Sustainability

Research

8 pages, 1210 KiB

Open AccessCommunication

Sustainable Treatment for Sulfate and Lead Removal from Battery Wastewater

by Hong Ha Thi Vu, Shuai Gu, Thenepalli Thriveni, Mohd Danish Khan, Lai Quang Tuan and Ji Whan Ahn

Sustainability 2019, 11(13), 3497; https://doi.org/10.3390/su11133497 - 26 Jun 2019

Cited by 23 | Viewed by 4619

Abstract

In this study, we present a low-cost and simple method to treat spent lead–acid battery wastewater using quicklime and slaked lime. The sulfate and lead were successfully removed using the precipitation method. The structure of quicklime, slaked lime, and resultant residues were measured [...] Read more.

In this study, we present a low-cost and simple method to treat spent lead–acid battery wastewater using quicklime and slaked lime. The sulfate and lead were successfully removed using the precipitation method. The structure of quicklime, slaked lime, and resultant residues were measured by X-ray diffraction. The obtained results show that the sulfate removal efficiencies were more than 97% for both quicklime and slaked lime and the lead removal efficiencies were 49% for quicklime and 53% for slaked lime in a non-carbonation process. After the carbonation step, the sulfate removal efficiencies were slightly decreased but the lead removal efficiencies were 68.4% for quicklime and 69.3% for slaked lime which were significantly increased compared with the non-carbonation process. This result suggested that quicklime, slaked lime, and carbon dioxide can be a potential candidate for the removal of sulfate and lead from industrial wastewater treatment. Full article

(This article belongs to the Special Issue Emerging Technologies and Solutions for the Sustainable Climate Change Challenges)

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11 pages, 2065 KiB

Open AccessArticle

Sulfation–Roasting–Leaching–Precipitation Processes for Selective Recovery of Erbium from Bottom Ash

by Josiane Ponou, Marisol Garrouste, Gjergj Dodbiba, Toyohisa Fujita and Ji-Whan Ahn

Sustainability 2019, 11(12), 3461; https://doi.org/10.3390/su11123461 - 24 Jun 2019

Cited by 8 | Viewed by 3895

Abstract

Bottom ash (BA) is mainly composed of compounds of Al, Fe, Ca, and traces of rare earth elements (REEs). In this study, the selective recovery of erbium (Er) as REEs by means of sulfation–roasting–leaching–precipitation (SRLP) using BA was investigated. A pre-treatment process of [...] Read more.

Bottom ash (BA) is mainly composed of compounds of Al, Fe, Ca, and traces of rare earth elements (REEs). In this study, the selective recovery of erbium (Er) as REEs by means of sulfation–roasting–leaching–precipitation (SRLP) using BA was investigated. A pre-treatment process of sulfation and roasting of BA was developed to selectively recover REEs using ammonium oxalate leaching (AOL) followed by precipitation. Most of the oxides were converted to their respective sulfates during sulfation. By roasting, unstable sulfates (mostly iron) decomposed into oxides, while the REE sulfates remained stable. Roasting above 600 °C induces the formation of oxy-sulfates that are almost insoluble during AOL. Dissolved REEs precipitate after 7 days at room temperature. The effects of particle size, roasting temperature, leaching time, and AOL concentration were the important parameters studied. The optimal conditions of +100–500 μm particles roasted at 500 °C were found to leach 36.15% of total REEs in 2 h 30 min and 94.24% of the leached REEs were recovered by precipitation. A total of 97.21% of Fe and 94.13% of Al could be separated from Er. Full article

(This article belongs to the Special Issue Emerging Technologies and Solutions for the Sustainable Climate Change Challenges)

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11 pages, 7703 KiB

Open AccessArticle

Production of the Hydroxyl Radical and Removal of Formaldehyde by Calcined Green Tuff Powder and Tile

by Toyohisa Fujita, Lanyin Zhang, Gjergj Dodbiba, Ji-Whan Anh, Yuezhou Wei, Hiromi Kurokawa, Hirofumi Matsui, Shigeki Yamamoto and Hiroshi Kawaguchi

Sustainability 2019, 11(12), 3390; https://doi.org/10.3390/su11123390 - 19 Jun 2019

Cited by 5 | Viewed by 3307

Abstract

Waste green tuff powder produced by cutting Towada stone has been utilized to eliminate formaldehyde related to greenhouse gases. The green tuff contains TiO₂ on zeolite as observed by scanning electron microscope (SEM)t. The green tuff is a natural catalyst that can [...] Read more.

Waste green tuff powder produced by cutting Towada stone has been utilized to eliminate formaldehyde related to greenhouse gases. The green tuff contains TiO₂ on zeolite as observed by scanning electron microscope (SEM)t. The green tuff is a natural catalyst that can produce hydrogen peroxide with moisture and oxygen with light. The optimum temperature for calcination of the green tuff powder has been investigated in order to produce hydroxyl radicals from the decomposition of hydrogen peroxide using ultraviolet light (UV) and no light. The green tuff calcined at 800 °C showed a high decomposition rate of hydrogen peroxide with no UV light under high alkaline conditions when measured by using ESR. With UV light, the optimum temperature for calcination of green tuff powder in order to reduce the hydroxyl radical was also 800 °C. Next, the powder calcined at 800 °C was used to produce the tile by compression and heating, and then the formaldehyde adsorption rate was measured. The green tuff powder calcined at 800 °C showed a high adsorption rate, similar to that of the activated carbon. The tiles formed at 40 MPa and heated at 1100 °C were the strongest and also showed adsorption with respect to formaldehyde. The adsorbed formaldehyde on the green tuff tile and powder was possibility decomposed by the hydroxyl radical produced by photocatalysis. Full article

(This article belongs to the Special Issue Emerging Technologies and Solutions for the Sustainable Climate Change Challenges)

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18 pages, 16501 KiB

Open AccessArticle

Pressurization Ventilation Technique for Controlling Gas Leakage and Dispersion at Backfilled Working Faces in Large-Opening Underground Mines: CFD Analysis and Experimental Tests

by Van-Duc Nguyen, Won-Ho Heo, Rocky Kubuya and Chang-Woo Lee

Sustainability 2019, 11(12), 3313; https://doi.org/10.3390/su11123313 - 15 Jun 2019

Cited by 6 | Viewed by 3399

Abstract

Pressurization ventilation techniques, originally designed to control building fires, have never been applied to the mines. The working face, backfilled with fly-ash-based materials, is likely to be contaminated during, and even after, the curing period of the backfill materials. Gases such as NH [...] Read more.

