Biochar obtained from the thermal conversion of biomass has high potential as a substitute material for activated carbon and other carbon-based materials because it is economical, environmentally friendly, and carbon-neutral. The physicochemical properties of biochar can also be controlled by a range of activation methods such as physical, chemical, and hydrothermal treatments. Activated biochar can be used as a catalyst for the catalytic pyrolysis of a biomass and as an absorbent for the removal of heavy metal ions and atmospheric pollutants. The applications of biochar are also expanding not only as a key component in producing energy storage materials, such as supercapacitors, lithium ion batteries, and fuel cells, but also in carbon capture and storage. This paper reviews the recent progress on the activation of biochar and its diverse present and future applications.

Solid waste management is currently a topic of concern, particularly in the protection of humans and the environment from toxic pollutants and hazardous materials. The importance of solid waste management is recognized at international, national, and community levels. Different agendas have been prioritized and assigned to improve quality of life, productivity, and health, and reduce the burden of pollution. Suitable management of solid waste requires appropriate technology that is affordable, socially accepted, and environmentally friendly. The use of a smart management system involving system dynamics can save energy, money, and labor. System dynamics is a computer-based approach that aids in predicting the behavioral patterns of variables, and correlating dependent and independent variables. The inclusion of system dynamics-based models in solid waste management has recently become more common. In this review, we used system dynamics to determine methods to disentangle solid waste management systems and analyzed different studies on solid waste management using system dynamics in different countries in detail. We also discussed the various software packages that are available for system dynamics and their usefulness for waste management. This review may help in understanding current solid waste management practices using system dynamics.

산업발달로 인한 화석 연료의 급격한 사용으로 기후변화와 연료고갈 문제가 대두되고 있어 폐기물자원화 및 신재생에너지에 대한 관심이 급증하고 있다. 선행되어온 연구들은 바이오매스나 플라스틱의 대체연료 가능성 연구들로 국한되어 진행되었다. 폐플라스틱 필름의 경우 많은 연구가 진행되어 왔으나, 현재 발생되는 폐플라스틱 필름에 관한 연구는 미비한 상황이다. 많은 폐플라스틱 필름의 발생량에 비해 절반정도를 웃도는 재활용처리 비율은 다른 폐플라스틱 필름 처리방안 마련이 필요하다는 점을 시사한다. 열분해를 이용한 오일 및 화학원료 생산에 대한 관심이 높아지고 있다. 따라서 본 연구에서는 폐플라스틱 필름의 물리･화학적 특성 분석 및 열중량분석기를 통한 동역학분석과 파이롤라이저-가스크로마토그래피 /질량분석기를 이용한 반응 생성물 분석하여 폐플라스틱 필름의 열분해 공정 도입 가능성을 추가 확인하고자 한다. 또한 현재 배출되는 폐플라스틱 필름류의 열분해 특성과 어떤 성분이 생성되는지 알아보고 공정설계 기초자료로 활용되고자 폐플라스틱 필름의 열분해 특성연구를 수행하였다.

Non-CO2 온실가스인 염화불화탄소(Chlorofluorocarbons, CFCs)와 수소염화불화탄소(Hydro-Chlorofluorocarbons, HCFCs)는 오직 인류의 경제(산업) 활동에 의해 발생하며 인체에 무해하고 안정한 물질이기 때문에 냉매, 분사제, 발포제 등 여러 분야에서 다양하게 사용되었지만 오존층 파괴물질으로 국제협약인 몬트리올 의정서에 의해 생산과 사용이 규제되었다. 이에 대한 대체물질로써 수소화불화탄소(Hydrofluorocarbons, HFCs)와 과불화탄소(Perfluorinated compounds, PFCs)가 개발되었지만 여전히 높은 지구온난화지수(Global Warming Potential, GWP)를 지닌 것으로 알려져 있다. 또한 국내 HFCs 소비량은 꾸준히 증가하고 있는 추세로 HFCs 중 전기･전자제품 및 자동차에 99% 이상 냉매로 사용되는 HFC-134a(1,1,1,2-Tetrafluouroethane, CH2FCF3)는 물리･화학적으로 안정된 난처리성 물질로써 처리 시 많은 에너지(높은 온도)가 필요하며, 강산으로 알려진 불산(Hydrogen fluoride, HF)의 발생으로 처리시설의 부식을 야기시킨다. 이에 따라 HFC-134a의 안정적이고 효율적인 분해 기술 개발을 위한 연구가 필요하다 사료되며 본 연구는 수직형 관형흐름 반응기를 이용한 촉매열분해를 적용하여 촉매별 HFC-134a 분해효율 연구하고, 각 촉매별 열분해 반응 생성물의 비교를 통해 HFC-134a의 촉매열분해 특성을 알아보고자 하였다.

This paper applied a new methodology to estimate the generation rate of waste refrigerator using Population Balance Model as well as assigning Weibull Distribution Function as probability distribution function (PDF) of lifespan. In order to determine the generation rate of waste refrigerator, it is necessary to estimate yearly sales quantity of new refrigerator and lifespan PDF of refrigerator. The average lifespan of refrigerator is determined to be 16.8 years as a result of averaging the lifespans of 4,682 waste refrigerators. We also developed a methodology to calibrate the PDF of lifespan of waste refrigerator. The generation rate of waste refrigerator in 2014 is estimated to be 1,822,633 decreasing sharply with time. The new methodology developed here can be applied to estimate the generation rates of other e-wastes.

