• Journal of the Korean Society for Railway
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• v.18 no.6
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• pp.552-557
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• 2015

Ballast gravel in a railroad field is often polluted by grease and heavy metals. In this paper, the performances of a dry cleaning method for polluted ballast gravel in which pollutants on the gravel surface can be physically removed was extensively studied. A polluted ballast cleaning device able to shoot emery blasting media onto the surface using compressed air was prepared. Polluted ballast gravel was put into this device for cleaning, with the treatment time varied from 1 to 10 min. The cleaning efficiency of the total petroleum hydrocarbons and heavy metals were studied. The total petroleum hydrocarbon removal efficiency was 70-80% for gravels sampled from a locomotive waiting line, while it was 40-60% for gravels sampled from a turnout area. The heavy metal removal efficiency exceeded 90% for copper and lead, while it was 65-80% for nickel and zinc. This system was found to be effective for the remediation of polluted ballast gravels.

• Resources Recycling
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• v.30 no.3
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• pp.63-69
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• 2021

Supply deficit of lead commodities and environmental pollution can be simultaneously resolved through the recovery and recycling of waste lead. The recent recovery of lead through recycling of the lead battery waste is a positive development. To maximize the effect of lead recovery and recycling in the future, the updated status of the lead material flow should be recognized. However, such an analysis at the preliminary stages may be cumbersome owing to the complexity and diversity of emission sources and material streams. At this stage, a preliminary screening by domestic lead flow using public information should be feasible. Therefore, in this study, using the data from the UN Comtrade and domestic PRTR (Pollutant Release and Transfer Register) databases, the amounts of lead import, emission, and transfer were identified and cross-checked with the domestic lead flow described in the National Material Flow Analysis database. The lead flow for major categories such as waste lead-acid batteries showed a rough consistency between the databases.

• Membrane Journal
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• v.32 no.1
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• pp.33-42
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• 2022

Growing industrialization leads to severe water pollution. Organic effluents from pharmaceuticals and textile industries released in wastewater adversely affect the environment and human health. Presence of antibiotics used for antibacterial treatment in wastewater leads to the growth of drug resistance bacteria, which is very harmful for human being. Various small organic molecules are used for the preparation of organic dye molecules in the textile industries. These molecules hardly degrade, which is present in the wastewater effluents from printing and dyeing industries. In order to address these problems, photoactive catalyst is embedded in the membrane and wastewater are passed through it. Through this process, organic molecules are photodegraded and at the same time, the degraded compounds are separated by the membrane. Titanium dioxide (TiO₂) is a semiconductor which behave as excellent photocatalyst. Photocatalytic ability is enhanced by the making its composite with other transition metal oxide and incorporated into polymeric membrane. In this review, the degradation of dye and drug molecules by photocatalytic membrane are discussed.

• Journal of the Korean Society for Heat Treatment
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• v.36 no.1
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• pp.22-32
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• 2023

In general, when scrap is dissolved in an electric arc furnace, the amount of electric furnace steel dust (EAFD) generated is about 1.5% of the scrap charge amount, and the electric furnace steel dust collected by the bag filter is charged into the Rotary Kiln or Rotary Hearth Furnace (RHF), and the zinc component is recovered as crude zinc oxide, at which time a clinker of Fe-Base is generated. In this research, first, for the efficient resource conversion of electric furnace steel dust, a reduction and roasting experiment was conducted and the reaction kinetics was examined. As a result of the experiment, it was observed that the reduction and roasting reaction was actively conducted in the range of 1100~1150℃, and melting occurred in the range of 1250℃. In the past, this clinker was widely used as a roadbed material for road construction and an Fe-Source for cement production, but in recent years, it has been mainly reclaimed due to strengthening environmental standards. However, landfill treatment is by no means a desirable treatment method due to environmental pollution caused by leachate, expensive landfill costs, and waste of Fe resources. Therefore, in order to more actively recycle the Fe component in the clinker, first of all the clinker was pulverized into an optimal particle size, and anthracite and binder (starch) were added to the magnetic material obtained by specific gravity and magnetic separation for briquet. As a experimental results, it was possible to efficiently separate clinker as Fe component and other slag component by specific gravity and magnetic force. As a results of loading and dissolving the manufactured briquet clinker in an electric arc furnace, it was observed that the unit of power and production yield were clearly improved and the carbon addition effect in molten metal was also somewhat.

