간행물
한국폐기물자원순환학회지 KCI 등재 Journal of Korea Society of Waste Management
- 발행기관 한국폐기물자원순환학회
- 자료유형 학술지
- 간기 연8회
- ISSN 2093-2332 (Print)2287-5638 (Online)
- 수록기간 1984 ~ 2018
- 주제분류 공학 > 환경공학 공학 분류의 다른 간행물
- 십진분류KDC 539DDC 628
권호리스트/논문검색
제30권 제2호 (2013년 3월) 13건
Original Paper
1.
2013.03
서비스 종료(열람 제한)
Land application of biochar (or charcoal) has increasingly been recognized due to its favorable effect as soil amendments. However, depending upon the nature of biomass and pyrolysis condition, biochar may be rich in hazardous inorganic elements. Giant Miscanthus showed its potential as a promising source for biochar manufacture but, the risk of heavy metal leaching from Giant Miscanthus-derived biochar (GMB) has not investigated. The objective of this study was to investigate the heavy metal leachability of GMB manufactured from 3 different temperatures (400, 500, and 700oC). Elemental composition of C, N, H, S, O and 18 metals were analyzed. Leaching concentration of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn was analyzed using 4 different methods (0.1 N HCl, 1 N NH4OAc, toxicity characteristic leaching procedure, and synthetic precipitation leaching procedure). For comparison, same analysis were performed for two char materials, municipal solid waste char (MWC) and sewage sludge char (SSC), manufactured from pilot-scale muncipal waste gasification plant. Elemental composition of GMB complied with the fertilizer guideline whereas the several heavy metal content (Cd, Ni, Pb, and Zn for MWC, Cr, Cu, Ni, and Zn for SSC) was beyond the criteria. From leaching test, concentration of heavy metals from GMB was positively increased with pyrolysis temperature and the acidity of extractant solution. Leaching concentration of plant nutrients (Ca, K, and Mg) was the highest by 1N NH4OAc. Meanwhile, leaching concentration of Cu from MWC and Pb from SSC exceeded the regulatory standard of Korea and US EPA, respectively. In conclusion, with respect to the risk of heavy metals, Giant Miscanthus-derived biochar will be suitable for land application as a soil amendment, while care should be taken for using municipal waste-derived char materials.
2.
2013.03
서비스 종료(열람 제한)
Although scrap domestic refrigerator is regarded as a major source of HFC-134a, little information is available for its emission characteristics of HFC-134a. This paper addresses the fugitive emission factors of domestic refrigerator at usephase and disposal-phase. The residual quantities of Korean-made forty three scrap domestic refrigerators were weighed using a commercial recover of refrigerants to determine the emission factors at the disposal-phase. On the other hand, the emission factors at use-phase were estimated from the residual quantities and operating times. The average residual rate of forty three scarp domestic refrigerators is determined to be 75.1 ± 5.2%. The emission factor at the use-phase is estimated to be 2.4 ± 0.5%/yr as a result of using average age of 12.3 years and the average residual rate determined here. The emission factor at the disposal-phase is determined to be 31.9% after adopting 38% of the recycling rate of refrigerant reported by Recycling Center. We estimate 2.9 g/yr for the average emission quantity of HFC-134a per operating refrigerator, while 33.5 g for that per scrap domestic refrigerator. Since the chemical compositions of refrigerant of scrap domestic refrigerator were the same as those of new refrigerant, it is expected that the HFC-134a recovered from scrap domestic refrigerator can be reused for refrigerant.
3.
