류재용 Jae-yong Ryu , 손영일 Young-il Son , 장성호 Seong-ho Jang

DOI:10.9786/kswm.2015.32.1.1

Abstract

Nitrogen trifluoride (NF₃) and Sulfur hexafluoride (SF₆) are usually used as novel etching and cleaning gases in semiconductor industry and electrical equipments. Recently, the many studies about PFCs decomposition have been performed due to high global warming potential (GWP). This study is to identify the effects of the hydrogen on the destruction and removal efficiency (DRE) of NF₃ and SF₆ when using the electron-beam. The experiment was conducted at a flow rate of 10 LPM with NF3 and SF₆ of 1,000 ppm. Absorbed dose (electric current) was 1,028 kGy (5 mA). The DREs of NF₃ and SF₆ gases increased about 54% and 68% respectively with hydrogen injection. By-products formed by NF₃ and SF₆ destruction were mainly HF and F₂ gases. In addition, the particles were generated during the NF₃ and SF₆ destruction due to corrosion of reactor and SF₆ decomposion, respectively.

Key Words

Electron-beam, PFCs, NF₃, SF₆, Semiconductor process

황현욱 Hyeon Uk Hwang , 김명균 Myung Gyun Kim , 김영주 Young Ju Kim

DOI:10.9786/kswm.2015.32.1.7

Abstract

In this study, activation energy of lignite, RPF and a sample mixed both of them was obtained through kinetics characteristics analysis in pyrolysis in order to identify the applicability of RPF as an assistant fuel. TGA (Thermogravimetric analysis) was conducted with follow experimental conditions; in a nitrogen atmosphere, gas flow rate of 20 ml/min, heating rate of 5 ~ 50℃/min, and maximum hottest temperature of 800℃. As a result of TGA, it showed that pyrolysis of samples mixed with 20% and 10% of RPF were more stable than other mixed ratio, and 20% of RPF was the most similar with lignite in activation energy.

Key Words

Kinetic, Activation energy, RPF, Lignite, TGA

장부용 Boo-yong Jang , 오용걸 Yong-keol Oh , 신동철 Dong-chul Shin , 박철휘 Chul-hwi Park

DOI:10.9786/kswm.2015.32.1.14

Abstract

The objectives of this study were to evaluate biogas production and changes of CH₄ contents by trace elements solution dosing to improve the operation efficiency of anaerobic digestion. The solution with trace elements was manufactured by Co, Mo, Ni, and Fe, and the trace elements dosages were gradually increased from reactor R1 to R4. Operation was performed as four modes and organic loading rate was increased from R1 to R4. As a result, digestion efficiency of R2 or R3 was higher than R1 without trace elements solution. Also, it showed that biogas production and CH₄ contents of R3 were high compared with R2. However, R4 had a negative effect on the efficiency of anaerobic digestion due to the additional dosing of unnecessary trace elements. Moreover, from the results compared with anaerobic digestion conditions on effect of each trace element, it showed that experiment with the mixture of Co, Ni, Mo, and Fe was the highest digestion efficiency and individual trace element showed high digestion efficiency in the order of Fe, Co, Mo, and Ni. In conclusion, the additional dosing of optimum trace elements is essential to enhance the efficiency of anaerobic digestion.

Key Words

Anaerobic digestion, Food wastewater, Trace element, Biogas production, Methane contents

이정연 Jeong-yeon Lee , 김승도 Seungdo Kim , 한태욱 Tae Uk Han , Unvrbayar Bayasgalan , 최성범 Seong-beom Chae

DOI:10.9786/kswm.2015.32.1.22

Abstract

This paper estimated the Arrhenius parameters as well as the pyrolysis reaction model for epoxy printed circuit boards (e-PCB) by analyzing isothermal kinetic data. This paper introduces the use of thermobalance that is capable of monitoring a weight decrease with time under pure static condition. Three isothermal kinetic experiments were performed at 270, 275 and 280℃, that were chosen within a temperature range where main decompositions were observed from nonisothermal kinetic results. Comparing experimental reduced-time-plot (RTP) with theoretical ones, the pyrolysis reaction model of e-PCB fitted best to the Avrami-Erofeev (A2) Model. Consequently, the activation energy and pre-exponential factor were then estimated to be 141 kJ·mol^-1and 29.9 (lnA, A : min^-1), respectively.

