임선미 Seonmi Lim , 심지연 Jiyeon Sim , 이수호 Sooho Lee , 박혜완 Hye-wan Park , 손유 Yoo Son , 박충화 Chunghwa Park , 김영재 Youngjae Kim

DOI:10.9786/kswm.2026.43.3.131

Abstract

Forestry by-products generated during arboretum management, such as leaf litter and weeds, possess distinct physicochemical properties characterized by higher carbon and lower nitrogen contents compared to conventional agricultural residues. This study investigated the composting characteristics of hardwood leaves (carbon source) and mixed weeds (nitrogen source) collected from the Korea National Arboretum(KNA) by establishing three experimental treatments based on volumetric mixing ratios (v/ v): C3:N1, C1:N1, and C1:N3. Key indicators, including temperature, pH, electrical conductivity (EC), carbon-to-nitrogen ratio (C/N), and organic matter-to-nitrogen ratio (OM/N), were monitored to evaluate maturity and stability. While all treatments reached the "mature" stage according to CoMMe-100, significant differences in chemical stability and practical applicability were observed among the ratios. The C3:N1 treatment showed limited nitrogen-use efficiency and delayed maturation, with its OM/ N ratio (46.7) exceeding the standard guideline. Conversely, the C1:N3 treatment exhibited process instability, characterized by a sharp increase in EC (17.6 dS/m), persistent odor, and material clumping. In contrast, the C1:N1 treatment demonstrated the most balanced physicochemical properties, satisfying all regulatory standards for C/N and OM/N while maintaining process stability. These findings highlight the necessity of optimizing mixing ratios to reflect the unique composition of forest waste and propose C1:N1 as a practical and effective composting condition for arboretum and forest management practices.

Key Words

Forest by-products, Composting, Mixing ratio, Physico-chemical properties, Korea national arboretum

박명선 Myoung-sun Park , 이규림 Gyu-lim Lee , 민달기 Dal-ki Min , 황용우 Yong-woo Hwang

DOI:10.9786/kswm.2026.43.3.141

Abstract

Since its implementation in 1995, South Korea’s Volume-Based Waste Fee (VBWF) system has operated successfully for approximately 30 years. However, the system is currently experiencing declining economic efficiency due to the growing financial burden of free collection of recyclable waste. This study analyzes waste generation trends and VBWF statistical data in Seoul to propose measures for enhancing the financial selfsufficiency of the Municipal Solid Waste (MSW) management budget. Recent data indicate that the increase in non-household MSW has contributed to the overall growth in waste generation in Seoul. In particular, the significant increase in recyclable waste has adversely affected fiscal stability. The revenue-to-expenditure ratio for freely collected recyclables is only 0.075, indicating significant financial imbalance. As the volume of recyclables continue to increase, the sustainability of the MSW management budget further declines. To restore economic viability while maintaining the current VBWF framework, this study proposes adjustments to the prices of standard waste bags and food waste bags. The analysis shows that increasing bag prices by 20%, 40%, 60%, 80%, and 100% would improve financial self-sufficiency to 45%, 53%, 61%, 68%, and 75%, respectively. In accordance with the pay-as-you-throw principle, achieving fiscal sustainability requires the gradual transfer of the full cost burden to residents.

Key Words

Waste management, Volume-based waste fee system, VBWF, Municipal solid waste, MSW, Seoul city, Financial self-sufficiency

진예은 Yeeun Jin , 조수하 Suha Cho , 이상민 Sangmin Lee

DOI:10.9786/kswm.2026.43.3.149

Abstract

This study develops a continuous accelerated mineral carbonation process by integrating desalination brine electrolysis with coal fly ash (CFA) leaching, situated within a carbon capture, utilization, and storage (CCUS) framework to support carbon neutrality. Conventional mineral carbonation research has frequently been constrained by the absence of an integrated strategy capable of simultaneously regulating alkalinity and providing a consistent supply of calcium ions during continuous operation. To address these limitations, desalination brine electrolysis was coupled with the acid leaching of CFA to modulate pH levels and ensure a robust Ca²⁺ supply for carbonation. In the proposed system, the alkaline catholyte generated via electrolysis facilitates efficient CO₂ absorption and subsequent carbonate precipitation, while CFA serves as a cost-effective, abundant calcium source. Batch experiments demonstrated that a leachate-to-catholyte ratio of 6:4 achieved a CO₂ removal efficiency of 30.2%. In the continuous-loop system, maintaining alkalinity with 8.5 g/L of NaOH resulted in a significant breakthrough, achieving a CO₂ removal efficiency of 85.0% and a total CO₂ removal of 354.3 mmol. By substituting expensive chemical reagents, such as NaOH, with Ca²⁺-rich leachate derived from industrial byproducts, the process enhances both economic feasibility and operational stability. Furthermore, the synergistic utilization of desalination brine and CFA minimizes reliance on external alkaline and calcium ion inputs and provides a sustainable pathway for the valorization of marine resources and industrial waste.