2013.03
서비스 종료(열람 제한)
Sediments samples were collected at Busan South harbor where dredging has been initiated since 2010 to clean up the bottom of harbor. In this study, we tried to determine physico-chemical properties and heavy metal contents of sediments for the purpose of deciding contamination levels of the sediments. From the total organic carbon, XRD, and XRF analyses, all samples showed similar elements, oxides, and minerals. In general, moderately high concentrations of Cu, Pb, and Zn were found in the samples. Heavy metal contents of sediments were compared with USEPA sediment quality standards and ontario sediment quality guidelines. Ignition losses of the samples were greater than 8%, which is a value indicating whether the sample is heavily polluted or moderately polluted. All the samples were classified as heavily polluted. Therefore, sediments obtained from dredging should be carefully treated to avoid other adverse environmental effects.
4.
2013.03
서비스 종료(열람 제한)
Gasification, one of the thermo-chemical conversion technologies, has been known and researched for the conversion of low graded solid feedstock to gaseous form of fuel. Gasification for obtaining high-valued combustible gas such as hydrogen and carbon monoxide has been focused again due to high oil price with needs of alternative energy. And the gaseous product, known as synthesis gas (syngas) can be effectively utilized in a variety of ways ranging from electricity production to chemical industry. Gasification and melting processes are also operated at high temperatures with the destruction of hazardous components and production of gases, mainly CO and H2, which can be utilized as fuel gas or raw chemicals after cleaning. In this study, sawdust was experimented on in a lab-scale gasification process in order to characterize the gaseous products. At isothermal conditions at a fixed temperatures (800, 1000, 1200oC), the concentrations of CO, H2 and CH4 increased but CO2 and N2 decreased with lower equivalent ratio (ER). C2H6 concentration was varying and not depending upon ER. Carbon conversion efficiency, gas and tar yields increased with increasing ERs. Tar yield was related to carbon conversion efficiency and gas yield.
5.
2013.03
서비스 종료(열람 제한)
Photogrammetry technique was applied to estimate the amount of recyclable waste paper from an apartment complex. Photos were taken to calculate pile volume of waste paper, and at the same time the weight of separated recyclable waste paper was measured. Volume of waste paper was calculated by PhotoModeler 2012, which is commercial photogrammetry software. At least three photos were required to calculate the volume of waste paper pile. After 4 times of field measurement and volume calculation, we obtained standard density of recyclable waste paper pile. The weight of waste paper pile was estimated by multiplying the density of waste paper pile by the estimated volume of waste paper pile. As results, the density of recyclable waste paper pile from an apartment complex was 32.6 kg/m3 (standard deviation was 10.1 kg/m3), and 70.2% of man·hour was saved by using photogrammetry technique. The amount of average recyclable waste paper generation from apartment complex was 91.8 g/capita/day, and the standard deviation was 12.4 g/capita/day.
6.
2013.03
서비스 종료(열람 제한)
This paper presents the actual recycling rates and recycling processes of waste plastic recycling facilities using material flow analysis. Determination of actual recycling rates through the processes of waste plastics is a very important subject not only from the point of plastic recycling efficiency energy conversion but also from the perspective of the recycling technology level. In this study, the recycling processes and recycling rates of waste plastic recycling facilities were evaluated by the MFA analysis based on 14 site visits and 25 questionnaires. The MFA methodology based on mass balance approach applied to identify the inputs and outputs of recyclable plastic materials in the recycling processes at recycling facilities. It is necessary to determine the composition and flows of the input materials to be recycled in a recycling facility. A complete understanding of the waste flows in the processes along with the site visit and data surveys for the recycling facilities was required to develop a material flow for the processes and determine the actual recycling rate. The results show that the average actual recycling rates for the recycling facilities by the site visit and the questionnaire was found to be approximately 87.5 ± 7.1% and 84.3 ± 14.5%, respectively. The recycling rates depended upon several factors including the quality of incoming waste plastics, the type and operating conditions of recycling processes, and the type of final products. According to the national statistics, the recycling rate of waste plastics was about 53.7%, while the actual recycling rate at national level was estimated to be approximately 45.1% by considering the recycling performance evaluated as well as the type of recycling process applied. The results of MFA for the recycling processes served as a tool to evaluate the performance of recycling efficiency with regard to the composition of the products during recycling. They may also support the development of the strategy of improvement of recycling processes to maximize resource recovery out of the waste plastic materials.
