박상우 Sang-woo Park , 박소이 So-yee Park

DOI:10.9786/kswm.2021.38.3.185

Abstract

In December 2020, the Korean government established a plastic waste circulation policy to realize sustainable development and carbon neutrality. This policy aims to reduce the amount of plastic wastes by 20% and achieve a plastic recycling rate of 70% by 2025. The government also presented implementation measures to achieve these goals. However, the policy lacks comprehensiveness, and a statement on compliance with the basic principles of plastic circulation is required. Furthermore, local governments need to improve public awareness and establish quality certifications and standards to improve recycling. To achieve the expected recycling goal, a system that facilitates supply and demand of recycled plastic must be developed. An additional measure to promote the use of alternative materials (bioplastics) for products that require plastic usage must be devised. Plastic materials that are repeatedly recycled have degraded quality. Therefore, a technology to recycle the raw materials through chemical recycling should be developed. Further, these alternative materials or chemical recycling must meet sustainability standards. Plastic recycling and recirculation are expected to be implemented effectively if the measures proposed herein are adopted to supplement the governmental policy.

Key Words

Waste Policy, Plastic Circulation, SDGs, Carbon Neutrality

박상하 Sangha Park , 김욱 Wook Kim , 김명선 Myeongsun Kim , 김연정 Yeonjeong Kim , 정석희 Sokhee P. Jung

DOI:10.9786/kswm.2021.38.3.200

Abstract

Solar energy is attracting attention as a major source of renewable energy. Solar power generation has grown rapidly since the 2000s. Owing to the recent indications of a rapid increase in solar power generation wastes, it is imperative that countermeasures be implemented. Accordingly, the Korean government introduced an extended producer responsibility (EPR) system to resolve the problem of solar panel disposal and recycling; however, there are some requirements that do not reflect the domestic conditions. This paper discusses the EPR system expected to be introduced in the future and the directions of improvement of domestic laws in the treatment of solar panel wastes. First, necessary measures must be considered to prevent leakage of lead and harmful substances in landfills during waste panel treatment. Currently, most of the solar panels that are not exported are being disposed through landfills. Lead and arsenic were detected in these wastes by dissolution analysis of the solar panel samples manufactured in Korea, which shows their capacity for environmental damage. Therefore, it is necessary to improve the existing treatment methods and to prepare countermeasures against illegal disposal of solar panel wastes. Second, it is necessary to take action against enterprises responsible for demolition, transportation, and disposal of such wastes. Solar power generation facilities are generally installed by legally specified contractors, but in the case of dismantling and transporting waste panels, there are no legal designations for relevant personnel. Third, it is necessary to establish a recycling system for these wastes. Domestic solar panels are generally exported overseas, but there is uncertainty about export to overseas markets, so the domestic recycling market should be revitalized. In Korea, a recycling system is not established, and no technology is available for recycling. Therefore, research on recycling technologies and establishment of a rational system are necessary. Finally, it is necessary to extend the lifespan, improve efficiency, and increase the possibility of reusing solar panels by improving their technology. Currently, the installed photovoltaic power generation facilities are vulnerable to recycling and reuse and have short lifespans. Therefore, it is necessary to increase the lifespans of solar panels through technological developments, efficiency improvements, and focus on future reuse of the panels.

Key Words

Photovoltaics, Solar panel, Solar panel waste, Extended producer responsibility (EPR)

박상우 Sang-woo Park

DOI:10.9786/kswm.2021.38.3.214

Abstract

The South Korean government established plastic generation reduction and recycling measures in December 2020 to reduce plastic waste generation by 20% and achieve a recycling rate of 70% by 2025. To attain these goals, detailed implementation plans are required; however, the enabling system should be preceded. This study investigated waste-related legal systems focusing on the enactment and revision contents of the Plastic Act of the EU and Japan to draw implications for South Korea. The research results show that the EU and Japan have implemented operations related to packaging and plastic wastes, whereas South Korea does not have specialized laws in this regard. Although the EU and Japan have already enforced the packaging waste act, the plastic act has been additionally implemented to counteract international trends concerning sustainable development and carbon neutrality and lead the global market and policies associated with plastic. Such policies are also required in South Korea due to long-standing plastic-related problems; the current fragmentary measures implemented by the government are also insufficient for addressing these issues. Therefore, necessary laws must be enforced to manage plastic disposal and reuse in South Korea professionally.

