• 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.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.331-337
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• 2000

When microorganism is injected into porous medium such as soils, biomass retained in the pore. Bacteria within these microcolonies produced large amounts of exopolysaccharides and formed a plugging biofilm. Soil pore size and shape are varied from the initial condition as a result of biofilm formation, which make hydraulic conductivity reduced and friction rate between soil aggregates increased. In this research, hydraulic conductivity reduction was measured after microorganism are inoculated and cultured with synthetic substrate and nutrient. Also, pore sand of before and after biofilm formation compared with scanning electron microscopy. Hydraulic conductivity of Sand and Poorly Graded Sand was decreased approximately 1/10∼1/100 after biomass inoculation and cultivation. Biofilm attached on soil aggregates is resistant to acidic or basic condition.

• Microbiology and Biotechnology Letters
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• v.37 no.4
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• pp.293-305
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• 2009

Methane, as a greenhouse gas, is some 21~25 times more detrimental to the environmental than carbon dioxide. Landfills generally constitute the most important anthropogenic source, and methane emission from landfill was estimated as 35~73 Tg per year. Biological approaches using biocover (open system) and biofilter (closed system) can be a promising solution for older and/or smaller landfills where the methane production is too low for energy recovery or flaring and installation of a gas extraction system is inefficient. Methanotrophic bacteria, utilizing methane as a sole carbon and energy source, are responsible for the aerobic degradation (oxidation) of methane in the biological systems. Many bench-scale studies have demonstrated a high oxidation capacity in diverse filter bed materials such as soil, compost, earthworm cast and etc. Compost had been most often employed in the biological systems, and the methane oxidation rates in compost biocovers/boifilters ranged from 50 to $700\;g-CH_4\;m^{-2}\;d^{-1}$. Some preliminary field trials have showed the suitability of biocovers/biofilters for practical application and their satisfactory performance in mitigation methane emissions. Since the reduction of landfill methane emissions has been linked to carbon credits and trading schemes, the verified quantification of mitigated emissions through biocovers/biofilters is very important. Therefore, the assessment of in situ biocovers/biofilters performance should be standardized, and the reliable quantification methods of methane reduction is necessary.

• Environmental and Resource Economics Review
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• v.29 no.3
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• pp.335-362
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• 2020

Using the Hedonic pricing model using Box-Cox transformation, this paper estimated the marginal effect (implicit price) of odors from landfill in the metropolitan area on housing prices and the willingness to pay for changes in certain odor conditions. This paper utilized the proximity from the landfill in the metropolitan area as a environmental variable, and analyzed the effect of various housing characteristic variables on the sale price of apartments within a radius of 5 km from the landfill. In particular, because odors factor have various heterogeneity, we applied hedonic price models instead of stated-preference methods with various types of functional forms through Box-Cox transformation, considering the heterogeneity of each region. Estimates show that the marginal value (implicit price) for the distance from the odor source was 0.227 to 0.533 depending on the function type of the estimated model. In addition, when other house factors are the same, the marginal willingness to pay for a distance of 1km from the odor source was calculated to be 16.79 to 51.76 thousand dollar depending on the type of function. Finally for the general Box-Cox model, the annual WTP was estimated to be 3,229dollar.

• Journal of the Mineralogical Society of Korea
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• v.27 no.4
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• pp.311-320
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• 2014

A magnetic separation study was conducted for a soil sampled from a landfill site where steel slag had been dumped for a long time. Heavy metal concentrating effect was evaluated by analyzing heavy metal content of magnetically separated soil and passed through soil. The effect was compared between soil after soil-washing process and original landfill soil and the effect was also tested between wet condition-magnetic separation and dry condition-magnetic separation. Separated ratio was relatively higher in non-soil washed sample. The water content has no significant effect on the separation rate. The concentrating effect of Fe, Pb, Cu, and Cd were 3.2, 2.1, 12.1, 2.5, 1.5 and 17.4, 7.0, 15.7, 9.6, 7.0 respectively for non-soil washed sample and soil washed sample. We can expect a bigger volume reduction effect from soil-washed samples. The volume reduction effect was obtained from the separation in dry condition. However, when the separation ratio is too high the volume reduction effect decreases. The magnetic separation leads to a volume reduction and concentration of heavy metals into a portion of soil in case of paramagnetic particles contained soil.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.9
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• pp.1035-1043
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• 2007

A leachate containing an elevated concentration of organic and inorganic compounds has the potential to contaminate adjacent soils and groundwater as well as downgradient areas of the watershed. Moreover high-strength ammonium concentrations in leachate can be toxic to aquatic ecological systems as well as consuming dissolved oxygen, due to ammonium oxidation, and thereby causing eutrophication of the watershed. In response to these concerns landfill stabilization and leachate treatment are required to reduce contaminant loading sand minimize effects on the environment. Compared with other treatment technologies, leachate recirculation technology is most effective for the pre-treatment of leachate and the acceleration of waste stabilization processes in a landfill. However, leachate recirculation that accelerates the decomposition of readily degradable organic matter might also be generating high-strength ammonium in the leachate. Since most landfill leachate having high concentrations of nitrogen also contain insufficient quantities of the organic carbon required for complete denitrification, we combined a shortcut biological nitrogen removal (SBNR) technology in order to solve the problem associated with the inability to denitrify the oxidized ammonium due to the lack of carbon sources. The accumulation of nitrite was successfully achieved at a 0.8 ratio of $NO_2^{-}-N/NO_x-N$ in an on-site reactor of the sequencing batch reactor (SBR) type that had operated for six hours in an aeration phase. The $NO_x$-N ratio in leachate produced following SBR treatment was reduced in the landfill and the denitrification mechanism is implied sulfur-based autotrophic denitrification and/or heterotrophic denitrification. The combined leachate recirculation with SBNR proved an effective technology for landfill stabilization and nitrogen removal in leachate.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.10
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• pp.942-948
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• 2010