Pressurization ventilation techniques, originally designed to control building fires, have never been applied to the mines. The working face, backfilled with fly-ash-based materials, is likely to be contaminated during, and even after, the curing period of the backfill materials. Gases such as NH₃ and CO₂ may leak out prolongedly from the backfilled sites. Proper ventilation schemes should be implemented to control toxic gas leakage and thus minimize the workers’ exposure. This study aims at evaluating the applicability of a pressurization ventilation scheme at backfilled working faces in large-opening limestone mines. To pressurize the working face, two different fans (15 kW and 37 kW) were developed and two ventilation scenarios were tested. Computational Fluid Dynamics (CFD) analysis was also carried out for comparison purposes. There is no established standard for differential pressure between the inside and outside of working faces to prevent gas leakage at mines. However, taking the differential pressure of 50 Pa in British standards for controlling building fires (where a relatively stronger dissipation force than the gas leakage of a mining face occurs), the pressure differential created by two blowing fans seems to be sufficient to control the gas leakage and dispersion within the work space. Full article

(This article belongs to the Special Issue Emerging Technologies and Solutions for the Sustainable Climate Change Challenges)

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10 pages, 563 KiB

Open AccessCommunication

Water Environment Policy and Climate Change: A Comparative Study of India and South Korea

by Mohd Danish Khan, Sonam Shakya, Hong Ha Thi Vu, Ji Whan Ahn and Gnu Nam

Sustainability 2019, 11(12), 3284; https://doi.org/10.3390/su11123284 - 14 Jun 2019

Cited by 10 | Viewed by 3965

Abstract

Climate change is considered to be a potential cause of global warming, which leads to a continuous rise in the global atmospheric temperature. This rising temperature also alters precipitation conditions and patterns, thereby causing frequent occurrences of extreme calamity, particularly droughts and floods. [...] Read more.

Climate change is considered to be a potential cause of global warming, which leads to a continuous rise in the global atmospheric temperature. This rising temperature also alters precipitation conditions and patterns, thereby causing frequent occurrences of extreme calamity, particularly droughts and floods. Much evidence has been documented by the Intergovernmental Panel on Climate Change, illustrating fluctuations in precipitation patterns caused by global climate change. Recent studies have also highlighted the adverse impact of climate change on river flow, groundwater recovery, and flora and fauna. The theoretical political approach and scientific progress have generated ample opportunities to employ previously allusive methods against impacts caused by varying climatic parameters. In this study, the current state of India’s water environment policy is compared with that of South Korea. The “3Is”—ideas, institutions, and interests—which are considered pillars in the international field of political science, are used as variables. The concept of “ideas” highlights the degree of awareness regarding climate change while formulating water environment policy. Here, the awareness of India’s management regarding emerging water issues related to climate change are discussed and compared with that of South Korea. The concept of “institutions” illustrates the key differences in water environment policy under the umbrella of climate change between both countries within the associated national administrations. India’s administrations, such as the Ministry of Environment, Forests, and Climate Change; the Ministry of Water Resources, River Development, and Ganga Rejuvenation; the Ministry of Rural Development; and the Ministry of Housing and Urban Affairs, are used as a case study in this work. Finally, the concept of “interest” elaborates the prioritization of key issues in the respective water environment policies. Common interests and voids in the policies of both countries are also briefly discussed. A comparison of India’s water environment policies with that of South Korea is made to expose the gaps in India’s policies with respect to climate change, thereby seeking to identify a solution and the optimal direction for the future of the water environment policy of India. Full article

(This article belongs to the Special Issue Emerging Technologies and Solutions for the Sustainable Climate Change Challenges)

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10 pages, 2374 KiB

Open AccessArticle

Synthesis of Nano-Calcium Oxide from Waste Eggshell by Sol-Gel Method

by Lulit Habte, Natnael Shiferaw, Dure Mulatu, Thriveni Thenepalli, Ramakrishna Chilakala and Ji Whan Ahn

Sustainability 2019, 11(11), 3196; https://doi.org/10.3390/su11113196 - 7 Jun 2019

Cited by 207 | Viewed by 15407

Abstract

The sol-gel technique has many advantages over the other mechanism for synthesizing metal oxide nanoparticles such as being simple, cheap and having low temperature and pressure. Utilization of waste materials as a precursor for synthesis makes the whole process cheaper, green and sustainable. [...] Read more.

The sol-gel technique has many advantages over the other mechanism for synthesizing metal oxide nanoparticles such as being simple, cheap and having low temperature and pressure. Utilization of waste materials as a precursor for synthesis makes the whole process cheaper, green and sustainable. Calcium Oxide nanoparticles have been synthesized from eggshell through the sol-gel method. Raw eggshell was dissolved by HCl to form CaCl₂ solution, adding NaOH to the solution dropwise to agitate Ca (OH)₂ gel and finally drying the gel at 900 °C for 1 h. The synthesized nanoparticle was characterized by scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FTIR), X-Ray fluorescence (XRF) and X-ray diffraction (XRD). The FTIR and XRD results have clearly depicted the synthesis of calcium oxide from eggshell, which is mainly composed of calcium carbonate. The FE-SEM images of calcium oxide nanoparticles showed that the particles were almost spherical in morphology. The particle size of the nanoparticles was in the range 50 nm–198 nm. Therefore, waste eggshell can be considered as a promising resource of calcium for application of versatile fields. Full article

(This article belongs to the Special Issue Emerging Technologies and Solutions for the Sustainable Climate Change Challenges)

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11 pages, 1374 KiB

Open AccessArticle

Leaching Characteristics of Low Concentration Rare Earth Elements in Korean (Samcheok) CFBC Bottom Ash Samples

by Lai Quang Tuan, Thriveni Thenepalli, Ramakrishna Chilakala, Hong Ha Thi Vu, Ji Whan Ahn and Jeongyun Kim

Sustainability 2019, 11(9), 2562; https://doi.org/10.3390/su11092562 - 3 May 2019

Cited by 27 | Viewed by 4687

Abstract

Coal-derived power comprises over 39% of the world’s power production. Therefore, a mass volume of coal combustion byproducts are generated and shifted the extra burden onto the economy and environment. Circulating fluidized bed combustion (CFBC) has been found to be a clean and [...] Read more.

