Effect of Alternative Fuel Substitution on Carbon Emissions from the Cement Clinker Burning Process 실제 시멘트 소성공정에서 폐합성수지 대체연료 사용에 따른 탄소 배출 특성 평가
최재원 Jaewon Choi , 백주익 Juik Baek , 김장중 Jangjung Kim , 원필성 Philsung Won
DOI:10.9786/kswm.2025.42.6.267
Abstract
This study evaluated the effects of process temperature and waste plastic-based alternative fuel substitution on the carbon emissions from an actual cement kiln system. The calciner maintained a stable temperature and consistently emitted less carbon as the fuel substitution level increased, whereas the carbon emissions from the kiln increased above a certain fuel substitution threshold, indicating the need for technical improvements to ensure stable combustion and heat efficiency when using waste plastic-based alternative fuels.
Key Words
Alternative fuels, Cement kiln, Calciner, Carbon emissions, Manufacturing process
Characterization of Oil Contamination in Prestressed Concrete Sleepers and Evaluation of Recyclability via Calcination 폐콘크리트 침목의 유류 오염 특성 분석 및 소성을 통한 재활용성 평가
김기태 Gi-tae Kim , 정원균 Won-gune Jeong , 이가빈 Ga-been Lee , 이재영 Jae-young Lee , 백기태 Kitae Baek
Characterization of Oil Contamination in Prestressed Concrete Sleepers and Evaluation of Recyclability via Calcination 폐콘크리트 침목의 유류 오염 특성 분석 및 소성을 통한 재활용성 평가
김기태 Gi-tae Kim , 정원균 Won-gune Jeong , 이가빈 Ga-been Lee , 이재영 Jae-young Lee , 백기태 Kitae Baek
DOI:10.9786/kswm.2025.42.6.277
Abstract
The increasing prevalence of contaminated prestressed concrete (PC) sleepers requires the development of effective treatment technologies. In response to this challenge, calcination has been proposed as a promising technique to remove oil from waste PC sleeper through thermal oxidation, as well as convert calcium hydroxide (Ca(OH)2) and calcium carbonate (CaCO3) into calcium oxide (CaO). However, oil removal is contingent upon the depth of oil in the PC sleeper and the dimensions of the sleeper particle. Consequently, it is imperative to investigate the contamination characteristics of oil on the PC sleeper, and to optimize the calcination conditions to achieve the complete removal of oil, as well as the conversion of Ca(OH)2 and CaCO3 into CaO, thus facilitating the effective recycling of PC sleeper. In this study, the characteristics of oil contamination on the PC sleeper were evaluated using the Green-Ampt model, and optimal calcination conditions were proposed based on weight loss during thermal treatment. Furthermore, an assessment was conducted on the recyclability of waste PC sleepers, utilizing a measurement of the compressive strength of concrete containing calcined waste PC sleepers. Consequently, calcination removed the oil completely from the contaminated PC sleepers. Furthermore, the incorporation of calcined PC sleepers into cement, at a replacement level of 20 wt.%, demonstrated a compressive strength of 28.5 MPa after a 28 days hydration. Consequently, the calcined waste PC sleeper can be used as a replacement material for cement.
Key Words
PC sleeper, Oil contamination, Calcination, Cement replacement
KOH-Activated Carbon from Waste Plastic Pyrolysis Residue: Surface Structure Optimization and Adsorption Properties
KOH-Activated Carbon from Waste Plastic Pyrolysis Residue: Surface Structure Optimization and Adsorption Properties
Eun-jin Moon , Byoungsun Park
DOI:10.9786/kswm.2025.42.6.285
Abstract
This study explored methods for recycling waste plastic pyrolysis residue into high-value-added activated carbon (AC) to promote the circular use of plastics. The residue obtained through the pyrolysis of waste plastic was used as a precursor to produce AC through chemical activation by KOH. Activation was undertaken at temperatures ranging from 700 to 900°C with KOH-to-plastic precursor ratios ranging from 0.5 to 2.0 to evaluate the effects on the AC surface area, pore characteristics, and surface molecular structure determined using Brunauer-Emmett-Teller surface area analysis, thermogravimetric analysis, X-ray diffractometry, Fourier transform infrared spectroscopy, and scanning electron microscopy. These analyses revealed that higher KOH ratios increased the AC surface area and pore volume. The optimal meso/micropore structure, which exhibited a surface area of 1,033.1 ㎡/g and total pore volume of 0.56 ㎤/g, was obtained at a pyrolysis temperature of 800°C using a KOH-to-precursor ratio of 1:1. Furthermore, methylene blue adsorption test results revealed that AC prepared at 800°C exhibited the highest adsorption efficiency. Thus, this study demonstrated a promising method for converting waste plastic into high-value AC materials, thereby contributing to the realization of a sustainable plastics economy.
