송형운 Hyoung Woon Song , 한성국 Seong Kuk Han , 김호 Ho Kim , 서진원 Jin Won Seo

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Abstract

Diverse studies are being conducted on sewage sludge treatment and recycling methods, but the demand for a lowcost treatment technology is high because the sewage sludge has an 80% or higher water content and a high energy consumption cost. We want to apply the thermal hydrolysis reaction that consumes a small amount of energy. The purpose of this study is to quantify the thermal conductivity of sewage sludge according to reaction temperature for optimal design of thermal hydrolysis reactor. We quantified continuously the thermal conductivity of dewatered sludge according to the reaction temperature. As the reation temperature increased, the dewatered sludge is thermally solubilized under a high temperature and pressure by the thermal hydrolysis reaction. Therefore, the bond water in the sludge cells comes out as free water, which changes the dewatered sludge from a solid phase to slurry of a liquid phase. As a result, the thermal conductivity of the sludge was more than 2.6 times lower than that of the water at 293 K, but at 470 K and above, became 0.708 W/m·K, which is about 4% lower than that of the water.

Key Words

Thermal hydrolysis, Sewage sludge, Thermal conductivity, Dewatered sludge, Bound water

김재경 Jae Kyeong Kim , 박명준 Myung Jun Park , 이문용 Moon Yong Lee , 구기갑 Kee Kahb Koo

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Abstract

For the reclamation of HEP (1-hydroxyethylpiperazine) and MDG (methyl diglycol) from waste photoresist stripper,lab-scale experiments with a packed bed vacuum column were carried out. Purity of recovered solution mixture of HEP and MDG was measured to be 99.3% and recovery yield was to be 65%. Those results confirm that some organic solvents reclaimed from waste PR stripper satisfies the product specification required for the formulation of photoresist stripper.

Key Words

Waste solvent recovery, Photoresist stripper, Vacuum distillation, HEP 1-hydroxyethylpiperazine, MDG, Methyl diglycol

이다은 Dae Un Lee , 김형석 Hyoung Seok Kim , 김진만 Jin Man Kim , 최선미 Sun Mi Choi , 조봉규 Bong Gyoo Cho , 허탁 Tak Hur

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Abstract

In this study, “Recycling of ladle furnace slag (LFS) in the electric furnace process to produce ultra rapid harding cement” is the target technology. Environmental and economic efficiencies of target technology are analyzed and ecoefficiency is assessed based on these results. The methodologies to analyze environmental and economic efficiencies are LCA (Life Cycle Assessment) and market price which is calculated based on LCC (Life Cycle Costing), respectively. Global warming potential (GWP) and abiotic resource depletion (ARD) are selected as indicator of environmental analysis. The reference flow of this study is considered 1kg of ultra rapid harding cement which made from the LFS. As a result of that, target process has environmental efficiency of 13.1 for global warming and 5.93 for abiotic resource depletion and has economic efficiency of 4.86. Eco-efficiencies are derived from this study can be applied to slag recycling policy formulation and effect analysis in the future. This can be also applied to improve process’s environmental and economic performances.

Key Words

Eco-efficiency, LCA, LCC, Ladle Furnace Slag, Recycling

손준익 Jun Ik Son , 홍용희 Yong Hee Hong , 조성진 Sung Jin Cho , 유흥민 Heung Min Yoo , 김기헌 Ki Heon Kim

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Abstract

This paper analyzed thermal and carbonization properties of sewage sludge in fixed bed reactor and obtained following results. The heavy metal (Pb, Ni, Mn, Cr, Cu) content of Char showed the highest level at unprocessed sewage sludge, followed by carbonized sludge at 600, 400, and 500oC. It was thought to be mainly due to the yield of char rather than the influence of temperature. Also, the migration-test results of heavy metals satisfied the landfill directive in all samples, which may be possible to use it as landfill cover materials. The concentration of dioxin by changes of pyrolysis temperature was higher in the low temperature conditions and the proportion of PCDDs was higher than that of PCDFs.

Key Words

Sewage Sludge, Fixed-Bed, Char, Carbonization

손준익 Jun Ik Son , 홍용희 Young Hee Hong , 김영란 Young Lan Kim , 박재성 Jae Sung Park , 김기헌 Ki Heon Kim

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Abstract

This study analyzed concentration and characteristics of hazardous substances in treatment of leachate from carcass burial areas by using high temperature thermal desorption (HTTD). Concentrations of pollutants emitted from HTTD treatment of leachate contaminated soil of carcass burial sites satisfied the emission standards for 11 pollutants from domestic waste incineration facilities. Dioxin concentration was 0.0060 ng I-TEQ/Sm3 and 0.0061 (0.0055-0.0070) ng ITEQ/ Sm3 in the normal operation condition and the experimental condition, respectively, which are much lower than the MSWI Standard of 0.1ng I-TEQ/Sm3. As a result, it was considered that leachate from carcass burial areas could be treated by high temperature thermal desorption (HTTD).