Coal-derived power comprises over 39% of the world’s power production. Therefore, a mass volume of coal combustion byproducts are generated and shifted the extra burden onto the economy and environment. Circulating fluidized bed combustion (CFBC) has been found to be a clean and ultimate technology for Korea’s coal-fired power plants to have effective power generation from low-grade imported coal with reduced emissions. Efforts have been made to broaden the utilization of CFBC coal ash, and to promote sustainable development of CFBC technology. Investigations provided numerous evidences for coal ash to be a potential deposit for rare earths reclamation. However, the basic characteristics and the methods of rare earth mining from the CFBC bottom ash lack detailed understanding and are poorly reported. This study highlighted an insight of the CBFC bottom ash with respect to REEs concentration. Moreover, agents were tested as a means for leaching REEs from Samcheok CFBC bottom ash. The leaching tests were performed in relation to variations in concentration, time and temperature. The results were applied to identify suitable processes to leach REEs from the ash and clarify the potential valuation of CFBC bottom ash. The leaching conditions attained by ANOVA analysis for hydrochloric concentration, temperature, and time of 2 mol L⁻¹, 80 °C, and 12 h, were found to provide a maximum extraction of yttrium, neodymium and dysprosium of 62.1%, 55.5% and 65.2%, respectively. Full article

(This article belongs to the Special Issue Emerging Technologies and Solutions for the Sustainable Climate Change Challenges)

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20 pages, 4405 KiB

Open AccessArticle

Waste Heat and Water Recovery System Optimization for Flue Gas in Thermal Power Plants

by Syed Safeer Mehdi Shamsi, Assmelash A. Negash, Gyu Baek Cho and Young Min Kim

Sustainability 2019, 11(7), 1881; https://doi.org/10.3390/su11071881 - 28 Mar 2019

Cited by 28 | Viewed by 6146

Abstract

Fossil-fueled power plants present a problem of significant water consumption, carbon dioxide emissions, and environmental pollution. Several techniques have been developed to utilize flue gas, which can help solve these problems. Among these, the ones focusing on energy extraction beyond the dew point [...] Read more.

Fossil-fueled power plants present a problem of significant water consumption, carbon dioxide emissions, and environmental pollution. Several techniques have been developed to utilize flue gas, which can help solve these problems. Among these, the ones focusing on energy extraction beyond the dew point of the moisture present within the flue gas are quite attractive. In this study, a novel waste heat and water recovery system (WHWRS) composed of an organic Rankine cycle (ORC) and cooling cycles using singular working fluid accompanied by phase change was proposed and optimized for maximum power output. Furthermore, WHWRS configurations were analyzed for fixed water yield and fixed ambient temperature, covering possible trade-off scenarios between power loss and the number of stages as per desired yields of water recovery at ambient temperatures in a practical range. For a 600 MW power plant with 16% water vapor volume in flue gas at 150 °C, the WHWRS can produce 4–6 MWe while recovering 50% water by cooling the flue gas to 40 °C at an ambient temperature of 20 °C. Pragmatic results and design flexibility, while utilizing single working fluid, makes this proposed system a desirable candidate for practical application. Full article

(This article belongs to the Special Issue Emerging Technologies and Solutions for the Sustainable Climate Change Challenges)

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9 pages, 3985 KiB

Open AccessArticle

Utilization of Calcium Carbonate-Coated Wood Flour in Printing Paper and Their Conservational Properties

by Yung Bum Seo, Dong Suk Kang and Jung Soo Han

Sustainability 2019, 11(7), 1867; https://doi.org/10.3390/su11071867 - 28 Mar 2019

Cited by 3 | Viewed by 2786

Abstract

Wood flours (WFs) are bulky lignocellulosic materials that can increase the bulk and stiffness of paper. To be used in printing paper for replacing chemical pulp, WFs were first fractionated by a 200-mesh screen to improve smoothness; second, they were coated with calcium [...] Read more.

Wood flours (WFs) are bulky lignocellulosic materials that can increase the bulk and stiffness of paper. To be used in printing paper for replacing chemical pulp, WFs were first fractionated by a 200-mesh screen to improve smoothness; second, they were coated with calcium carbonate by an in-situ CaCO₃ formation method (coated wood flours, CWFs) to improve brightness. The performance of CWFs for printing paper was compared to those of bleached wood flours (BWFs) and bleached chemical pulp. Equivalent brightness and much higher smoothness were obtained for the CWFs compared to the BWFs. Furthermore, BWFs caused a significant loss of yield and required wastewater treatment in the bleaching process, while the CWFs increased the yield greatly by attaching CaCO₃ to the wood flours, and caused no wastewater burden. An accelerated aging test showed that the CWFs caused lesser brightness and strength loss than the bleached chemical pulp and BWFs. CWFs still had room for improvement to replace chemical pulp, but showed slower aging in optical and close strength properties. Full article

(This article belongs to the Special Issue Emerging Technologies and Solutions for the Sustainable Climate Change Challenges)

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11 pages, 2566 KiB

Open AccessArticle

Utilization of Lime Mud Waste from Paper Mills for Efficient Phosphorus Removal

by Hong Ha Thi Vu, Mohd Danish Khan, Ramakrishna Chilakala, Tuan Quang Lai, Thriveni Thenepalli, Ji Whan Ahn, Dong Un Park and Jeongyun Kim

Sustainability 2019, 11(6), 1524; https://doi.org/10.3390/su11061524 - 13 Mar 2019

Cited by 26 | Viewed by 6745

Abstract

In this study, we utilized lime mud waste from paper mills to synthesize calcium hydroxide (Ca(OH)₂) nanoparticles (NPs) and investigate their application for the removal of phosphorus from aqueous solution. The NPs, composed of green portlandite with hexagonal shape, were successfully [...] Read more.