Key Words

Waste Policy, Plastic Circulation, SDGs, Plastic Act

강경모 Kyung-mo Kang , 형원길 Won-gil Hyung

DOI:10.9786/kswm.2021.38.3.225

Abstract

According to the greenhouse gas reduction policy, the government promotes power generation using a circulating fluidized bed boiler that provides excellent conversion efficiency. However, this method can cause a severe increase in industrial waste. Fly ash, a byproduct of a circulating fluidized bed boiler, can be used as a solidifying material for cement, while bottom ash cannot be recycled and is completely discarded. In this study, alkali-activated slag (AAS) mortar was fabricated using the bottom ash of a circulating fluidized bed boiler and aqueous NaOH solution as the stimulants. The physical properties and durability were evaluated. The possibility of using this substance as a cement substitute for the bottom ash of the circulation layer was also confirmed.

Key Words

Circulating fluidized bed combustion bottom ash, Granulated blast furnace slag, Fly ash

오승진 Seungjin Oh , 오민아 Minah Oh , 이재영 Jai-young Lee

DOI:10.9786/kswm.2021.38.3.231

Abstract

Currently, owing to the presence of large amounts of minerals such as pyrite (FeS₂) and marcasite (FeS) in minerals, acid mine drainage (AMD) is formed in Korea's coal mines. Currently, most of the sludge from processing AMD is reclaimed or used as secondary materials in cement. Road pavements until now were aimed at preventing water infiltration and not reducing the support of the road were thus far considered the best measures to enhance durability; therefore, in most cases, cement concrete or asphalt pavements have been applied. However, these pavements pose various problems, such as the inability of microorganisms to survive underground and soil desertification. One of the countermeasures proposed to remedy these problems is soil-cement pavement. In this research, environmentally safe mine sludge, which has low organic matter and has a soil-like yellowish-red color, is proposed as an admixture of the soil-cement pavement. Further, research was conducted to evaluate the appropriate compressive strength, durability, and environmental threats to using synthetic fibers as countermeasures to solve fissures owing to lack of long-term durability and winter-time freezing/thawing. Thus, the most suitable mixture was determined as 5 wt% of exhausted mine sludge and 0.5 wt% of synthetic fibers of length 20 mm, which satisfies the domestic soil-cement pavement standard requirements of compressive strength of 30 kg/cm² and above and weight loss of 14% and lower after freezing/thawing tests.

Key Words

AMD(Acid Mine Drainage), Soil-cement pavement, Mine sludge, Synthetic fiber, Freezing/Thawing, Lysimeter

김태훈 Tae Hun Kim , 이제욱 Jea Uk Lee , 홍진용 Jin-yong Hong

DOI:10.9786/kswm.2021.38.3.239

Abstract

Plastic waste has become one of the most pressing environmental issues, necessitating the development of innovative recycling techniques. As such, the recycling of plastic waste for use as a construction material is a promising solution to plastic pollution. This research aims to investigate the feasibility of replacing natural aggregates in concrete with recycled plastic film. Quantitative and qualitative analysis is conducted to determine the composition of polymer waste, which is predominantly composed of polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), and polyethylene terephthalate (PET). In addition, thermal analysis is employed to investigate the thermal stability of the plastic waste. An aggregate based on recycled plastic film with a cylindrical shape (diameter < 20 mm) is produced using conventional polymer extrusion processes and its physical properties examined.

Key Words

Plastic waste, Plastic film, Recycling, Aggregate, Concrete

강신영 Shin Young Kang , 김태환 Taehwan Kim , 기동원 Dongwon Ki

DOI:10.9786/kswm.2021.38.3.246

Abstract

Around 24 tons of incinerated sewage sludge ash (I-SSA) was generated daily at wastewater treatment facilities within S-city, South Korea in 2019. The generated I-SSA has been employed in solidified cement by paying for processing fees. In this study, we extended the usage of I-SSA as a value-added material for traditional ceramic applications. To determine whether the I-SSA had the necessary stability and suitability for use in ceramic applications, its physical and chemical characteristics, including particle size, moisture and organic contents, and chemical compositions were monitored regularly over a six-month period. We confirmed these characteristics were stable, with over 75% of the ash particles distributed between 10 and 200 μm with a mean particle size of 38.2(±12.4) μm. The organic and moisture contents were 1.2(±0.42)% and 0.2(±0.04)%, respectively, and SiO₂(29.6±2.1%), Al₂O₃(15.0±0.5%), Fe₂O₃(23.2±0.8%), and P₂O₅(17.2±1.4%) were the major oxide compounds. Based on this stability, the possibility of the use of I-SSA as a ceramic clay and pigment was investigated. We evaluated sintering temperatures of up to 1,245℃ and glazing conditions for clay specimens with I-SSA mixing ratios between 9 and 33% (w/w). We also tested several options for pigment applications, such as I-SSA grinding, iron separation, and additives, to determine whether the generated I-SSA pigments enhanced the layering and color expression. Overall, this research highlights the potential use of I-SSA as a ceramic clay and pigment, though further research is required for commercialization.