7.
2013.03
서비스 종료(열람 제한)
In this study, a gasification process has been investigated systematically by numerical method, in order to obtain design and operational concept for the gasification of RPF. A commercial scale of the facility of up-draft fixed bed gasifier was considered with the ignition by plasma torch. Turbulent reacting flow was calculated with the incorporation of the appropriate flow model for the turbulence in free space and inertial resistance for the porous region of waste loading. Further a detailed thermochemical model was employed for estimating the syngas composition by gasification. This study, focused on the S/C (steam/carbon mole ratio) and ER (Equivalence ratio) to show effective gasification process. Results show that better solution of the combined combustion and gasification process strongly and in a delicate manner depends on both equivalence ratio (ER) and steam and carbon mole ratio (S/C). This optimization of the gasifier is evaluated for the following ER (0.25, 0.35, 0.45), S/C (0.0, 2.2, 3). In this study, the gasification efficiency is the best at ER 0.35 and S/C 2.2.
8.
2013.03
서비스 종료(열람 제한)
Recycling the bottom ash from MSWI (Municipal solid waste incinerators) ash is required to reduce the secondary pollution. We characterized the bottom ash and investigated the possibility of application for subsidiary ceramic raw materials. Major components of bottom ash are analyzed as CaO, Al2O3, SiO2, P2O5, MgO, Fe2O3, which are the same components of the earth’s crust. This similarity of components implied that bottom ash could be recycled as ceramic products through systematic treatment. Considering the plasticity and water absorption results, the ceramics, which are the mixture with 74 wt % bottom ash and 26 wt% Pink Kaolin, showed 1.39% water absorption after sintering 1150oC for 1h. This result indicated the possibility of recycling of bottom ash for subsidiary ceramic raw materials.
9.
2013.03
서비스 종료(열람 제한)
Solid wastes are among the most pressing environmental and resource concerns in Korea. The Korean government has been implementing various management alternatives to reduce the production of solid wastes and recover valuable resources from them. Refuse-derived fuel (RDF) manufacturing facilities are one of projects that aim at recovering energy from solid wastes. This study used the emergy evaluation procedure to assess the feasibility of an RDF manufacturing facility in Wonju, Korea. By converting 10,442.6 tons of combustible solid wastes into 5,801 tons of solid fuel in 2007, this facility prevented the loss of useful resources with an emergy quantity of 3.70 × 1019 sej/yr. This amounted to a potential worth of 7.04 billion emW/yr. Total emergy input required to produce 5,801 tons of RDF was 5.91 × 1019 sej/ yr with an emvalue of 11.3 billion emW/yr. The Wonju RDF manufacturing facility contributed more to the Korean economy beyond its investment cost as revealed by the emergy yield ratio of 2.67. Direct emergy benefits and costs of the RDF facility were calculated as 1.20 × 1010 emW/yr and 3.31 × 109 emW/yr, respectively, resulting in the net emergy benefit/cost ratio of 2.62. This indicates that the RDF facility was a feasible option for managing solid wastes for the city of Wonju in Korea. This study demonstrated the usefulness of the emergy concept and methodology in evaluating management alternatives for solid wastes in Korea.
10.
2013.03
서비스 종료(열람 제한)
The amount of municipal solid waste (MSW) is steadily increasing leading to an urgent need for the effective treatment of these wastes. Incineration is one of the methods for the treatment of these solid wastes. The bottom ashes produced from the incineration process are very unstable at standard atmospheric conditions, so there is need for process to alleviate the ash problems. In this study, the bottom ashes were first converted into the slurry form and then the slurry was made to react with CO2 to produce the carbonates. This carbonate process by using bottom ashes and carbon dioxide will be source recovery technology from waste material and, moreover, will also help to reduce the amount of CO2 emissions. The aim of this study was to determine the optimum conditions for the precipitation of CaCO3 using Aspen plus modeling program. The temperature and pressure for the precipitation of CaCO3 process were varied 25 to 500oC and 1.05 bar to 90bar, respectively. For producing the slurry, the optimum ratio of H2O to calcium oxide was determined to be 10 : 1. And the optimum precipitating conditions for calcium carbonate process system were found to be at 35 bar - 210oC.
