홍승아 Seung Ah Hong , 이재동 Jae Dong Lee

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Abstract

Deacidification of waste cooking oil such as, palm oil or soybean oil, using supercritical carbon dioxide (scCO2) extraction has been widely investigated for reusing waste cooking oil. The deacidification process using scCO2 has been carried out under various experimental conditions temperature range between 40 and 100℃, pressure range between 20 and 35 MPa, CO2 flow rate range between 10 and 40 g/min, and extraction time range from 1 to 7 hours. The purified waste oils were characterized by their acid value and peroxide value measured. The optimized conditions were deduced in this paper at the temperature of 80℃, pressure of 20 MPa, and CO2 flow rate of 40g/min. At the optimized operating condition the peroxide value was existed between 40 and 100. Also 80% of the purified oil was recovered. The properties of the purified oil were shown as similar to those of the pure oil.

Key Words

Supercritical carbon dioxide, Extractiion, Waste cooking oil, Recycling process

정태호 Tae Ho Jeong , 남궁완 Wan Nam Koong

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Abstract

Difference in immobilization effect of heavy metal-contaminated soil between two different amendment emthods was evaluated; 1) both of steel slag (i.e., simultaneous amendment methods) and 2) soluble phosphate and steel slag was applied sequentially to the contaminated soil (i.e., sequentially amendment methods). The application rate of stabilizers to soils was determinated based on weight/weight ratio of 5% for steel slag and PO4/Pb molar ratio of 2.0 for phosphates, respectively. To identify difference of immobilization effect to test soil, three different soluble phosphates, such as Na2HPO4ㆍ12H2O, Ca(H2PO4)2ㆍH2O and (NH4)2HPO4 were used. The sequential amendment was 6~27% more effective than the simultaneous amendment in terms of the immobilization efficiency for Pb, Cu, and Cd in the contaminated soil. There was little difference in case of Zn. Among the three phosphates tested, (NH4)2HPO4 was clearly the most effective. Residual form of heavy metals concentration in sequentially methods is higher than those in simultaneously methods. At the same time, more exchangeable and carbonate-bound forms of heavy metals in simultaneously methods were observed than in sequentially case. These result implies that the sequential amendment method was more effective than the simultaneous amendment method in terms of heavy metal immobilization in the contaminated soil.

Key Words

Heavy metals, Contaminated soil, Immobilization, Amendment method

연익준 Ik Jun Yeon , 신현식 Hyun Shic Shin , 신택수 Taek Soo Shin , 김광렬 Kwang Yul Kim

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Abstract

The objective of this study is to manufacture an efficient activated carbon fiber (ACF) assemblies filter. Cellulose acetate and phenolic resin were dissolved in acetone and coated on a 2 ㎝-long and 2 ㎝-wide stainless steel mesh. Various concentrations of cellulose acetate and phenolic resin in acetone solution were examined for the extent of coating on the stainless steel mesh using a thermogravimetric analyzer (TGA), a surface area analyzer (BET) and a microscope. As a result, the best quality of coating on the stainless steel mesh was obtained with 2 wt, % cellulose acetate and 10 wt, % phenolic resin in acetone solution. The ACF filter was also impregnated with ZnCl2 KOH, H3PO4 and NA2CO3, respectively to enhance its adsorption capacity. Iodine number increased by impregnating with the chemical compound in the following order: KOH>ZnCl2>NA2CO3>H3PO4. Iodine numbers for the ACF filters impregnated with ZnCl2 (ACFz) and KOH (ACFk) were found to be 972~1,117 mg/g and 98~1,183 mg/g respectively.

