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Regional sustainability assessment using emergy accounting approach: The case of Nepal in South Asia
Keshab Shrestha,Izhar Hussain Shah,Zhe Liu,Hung-Suck Park 대한환경공학회 2022 Environmental Engineering Research Vol.27 No.5
Emergy accounting is an environmental assessment tool that accounts for all the energy pathways in production systems. In this regard, the System Thinking Experimental Learning Laboratory Animation (STELLA) with emergy model are used for a retrospective and prospective assessments. Nepal, a country having a relatively small economy but with faster recent growth as well as its geographical position and potentially high vulnerability to climate change was analyzed as a case study using data for 1998–2015 (retrospective) and 2015–2040 (prospective). As per our results, the rising use of non-renewable resources and decreasing use of locally extracted materials caused higher environmental load and reduced emergy sustainability scores. In addition, the effect of natural disasters, such as the Gorkha earthquake, on environmental performance of Nepal was analyzed by emergy accounting. Futuristic emergy analysis for 2015–2040 showed that total and non-renewable emergy would rise considerably, and the emergy sustainability index could further decrease by 33%. Based on these findings, small yet rapidly growing economies, such as Nepal, could improve their environmental management by reducing the material trade deficit (i.e., by increasing domestic material extraction and reducing imports of non-renewable resources), minimizing the use of non-renewables, improving soil fertility, and promoting renewable resource consumption.
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Thiomer를 활용한 ASR 소각재의 중금속 고형화 특성 연구
백진웅,( Aafaq Ur Rehman ),( Pham Viet Nguyen ),( Sun Guohua ),( Manyandi Venkatesan ),( Shrestha Keshab ),( Srinivasa Reddy Mallampati ),박흥석 한국폐기물자원순환학회(구 한국폐기물학회) 2016 한국폐기물자원순환학회 춘계학술발표논문집 Vol.2016 No.-
우리나라는 연간 많은 양의 원유를 해외에서 수입하며, 원유는 정제과정을 거쳐 다양한 석유제품으로 생산된다. 원유의 정제과정 중 탈황공정에서는 산업부산물인 부생유황이 생산되는데, 저유황유의 수요증가에 따라 부생유황의 생산량도 증가하는 추세에 있다. 부생유황에 유기물을 첨가하여 유황을 개질하면 유황폴리머바인더(Thiomer)가 되는데 시멘트와 아스팔트를 대체하는 친환경 건설자재로 활용되고 있다. 한편, 폐 자동차의 재활용률 기준의 향상에 따른 자동차파쇄잔재물(ASR)의 에너지화로 중금속 함량이 높은 ASR 소각재 발생량도 증가하고 있어, 이를 환경적으로 안전하게 처리하며, 재활용하는 방안이 필요한 실정이다. 본 연구는 유황폴리머바인더(Thiomer)를 활용한 ASR 소각재의 고형화를 위한 기초연구로 고형화에 따른 구조적 특성과 환경적 특성을 평가하였다. 이를 위해 ASR 소각재의 중금속함량을 측정하고, 유황폴리머바인더, 소각재 및 모래의 배합설계비에 따라 공시체(직경 50mm, 높이 100mm)를 제작하였다. 제작된 공시체는 24시간이 지난 후 탈형하고, 7일간 공기 중에서 양생하여 압축강도를 측정하였으며, 공시체를 5mm이하의 크기로 파쇄하여 중금속 용출농도를 측정하였다. 실험결과 고형화 후 압축강도는 유황폴리머바인더 40 wt%, 소각재 40 wt%, 모래 20 wt%의 배합설계비에서 최대 77.03MPa로 높은 강도가 나타났다. 중금속 용출은 지정폐기물판정 기준(Pb : 3.0 mg/l, Cu : 3.0 mg/l, Cd : 0.3 mg/l, Cr : 1.5 mg/l)보다 낮은 0.1 mg/l 이하로 고형화 효율이 90% 이상으로 나타났다. 이상의 결과는 ASR 소각재를 Thiomer로 고형화하여 건설자재로 활용함으로써 자동차 재활용률을 제고시킬 수 있는 가능성을 확인할 수 있었다.
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Effect of chemical impregnation on activated carbon fabrics for carbon dioxide capture
( Aafaq Ur Rehman ),( Jin Woong Baek ),( Muhammad Sohail ),( Pham Viet Nguyen ),( Manyandi Venkatesan ),( Shrestha Keshab ),( Hung Suck Park ) 한국폐기물자원순환학회(구 한국폐기물학회) 2016 한국폐기물자원순환학회 춘계학술발표논문집 Vol.2016 No.-
Climate change and acid rain triggered new research opportunities to reduce carbon emissions and acidic gases. However, indoor reduction of CO<sub>2</sub> and acid gases are also the challenging safety issues in building fire. To develop a safety mask with enhanced carbon dioxide adsorption capacity, activated carbon fabrics (ACF) was prepared by copper (II) nitrate trihydrate and ammonium chloride impregnation followed by carbonization and CO<sub>2</sub> adsorption tests were conducted in lab scale reactor with 150 mm in length and internal diameter of 16.12 mm at different moisture conditions (0-40%). Surface area, pore size distribution and cumulative pore volume of ACF samples were examined with BET surface area and porosity analyzer. ACF impregnated with copper showed large surface area (1087 m<sup>2</sup>·g<sup>-1</sup>) and high micre pore volume (0.40 cm<sup>3</sup>·g<sup>-1</sup>) with average pore size of 1.66 nm, while ACF modified with ammonium showed surface area of 861 m<sup>2</sup>·g<sup>-1</sup> and micro pore volume (0.38 cm<sup>3</sup>·g<sup>-1</sup>) with average pore size of 2.07 nm. This results show that carbonization of fabrics at 450℃ contribute to enhancing surface area as well as micro pore volume. The carbon uptake of ACF modified with ammonium chloride and copper nitrate trihydrate were 49.3 and 85 mg CO<sub>2</sub>/g ACF, 29 and 90 mg CO<sub>2</sub>/g ACF in dry and 25% moisture contents, respectively. As moisture content increase to 25%, CO<sub>2</sub> adsorption capacity increase to 2-3 times higher than those at dry conditions in both chemicals impregnation. However, further increase in the moisture content to 40% decease adsorption capacity of ACF due to change in functionalities of impregnated chemicals.
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