Key Words

Thermal-Desorption, Carcass Burial Areas, Hazardous Substances

박상우 Sang Woo Park

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Abstract

The following are the results from an evaluation of the combustion characteristics of biomass processed with lowtemperature carbonization and coal, and those of a blend of both. Differential thermo-gravimetric (DTG) analysis has revealed that the number of curves was reduced as a result of carbonization and that the fuel quality was improved due to the increase of initial temperature (IT). It was also confirmed that the carbonized samples consisting only of the biomass required less combustion time (tq), while samples blended with coal burned longer than the weighted average value. The combustion time of a blended sample was shorter at an carbonization temperature of 400oC than at 300oC, and the combustion stability was achieved due to a narrow range of change in the combustion characteristics. The reaction rate constant (k) of the samples blended with coal was found to be smaller for all blend ratios, when compared with that of the unblended samples (raw, carbonized biomass). The combustion reaction models that were applicable for the devolatilization-combustion zone were diffusion (D1, D3) and Reaction order (O3) models; diffusion (D1-D4) model was primarily employed in the char combustion zone. In summary, low-temperature carbonization contributed to minimizing the change in the combustion characteristics of the biomass/coal blend.

Key Words

Biomass, Carbonization, Combustion characteristic, Reaction model

정태호 Tae Ho Jeong , 남궁완 Namkoong Wan

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Abstract

The objective of this study was to evaluate the leaching characteristics of heavy metals (Cu, Pb, Zn and Cd) in an abandoned mine soil stabilized by applying both soluble phosphates and steel slag. Leaching characteristics of heavy metals in the contaminated soils was evaluated by toxicity characteristics leaching procedure (TCLP) and Column test. After leaching batch (TCLP) and column, Pb was found that the most greatly reduced by immobilized. Among the tested three phosphates (Na2HPO4·12H2O, Ca(H2PO4)2·H2O, (NH4)2HPO4), the leaching concentration of Ca(H2PO4)2·H2O and (NH4)2HPO4 decreased more than those of Na2HPO4·12H2O. The rate constant (k1) value was found to be about 1.5 ~ 2.0 times higher than ever before, it could be fast immobilized. The rate constant (k1) of Zn was the highest as 0.1629 ~ 0.1991/day, it was followed by Zn > Pb > Cd > Cu. Especially, Cu increased more than 2.0 times with the steel slag added, so it was very effective. Total leaching amount of heavy metal was the most TCLP test due to differences in the leaching conditions. Added with the slag, TCLP, Column and Exchangeable form (F1) more decreased. Phosphorus (P) leaching, stabilized by phosphate only, increased than the contaminated soil. But Leaching of P decreased considerably when it was processed in combination with slag. In particular Ca(H2PO4)2·H2O of phosphates showed to be the least leaching, it was expected made of metal-phosphate immobilized.

Key Words

Contaminated soil, TCLP, Column, Heavy metals, Phosphate, Steel slag

최수철 Su Cheol Choi , 이우근 Woo Keu Lee

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Abstract

In this work, the effect of CaO and Fe2O3 on the geopolymer made from mine tailing and melting slag has been studied. Geopolymer was made from mine tailing, melting slag and blast furnace slag. The mechanical property of geopolymer prepared was affected by raw material used. Compressive strength of the geopolymer using blast furnace slag was higher than the geopolymer using melting slag. Because CaO and Fe2O3 content of two-type geopolymers was different. Therefore, the content of these controled to find out how to affect the property of geopolymer. According to the result of FT-IR(Fourier transform infrared spectroscopy), the compressive strength of geopolymer increased by activation of CS- H gel with increasing CaO content. In contrast, the compressive strength of geopolymer decreased by inhibition of geopolymerization with increasing Fe2O3 content. According to the result of XRD(X-ray diffraction), the geopolymerization was weakened by formation of olivine, goethite.