In this study, we utilized lime mud waste from paper mills to synthesize calcium hydroxide (Ca(OH)₂) nanoparticles (NPs) and investigate their application for the removal of phosphorus from aqueous solution. The NPs, composed of green portlandite with hexagonal shape, were successfully produced using a precipitation method at moderately high temperature. The crystal structure and characterization of the prepared Ca(OH)₂ nanoparticles were analyzed by field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. The effects of Ca(OH)₂ NP dosage and contact time on removal of phosphorus were also investigated. The results show that the green portlandite NPs can effectively remove phosphorus from aqueous solution. The phosphorus removal efficiencies within 10 min are 53%, 72%, 78%, 98%, and 100% with the different mass ratios of Ca(OH)₂ NPs/phosphorus (CNPs/P) of 2.2, 3.5, 4.4, 5.3, and 6.2, respectively. Due to the efficient phosphorus removal, the calcium hydroxide nanoparticles (CNPs) could be a potential candidate for this application in domestic or industrial wastewater treatment. Full article

(This article belongs to the Special Issue Emerging Technologies and Solutions for the Sustainable Climate Change Challenges)

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8 pages, 472 KiB

Open AccessArticle

Development of a New Clean Development Mechanism Methodology for the Quantification of Greenhouse Gas in Calcium Sulfoaluminate Cement

by Eun-don Jeon, Kyu-uk Lee and Chung-kook Lee

Sustainability 2019, 11(5), 1482; https://doi.org/10.3390/su11051482 - 11 Mar 2019

Cited by 7 | Viewed by 3591

Abstract

The purpose of this research was to probe beyond the scope of the “National Strategy Project on Carbon Mineralization” to develop a “United Nations Framework Convention on Climate Change, Clean Development Mechanism” (UNFCCC CDM) methodology that enables reduction of greenhouse gas (GHG) by [...] Read more.

The purpose of this research was to probe beyond the scope of the “National Strategy Project on Carbon Mineralization” to develop a “United Nations Framework Convention on Climate Change, Clean Development Mechanism” (UNFCCC CDM) methodology that enables reduction of greenhouse gas (GHG) by “green cement” under the calcium sulfoaluminate (CSA) cement technologies. The findings will be utilized as the foundations and developed into the UNFCCC CDM project. There were two existing methodologies related to cement, but neither was applicable for CSA cement. The existing methodologies are applicable only when there is one clinker, but CSA cement utilizes more than one clinker. Through this research, we developed methodologies to use waste-based material for avoiding emission leakage and utilized more than one clinker to calculate GHG emissions and reduction. For this purpose, we utilized the CSA cement methodology for calculating GHG reduction compared to Portland cement and found that CSA cement allowed for a reduction of 0.281 tCO₂-eq/ton above the reduction enabled by Portland cement. We are presently preparing to register the CSA cement methodology for UNFCCC CDM methodology approval. With the technology transfer and support for this CSA cement technology and methodology, developing countries will be able to achieve their national GHG reduction targets and gain carbon credits. Thus, CSA cement technology could serve as an important tool to deal with GHG emissions and climate change. Full article

(This article belongs to the Special Issue Emerging Technologies and Solutions for the Sustainable Climate Change Challenges)

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20 pages, 5813 KiB

Open AccessArticle

Experimental Study on Hydromechanical Behavior of an Artificial Rock Joint with Controlled Roughness

by Seungbeom Choi, Byungkyu Jeon, Sudeuk Lee and Seokwon Jeon

Sustainability 2019, 11(4), 1014; https://doi.org/10.3390/su11041014 - 15 Feb 2019

Cited by 14 | Viewed by 3140

Abstract

Rock mass contains various discontinuities, such as faults, joints, and bedding planes. Among them, a joint is one of the most frequently encountered discontinuities in rock engineering applications. Generally, a joint exerts great influence on the mechanical and hydraulic behavior of rock mass, [...] Read more.

Rock mass contains various discontinuities, such as faults, joints, and bedding planes. Among them, a joint is one of the most frequently encountered discontinuities in rock engineering applications. Generally, a joint exerts great influence on the mechanical and hydraulic behavior of rock mass, since it acts as a weak plane and as a fluid path in the rock mass. Therefore, an accurate understanding on joint characteristics is important in many projects. In-situ tests on joints are sometimes consumptive in terms of time and expenses so that the features are investigated by laboratory tests, providing fundamental properties for rock mass analyses. Although the behavior of a joint is affected by both mechanical and geometric conditions, the latter are often limited, since quantitative control on the conditions is quite complicated. In this study, artificial rock joints with various geometric conditions, i.e., joint roughness, were prepared in a quantitative manner and the hydromechanical characteristics were investigated by several laboratory experiments. Based on the results, a prediction model for hydraulic aperture was proposed in the form of

{(e_{h} / e_{m})}^{3} = \exp (- 0.0462 c) \times {(0.8864)}^{J R C}

, which was a function of the mechanical aperture, joint roughness, and contact area. Relatively good agreement between the experimental results and predicted value indicated that the model is capable of estimating the hydraulic aperture properly. Full article

(This article belongs to the Special Issue Emerging Technologies and Solutions for the Sustainable Climate Change Challenges)

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20 pages, 26926 KiB

Open AccessArticle

Analyzing the Stability of Underground Mines Using 3D Point Cloud Data and Discontinuum Numerical Analysis

by Seung-Joong Lee and Sung-Oong Choi

Sustainability 2019, 11(4), 945; https://doi.org/10.3390/su11040945 - 13 Feb 2019

Cited by 7 | Viewed by 4540

Abstract

This study describes a precise numerical analysis process by adopting the real image of mine openings obtained by light detection and ranging (LiDAR), which can produce a point cloud data by measuring the target surface numerically. The analysis target was a section of [...] Read more.