Key Words

Activated carbon fibes, Adsorbent, Cullulose acetate, Phenolic resin, Carbon source

김석환 Seok Hwan Kim , 임병란 Byung Ran Lim , 이수구 Soo Koo Lee

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Abstract

The drying and fuel technologies for sewage sludge have been developed due to the prohibition of ocean dumping and new renewable portfolio standard. This study was performed to enhance the quality of sludge derived fuel and compare drying characteristics for thickened and digested sewage sludge at different temperature, pressure and mixing oil conditions in oil vacuum evaporation system. In addition to investigate calorific value and characteristic analysis of dried sludge. The thickened and digested sludge used in this study were taken from municipal sewage treatment plant and coagulated using polymer (C-310P) in laboratory. The drying rate was increased with temperature and degree of vacuum and it was 25mL/kg-sludgeㆍmin at 110℃ and -450mmHg. The moisture content of dried sludge products showed very low within 1% in the range of 0.4~0.8%. The evaporation rate of thickened sludge was lower than digested sludge and the constant evaporation period was also shorter. Compared the effect of waste cooking oil and refined waste petroleum oil on drying efficiency, the waste cooking oil showed more effective than refined oil in evaporation rate and drying time. The carbon and hydrogen contents of dried sludge with refined oil were higher than waste cooking oil. The low heating value of thickened dried sludge was higher than digested dried sludge about 400 kcal/kg and both of dried sludge showed high calorific value more than 4,000 kcal/kg.

Key Words

Sludge derived fuel (SDF), Vacuum, Evaporation, Sewage sludge, Drying characteristics

정철진 Cheol Jin Jeong , 최창식 Chang Sik Choi , 장정희 Jung Hee Jang , 한기보 Gi Bo Han , 이태진 Tae Jin Lee , 박노국 No Kuk Park , 강미숙 Mi Sook Kang

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Abstract

In this study, the thermo-catalytic hydrogenation using corn stark and wasted palm kernel shell was carried out for the production of hydrocarbon compounds in direct biomass liquefaction. The conversion of biomass in direct biomass liquefaction over Mo-based catalyst increased with increasing the reaction temperature and the content of the volatile matter contained in biomass and the corn starch was more available than the wasted palm kernel shell. And then, the conversion was about 97.9% using corn starch and was about 92.4% using wasted palm kernel shell at 400℃. It was confirmed that the liquefied products obtained after the thermo-catalytic reaction were C6, C7, C8-typed hydrocarbon compounds.

Key Words

Biomass, Direct liquefaction, Mo-based catalyst. Hydrocarbon compounds. Thermo-catalytic conversion

김용진 Yong Jin Kim , 진길선 Kil Sun Jin , 정승미 Seung Mi Jeong

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Abstract

To produce bioethanol from cellulosic biomass, the cellulosic biomass needs pretreatments for high efficiency saccharification. This study, thus, aims to evaluate the efficiency of several pretreatments using vegetables as a cellulosic biomass among food wastes. The evaluated pretreatment methods were acid treatment, ammonia treatment and hydrogen peroxide treatment, which were used by individual and/or incorporating method. As a result, the concentration of reducing sugar increased 4 ~ 15 times and that of glucose increased 5 ~ 26 times compared to the samples without pretreatment. The acid treatment as an individual treatment was the most efficient, and the efficiency of incorporating treatment showed higher than that of individual treatment. Besides, there were differences in the composition and content of hydrolyzed sugars although the saccharification efficiency was similar by the method of each pretreatment.

Key Words

Vegetables waste, Pretreatment, Sugar component, Bioethanol

박영규 Young Gyu Park , 이병관 Byung Kwan Lee

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Abstract

Several experiments have done to investigate the removal of hydrogen sulfide(H2S) synthetic gas from biogas streams by means of chemical absorption and chemical reaction with 0.1 M ? 1 M Fe/EDTA solution. The hydrogen sulfide of biogas was bubbled through an gas-lift column with Fe/EDTA resulting in the formation of sulfur particles. Wide range of optimal operating conditions were tested for both Fe/EDTA solution and the biogas, and the optimal ratio of Fe/EDTA concentration for efficient removal of hydrogen sulfide was found. The roles of Fe/EDTA were studied to enhance the removal efficiency of hydrogen sulfide because of oxidizing by Fe+3/EDTA. The motivation of this investigation is first to explore the feasibility of enhancing the toxic gas treatment in the biogas facility. The biogas purification strategy affords many advantages. For instance, the process can be performed under mild environmental conditions and at low temperature, and it removes hydrogen sulfide selectively. The end product of separation is elemental sulfur, which is a stable material that can be easily disposed of with minor potential for further pollution. The process to address over 90% removal efficiency of hydrogen sulfide does offer considerable advantages unrealized.