Key Words

e-PCB, Avrami-Erofeev, Isothermal kinetics, Reduce-time-plot (RTP)

Yashoda Padeyanda , 고영재 Youngjae Ko , 장용철 Yong-chul Jang

DOI:10.9786/kswm.2015.32.1.29

Abstract

Food waste, a putrescible form of waste, comprised of 30% of the total municipal solid waste stream in Daejeon Metropolitan City (DMC) in 2012. Proper management of food waste is a challenging task for local government. This study was conducted to determine material flows when treated food waste in various recycling facilities. Material flows in the recycling processes were collected by site surveys, field trips and discussion with operators and governmental employees. Material flow analysis (MFA) was conducted to quantify the flow of food waste from generation to disposal for the year 2012. MFA along with its mass transfer coefficients were determined based on the inputs, outputs and waste fluxes. According to the mass transfer coefficient results, treatment efficiency for the dry and wet feed manufacturing facility was found to be higher than other treatment facilities. Water consumption was higher for the composting site, resulting in large volume of wastewater (mass transfer coefficient 1.539). While large amounts of screening materials such as plastic, chopsticks, aluminum foils, and bottle caps were generated at the composting site, mass transfer coefficients (0.312) at the dry and wet feed facility were relatively high, implying effective treatment of food waste occurring. The results of this study help to facilitate waste management policy decision-makers in developing effective food waste management techniques in DMC.

Key Words

Food waste, Recycling, Composting, Feed manufacturing, MFA, Transfer coefficient

박견주 Kyun Joo Park , 김민영 Minyoung Kim , 석승환 Seunghwan Seok , 김영운 Young-wun Kim , 김도현 Do Hyun Kim

DOI:10.9786/kswm.2015.32.1.37

Abstract

The effect of the metal oxide catalyst in the dimerization of waste vegetable oil was investigated. The high efficiency and recyclability has allowed different metal oxides to be used as catalysts in numerous synthetic reactions. Herein, clay, aluminum, titanium, calcium, magnesium and silicon oxide micro/nanoparticles are used in a Diels-Alder reaction to catalyze the production of the dimer acids. The metal oxides assist the electron transfers during cyclization to produce the desired product. Liquid chromatography mass spectroscopy (LC-MS) and gel permeation chromatography (GPC) were used to verify the production of dimer acids. For the confirmation of cyclization, compounds were analyzed using the nuclear magnetic resonance (NMR) spectroscopy. From the analysis, silylated or pristine clay showed its effectiveness as a catalyst in dimerization. Furthermore, alumina and alumina/silica composite showed successful performance in the reaction to yield cyclic dimer acids. These result suggested that metal oxides and montmorillonite might be used in synthesis of dimer acids for the recycle of waste vegetable oils.

Key Words

Metal oxide, Dimer acid, Fatty acid, Waste oil, Recycling

김성천 Seong Cheon Kim , 김승호 Seong Ho Kim , 전영남 Young Nam Chun

DOI:10.9786/kswm.2015.32.1.46

Abstract

Recently, the energy supply uses mostly fossil fuels such as coal, petroleum, natural gas etc... however, they are limited and they present an issue for the environment. Biomass derived energy is considered promising for reducing the emissions of CO₂, the significant contributor to global warming. Also it can be converted to various forms of energy through thermochemical conversion processes. In this study, a screw gasifier has been engineered for wood biomass gasification. Waste wood chip was used as biomass and the producer gas, tar; char were then achieved by gasification in the presence of CO₂. The results showed that with the increase of the gasification temperature, the producer gas increased and the tar decreased. Also, due to thermal cracking, the light tar increased by the decomposition of the gravimetric tar. And a development of char pore structure was confirmed by SEM. The gasification of biomass in the presence of CO₂ at 800℃ produced an increase in the concentration of carbon monoxide according to the Boudoudard reaction and an increase in the char pore surface as well as its adsorption capacity. Thus the biomass gasification in the presence of CO₂ was confirmed to be effective for the production of CO and the development of char.

Key Words

Wood biomass, Carbon dioxide gasification, Tar, Char, Syngas

Yashoda Padeyanda , 고영재 Youngjae Ko , 장용철 Yong-chul Jang

DOI:10.9786/kswm.2015.32.1.54

Abstract

This study was initiated to examine the potential impacts on the environment during the management of food waste by anaerobic digestion in Daejeon Metropolitan City (DMC) that is built in 2017. The evaluation was based on both material flow analysis (MFA) and life cycle assessment (LCA). The MFA study was performed using STAN 2.5, while the LCA was conducted according to ISO standards by utilizing Total 4 LCA software with the incorporation of CML 2002 methodology. According to the LCA results, global warming potential (GWP), acidification potential (AP), eutrophication potential (EP), and photochemical ozone creation potential (POCP) were found to be approximately 166 kg CO_2-eq/ton of food waste, 0.43 kg SO_2-eq/ton of food waste, 0.66 kg PO₄ ^3-eq/ton of food waste, and 0.08 kg C₂H_4-eq/ ton of food waste, respectively. The disposal stage showed higher impact of GWP on the environment due to the landfilling of solid sludge and screening waste. In case of eutrophication potential, the treatment phase showed the highest impact on the environment, mainly because of the consumption of electricity. Based on the results of normalization, the highest environmental impacts was found in the treatment stage related to eutrophication potential. The results of LCA would provide policy-makers to identify and reduce potential environmental impacts associated with food waste to biogas conversion in DMC by life cycle.