• Journal of Animal Reproduction and Biotechnology
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• v.39 no.1
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• pp.48-57
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• 2024

Background: Cadmium (Cd) is toxic heavy metal that accumulates in organisms after passing through their respiratory and digestive tracts. Although several studies have reported the toxic effects of Cd exposure on human health, its role in embryonic development during preimplantation stage remains unclear. We investigated the effects of Cd on porcine embryonic development and elucidated the mechanism. Methods: We cultured parthenogenetic embryos in media treated with 0, 20, 40, or 60 µM Cd for 6 days and evaluated the rates of cleavage and blastocyst formation. To investigate the mechanism of Cd toxicity, we examined intracellular reactive oxygen species (ROS) and glutathione (GSH) levels. Moreover, we examined mitochondrial content, membrane potential, and ROS. Results: Cleavage and blastocyst formation rates began to decrease significantly in the 40 µM Cd group compared with the control. During post-blastulation, development was significantly delayed in the Cd group. Cd exposure significantly decreased cell number and increased apoptosis rate compared with the control. Embryos exposed to Cd had significantly higher ROS and lower GSH levels, as well as lower expression of antioxidant enzymes, compared with the control. Moreover, embryos exposed to Cd exhibited a significant decrease in mitochondrial content, mitochondrial membrane potential, and expression of mitochondrial genes and an increase in mitochondrial ROS compared to the control. Conclusions: We demonstrated that Cd exposure impairs porcine embryonic development by inducing oxidative stress and mitochondrial dysfunction. Our findings provide insights into the toxicity of Cd exposure on mammalian embryonic development and highlight the importance of preventing Cd pollution.

• Korean Journal of Environmental Agriculture
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• v.27 no.4
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• pp.328-336
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• 2008

Metal mining district drainage is a well recognized source of environmental contamination. Oxidation of metal sulfides produces acidic and metal-rich waters that contaminate local surface water and ground water in mines, mine dumps, and tailing impoundments. This monitoring study was carried out to investigate the stream water quality and pollution as affected by the Sambo mine drainage in relation to the relative distance from the mine. It obvious that pH values of the mine drainage ranged from 5.8 to 6.9, while the average concentrations of the dissolved chemical constituents for EC, $SO_4^{2-}$, $K^+$, $Ca^{2+}$, and $Mg^{2+}$ were $1.77\;dS\;m^{-1}$, 929, 14.6, 263.3, and 46.9 mg/L in mine drainage discharged from the main waste rock dumps (WRD), respectively. Furthermore, EC values and sulfate concentrations exceeded the critical toxicity levels in agricultural water for rice plant ($1.0\;dS\;m^{-1}$ for EC and 54.0 mg/L for $SO_4^{2-}$). Also, the average of dissolved cadmium concentrations ($0.016{\sim}0.021\;mg/L$) was higher than water quality standard (0.01 mg/L) for agricultural water in Korea, in addition to Zn, Fe and Mn were higher than trace metals maximum concentrations which recommended by FAO for irrigation water. The results indicate that mine drainage discharged from the Sambo mine affected stream water at least to distance of 1 km downstream of the mine water discharge point. EC values, $SO_4^{2-}$ and $Ca^{2+}$ concentrations in discharged water positively correlated with dissolved Cd, Zn, Al and Mn concentrations, while the pH values negatively correlated. In addition, EC values, $SO_4^{2-}$ and $Ca^{2+}$ concentrations were negatively correlated with pH values.

• Korean Journal of Environmental Agriculture
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• v.30 no.3
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• pp.310-315
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• 2011

BACKGROUND: Heavy-metal pollution represents an important environmental problem due to the toxic effects of metals, and their accumulation throughout the food chain leads to serious ecological and health problems. METHODS AND RESULTS: Optimum conditions in continuous-flow stirred tank reactor (CSTR) and packedbed column contactor (PBCC) using brown seaweed biosorbent were investigated. Under optimum conditions from both lab-scale biosorbent systems, removal efficiency of copper (Cu) in a large-scale PBCC system was investigated. Removal capacity of Cu using brown seaweed biosorbent in a lab-scale CSTR system was higher than that in a lab-scale PBCC system. On the other hand, over 48 L/day of flow rate in Cu solution, removal efficiency of Cu in a lab-scale PBCC system was higher than that in a lab-scale CSTR system. Optimum flow rate of Cu was 24 L/day, optimum Cu solution concentration was 100 mg/L. Removal capacity of Cu at different stages was higher in the order of double column biosorption system > single column biosorption system. Under different heavy metals, removal capacities of heavy metal were higher in the order of Pb > Cr > Ni > Mn ${\geq}$ Cu ${\geq}$ Cd ${\fallingdotseq}$ Zn ${\geq}$ Co. Removal capacity of Cu was 138 L in a large-scale PBCC system. Removal capacity of Cu a large-scale PBCC system was similar with in a lab-scale PBCC system. CONCLUSION(s): Therefore, PBCC system using brown seaweed biosorbent was suitable for treating heavy metal wastewater.