Key Words

Fe-EDTA, Hydrogen sulfide, Biogas, Optimal condition

정재진 Jae Jin Jeong , 박주석 Joo Seok Park , 이용석 Yong Seok Lee , 이병하 Byung Ha Lee

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Abstract

Ceramic welding backing material is a mullite-cordierite composite that is currently being used for welding processes in plant and shipbuilding. It is the optimal material for welding processes thanks to its extremely low thermal expansion coefficient and strong resilience against high temperature. However, due to the pollutants from welding such as iron and carbon, the entire amount of ceramic welding backing material is being land-filled after a single-time use. In this study, ceramic welding backing material was mixed with clay and kaolin to be used as a new ceramic body. A composition with 20 ~ 50% of ceramic welding backing material showed sufficient plasticity, and when fired at 1,250℃, it was deemed available for ceramic block and others with the porosity of 2.27 ~ 5.94%, water absorption ratio of 0.99 ~ 3.96% and bending strength of 720 ~ 810 kgf/cm2. In addition, color ceramic body, which was made from a waste welding backing material, of which iron was partially removed, added with 3wt% of high temperature pigment and fired at 1,250℃, displayed the unique color of the pigment, meaning that waste welding backing material could be used for ceramic bodies of a variety of colors.

Key Words

Ceramics, Welding backing material, Mullite-cordierite composite, Color block

박찬일 Chan Il Park , 김형석 Hyoung Seok Kim , 정진기 Jin Ki Jeong , 조봉규 Bong Gyoo Cho , 허탁 Tak Hur

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Abstract

Through industrial developing, electronic waste is occurred by short lifespan of electronic products. This study discusses an approach of the eco-efficiency for waste PCB (Printed Circuit Board) recycling process through environment and economic analysis. The recycling of waste PCB 1 kg has 1.89E + 00kg CO2 eq. of global warming potential and 2.84E ?02 kg antimony eq. of abiotic resource depletion. In terms of economy, this process costs 6,601.91 KRW per 1kg waste PCB recycling. Use of economic and environmental result, when compare with same amounts of virgin metal, environmental-efficiency of GWP (Global Warming Potential) is at 4.16E + 00 and ARD(Abiotic Resource Depletion) is at 2.91E + 00. And compare with secondary metal, environmental-efficiency of GWP is at 2.11E + 00 and ARD is at 8.49E ? 01. In addition economic-efficiency is at 1.19E + 00. The results of optimization of this process will be increased. This study will show the process economical and environmental decision making.

Key Words

Waste PCB, Eco-efficiency, Recycling of waste PCB

정승미 Seung Mi Jeong , 김용진 Yong Jin Kim

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Abstract

To improve the conversion rate of the saccharification liquid of food wastes, containing a mixture of pentose and hexose, to bioethanol, this study aimed to investigate the fermentation characteristics by P. stipites which is used in the fermentation of xylose as well as glucose as a substrate. Saccharification liquid of cellulosic food wastes such as Chinese cabbage, cabbage, and Chinese chive contained hexose, mainly glucose and fructose, and pentose, mainly xylose and trace disaccharide. The pentose in reducing sugar occupied 32%, meaning that the conversion rate to ethanol could be increased by the fermentation of such a pentose. From the result of ethanol fermentation, although the rate of fermentation by P. stipites was slower than by S. coreanus, it was verified the consumption of pentose as well as hexose in the process of the forced air injection, consequently, it was confirmed the increase of ethanol yield.