Key Words

Geopolymer, Mine tailing, Melting slag, Blast furnace slag, Compressive strength

박종은 Jong Eun Park , 강영렬 Young Yeul Kang , 김우일 Woo Ii Kim , 신선경 Sun Kyong Shin , 김종국 Jong Guk Kim

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Abstract

In this study, we analyzed Polybrominated Diphenyl Ethers (PBDEs) contained in TV covers of 15 and refrigerator components of 9 produced in Korea. In the TV front covers, 70 ~ 2,296 mg/kg of PBDEs were detected and in the back covers, the PBDEs detection was as follows: 128,773 ~ 158,104 mg/kg for TVs produced between 1983 ~ 1997, and 42 ~ 41,625 mg/kg between 2000 ~ 2005, which indicates that PBDEs content started to substantially decrease from 2000. When comparing these figures with those from other countries, we found that the front covers of televisions contain lower levels of PBDEs than those produced in Japan and back covers had similar or higher levels. The concentrations of the components of the refrigerator samples ranged from N.D. to 445 mg/kg. By comparing isomer patterns of PBDEs obtained from the products and those reported to be found in the environment, this study estimated distribution characteristics of PBDEs and the correlation between their pollution sources and the environment. The results showed that deca-BDE used in TVs has an impact on the environment, for example, indoor dust and sediment in rivers. We suggest that in order to prevent hazardous substances contained in electrical and electronic products from continuously circulating in the environment, the E-waste should be managed in terms of waste treatment and that the XRF screening method is appropriate to regulate the contents of toxic substances in an economic and effective way.

Key Words

E-waste, WEEE, PBDEs, Brominated flame retardants, Management

최창용 Chang Yong Choi , 류재용 Jae Yong Ryu , 김종범 Jong Bum Kim , 장성호 Seong Ho Jang , 김승곤 Seung Gon Kim , 김부길 Boo Gil Kim

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Abstract

Nitrogen trifluoride (NF3) has been used as a novel etching and cleaning gas in semiconductor industry. Recently, the many studies about NF3 decomposition have been performed due to high global warming potential (GWP : 17,000). In this study, the role of conditioning agents such as H2, O2, and H2O (water vapor) in the destruction of NF3 gas using electron-beam technology is assessed in terms of the destruction and removal efficiency (DRE, %). The inlet concentration of NF3 was 1,000 ppm and the concentration of conditioning agents ranged from 250 to 1,500 ppm respectively and electron beam current was 5 mA. From the result, the by-products of NF3 decomposition were NO, N2O, and HF.

Key Words

Nitrogen trifluoride NF3, Electron-beam, Conditioning agent, Global Warming, PRCs perfluorinated compounds

김종범 Jong Bum Kim , 류재용 Jae Yong Ryu , 최창용 Chang Yong Choi , 장성호 Seong Ho Jang , 윤영훈 Young Hun Yoon , 김부길 Boo Gil Kim

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Abstract

SF6 (sulfur hexafluoride) gas has an extremely high global warming potential (GWP) because of strong absorption of infrared radiation and long atmospheric lifetime which cause the global warming effect. The objective of this study is to identify the effects of destruction and removal efficiency (DRE) of SF6 by the addition of oxygen, water vapor and hydrogen. The applied dose of ionization energy was 1,028 kGy(5 mA). The initial concentrations of SF6, O2, H2O and H2 gases were 1,000 ppm, 1,000 ppm, 3,000 ppm, 3,000 ppm, respectively. The DRE was increased about 2 times with O2 gas injection. The SF6 was completely removed with H2O and H2 gas injection. By-products formed by SF6 destruction were mainly HF and F2 gases. In addition, SF2, NF3, N2O, SO2, SO2F2, and NOx gases were produced.

Key Words

Sulfur hexafluoride SF6, High ionization energy, Conditioning agent, O2 gas, H2 gas, Water vapor, By-product

이경호 Kyeong Ho Lee , 유경선 Kyung Seun Yoo , 천승규 Seung Kyu Chun

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Abstract

The 2nd landfill of Sudokwon landfill site has been collecting landfill gas flowing into vertical wells using the vacuum generated by blowers. The vacuum applied to the wells enables the landfill gas within the collection boundary to be collected and the air in the atmosphere to be penetrated through landfill cover soil, as well. In this study, we tried to investigate the impact of active landfill gas collection with vertical wells on landfill aeration. The pressure changes and the compositions of landfill gas, measured at the wells and 4 bore holes made in the landfill for this study, showed the air penetrates the landfill cover and inflows into the vertical wells. The concentration of nitrogen in the landfill gas collected from the 2nd landfill site has been increased to 14 ~ 15% as of February 2013, indicating 18 ~ 19% of the air is being included in the landfill gas.