Key Words

Carbon neutrality, CCUS, Coal fly ash, Mineral carbonation, Water electrolysis

곽인호 Inho Kwak , 이병현 Byeonghyeon Lee , 박종규 Jongkyu Park , 김훈규 Hoongyu Kim

DOI:10.9786/kswm.2026.43.3.162

Abstract

The steel industry is a major greenhouse gas (GHG)-emitting sector and contributes substantially to industrial carbon emissions. In response to carbon neutrality targets, many steel producers are shifting from blast furnace (BF) routes to electric arc furnace (EAF) processes, and the proportion of EAF production is expected to increase steadily. As EAF production expands, the generation of electric arc furnace dust (EAFD), a zinc-rich by-product, is also anticipated to rise. Recycling EAFD through zinc recovery has therefore emerged as an important strategy for resource circulation. A quantitative evaluation of the environmental performance of such recycling processes is essential, and life cycle assessment (LCA) is widely used for this purpose. However, even when identical recovery systems are assessed, the quantified environmental impacts may differ depending on the applied methodological frameworks and databases. This study utilized primary operational data obtained from a domestic zinc recovery facility and applied three assessment schemes: ISO 14040/44 using EF v3.1, the Korean Environmental Product Declaration (EPD) program, and the UK Carbon Trust certification. The objective was to estimate the carbon footprint of zinc oxide produced via a rotary hearth furnace (RHF) process. The functional unit was defined as 1 kg of zinc oxide, and the system boundary was established as cradle-to-gate. The calculated results were compared and analyzed. The carbon footprint values were 1.79, 2.11, and 2.24 kgCO₂-eq/kg under the Korean EPD, ISO 14040/44, and Carbon Trust methodologies, respectively. These differences were primarily attributed to variations in electricity emission factors, atmospheric emission factors, and the use of different databases, including the KEITI database and the Ecoinvent database. The results indicate that, even within an ISO 14040/44-based assessment framework, certification methodologies can lead to variations in quantified carbon footprint results. Nevertheless, the major emission contribution patterns and overall emission characteristics were consistent across the applied methodologies. This study demonstrates that although methodological selection affects numerical outcomes, the fundamental emission structure of the EAFD recycling process remains comparable across certification schemes.

Key Words

Electric arc furnace dust, Life cycle assessment, Carbon footprint, Certification methodology, Emission factors

정성경 Seong-kyeong Jeong , 엄남일 Namil Um , 박춘화 Choon Hwa Park , 박영권 Young-kwon Park

DOI:10.9786/kswm.2026.43.3.172

Abstract

This study evaluated the hazardous characteristics of slag generated from non-ferrous metal smelting and processing industries classified under KSIC C-242 by analyzing a total of 35 slag samples from 35 facilities using leaching tests and total content analyses. The results showed that leaching and total content characteristics varied by process group, with several smelting-related groups exhibiting exceedances or large variability for metals such as Pb, Cd, and Cu, and other processing-related groups demonstrating lower leaching levels but still requiring consideration of total content and process- specific variability. High total content, however, did not always correspond to high leaching concentrations, indicating that both mobility and accumulation potential should be considered during hazard assessments. These results should be interpreted as preliminary screening information for identifying hazardous substances and follow-up assessment items. Final recycling applicability, meanwhile, should be determined through a comprehensive recycling environmental assessment considering waste characteristics, recycling processes, recycled products, and actual use conditions.

Key Words

Slag waste recycling, Environmental hazard assessment, Copper smelting process

김경철 Gyeongcheol Kim , 모달리모히트 Mohamadali Mohit , 문충만 Chungman Moon , 최영화 Younghoa Choi , 김동훈 Dong-hoon Kim

