International efforts are being made to reduce environmental pollution caused by microplastics (MPs). Microplastics are released into the environment through sewage treatment sludge, and the use of sludge as a soil improvement agent is increasing rapidly, emphasising the importance of controlling microplastics in sewage treatment facilities. The release of microplastics into the environment is an increasingly significant concern, with sources including sewage treatment sludge. This study focuses on the analysis of microplastics in sewage sludge using optical (Fourier-transform infrared spectroscopy, FTIR) and thermal (Thermo Extraction Desorption–Gas Chromatograph–Mass Spectroscopy, TED-GC-MS) processing-based analytical equipment. The average amount of MPs in the sewage sludge analysed using FTIR was 228.5 microplastics/g of sludge (MPs/g), primarily of the polypropylene type. Approximately 75% of the MPs were 0.1 mm in size or smaller. However, the average amount of MPs in the sewage sludge determined using TED-GC-MS was 95.79 µg-MPs/g. For the systematic management of microplastics, it is important to estimate the amount of microplastics generated by sewage treatment plants. Therefore, a microplastic generation calculation formula was proposed and used to estimate the potential microplastic generation in sewage treatment plants. The total amount of MPs generated from sewage treatment plants in South Korea, calculated using the equation, was approximately 364 ton/yr; we further divided the total amount by administrative regions. The findings of this study can be applied to assess global trends in MP research.

This study involves a material flow analysis (MFA) of single-use plastics (SUPs) and packaging materials in the Republic of Korea, focusing on their short lifespans and significant contributions to plastic waste. Based on the MFA results, recommended policies for managing packaging materials and SUPs were proposed. In 2021, 6.340 Mt of synthetic resin were produced, with 39.7% (2.518 Mt) utilized for packaging materials and SUPs. The per capita consumption of these materials was 48.7 kg/year, surpassing global averages. The separate collection rate was 54.6%, with films (26.2%) and manufacturing facilities (10.6%) exhibiting the lowest rates. The overall recycling rate was 52.7%, and 981 t of recycled waste was directly placed in soil. The reliability of the MFA results was estimated to be 83.1%, which is an improvement compared to previous studies. Recommendations include reducing plastic use, expanding recycling infrastructure, raising public awareness, and implementing stricter regulations to control soil contamination.

The increasing adoption of electric vehicles (EVs) has highlighted the need for sustainable lithium-ion battery (LIB) management. This study presents a material flow analysis (MFA) of EV LIBs in the Republic of Korea (RoK), using both a mass-based MFA and a substance flow analysis (SFA). The analysis defines 33 systems and 170 flows across the manufacturing, consumption, discharge and collection, and treatment stages, based on national statistics and data from 11 commercial facilities. In 2022, about 72,446 t of EV LIBs entered the consumption stage through new vehicle sales and battery replacements. However, domestic recovery was limited, as approximately 76.5% of used EVs were exported, reducing the volume of batteries available for recycling. The SFA, focusing on nickel (Ni), cobalt (Co), manganese (Mn), and lithium (Li), showed recovery rates of 69% for Ni, 80% for Co, 1% for Mn, and 80% for Li. Mn was not recovered because its low market price made the recovery process economically impractical. Additional losses occurred from the incineration of separators containing black mass and lithium discharged through wastewater. These findings offer data-driven insights to improve recovery efficiency, guide policy, and enhance the circularity of EV LIB management in the RoK.

Steel slag is a major waste product of the steelmaking process. Owing to its chemical composition, it can be reused as a raw material in steel mills and a substitute for aggregates in engineering. In 2016, the Republic of Korea (ROK) introduced the Environmental Assessment of Recycling (EAoR) system for the safe recycling of waste products, which divides recycling methods into either matrix contact or non-matrix contact types; numerous challenges have been raised regarding weaknesses in the matrix contact type. Consequently, the standards for matrix contact recycling of slag (inorganic waste) have become stricter, and the recycling applications have also become more diverse. This study investigates the treatment, recycling, and management of steel slag in the ROK. In 2019, the annual generation of slag in the ROK exceeded 23.03 million tons with a recycling rate of 98.3%, showing a high level of recycling, compared with that of the United States (81.3%), the European Union (87%), Australia (100%), and Japan (98.4%). However, a comparative analysis of overseas slag recycling systems and recycling standards found that the recycling applications and recycling standards of slag in the ROK were somewhat stricter than those in the European Union and the United States. Furthermore, an investigation comparing the applications of recycled slag in different countries showed that the ROK could expand its applications of recycled slag. The limitation of the EAoR system was that the excluding products, environmentally certified from Korean Standards in the EAoR regulations, might be attributing to environmental pollution. The leaching and toxicity tests for recycling application of steelmaking slag were evaluated and showed no significant negative effects. Lastly, there is an urgent need for environmental standards relating to slag that can be recycled as a product, and the recycling and environmental label certification for products should also be amended. In addition, the applications of steelmaking slag were necessary to partially extend according to the hazardous characteristics.

The quantity of waste from end-of-life vehicles is increasing with an increase in the number of scrapped internal combustion engine vehicles owing to international trends such as carbon neutrality and particulate matter reduction. The recycling rate must be ≥95%; however, the average recycling rate remains at approximately 89%. Therefore, the improvement of the recycling of automobile shredder residues (ASR) is gaining attention. In this study, four types of products (interlocking, clay, and lightweight swelled ceramic (LSC) bricks, and asphalt paving aggregate (APA)) were manufactured using ASR melting slag (ASRMS). Environmental performance, quality standards, and technology were evaluated to assess the recyclability of the manufactured bricks. The interlocking brick substituted melting slag for sand and stone powder as an aggregate. As melting slag content increased, absorption decreased and bending strength increased. Clay brick was manufactured by replacing kaolin and feldspar with melting slag that substituted for 20%. The quality of clay bricks mixed with over 15% melting slag was not better than standard. Asphalt paving aggregate was used to investigate the optimum condition of slag content in mixed asphalt; the mixture ratio showed that 61% broken stone of 13 mm, 6% screenings, 10% melting slag, 15% sand and 8% filler was most effective. A lightweight swelled ceramic brick was manufactured by using melting slag, front glass, and so on. Specific gravity and compressive strength ranged from 0.38 to 0.51 and from 339.7 to 373.6 N/cm². ASRMS exhibited an environmental performance suitable for recycling and the manufactured bricks satisfied the quality standards. The recyclability of ASR was also assessed in terms of waste usage, conformance to quality standards, market size, and demand prediction. APA showed the best results followed by interlocking, clay, and LSC bricks.

During the coronavirus disease 2019 (COVID-19) pandemic, 24,289 tons of infectious waste was generated in 2021 in Korea, a 320% increase compared to that generated in 2020 (5788 tons). The disposal of other healthcare waste has been delayed because COVID-19 infectious waste must be disposed of first, leading to long-term concerns related to the lack of healthcare waste disposal capacity. To solve this problem, this study investigated healthcare waste classification systems in Korea and overseas. We analyzed the current state of healthcare waste in Korea and compared the treatment methods and healthcare waste treatment systems by country. The results showed that Korea has a strict healthcare waste management system compared to other countries, which relies on dedicated incinerators and transport. It is difficult to expand incinerators exclusively for healthcare waste due to site selection issues because they incinerate infectious waste. Therefore, to solve the healthcare waste disposal problem, Korea should improve its management system to reduce treatment amounts. This study suggests that general healthcare waste that is considered less infectious should be excluded from healthcare waste-exclusive treatment and that sterilization/grinding as an intermediate treatment method should be allowed.