This study describes a precise numerical analysis process by adopting the real image of mine openings obtained by light detection and ranging (LiDAR), which can produce a point cloud data by measuring the target surface numerically. The analysis target was a section of an underground limestone mine, to which a hybrid room-and-pillar mining method that was developed to improve ore recovery was applied. It is important that the center axis and the volume of the vertical safety pillar in the lower parts match those in the upper parts. The 3D survey of the target section verified that the center axis of the vertical safety pillar in the lower parts had deviated in a north-westerly direction. In particular, the area of the lower part of the vertical safety pillar was approximately 34 m² lower than the designed cross-sectional area, which was 100 m². In order to analyze the stability of the vertical safety pillar, a discontinuum numerical analysis and safety factor analysis were conducted using 3D surveying results. The analysis verified that instability was caused by the joints distributed around the vertical safety pillar. In conclusion, investigation of the 3D survey and 3D numerical analysis techniques performed in this study are expected to provide higher reliability than the current techniques used for establishing whether mining plans require new mining methods or safety measures. Full article

(This article belongs to the Special Issue Emerging Technologies and Solutions for the Sustainable Climate Change Challenges)

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10 pages, 3355 KiB

Open AccessArticle

Semi-Dry Carbonation Process Using Fly Ash from Solid Refused Fuel Power Plant

by Jung Hyun Kim and Woo Teck Kwon

Sustainability 2019, 11(3), 908; https://doi.org/10.3390/su11030908 - 11 Feb 2019

Cited by 15 | Viewed by 3902

Abstract

The increasing CO₂ concentration in the Earth’s atmosphere, mainly caused by fossil fuel combustion, has led to concerns about global warming. Carbonation is a technique that can be used as a carbon capture and storage (CCS) technology for CO2 sequestration. In this [...] Read more.

The increasing CO₂ concentration in the Earth’s atmosphere, mainly caused by fossil fuel combustion, has led to concerns about global warming. Carbonation is a technique that can be used as a carbon capture and storage (CCS) technology for CO2 sequestration. In this study, the utilization of the fly ash from a solid refused fuel (SRF) power plant as a solid sorbent material for CO₂ capture via semi-dry carbonation reaction was evaluated as a simple process to reduce CO₂. The fly ash was exposed to accelerated carbonation conditions at a relative humidity of 25, 50, 75, and 100%, to investigate the effects of humidity on the carbonation kinetics of the fly ash. The reaction conditions such as moisture, concentration of CO₂, and reaction time can affect CO₂ capture performance of fly ash. Due to a short diffusion length of H₂CO₃ in water, the semi-dry process exhibits faster carbonation reaction than the wet process. Especially, the semi-dry process does not require a wastewater treatment plant because it uses a small amount of water. This study may have important implications, illustrating the possibility of replacing the wet process with the semi-dry process. Full article

(This article belongs to the Special Issue Emerging Technologies and Solutions for the Sustainable Climate Change Challenges)

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12 pages, 1596 KiB

Open AccessArticle

Process Design Characteristics of Syngas (CO/H₂) Separation Using Composite Membrane

by Jeeban Poudel, Ja Hyung Choi and Sea Cheon Oh

Sustainability 2019, 11(3), 703; https://doi.org/10.3390/su11030703 - 29 Jan 2019

Cited by 24 | Viewed by 6726

Abstract

The effectiveness of gas separation membranes and their application is continually growing owing to its simpler separation methods. In addition, their application is increasing for the separation of syngas (CO and H₂) which utilizes cryogenic temperature during separation. Polymers are widely [...] Read more.

The effectiveness of gas separation membranes and their application is continually growing owing to its simpler separation methods. In addition, their application is increasing for the separation of syngas (CO and H₂) which utilizes cryogenic temperature during separation. Polymers are widely used as membrane material for performing the separation of various gaseous mixtures due to their attractive perm-selective properties and high processability. This study, therefore, aims to investigate the process design characteristics of syngas separation utilizing polyamide composite membrane with polyimide support. Moreover, characteristics of CO/H₂ separation were investigated by varying inlet gas flow rates, stage cut, inlet gas pressures, and membrane module temperature. Beneficial impact in CO and H₂ purity were obtained on increasing the flow rate with no significant effect of increasing membrane module temperature and approximately 97% pure CO was obtained from the third stage of the multi-stage membrane system. Full article

(This article belongs to the Special Issue Emerging Technologies and Solutions for the Sustainable Climate Change Challenges)

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12 pages, 2830 KiB

Open AccessArticle

Development of a New Method for the Quantitative Generation of an Artificial Joint Specimen with Specific Geometric Properties

by Seungbeom Choi, Sudeuk Lee, Hoyoung Jeong and Seokwon Jeon

Sustainability 2019, 11(2), 373; https://doi.org/10.3390/su11020373 - 12 Jan 2019

Cited by 3 | Viewed by 3419

Abstract

A rock joint is a planar discontinuity that has significant influence on the mechanical and hydraulic characteristics of rock mass. Laboratory experiments are often conducted on a joint to investigate and provide fundamental information for rock mass analysis. Although joint roughness and mechanical [...] Read more.