Key Words

Clay, Pigment, Porcelain, Wastewater sludge, Recycle

이진주 Jin Ju Lee , 조우리 Woori Cho , 장진만 Jin-man Chang , 이재영 Jai-young Lee

DOI:10.9786/kswm.2021.38.3.257

Abstract

In this study, the feasibility of recycling coal gasification slag and flue gas desulfurization gypsum as a stabilizer for lead-contaminated soil is evaluated. The study is divided into three stages. First, the heavy metal content and leachability of the coal gasification slag and flue gas desulfurization gypsum were assessed to confirm their environmental safety as a recycling material. Second, the stabilization of lead-contaminated soil was evaluated via dissolution testing by mixing either slag or gypsum with artificially contaminated soil at levels of 1%, 4%, 7%, and 10%. Finally, XRD and SEMEDS analysis was conducted to identify the stabilization mechanisms using the soil and stabilizer mixture cured for 28 days. It was found that the slag and gypsum had no heavy metal content or elution, meaning they were suitable for recycling in accordance with Korean waste recycling criteria. When the slag and gypsum were mixed independently with the contaminated soil, it was found that an application ratio of 7% had the highest stabilization efficiency, thus this was selected as the optimal mixing ratio. XRD analysis of soil samples stabilized for 28 days with the addition of 7% slag and gypsum, peaks for ettringite (3CaO·Al₂O₃·3CaSO₄·32H₂O), calcite (CaCO₃), and portlandite (Ca(OH)₂) were observed. Through SEM-EDS analysis, acicular ettringite with a structure suitable for adsorbing or solid solution of heavy metals was identified. Therefore, in this study, the potential of coal gasification slag and flue gas desulfurization gypsum as stabilizers in lead-contaminated soil was confirmed, representing an economical and environmentally friendly means of recycling by-products from power plants.

Key Words

Heavy metals stabilization, Artificially contaminated soil, Coal gasification slag, Flue gas desulfurization gypsum

이소라 Sora Yi , 이진혁 Jin-heuck Lee , 주문솔 Munsol Ju

DOI:10.9786/kswm.2021.38.3.266

Abstract

In this study, the resource efficiency management index for the life cycle stages in resource circulation from input to disposal was calculated based on actual industrial data and compared between sectors to derive implications. Based on the current national resource management index, auxiliary (or indicators) and monitoring statistical indicators were established based on an analysis of overseas cases, and waste management priority indicators were developed for the first time; these were calculated using actual data from 18 industries and 2,968 companies. The resource efficiency management index was higher than other industries such as the manufacturing of food products, nonmetal mineral product manufacturing, and primary metal manufacturing, as well as waste management priority. On the other hand, the lowest priority for waste management was coke, coal, and oil-refined product manufacturing, the waste from which is mainly disposed of via incineration or landfills. Based on these results, it is expected that it will be used as the foundation for future research, such as developing supplementary indices for effective resource efficiency management at each stage and for the comparative verification of characteristic indicators by industry.

Key Words

Resource efficiency management index, Material flow analysis, Resource circulation, Sustainable development

윤상혁 Sang-hyuck Yoon , 이세현 Sea-hyun Lee

DOI:10.9786/kswm.2021.38.3.273

Abstract

Depending on the ratio of recycled aggregate used, the strength was similar to that of general concrete. There was no decrease in strength, and it is believed that achieving the target strength is possible. When the ratio of the recycled coarse aggregate is 25% of the total amount of aggregate (50% of the total coarse aggregate) or lower, slump is not expected to occur. It is believed that the higher the design standard strength, the greater the amount of powder. In addition, the management of slump, unit quantity, and the performance system is necessary.

Key Words

Recycled Aggregate Concrete, Recycled coarse aggregate, Specified Concrete Strength