Key Words

Food waste, LCA, MFA, Environmental impact, Global warming potential

정승미 Seung-mi Jeong , 황다혜 Da-hye Hwang , 박은영 Eun-young Park , 김용진 Yong-jin Kim

DOI:10.9786/kswm.2015.32.1.63

Abstract

Bioethanol was produced from Laminaria japonica hydrolystaes by sequential acidic (0.108 N HCl)/distilled water and enzymatic hydrolysis (Celluclast® 1.5 L) using Saccharomyces coreanus immobilized into/on aluminum silicate. Reducing sugar were hydrolyzed 140.5 and 122.7 mg/g-dry biomass under a acidic-enzymatic condition and a distilled waterenzymatic condition, respectively. In addition, the 8 repetition batch fermentations were carried out with the immobilized S. coreanus to verify the advantage of immobilization cell. As a result, we can obtain the ethanol of 12.1 ~ 24.3 mg/gdry biomass, and reuse the support, aluminium silicate, for 8 repetition batch fermentations without any breakdown.

Key Words

Laminaria japonica, Hydrothermal hydrolysis, Enzymatic hydrolysis, Support material, Immobilization

박성준 Sung-joon Park , 김지훈 Ji-hoon Kim , 형원길 Won-gil Hyung

DOI:10.9786/kswm.2015.32.1.70

Abstract

Environmental problems caused by the occurrence of carbon dioxide are recognized as a critical issue throughout the world. As a result, a measure for the use of cement and improvement of its quality must be sought out. In order to reduce the occurrence of carbon dioxide during the manufacturing process of cement, this study creates an alkali-activated slag cement that utilizes ground granulated blast furnace slag, an industrial by-product, and substitutes metakaolin as an alternative for silica fume to improve the process of manufacturing high-strength concrete and its quality. The study discerns the mechanical characteristics by measuring the flexibility and compressive strength through the mortar matrix and discerns the durability by conducting an acid resistance test and chloride ion penetration resistance test. Also, the study discerns the hydration products through an XRD test. Based on the results of such tests, it is anticipated that it may be used as a secondary product for concrete or buildings that require superior long-term strength and durability compared to regular Portland cement. However, as no clear results were found in this study regarding the substitution of metakaolin, it displayed mixed results in comparison to previous studies. Nevertheless, it is expected that metakaolin will become a more superior admixture if its issues are improved through continuous research studies.

Key Words

Ground granulated blast furnace slag, Alkali activated slag, Metakaolin

이주용 Joo-yong Lee , 서정윤 Jeoung-yoon Seo

DOI:10.9786/kswm.2015.32.1.78

Abstract

Waste heavy oil sludge is considered oil waste that can be utilized as a renewable energy source. In this study, an attempt has been made to convert the mixtures of waste heavy oil sludge and sawdust into solid biomass fuels. The solid fuel pellets from waste heavy oil sludge and sawdust could be manufactured only with a press type pelletizer. The mixing ratios of waste heavy oil sludge and sawdust capable of manufacturing a solid fuel pellet were 30 : 70, 40 : 60 and 50 : 50. Ultimate analysis result revealed that these mixtures had C 50.21 ~ 54.77%, H 10.25 ~ 12.66%, O 25.84 ~ 34.83%, N 1.01 ~ 1.04%, S 1.03 ~ 1.07%. With increasing the mixing ratio of waste heavy oil sludge, the carbon and hydrogen content in solid fuel pellets were increased, while the oxygen content was decreased. But the nitrogen and sulfur content in solid fuel pellets did not show much difference. Their lower heating values ranged from 4,780 kg/kcal to 5,530 kg/kcal. The density of the solid fuel pellets was increased from 0.63 g/cm³ to 0.85 g/cm³ with increasing the mixing ratio of waste heavy oil sludge and the collapse of the solid fuel pellets occurred at a moisture content of 21%. As the mixing ratio of waste heavy oil sludge in the solid fuel pellets was increased, the reaction of thermal cracking became faster. It was also observed that the solid fuel pellets were thermally decomposed in two steps and their DTG curves were simpler with increasing the mixing ratio of waste heavy oil sludge. The activation energy and the pre-exponential factor of the solid fuel pellets ranged from 18.90 kcal/mol to 21.36 kcal/mol and from 201 l/sec to 8,793 l/sec, respectively. They were increased with increasing the mixing ratio of waste heavy oil sludge.