A rock joint is a planar discontinuity that has significant influence on the mechanical and hydraulic characteristics of rock mass. Laboratory experiments are often conducted on a joint to investigate and provide fundamental information for rock mass analysis. Although joint roughness and mechanical aperture exert great effects on the experimental results, controlling them in quantitative manner is quite complicated and consumptive in terms of specimen preparation. A new and simple method for the quantitative generation of the joint specimen was proposed in this study. Based on random midpoint displacement method, a joint specimen with a void space inside was generated. Parametric studies for the roughness and mechanical aperture were carried out, and as a result, the two joint properties could be controlled by manipulating input parameters of random midpoint displacement method. In order to validate the proposed method, two joint specimens, which had different levels of roughness and aperture, were generated and printed. Surface coordinates of the specimens were obtained by a 3D laser scanner, and calculated to make a comparison between the target values and the estimated values. Results showed that the method was capable of generating joint specimens with satisfactory precision. Full article

(This article belongs to the Special Issue Emerging Technologies and Solutions for the Sustainable Climate Change Challenges)

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17 pages, 4367 KiB

Open AccessArticle

Utilization of CFBC Fly Ash as a Binder to Produce In-Furnace Desulfurization Sorbent

by Chulseoung Baek, Junhyung Seo, Moonkwan Choi, Jinsang Cho, Jiwhan Ahn and Kyehong Cho

Sustainability 2018, 10(12), 4854; https://doi.org/10.3390/su10124854 - 19 Dec 2018

Cited by 19 | Viewed by 4822

Abstract

Circulating fluidized bed combustion (CFBC) power generation technology is known to efficiently reduce the emission of air pollutants, such as SO₂ and NO₂, from coal combustion. however, CFBC coal ash contains high contents of free CaO, making it difficult to [...] Read more.

Circulating fluidized bed combustion (CFBC) power generation technology is known to efficiently reduce the emission of air pollutants, such as SO₂ and NO₂, from coal combustion. however, CFBC coal ash contains high contents of free CaO, making it difficult to recycle. This research has been conducted to find ways to use the self-hardening property of CFBC coal ash, one of its inherent characteristics. As part of these efforts, the present study intended to investigate the properties and desulfurization efficiency of Ca-based desulfurization sorbents using CFBC fly-ash as a binder. Limestone powder was mixed with CFBC fly-ash and Ca(OH)₂ to fabricate desulfurization sorbents, and it generated hydrate of cement, including portlandite, ettringite, and calcium silicate, etc. The compressive strength of the desulfurization absorbent prepared by CFBC fly ash and Ca(OH)₂ was 72–92% that of the desulfurized absorbent prepared by using general cement as a binder. These absorbents were then compared in terms of desulfurization efficiency using a high-temperature fluidized bed reactor. It was confirmed that the desulfurization absorbents fabricated using CFBC fly-ash as a binder achieved the best performance in terms of absorption time, which reflects the time taken for them to remove over 90% of high-concentration SO₂ gas, and the conversion ratio, which refers to the ratio of CaO turning into CaSO₄. Full article

(This article belongs to the Special Issue Emerging Technologies and Solutions for the Sustainable Climate Change Challenges)

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13 pages, 4118 KiB

Open AccessArticle

Stiffness and Cavity Test of Concrete Face Based on Non-Destructive Elastic Investigation

by Jinpyo Hong, Seokhoon Oh and Eunsang Im

Sustainability 2018, 10(12), 4389; https://doi.org/10.3390/su10124389 - 24 Nov 2018

Cited by 4 | Viewed by 4161

Abstract

A non-destructive testing (NDT) method was used in a concrete face rockfill dam (CFRD) to identify the condition of the concrete face slab and detect any existing cavities between the concrete face slab and the underlying support layer. The NDT for the concrete [...] Read more.

A non-destructive testing (NDT) method was used in a concrete face rockfill dam (CFRD) to identify the condition of the concrete face slab and detect any existing cavities between the concrete face slab and the underlying support layer. The NDT for the concrete face slab was conducted using the impulse response (IR) method and the electrical resistivity tomography (ERT) method with the application of non-destructive electrodes. Information regarding the dynamic stiffness and average mobility of the concrete was obtained based on the mobility-frequency of the IR method, and cavity detection under the plate structures was analyzed using the two-dimensional (2D) electrical resistivity section of the ERT method. The results of the IR method showed that zones with low dynamic stiffness and high average mobility were expected to be found in concrete of poor quality and in cavities beneath the concrete face slab. The results of the ERT method showed that zones with high resistivity were expected to be cavities between the concrete face slab and the underlying support layer. As a result, the tendency toward low dynamic stiffness, high average mobility, and high resistivity in both methods implies unstable concrete conditions and the possible occurrence of a cavity. The results of the two methods also showed a good correlation, and it was confirmed that the NDT method was reliable in terms of cavity estimation. Full article

(This article belongs to the Special Issue Emerging Technologies and Solutions for the Sustainable Climate Change Challenges)

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15 pages, 4272 KiB

Open AccessArticle

Optimizing the Design of a Vertical Ground Heat Exchanger: Measurement of the Thermal Properties of Bentonite-Based Grout and Numerical Analysis

by Daehoon Kim and Seokhoon Oh

Sustainability 2018, 10(8), 2664; https://doi.org/10.3390/su10082664 - 29 Jul 2018

Cited by 6 | Viewed by 3315

Abstract

We prepared bentonite-based grouts for use in the construction of vertical ground heat exchangers (GHEs) using various proportions of silica sand as an additive, and measured the thermal conductivity (TC) and specific heat capacity (SHC) of the grouts under saturated conditions. Furthermore, we [...] Read more.