• Resources Recycling
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• v.32 no.1
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• pp.50-59
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• 2023

The amount of dust generated during the dissolution of scrap in an electric arc furnace is approximately 1.5% of the scrap metal input, and it is primarily collected in a bag filter. Electric arc furnace dust primarily consists of zinc and ion. The processing of zinc starts with its conversion into pellet form by the addition of a carbon-based reducing agent(coke, anthracite) and limestone (C/S control). These pellets then undergo reduction, volatilization, and re-oxidation in rotary kiln or RHF reactor to recover crude zinc oxide (60%w/w). Next, iron is discharged from the electric arc furnace dust as a solid called Fe clinker (secondary by-product of the Fe-base). Several methods are then used to treat the Fe clinker, which vary depending on the country, including landfilling and recycling (e.g., subbase course material, aggregate for concrete, Fe-source for cement manufacturing). However, landfilling has several drawbacks, including environmental pollution due to leaching, high landfill costs, and wastage of iron resources. To improve Fe recovery in the clinker, we pulverized it into optimal -sized particles and employed specific gravity and magnetic force selection methods to isolate this metal. A carbon-based reducing agent and a binding material were added to the separated coarse powder (>10㎛) to prepare briquette clinker. A small amount (1-3%w/w) of the briquette clinker was charged with the scrap in an electric arc furnace to evaluate its feasibility as an additives (carbonaceous material, heat-generating material, and Fe source).

• Journal of Wetlands Research
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• v.25 no.4
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• pp.306-314
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• 2023

Stream sediments are an important component of water quality management because they are receptors of various pollutants such as heavy metals and organic matters emitted from upland sources and can be secondary pollution sources, adversely affecting water environment. To effectively manage the stream sediments, identification of primary sources of sediment contamination and source-associated control strategies will be required. We evaluated the performance of machine learning models in identifying primary sources of sediment contamination based on the physico-chemical properties of stream sediments. A total of 356 stream sediment data sets of 18 quality parameters including 10 heavy metal species(Cd, Cu, Pb, Ni, As, Zn, Cr, Hg, Li, and Al), 3 soil parameters(clay, silt, and sand fractions), and 5 water quality parameters(water content, loss on ignition, total organic carbon, total nitrogen, and total phosphorous) were collected near abandoned metal mines and industrial complexes across the four major river basins in Korea. Two machine learning algorithms, linear discriminant analysis (LDA) and support vector machine (SVM) classifiers were used to classify the sediments into four cases of different combinations of the sampling period and locations (i.e., mine in dry season, mine in wet season, industrial complex in dry season, and　industrial complex in wet season). Both models showed good performance in the classification, with SVM outperformed LDA; the accuracy values of LDA and SVM were 79.5% and 88.1%, respectively. An SVM ensemble model was used for multi-label classification of the multiple contamination sources inlcuding landuses in the upland areas within 1 km radius from the sampling sites. The results showed that the multi-label classifier was comparable performance with sinlgle-label SVM in classifying mines and industrial complexes, but was less accurate in classifying dominant land uses (50~60%). The poor performance of the multi-label SVM is likely due to the overfitting caused by small data sets compared to the complexity of the model. A larger data set might increase the performance of the machine learning models in identifying contamination sources.

• Korean Journal of Environmental Agriculture
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• v.25 no.4
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• pp.323-330
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• 2006

This experiment was conducted to investigate heavy metal transition and bioavailability from soil to the edible pare of water dropwort near industrial complex. The soils were collected from the paddies cultivating water dropwort stream sediments, and background soils near industrial complex. The pH values, organic matter, Av. $P_2O_5$, Ex. Ca content of paddy soils were higher than those measured for nor-contaminated paddy fields in 2003. The contents of Cd and Cu was higher than those of standard level for soil contamination by Soil Environmental Conservation Act in Korea. The pollution index in stream sediments were higher than those of paddies cultivating water dropwort. The geoaccumulation index of heavy metals in paddy soils and stream sediment were in the order Cu>Cd>Ni>Zn>Pb. The rates of 0.1N-HCl extractable heavy metals to total contents in soils were in the order Cd>Cu>Zn>Ni>Pb. In case of Cd and Ni in paddy soils near industrial complex, 0.1N-HCl extractable heavy metals and total content were highly correlated with each other. Heavy metal contents in mot parts were higher than those in top pare of water dropwort. The Zn and Cu transfer factor from soil to the top pare of water dropwort were higher than those of other heavy metals. The bioavailability of water dropwort varied considerably between the different parts and heavy metals. Cd, Cu and Ni contents in water dropwort were correlated with each elements in paddy soils.