Key Words

Sawdust, Waste heavy oil sludge, Solid fuel pellet, Renewable energy

이주용 Joo-yong Lee , 서정윤 Jeoung-yoon Seo

DOI:10.9786/kswm.2015.32.1.85

Abstract

Waste heavy oil sludge is considered oil waste that can be utilized as a renewable energy source. Although it has high calorific values, it should be treated as a designated waste. During the recycling process of construction and demolition wastes or the trimming process of woods, a lot of sawdust is produced. In this study, the feasibility of BOF (biomass and waste heavy oil sludge fuel) as a source of renewable energy was estimated. To investigate its combustion characteristics, a lab scale batch type combustion reactor was used, and temperature fluctuation and the flue gas composition were measured for various experimental conditions. The results could be summarized as follows: The solid fuel pellets manufactured from waste heavy oil sludge and sawdust had C 50.21 ~ 54.77%, H 10.25 ~ 12.66%, O 25.84 ~ 34.83%, N 1.01 ~ 1.04%, S 1.03 ~ 1.07%. Their lower heating values ranged from 4,780 kg/kcal to 5,530 kg/kcal. The density of the solid fuel pellets was increased from 0.63 g/cm³ to 0.85 g/cm³ with increasing the mixing ratio of waste heavy oil sludge. The maximum CO₂ concentration in the flue gas was increased with increasing waste heavy oil sludge content in BOF. SO₂ concentration in the flue gas was showed a tendency such as the highest CO₂ concentration in the flue gas. With increasing waste heavy oil sludge content in BOF, the combustion time became rather shorter although the increase of the CO₂ concentration in the flue gas was delayed. Because the carbon conversion rate showed small difference with increasing the mixing ratio of waste heavy oil sludge in BOF, BOF with the mixing ratio of waste heavy oil sludge of 30% was effective for combustion. With increasing the mixing ratio of waste heavy oil sludge in BOF, activation energy and the amount of total CO emissions were increased, while activation energy was decreased with increasing the air/fuel ratio. Therefore, the optimal air/fuel ratio for the combustion of BOF was 1.5.

Key Words

Sawdust, Waste heavy oil sludge, Activation energy, Combustion characteristic, Fuel gas

김완기 Wan-ki Kim , 조영국 Young-kug Jo

DOI:10.9786/kswm.2015.32.1.94

Abstract

The purpose of this study is to develop eco-friendly finishing materials of acrylic emulsion-modified mortars using lightweight aggregate carrier which contains pyroligneous liquid. Four types of light-weight aggregate carriers such as perlite, vermiculite, charcoal and zeolite are selected. The acrylic emulsion-modified mortars are prepared with light-weight carrier replacements to dolomite of 0, 5, 10, 15, 20%, and tested for flowability, adhesion in tension, water absorption coefficient and antibiosis. As a result, the flowability of acrylic emulsion-modified mortars using zeolite light-weight is improved with increasing light-weight carrier content. The adhesion in tension of acrylic emulsion-modified mortars using lightweight carrier is satisfied with KS requirement. Especially, the adhesion in tension of acrylic emulsion-modified mortars using light-weight aggregate carrier at a high temperature of 40℃ are better than the low temperatures of 0℃ and 20℃. The water absorption coefficient of acrylic emulsion-modified mortars using light-weight aggregate carriers is increased with increasing light-weight carrier content. However, the water absorption coefficient is satisfied with KS requirement. The antibiosis of acrylic emulsion-modified mortars using zeolite light-weight carrier is remarkably improved with increasing light-weight carrier content.

Key Words

Pyroligneous liquid, Light-weight carrier, Adhesion in tension, Antibiosis

류선영 Sun Young Ryu

DOI:10.9786/kswm.2015.32.1.104

Abstract

Inner ware body was manufactured using sanitary ware waste and kairome clay. The prepared body was characterized by XRD, SEM, and XRF. The plasticity of body was decreased due to increase of waste. Thus it is considered that wheel throwing is available up to CS-6 composition. The inner ware body, containing the 60wt% sanitary ware waste, showed the linear firing shrinkage of 12.2%, apparent porosity of 19.6%, 3-point bending strength value of 21.5 N/mm², after sintering at 1150℃ for 1 hr. As the content of waste was increased from 40wt% to 60wt% in the composition, bending strength was increased with increasing the amount of mullite phase. According to the microstructure, glass phase was observed with the body surface, which can explain the increased glass phase of the composition containing high content of waste.

Key Words

Inner ware body, Sanitary ware waste, Wheel throwing, Mullite phase, Glass phase