We prepared bentonite-based grouts for use in the construction of vertical ground heat exchangers (GHEs) using various proportions of silica sand as an additive, and measured the thermal conductivity (TC) and specific heat capacity (SHC) of the grouts under saturated conditions. Furthermore, we performed numerical simulations using the measured thermal properties to investigate the effects of grout-SHCs, the length of the high-density polyethylene (HDPE) pipe, the velocity of the working fluid, and the operation time and off-time during intermittent operation on performance. Experimentally, the grout TCs and SHCs were in the ranges 0.728–1.127 W/(mK) and 2519–3743 J/(kgK), respectively. As the proportions of bentonite and silica sand increased, the TC rose and the SHC fell. Simulation showed that, during intermittent operation, not only a high grout TC but also a high SHC improved GHE performance. Also, during both continuous and intermittent operation, GHE performance improved as the working fluid velocity increased, and there was a critical working fluid velocity that greatly affected the performance of the vertical GHE, regardless of operation mode, high-density polyethylene (HDPE) pipe length, or grout thermal properties; this value was 0.3 m/s. Finally, during intermittent operation, depending on the operation time and off-time, critical periods were evident when the ground temperature had been almost completely restored and any beneficial effect of intermittent operation had almost disappeared. Full article

(This article belongs to the Special Issue Emerging Technologies and Solutions for the Sustainable Climate Change Challenges)

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Review

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34 pages, 7803 KiB

Open AccessReview

Recent Progress of Electrochemical Energy Devices: Metal Oxide–Carbon Nanocomposites as Materials for Next-Generation Chemical Storage for Renewable Energy

by Dohyeong Seok, Yohan Jeong, Kyoungho Han, Do Young Yoon and Hiesang Sohn

Sustainability 2019, 11(13), 3694; https://doi.org/10.3390/su11133694 - 5 Jul 2019

Cited by 46 | Viewed by 6928

Abstract

With the importance of sustainable energy, resources, and environmental issues, interest in metal oxides increased significantly during the past several years owing to their high theoretical capacity and promising use as electrode materials for electrochemical energy devices. However, the low electrical conductivity of [...] Read more.

With the importance of sustainable energy, resources, and environmental issues, interest in metal oxides increased significantly during the past several years owing to their high theoretical capacity and promising use as electrode materials for electrochemical energy devices. However, the low electrical conductivity of metal oxides and their structural instability during cycling can degrade the battery performance. To solve this problem, studies on carbon/metal-oxide composites were carried out. In this review, we comprehensively discuss the characteristics (chemical, physical, electrical, and structural properties) of such composites by categorizing the structure of carbon in different dimensions and discuss their application toward electrochemical energy devices. In particular, one-, two-, and three-dimensional (1D, 2D, and 3D) carbon bring about numerous advantages to a carbon/metal-oxide composite owing to the unique characteristics of each dimension. Full article

(This article belongs to the Special Issue Emerging Technologies and Solutions for the Sustainable Climate Change Challenges)

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21 pages, 743 KiB

Open AccessReview

Opportunities for Mineral Carbonation in Australia’s Mining Industry

by Mehdi Azadi, Mansour Edraki, Faezeh Farhang and Jiwhan Ahn

Sustainability 2019, 11(5), 1250; https://doi.org/10.3390/su11051250 - 27 Feb 2019

Cited by 26 | Viewed by 9803

Abstract

Carbon capture, utilisation and storage (CCUS) via mineral carbonation is an effective method for long-term storage of carbon dioxide and combating climate change. Implemented at a large-scale, it provides a viable solution to harvesting and storing the modern crisis of GHGs emissions. To [...] Read more.

Carbon capture, utilisation and storage (CCUS) via mineral carbonation is an effective method for long-term storage of carbon dioxide and combating climate change. Implemented at a large-scale, it provides a viable solution to harvesting and storing the modern crisis of GHGs emissions. To date, technological and economic barriers have inhibited broad-scale utilisation of mineral carbonation at industrial scales. This paper outlines the mineral carbonation process; discusses drivers and barriers of mineral carbonation deployment in Australian mining; and, finally, proposes a unique approach to commercially viable CCUS within the Australian mining industry by integrating mine waste management with mine site rehabilitation, and leveraging relationships with local coal-fired power station. This paper discusses using alkaline mine and coal-fired power station waste (fly ash, red mud, and ultramafic mine tailings, i.e., nickel, diamond, PGE (platinum group elements), and legacy asbestos mine tailings) as the feedstock for CCUS to produce environmentally benign materials, which can be used in mine reclamation. Geographical proximity of mining operations, mining waste storage facilities and coal-fired power stations in Australia are identified; and possible synergies between them are discussed. This paper demonstrates that large-scale alkaline waste production and mine site reclamation can become integrated to mechanise CCUS. Furthermore, financial liabilities associated with such waste management and site reclamation could overcome many of the current economic setbacks of retrofitting CCUS in the mining industry. An improved approach to commercially viable climate change mitigation strategies available to the mining industry is reviewed in this paper. Full article

(This article belongs to the Special Issue Emerging Technologies and Solutions for the Sustainable Climate Change Challenges)

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18 pages, 636 KiB

Open AccessReview

Recent Progress in Green Cement Technology Utilizing Low-Carbon Emission Fuels and Raw Materials: A Review

by Ali Naqi and Jeong Gook Jang

Sustainability 2019, 11(2), 537; https://doi.org/10.3390/su11020537 - 21 Jan 2019

Cited by 257 | Viewed by 27628

Abstract

The cement industry is facing numerous challenges in the 21st century due to depleting natural fuel resources, shortage of raw materials, exponentially increasing cement demand and climate linked environmental concerns. Every tonne of ordinary Portland cement (OPC) produced releases an equivalent amount of [...] Read more.