DOI:10.9786/kswm.2026.43.3.186

Abstract

This study evaluated the structural consistency of direct methane (CH₄) emission estimation in wastewater treatment plants (WWTPs) by defining the anaerobic digester as separate from the overall system boundary and examining the effect. Under current Korean guidelines, the entire WWTP is treated as a single system boundary, and CH₄ emissions are estimated based on overall organic matter removal and the amount of CH₄ recovered from anaerobic digestion. However, this approach does not explicitly distinguish CH₄ generation, recovery, and residual emissions occurring within the anaerobic digester from those of the overall facility. To address this gap, a process-based organic matter mass balance was developed using an influent load normalized to 100 ton BOD, with the potential organic load entering the anaerobic digester estimated at 42.1 ton BOD. Using the current guideline, direct CH₄ emissions were calculated as 0.86 ton CH₄ without anaerobic digestion and 1.17 ton CH₄ with anaerobic digestion, indicating that reported emissions can increase even when CH₄ is recovered. When the waste activated sludge feeding ratio to the anaerobic digester was reduced from 100% to 50% and 0%, the actual digester influent load decreased from 42.1 to 36.0 and 30.0 ton BOD, and recovered CH₄ decreased from 15.36 to 13.15 and 10.94 ton CH₄, respectively. In contrast, direct emissions estimated using the current method increased from 1.17 to 2.49 and 3.80 ton CH₄, demonstrating a reversal between actual CH₄ generation potential and reported emissions. However, when the anaerobic digester was defined as a separate system boundary from the overall WWTP, total direct CH₄ emissions consistently decreased from 1.67 to 1.55 and 1.43 ton CH₄, demonstrating an improvement in the consistency of direct CH₄ emission estimation and better reflecting variations in digester influent load.

Key Words

Wastewater treatment plant, Methane emission, Anaerobic digestion, Emission factor, Dual-boundary accounting

심지빈 Ji-bin Sim , 박세원 Se Won Park , 강신영 Shin Young Kang , 서명원 Myung Won Seo

DOI:10.9786/kswm.2026.43.3.196

Abstract

The continuous growth in global plastic production and consumption has led to a significant increase in plastic waste generation, highlighting the need for efficient resource recovery strategies. This study, therefore, aimed to evaluate suitable pathways for the chemical recycling of plastic waste generated in Seoul and to provide baseline data for urban-scale plastic resource recovery planning. To achieve this, material flow analysis (MFA) data from the Seoul Institute were used to classify Seoul's plastic waste by resin type and disposal method, including mixed waste and separate collection streams. Based on these characteristics, PET bottles were assigned to depolymerization, while single-use products were assigned to gasification. Film-type packaging materials and rigid plastic containers, meanwhile, were considered applicable to both pyrolysis and gasification; therefore, four pyrolysis-to-gasification allocation scenarios were established: 20:80, 40:60, 60:40, and 80:20. The results showed that approximately 759.0 tons/day of Seoul's plastic waste could be considered as potentially recoverable through chemical recycling pathways, and depending on the allocation scenario, the processable amount ranged from 99.8 to 399.2 tons/day for pyrolysis and from 243.8 to 543.2 tons/day for gasification, while the amount assigned to depolymerization remained constant at 116.0 tons/day. These results suggest that in selecting chemical recycling pathways for Seoul's plastic waste, resin characteristics, disposal methods, and the operational flexibility of pyrolysis and gasification processes should be considered. The findings provide a quantitative basis for establishing plastic waste resource recovery strategies and planning future chemical recycling facilities in urban waste management systems.

Key Words

Plastic waste, Chemical recycling, Pyrolysis, Gasification, Depolymerization

윤석표 Seok-pyo Yoon , 이동훈 Dong-hoon Lee

DOI:10.9786/kswm.2026.43.3.212

Abstract

As the transition toward a circular economy accelerates, the establishment of accurate national waste statistics has become essential for effective policy formulation. Although South Korea conducts the National Waste Statistical Survey every five years, the current framework faces several limitations, including fragmented survey categories, double counting of primary and secondary waste, and difficulties in tracking material flows. To address these challenges, this study compares the Korean system with advanced statistical methodologies implemented in the European Union (EU), Germany, and Denmark. The analysis indicates that the EU applies a dual classification system, consisting of the List of Waste (LoW) and EWC-Stat, to differentiate primary and secondary waste while maintaining material flow consistency. Germany operates a four-tier survey system supported by waste balance cross-validation. Denmark employs an administrative electronic reporting system based on the Affaldsdatasystem (ADS) and H/E codes. Based on these benchmark cases, this study proposes five recommendations to improve the Korean waste statistics system: ① simplification of household waste surveys through integration with administrative data; ② introduction of material- based statistical classification codes, such as EWC-Stat format; ③ establishment of clear definitions to prevent double counting of secondary waste; ④ clarification of End-of-Waste criteria for the calculation of the Circular Material Use Rate (CMUR); and ⑤ legal obligation for waste treatment facilities to submit statistical data. These improvements are expected to enhance data reliability, ensure traceability of material flows, and strengthen the statistical foundation of Korea’s waste management sector.

Key Words

Waste statistics, Circular economy, EWC-Stat, Secondary waste, National waste statistical survey

한국폐기물자원순환학회

DOI:10.9786/kswm.2026.43.3.223

Abstract

Key Words