Key Words

Landfill gas, Active collection, Landfill aeration

장동순 Dong Soon Jang , 신미수 Mi Soo Shin , 방건웅 Gun Woong Bahng

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Abstract

The stoichiometric gas from an advanced alkaline electrolysis process as developed by Yull Brown is called as HHO gas or Brown gas. By this process, two moles of H2 and 1mole of O2 gases are generated stoichiometrically in a wellpremixed state. Due to the fact that very clean fuel can be obtained relatively easily by the simple equipment of electrolysis, the research of this gas has been continuously performed, even though the criticism has been made by many researcher of this area. The main controversial argument is in that the use of high quality electrical energy is used again for the generation of another combustible fuel with less than 100% efficiency in its energy transform. In fact, since Brown gas exists in the state of a completely mixed state only with oxygen molecule, there is no time delay due to turbulent mixing occurring in practical combustion process. Therefore, the high reaction rate is likely to have a high chance of backfire. Further, since there is no inert material like nitrogen as in air, the flame temperature rises unnecessarily high. In order to prevent the backfire phenomenon, the increase of injection velocity of fuel nozzle causes the formation of very unstable long flame with good chance of flame lift-off. One of practical application methods, the co-combustion of Brown gas with other fuel like gasoline and LNG, etc has been reported in open literature in order not only to increase the combustion efficiency but also for the reduction of pollutant emission such as NOx. In order to control the negative aspect of flame characteristics of Brown gas, in this study, an novel method is employed by premixing Brown gas with water vapor and the co-combustion performance and characteristics has been studied numerically for a combustor operated for kiln drying method. To this end, a commercial code(STAR-CCM+7.06) has been employed with the program verification against operational data of kiln drying combustor and a parametric numerical calculation has been made with the change of the amount of water vapor in the fuel mixture of Brown gas and water vapor. The calculation results show that the combustion feature looks quite stable without showing any unstable flame feature like long thin flame and backfire. Further temperature and streamline contours with the amount of water vapor content look consistent and physically acceptable. This result suggests that the addition of water vapor in the Brown gas looks one of promising method for the use of Brown gas as clean fuel.

Key Words

Brown gas, HHO gas, Clean fuel, Backfire, Water vapor, Brown gas & water vapor mixed fuel

정상재 Sang Jae Jeong , 김재영 Jae Yong Kim

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Abstract

Needs for more accurate greenhouse gas (GHG) emission estimation are increasing to prepare for post-Kyoto protocol and emission trading starting from 2015 in Korea. Although GHG emission from landfill is relatively low, uncertainty of methane emissions from landfill is very high compared to the other sectors. Moreover, accurate estimation is needed to design landfill gas collection system and energy generation plant. In this paper, we investigated development methodologies of parameters comprising methane generation potential (L0) which is one of key parameters in methane emission estimation models. DOC included four steps including analysis of waste component, water content, organic carbon content, fossil carbon content. Instead of analysis of organic carbon content and fossil carbon content, biochemical analysis, measuring content of cellulose, hemicellulose, and lignin, is used in MELMod, landfill gas generation model in UK. Methodologies to develop DOCF has several methods including batch test, lysimeter test and test cell. They had difference in scale and similarity to landfill, but it is hard to consider the best method at the present stage. Preceding research on MCF is little. Lysimeter test and test cell can be the candidate to develop MCF, because of flexibility on test condition to characterize the structure of landfill sites. F is defined as fraction of methane in landfill gas. But by carbon flow and mass balance, F should represent fraction of methane in biogas generated by anaerobic decomposition. In this definition, F can be derived by same methods to that of DOCF.

Key Words

Solid waste landfill, Greenhouse gas, Landfill gas, Carbon sequestration, IPCC, Methane generation potential

전관수 Kwan Soo Jun , 권상우 Sang Woo Kwon , 양봉호 Bong Ho Yang

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Abstract

Economic and environmental aspects of electrochemical copper recovery from LCD manufacturing process and through hole plating process for PCB circuit board wastewater were evaluated. The extraction rate of copper per unit energy was decreased as HRT increased and initial copper concentration decreased. About 65 minutes was determined as the optimal HRTs which could maximize the productivity of copper recovery on energy. The extracted mass of copper from the wastewater were 0.045 g at 50 mg Cu/L, 0.083 g at 1,000 mg Cu/L and 0.098 g at 3,000 mg Cu/L by unit energy (Wh) for 60 minutes, respectively. LCA (Life Cycle Assessment) technique determined the electrochemical recovery of copper to have more effect on global warming than other environmental impact categories.

Key Words

Copper, Electrochemical reduction, WASTEWATER TREATMENT, lca, Electroplating, Urban mining