The cement industry is facing numerous challenges in the 21st century due to depleting natural fuel resources, shortage of raw materials, exponentially increasing cement demand and climate linked environmental concerns. Every tonne of ordinary Portland cement (OPC) produced releases an equivalent amount of carbon dioxide to the atmosphere. In this regard, cement manufactured from locally available minerals and industrial wastes that can be blended with OPC as substitute, or full replacement with novel clinkers to reduce the energy requirements is strongly desirable. Reduction in energy consumption and carbon emissions during cement manufacturing can be achieved by introducing alternative cements. The potential of alternative cements as a replacement of conventional OPC can only be fully realized through detailed investigation of binder properties with modern technologies. Seven prominent alternative cement types are considered in this study and their current position compared to OPC has been discussed. The study provides a comprehensive analysis of options for future cements, and an up-to-date summary of the different alternative fuels and binders that can be used in cement production to mitigate carbon dioxide emissions. In addition, the practicalities and benefits of producing the low-cost materials to meet the increasing cement demand are discussed. Full article

(This article belongs to the Special Issue Emerging Technologies and Solutions for the Sustainable Climate Change Challenges)

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Other

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13 pages, 235 KiB

Open AccessCase Report

A Case Study of Environmental Policies and Guidelines for the Use of Coal Ash as Mine Reclamation Filler: Relevance for Needed South Korean Policy Updates

by Hanna Cho, Sang-woo Ji, Hee-young Shin and Hwanju Jo

Sustainability 2019, 11(13), 3629; https://doi.org/10.3390/su11133629 - 2 Jul 2019

Cited by 13 | Viewed by 7474

Abstract

The South Korean government is pursuing a national project to use the complex carbonates found in coal ash to capture CO₂ and promote coal ash recycling. One possible approach is the use of coal ash as fill material in mine reclamation, but [...] Read more.

The South Korean government is pursuing a national project to use the complex carbonates found in coal ash to capture CO₂ and promote coal ash recycling. One possible approach is the use of coal ash as fill material in mine reclamation, but environmental concerns have so far blocked the implementation of this procedure, and no relevant regulations or guidelines exist. In this study, we review international approaches to the environmental management of coal ash recycling and consider how the lessons learned can be applied to South Korea. Each studied country was proactively using coal ash for beneficial uses under locally suitable conditions. The United States, European Union, United Kingdom, Australia, and Japan are all putting coal ash to beneficial use following thorough analyses of the environmental impact based on several considerations, including bulk concentration, coal ash leachate concentration, field inspections, and water quality monitoring. Our findings can contribute to the development of proper regulations and policies to encourage the use of recycled coal ash in South Korea as an approach to managing carbon emissions and climate changes. There are currently no relevant regulations in South Korea, so we consider the adoption of the strictest standards at each stage of the other cases at the time of introduction. Based on our findings, detailed and appropriate management guidelines can be developed in the future. Establishing management plans for complex carbonates, verifying their environmental stability, and using them as fill material will provide clear benefits for South Korea in the future. Full article

(This article belongs to the Special Issue Emerging Technologies and Solutions for the Sustainable Climate Change Challenges)

11 pages, 2464 KiB

Open AccessProject Report

Strategy of Developing Innovative Technology for Sustainable Cities: The Case of the National Strategic Project on Carbon Mineralization in the Republic of Korea

by Jongyeol Lee, Changsun Jang, Kyung Nam Shin and Ji Whan Ahn

Sustainability 2019, 11(13), 3613; https://doi.org/10.3390/su11133613 - 1 Jul 2019

Cited by 2 | Viewed by 3090

Abstract

Technology cooperation, including technology transfer, development of projects, and establishment of international networks, is an important instrument for attaining greenhouse gas mitigation and the sustainable development of a global society. In this context, carbon mineralization technology has received attention because of its high [...] Read more.

Technology cooperation, including technology transfer, development of projects, and establishment of international networks, is an important instrument for attaining greenhouse gas mitigation and the sustainable development of a global society. In this context, carbon mineralization technology has received attention because of its high potential for carbon sequestration, environmental conservation, and economic market value. This project report introduces a national top-down approach for developing and implementing international technology cooperation in the Republic of Korea, focusing on carbon mineralization. The Ministry of Science and Information and Communication Technology (MSIT) leads international technology cooperation, identifies prominent climate technologies, and addresses scientific agendas to presidential meetings. The inter-ministerial bodies established the climate technology roadmap and masterplan for a climate change response. With the support of these inter-ministerial efforts, a National Strategic Project on carbon mineralization was developed by a presidential-level decision as a top-down approach. Furthermore, the demonstration of this technology was emphasized to enhance the possibility of success in commercialization. This project also includes demonstration of a pilot, sequestering 6000 tons of CO₂ and manufacturing 30,000 tons of carbonate. This successive and holistic approach, comprising of a range of hierarchical levels of government, is recommended for deriving a high impact on global society of prominent climate technology. Full article

(This article belongs to the Special Issue Emerging Technologies and Solutions for the Sustainable Climate Change Challenges)

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10 pages, 1502 KiB

Open AccessTechnical Note

A Brief Note on the Heap Leaching Technologies for the Recovery of Valuable Metals

by Thriveni Thenepalli, Ramakrishna Chilakala, Lulit Habte, Lai Quang Tuan and Chun Sik Kim

Sustainability 2019, 11(12), 3347; https://doi.org/10.3390/su11123347 - 17 Jun 2019

Cited by 30 | Viewed by 13791

Abstract

Heap leaching is a low-cost technology used in industrial mining to recover precious metals such as gold and uranium, along with several other highly sought after metals like copper, from their primary resources (ores and minerals). For many decades, there has been a [...] Read more.

Heap leaching is a low-cost technology used in industrial mining to recover precious metals such as gold and uranium, along with several other highly sought after metals like copper, from their primary resources (ores and minerals). For many decades, there has been a growing demand for heap leaching due to its environmental benefits. Heap leaching provides mining operators with a benign, effective and economical solution for the environment and produces only minor emissions from furnaces. The cost of the heap leaching process is low, making this process an attractive option from a financial standpoint. Here, we shall present a brief review of the heap leaching process when applied to the extraction of different metals from primary resources (ores and minerals). This paper presents a roadmap to satisfy future national demands for rare earth elements (REEs). This heap leaching process is applicable for the recovery of REEs from secondary resources such as mining and coal residues. Heap leaching plays a significant role in the recovery of critical elements which are used in clean and green energy applications. In the mining sector, heap leaching is a distinguished method for the recovery of valuable/beneficial metals from low-quality ore. In the present study, we shall report briefly on the heap leaching technologies for valuable metal recovery with economic advantages. Full article

(This article belongs to the Special Issue Emerging Technologies and Solutions for the Sustainable Climate Change Challenges)

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