To predict the potential reduction of $CH_4$ by recovering several types of wastes as of reusable energy sources like RDF, the $CH_4$ emission for each type of waste from Landfill Site 3 of SUDOKWON Landfill was estimated for the period of 2017 to 2024. Without any recovering effort on types of wastes being disposed of at the Landfill, there are producing a total of $526{\times}10^6\;Nm^3$ of $CH_4$; municipal waste of $337{\times}10^6\;Nm^3$, construction waste of $178{\times}10^6\;Nm^3$, and facility waste of $11{\times}10^6\;Nm^3$. It composed of 41.5% to that observed from 2002 to 2009. With properly retrieved by MT(Mechanical Treatment), it released a total of $158{\times}10^6\;Nm^3$ $CH_4$; $127{\times}10^6\;Nm^3$, $28{\times}10^6\;Nm^3$, and $4{\times}10^6\;Nm^3$, respectively. Additionally, when biologically degradable residues can be fully treated by MBT (Mechanical & Biological Treatment) system, the total amount of $CH_4$ emitted from the site will be lowered down as low as $115{\times}10^6\;Nm^3$, which is comparably lower showing only 21.8% to that for without any energy recovery practice. Futhermore, it is far less showing 9.1% to that obtained from 2002 to 2009. It can be decided that predictable amount of $CH_4$ emission reduced could be successfully accomplished and enhanced through ways of energy recovery efforts such as further scale adjustment of LFG treatment capacity in association with currently implemented practices in the landfill site.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.5
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• pp.639-646
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• 2005

In this research, we tried to develop the application method to water management and treatment using toxicity test method. When we measure the toxicity of environmental samples, we have to decide whether we take some countermeasures to reduce the toxicity or not. The first issue is how to set these action levels in each bioassays. A new idea was attempted to authorize indirect approach of each bioassays through the response characteristics against mixture of chemicals in water quality standard. The significant response in the cell-growth-inhibition bioassay was detected for standards-mixture(STDs). For acute toxicity assay, STDs-based implicit correlation between risks to humans and bioassay data showed a rational approach to set action levels in practical management. A simple model was proposed to describe and predict the changes in the total toxicity based on the concentrations of toxic-controlling chemicals during the ozonation of landfill leachates. On the basis of this simple model, toxicity reduction was predicted for pre-aggregation treatment before ozonation and ozone concentration during the ozonation. The method proposed in this study would be useful in optimizing water treatment processes and their running conditions in terms of the toxicity reduction efficacy.

• Environmental and Resource Economics Review
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• v.14 no.2
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• pp.419-445
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• 2005

In 2002, the waste was generated about 277,533tons per day. The treatments of waste were recycling, which had accounted for almost 70%, landfill, which had accounted for 19.8%, and incineration, which had accounted for 6.5%. The energy recovery from incineration has been increased since 1995. The portion of waste in the renewable energy has been increased. Waste incineration heating system generates total 134TOE of $CO_2$ as compared to 6,800TOE of GHG from LNG boiler centralized heating system to bring 98% reduction rate of GHG emissions. We need the integrated model to examine the impacts of waste managements on economy and environments. The Asia-Pacific Integrated Model is introduced as the example of the integrated model.

• Microbiology and Biotechnology Letters
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• v.40 no.2
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• pp.128-134
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• 2012

Foot and mouth disease (FMD) is one of the most notorious and contagious viral diseases afflicting cloven-hoofed animals. In this study, the physicochemical properties of leachate from a FMD landfill site at 773-1, Waryong, Andong, Korea and the ground water from 777, Waryong, Andong, Korea, were analyzed for 1 year from December $10^{th}$ 2010 to November $17^{th}$ 2011. The leachate was collected from the FMD landfill site during March, May, July, September and November, 2011 and changes in pH, brix, water content, insoluble solids, crude proteins, crude lipids, total and reducing sugars and ash content were determined. Considering the annual profiles of temperature and rainfall at the FMD landfill site, the dramatic changes in the physicochemical properties of the leachate from March to July, and especially from May to July, such as increases in pH, and a rapid reduction of brix and organic matter, may be closely linked to the growth of microorganisms in the leachate. The sharp decreases in the concentration of biominerals, such as Mg, Ca, and Fe from 1073, 4311 and 56.2 ppm in March to 151, 78, and 0.1 ppm in November, further suggest that decreases in organic matter in the leachate result from degradation by microorganisms originating from the intestines of the livestock. Analysis of the profiles of the organic materials in the leachate revealed that the properties of the leachate were similar to those of excremental matter-derived water. These results could be applied to a number of fields for the analysis of organic matter behavior, the development of the degradation process, and risk analysis in the environment for hygiene and food industries, of leachate from FMD landfill sites.