants, and these materials show enhanced selectivity towards the specific pollutants. The review inherently discusses various methods employed in the modification of clays and addresses the challenges in synthesizing the advanced engineered materials precursor to natural clay minerals. The changes in physical and chemical properties, as investigated by various characterization techniques before and after the modifications, are broadly explained. Further, the implications of these materials for the decontamination of waterbodies as contaminated with potential water pollutants are extensively discussed. Additionally, the insights involved in the removal of organic and inorganic pollutants are discussed in the review. Furthermore, the future perspectives and specific challenges in the scaling up of the treatment methods in technology development are included in this communication.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.67-70
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• 2002

Remediation of groundwater contaminated with chlorinated organics, nitro aromatics, and heavy metals using zero valent iron (ZVI) filings has paid considerable attention in recent years. When the contaminants of high concentration leaked abundantly in subsurface environment, permeable reactive barrier technology using iron filing is taken a long time for the remediation of contaminated groundwater, The problem of contaminant shock is able to be solved using surfactant (hexadecyltrimethylammonium, HDTMA) modified bentonite (SMB) as immobilizing material. Therefore, the purpose of this research was to develop the combined remediation technology using conventional permeable reactive and immobilizing barrier for the enhanced decontamination of chlorinated compounds. Four column experiments were conducted to assess the performance of the mixed reactive materials with Ottawa sand, iron filing, and HDTMA-bentonite for trichloroethylene (TCE) removal under controlled groundwater flow conditions. TCE reduction rates with sand/iron filing/HDTMA-bentonite were highest among four column due to dechlorination of TCE by iron filing and sorption of TCE by SMB.