Development of a Deep Learning Model for Forecasting Sewage Sludge Generation and Treatment Pathways Using a Time-Series Segmentation Approach 시기별 시계열 분할 접근법을 이용한 하수슬러지 발생 및 처리 방법 예측 딥러닝 모델 개발
Development of a Deep Learning Model for Forecasting Sewage Sludge Generation and Treatment Pathways Using a Time-Series Segmentation Approach 시기별 시계열 분할 접근법을 이용한 하수슬러지 발생 및 처리 방법 예측 딥러닝 모델 개발
최원찬 Wonchan Choi , 최동혁 Donghyuk Choi
DOI:10.9786/kswm.2025.42.6.298
Abstract
Forecasting sewage sludge generation through complex treatment pathways is uniquely challenging in South Korea owing to severe statistical disconnections caused by major policy interventions, such as the 2012 Ocean Dump Banning. This study accordingly constructed a consistent 21-year (2004-2024) time-series dataset by applying linear interpolation to bridge policy-induced gaps and reclassifying statistical items to ensure longitudinal consistency. The primary innovation of this study lies in its development and validation of a novel two-stage, three-model ensemble gated recurrent unit (GRU) architecture designed to interpret complex, non-stationary data. The constructed dataset exhibited multiple distinct dynamic regimes (e.g., policy shock, transition, and stability) that required specialized modeling approaches. Our hierarchical framework effectively addressed these different regimes by: (1) separating the forecasting of the macro-scale “generated_total” sludge from the seven treatment pathways, and (2) training separate expert GRU models optimized for long-term, mid-term, and short-term time horizons. Model evaluations conducted using the 2024 test set demonstrated highly accurate predictions of macro-trends driven by stable policy and infrastructure, predicting the “generated_total” sludge with a 1.99% mean absolute error (MAE) and “fuelization” sludge with a 2.91% MAE. Furthermore, the model determined that highly volatile sludge treatment pathways such as “composting” (19.04% MAE) are governed by different mechanisms, including external structural factors and regulatory quality standards, rather than simple macro-level drivers. This performance divergence validates the effectiveness of the proposed ensemble approach in disentangling the effects of policy, infrastructure, and external dynamics across different time periods. Consequently, this study established a robust and interpretable modeling framework offering considerable value in data-driven environmental policy planning.
Key Words
Sewage sludge, Time-series forecasting, Deep learning, GRU, Ensemble model
The Necessity of Introducing Battery Life-Cycle Carbon Footprint Reporting Regulations in Korea
The Necessity of Introducing Battery Life-Cycle Carbon Footprint Reporting Regulations in Korea
Choha Kim , Sanghoon Kwak
DOI:10.9786/kswm.2025.42.6.309
Abstract
The European Union (EU) is promoting the EU Battery Regulation, which mandates battery life-cycle carbon footprint reporting. In response, Korea has introduced the guideline for calculating battery-related carbon emissions, and Korean companies are addressing the EU regulation by obtaining certifications or establishing systems for real-time carbon emission monitoring. However, Korea currently lacks a specific battery regulation requiring life-cycle carbon footprint reporting. Instead, existing Korean policies focus on recycled material certification systems, battery life-cycle management systems, and pre-removal performance evaluation of electric vehicle (EV) batteries. This paper suggests the necessity of introducing battery life-cycling carbon reporting regulations in Korea.
Key Words
Carbon footprint, Waste battery regulation, EU waste battery regulation
Selective Removal of Low-Melting PET Sheaths via Pretreatment for Recycling Automotive Interior Materials 자동차 내장재 재활용을 위한 PET 전처리 기반 저융점 LM PET Sheath 선택적 제거 기술 연구
김관용 Gwanyong Kim , 류지원 Jiwon Yu , 이상철 Sangchul Lee
Selective Removal of Low-Melting PET Sheaths via Pretreatment for Recycling Automotive Interior Materials 자동차 내장재 재활용을 위한 PET 전처리 기반 저융점 LM PET Sheath 선택적 제거 기술 연구
김관용 Gwanyong Kim , 류지원 Jiwon Yu , 이상철 Sangchul Lee
DOI:10.9786/kswm.2025.42.6.320
Abstract
This study investigates the selective removal of low-melting sheaths in low-melting polyethylene terephthalate (LM PET) used in automotive interior materials. The material composition of automotive interior parts was analyzed, and solvent-based dissolution and pretreatment experiments were conducted using LM PET and high-melting PET. Fourier-transform infrared spectroscopy and differential scanning calorimetry analyses showed a reduction in the low-melting peak, confirming effective sheath removal and improved recycling efficiency of end-of-life vehicle composites.
Enhanced Biological H2S Removal via Polyvinylpyrrolidone Cell Immobilization Polyvinylpyrrolidone 담체 고정화를 통한 생물학적 황화수소 처리 향상
조민정 Min-jeong Jo , 차진명 Jin-myoung Cha , 김종두 Jong-doo Kim , 김현우 Hyun-woo Kim
DOI:10.9786/kswm.2025.42.6.328
Abstract
A novel facultative chemolithoautotrophic bacterium, Thiobacillus sp. IW, isolated from coal mine water, demonstrates broad substrate specificity while maintaining mixotrophic growth and denitrification capability under anaerobic conditions. This study characterizes the physiological, biochemical, and kinetic properties of this strain to evaluate its potential for sulfur compound remediation. Growth kinetics indicated that sulfate accumulation-induced acidification was identified as a key growth-limiting factor. To mitigate this limitation, cell immobilization using polyvinylpyrrolidone (PVP) was applied, resulting in enhanced cell stability and improved hydrogen sulfide (H2S) removal performance. Kinetic analysis showed a maximum H2S removal rate (Vm) of 52.4 g S kg⁻¹ PVP d⁻¹ (dry basis) and a saturation constant (Km) of 62.9 ppm. Under immobilized conditions, H2S removal experiments conducted over an inlet concentration range of 200-1,800 ppm demonstrated removal efficiencies exceeding 90% at 1,000 ppm and remaining above 85% under shock load conditions (≥1,500 ppm). These results indicate that Thiobacillus sp. IW is a robust biocatalyst for high-load H2S treatment and a useful model organism for investigating sulfur oxidation processes.