11.
2013.03
서비스 종료(열람 제한)
Of the 6 most abundantly recognized Greenhouse Gases, SF6 (Sulfur Hexafluoride) is one of the most potentially consequential gases to Global Warming. The permeation characteristics of fluorinated gases N2 and SF6 used in the semiconductor processes were examined by study through the processes that occur during the Hollow Fiber Membrane Separation Technology. The developed module had a permeance of 8.83 ~ 17.40 GPU for N2 with N2/SF6 selectivity of 8.64 ~ 40.80 at various pressure and temperature. The SF6 isolation results showed the variables increased SF6 concentration levels of 13% ~ 63%, with a yield increase of 50% ~ 96%. These results are proven to be well utilized in the semiconductor manufacturing processes in the recovery of SF6 through the Hollow Fiber Membrane Separation Technology.
12.
2013.03
서비스 종료(열람 제한)
Acid hydrolysis of cellulose using hydrothermal reaction was conducted to maximize reducing sugar concentration and the response surface methodology (RSM) was applied to study the effects of independent variables, such as reaction temperature (116 ~ 184oC), reaction time (12 ~ 28 min) and hydrochloric acid concentration (HCl, 0.0159 ~ 0.1841 N) on reducing sugar concentration and production yield from the cellulose. With the optimum conditions of the acid-catalyzed hydrothermal hydrolysis, the reducing sugar (RS) was obtained as 369.14 mg-RS/g-cellulose in 172.77oC of the reaction temperature, 28.41 min of the reaction time and 0.067 N of the hydrochloric acid concentration. The glucose (Glu) was obtained as 281.94 mg-Glu/g-cellulose in 154.70oC of the reaction temperature, 11.59 min of the reaction time and 0.184 N of the hydrochloric acid concentration.
13.
2013.03
서비스 종료(열람 제한)
Recently, the recycling of end-of-life vehicles is becoming increasingly interesting for less waste discharge and recovering useful materials such as valuable metals. Hence, in Korea, the target of the recycling rate is made to 85% until 2014 (energy recovery within 5%) and the recycling rate to 95% after 2015 (energy recovery within 10%) according to the law of "regulation about resource recycling of electrical and electronic products and automobiles". However, the recycling rate is around 84% in 2010, and registered numbers of shredder residue recyclers among dismantling recyclers, crushing recyclers, shredder residue recyclers, and waste gases recyclers are very few. In order to meet the goal of 85% until 2014, Korean recycling industry of ASR should grow bigger and innovative recycling technologies have to be developed as well. In the meantime, a recycling technology of automobile shredder residue is developed in the present study, in which ASR is introduced to a copper smelting process. This process is very promising because of co-beneficial effects such as recovering copper and process heat simultaneously from ASR. In this study, lab-scale melting furnace was developed and melting tests for various ASR were carried out. From the results, the physicochemical characteristics of Korean ASR were analyzed and its melting behavior was investigated for the application to the copper smelting process. In particular, melted slag products were fabricated at different melting temperatures. Then, the basicity and pouring index in the lab-scale melting furnace were examined to find out appropriate operating conditions for the melting process. As a result, Because the amount of lump coal that included in existing process samples is a little, melting state and value of pouring index are very similar to existing process samples. In result of this experiment, in case of changing lump coal to ASR, The existing copper smelting facilities, if basicity and melting temperature are well controlled, flow of melting material is considered that is almost not affected.