Key Words

Bioethanol, Fermentation, Cellulosic food wastes, P. Stipitis, Pentose

손영금 Yeong Geum Son , 이우근 Woo Keun Lee

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Abstract

In this work, Lightweight brick was prepared from aluminum dross, MS and MBA. Aluminum dross is discharged as by-product through the process of aluminum smelting. It can be used as foaming agent, because it produces hydrogen gas due to the reaction with alkali activator. In this study, the specific gravity and compressive strength of prepared brick was discussed with the addition of aluminum dross. Compressive strength, flexural strength and specific gravity was 36 MPa, 2.6 MPa and 1.48 at mixing ratio of 0.9wt% aluminum dross, respectively. The physical property of brick was debased with the addition of aluminum dross. Because the pore size was bigger in accordance with the addition of aluminum dross.

Key Words

Lightweight, MSWI bottom ash, Melting slag, Aluminum dross

박상우 Sang Woo Park

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Abstract

Thermogravimetric (TG) analysis was used to investigate the effects of carbonization and solvent extraction on the combustion characteristics of sewage sludge. Initial temperature (IT) and peak temperature (PT) represent combustion characteristics in carbonized sludge (CS). The sludge extracted (ECS) from CS using solvent extraction exhibited higher IT and PT than raw sludge (RS). First, indicate that carbonization was carried out at two different temperatures, 300 and 400℃, to produce CS300 and CS400; then, compare the corresponding IT and burnout temperature (BT). All IT and PT values for ECS300 were lower than those values for RS and CS. The activation energy determined for the combustions of CS300 and ECS300 was lower than the one for the combustion of RS. The ECS300 activation energy (combustion zone of char) was determined to be 90.7 ~ 99.1 kJ/mol, lower to the range of 109.3 ~ 126.9 kJ/mol for coal.

Key Words

Sewage sludge, Carbonization, Solvent-extraction, Combustion Characteristics

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

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Abstract

According to the statistics of the Ministry of Environment, the emission of sewage sludge is increased by 7 ~ 9% yearly. In the future, it will be increased continuously because of extension of sewage disposal plants, high class treatment for removing nitrogen and phosphorus. The objective of this study is to examine the possibility of the carbonization of the sewage sludge by pyrolysis. The pyrolysis behavior of the sewage sludge was investigated by the thermogravimetric analysis as a function of heating rate. In the pyrolysis studies measurements in weight loss was made and reported as a function of test temperature. To minimize energy consumption used for drying sewage sludge, naturally dried sludge were applied evaluate characteristics of thermal and carbonization treatment using a fixed-bed reactor. The most effective treatment temperature of carbonized material production was 400℃. The temperature of highest total yield of char and oil was 500℃. In the pyrolysis studies measurements in weight loss was made and reported as a function of test temperature. According to the result, the optimum pyrolysis temperature of sewage sludge were found to be ranged from 100℃ to 600℃, respectively. About 91% of pyrolysis was completed between 100℃ and 600℃. If applying the carbonization, it can be easily utilized as the replaced resource of energy(fuel) in the countries whose energy resources are insufficient, like our country.

Key Words

Sewage sludge, Fixed-Bed, Char, Carbonization

국진우 Jin Woo Kook , 전수지 Su Ji Jeon , 박소연 So Yeon Park , 유호성 Ho Sung Yoo , 신지훈 Ji Hoom Shin , 이시훈 See Hoon Lee

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Abstract

Biomass resources might be recognized as a promising way to after fossil fuels, such as petroleum oil, natural gas and coal and to prevent the emission of greenhouse gases which will bring about global warming. Therefore many countries have tried to identify and secure available biomass resources. In this study, the energy potential of Korean biomass resources, such as agricultural biomass wastes, municipal solid wastes, and livestock wastes, was analyzed and calculated by using various data. The available energy potential in 5 major cities in Korea over 3.5 M TOE. Especially the municipal solid wastes was over 1.5 M TOE, so the conversion of municipal solid wastes might be easily adopted.

Key Words

Biomass, Energy potential, Waste, Thermochemical conversion