This paper attempted to elucidate pyrolysis reaction characteristics of waste paper laminated phenolic-printed circuit board (p-PCB). Thermogravimetric analysis was performed for the pyrolysis kinetic analysis of waste p-PCB and Pyrolyzer-gas chromatography/mass spectrometry (Py-GC/MS) was also employed to analyze the product distribution of waste p-PCB pyrolysis reaction under isothermal condition (230, 350, 600oC). Kinetic analysis and isothermal Py-GC/MS results showed that the pyrolysis reaction of waste p-PCB has three reaction temperature regions: 1) low temperature decomposition region (< 280oC), 2) medium temperature decomposition region (280 ~ 380oC), 3) high temperature decomposition region (> 380oC). At the first region, triphenyl phosphate used as fire retardant, water, and phenol were vaporized. At the second region, phenolic resin, tetrabromobisphenol-A (TBBA), and laminated paper are decomposed and produce phenols, brominated compounds, and levoglucosan which were the specific pyrolysis reaction products of phenolic resin, TBBA, and laminated paper, respectively. In the final region, cresol and alkyl benzene were detected which can be considered as the decomposition products of phenolic resin. By above results, pyrolysis reaction pathway of waste p-PCB is accounted for a series reaction with four independent reactions of phosphate based frame retardant, TBBA, laminated paper, and phenolic resin.

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 280oC, 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.

This paper addresses the fugitive emission factors of showcase at use-phase and disposal-phase. The residual quantities of Korean-made fifty- two waste showcase 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 fifty two scarp showcase is determined to be 75.6 ± 5.3%. The emission factor at the use-phase is estimated to be 2.8 ± 0.7%/yr in the case of using average age of 11.1 years and the average residual rate determined here. The emission factor at the disposal-phase, refrigerant is accomplished has not recycled, the residual rate was assumed that the emission factor. We estimate 7.8 g/yr for the average emission quantity of refrigerant per operating showcase, while 234.4 g for that per waste showcase. Since the chemical compositions of refrigerant of waste showcase were the same as those of new refrigerant, it is expected that the refrigerant recovered from waste showcase can be reused for refrigerant.

This paper attempted to estimate the emissions of HFC-134a from scrap truck as a result of measuring the residual quantities of HFC-134a in air conditioner of scrap truck. We measured the residual amounts in the scrap truck of 138 by applying commercial recover for refrigerants. The average residual rate(disposal-phase emission factor) is reported to be 44.3±3.3% within a confidence interval of 95%. Recent year model trucks exhibit the higher residual rates. Little variation, however, is observed in regard to vehicle size. The HFC-134a emission quantity from scrap truck in 2011 is estimated to be 55,908 tCO2-eq that demonstrates 21.4% increase to compare with that in 2007. As the numbers of truck have increased dramatically during the last two decades, the emissions of HFC-134a from scrap truck would increase sharply in the next coming years. HFC-134a is a very high GWP greenhouse gas. therefore have to reduce the emissions from the scrap truck and need to find ways to recycle. The chemical compositions of refrigerants from scrap truck are quite similar to those of new refrigerants, suggesting that the refrigerants from scrap truck could be reused as refrigerant.

This research was designed to elucidate the pyrolysis reaction characteristics of waste epoxy printed circuit board (e- PCB). The samples were pulverized after removing coppers by gravity separator. Non-isothermal pyrolysis kinetic results by Thermogravimetric Analyzer (TGA) displayed two apparent reaction regions : 1) fast degradation zone and 2) slow degradation zone. According to batch experiments, solid by-products are responsible for about 78%, while liquid and gas by-products, respectively, represent 13 and 9%. The high content of solid by-products is ascribed to that of SiO2 that is a major components of e-PCB. Liquid by-products exhibit high content of oxygen (19%) and contain the nitrogen of about 1%. It is recommended that gas, liquid, and solid by-products of waste e-PCB would not be applied directly as fuels. Instead, pyrolysis of e-PCB would be applied to recover valuable rare metals and coppers from solid by-products. Application of liquid by-products is likely to be limited due to the presence of brominated oils precursor in liquid byproducts. It is necessary to develop upgrading methods for improving the quality of liquid by-products of waste e-PCB. According to kinetic analysis and product characterization, pyrolysis reaction model of waste e-PCB is accounted for by a series reaction with two independent reactions of two resins: brominated epoxy resins and non-brominated epoxy resins. At the first-stage, two resins are independently decomposed to generate thermally stable intermediates followed by slow degradation of the intermediates to be converted into char.

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.

This paper attempted to estimate the emissions of HFC-134a from scrap passenger vehicles as a result of measuring the residual quantities of HFC-134a in scrap vehicles. We measured the residual amounts in the scrap passenger vehicles of 196 by applying commercial recover for refrigerants. The average residual rate is reported to be 61.2 ± 2.4% with a confidence interval of 95%. As expected, the higher residual rates are shown for recent models. Little variation, however, is made with vehicle size. The HFC-134a emission quantity from scrap passenger vehicles in 2011 is estimated to be 326,236.83 tCO2 eq that demonstrates 53% increase to compare with that in 2007. As the numbers of passenger vehicles have increased dramatically during the last two decades, the emissions of HFC-134a from scrap passenger vehicles would increase sharply in the next coming years. The chemical compositions of refrigerants from scrap passenger vehicles are quite similar to those of new refrigerants, suggesting that the refrigerants from scrap passenger vehicles could be reused.