명지원 Jiwon Myung , 장규민 Kyumin Jang , 김석휘 Seok-hwi Kim , 박진원 Jinwon Park

DOI:10.9786/kswm.2025.42.4.167

Abstract

Large quantities of oyster shells generated along Korea’s coastal regions are mostly treated as waste, even though their principal component is calcium carbonate (CaCO₃), raising concerns over environmental impact and resource loss. This study proposes a resource-circulating process that converts oyster shells into a high-purity calcium oxide (CaO) source and subsequently produces high-purity calcium carbonate (CaCO₃) through wet carbonation. The process integrates calcination, hydration, and carbonation in a continuous sequence. This integrated process is specifically designed so that the concentrated CO₂ released during calcination is directly recycled into the subsequent carbonation step, enabling simultaneous CO₂ capture and mineral carbonation without any external resource input. Calcining oyster shells at 850℃ for 3h resulted in the complete conversion of CaCO₃ to high-purity CaO. The resulting calcium hydroxide (Ca(OH)₂), produced during hydration, achieved a conversion close to the theoretical maximum (0.98-1.00 mol CO₂ per mol CaO) upon reaction with CO₂. pH monitoring and thermogravimetric analysis confirmed changes in product purity during the reaction, showing that a lower final pH increased CaCO₃ purity, reaching over 91% at pH 7-8. X-ray diffraction indicated that calcite remained the dominant crystalline phase throughout the reaction period, with no phase transitions observed over time. These findings demonstrate that the integrated carbonation process based on oyster shells is a highly efficient route to achieving both resource circularity and carbon neutrality, providing foundational data for future industrial applications.

Key Words

Oyster shell, Carbon mineralization, Calcium carbonate, High quality, Recycle

장현민 Hyun Min Jang

DOI:10.9786/kswm.2025.42.4.177

Abstract

This study investigated the physicochemical properties of swine manure (SM)-derived biochar (BC), and its adsorption capacity for levofloxacin (LEV). Raw SM exhibited a BET surface area of 0.46 m²/g, a pore volume of 0.0007 cm³/g, and a pore size of 62.50 A. In contrast, SM-BC produced via pyrolysis (600℃, 3 h) showed a significantly higher BET surface area (362.48 m²/g), approximately 788 times greater than that of raw SM. Pore volume increased to approximately 0.028 cm³/g, while pore size decreased to 33.68 A. Adsorption kinetic analysis indicated that the pseudo-second order (R² = 0.92) and Elovich models (R² = 0.94) fitted experimental data better than the pseudo-first order model (R² = 0.56), suggesting that LEV adsorption onto SM-BC is primarily governed by chemisorption rather than physisorption. The Freundlich isotherm model demonstrated a better fit (R² = 0.96) than the Langmuir model (R² = 0.85), indicating multilayer LEV adsorption on a heterogeneous surface. The maximum adsorption capacity of SM-BC for LEV is 148.65 mg/g, higher than that of various other adsorbents (2.71-41.35 mg/g) and comparable to commercial activated carbons (82-164 mg/g). Collectively, these results suggest that SM-BC has strong potential as an adsorbent for the removal of levofloxacin from aqueous environments.

Key Words

Swine manure, Biochar, Aquatic system, Adsorption, Levofloxacin

이유민 Youmin Lee , 이태우 Taewoo Lee , 길준호 Jun-ho Kil

DOI:10.9786/kswm.2025.42.4.183

Abstract

The cement industry is a major source of carbon dioxide (CO₂) emissions. To reduce these emissions, this industry is promoting fossil fuel alternatives, such as waste rubber and plastics, which serve as heat sources in calciners for raw materials. However, the increased use of low-quality alternative fuels and their variable quality lead to reduced combustion efficiency and process instability. One effective countermeasure is to increase the fuel’s surface area. For this, a two-way design for the fuel inlet provides a practical solution. This study aimed to improve combustion performance deteriorated by the increased use of alternative fuels and their variable quality. Therefore, we conducted computational fluid dynamics (CFD) analysis to examine process changes resulting from a two-way design for the waste plastic inlets in the calciner. The CFD results revealed that the two-way design enhanced the dispersion of raw materials and waste plastics, thereby reducing direct falling and combustion delay. Field application and subsequent process monitoring confirmed an increase in the use of waste plastics, a reduction in CO emissions, and a decrease in coal consumption.

Key Words

Combustion efficiency, Calciner, Alternative fuel injection, CFD, Two-way fuel feeding

김은솔 Eun-sol Kim , 전윤주 Yun-ju Jeon , 김태훈 Tae-hoon Kim , 윤여명 Yeo-myeong Yun

DOI:10.9786/kswm.2025.42.4.193

Abstract

Conductive materials can facilitate methane production in anaerobic digestion through direct interspecies electron transfer (DIET), which has made them subjects of increasing academic interest. Unlike most previous studies, which used simple, easily degradable substrates, this study used real livestock manure, characterized by low biodegradability and weak hydrolytic potential, to examine the effects of carbon nanotubes (CNT) and powdered activated carbon (PAC). Overall, PAC outperformed CNT across all tested concentrations. At 200 mg/L, CNT exhibited low efficiency, producing only 1₄.6 ± 0.9 mL CH₄/g COD, which was 18.₄% lower than the control. This is likely due to microbial inhibition and insufficient DIET activation. This delayed the onset of methane production and increased organic acid accumulation. In contrast, PAC, owing to its high specific surface area and adsorption capacity, reduced total organic acid accumulation and enhanced methane production, even at 200 mg/L. Notably, PAC achieved the highest methane yield of 65.1 ± 5.6 mL CH₄/g COD at 800 mg/L, which was 263.7% higher than the control (17.9 ± 0.9 mL CH₄/g COD). These findings highlight the importance of selecting suitable conductive materials and optimizing the dose to enhance hydrolysis and stabilize methane production in AD systems for treating complex substrates.

Key Words

Anaerobic digestion, Conductive materials, CNT, PAC, Organic acids

안지혜 Ji-hye Ahn , 전윤주 Yun-ju Jeon , 김태훈 Tae-hoon Kim , 윤여명 Yeo-myeong Yun

DOI:10.9786/kswm.2025.42.4.201

Abstract

This study investigated the impact of carbon-based nanomaterials on the anaerobic digestion performance of swine manure (SM). Specifically, 60-day biochemical methane potential (BMP) tests were conducted using SM as the substrate, with multi-walled carbon nanotubes (MWCNT) added at concentrations ranging from 0 to 50 mg/g of volatile solids (VS). The highest methane production rate (158 ± 7 mL CH4/L/day) was achieved with the addition of 13 mg/g VS MWCNT (MWCNT 13), which was approximately 2.8 times greater than that of the control without MWCNT. MWCNT 13 also demonstrated the most efficient digestion performance, as indicated by its total organic acid concentration being the lowest (1,296 ± 280 mg COD/L). Ammonia concentrations increased with MWCNT addition (13-50 mg/g VS), likely due to enhancements in the hydrolysis of nitrogenous organics in SM. Despite the increase in ammonia, the corresponding improvement in methane yield suggests that better substrate degradation boosted digestion performance. Microbial community analysis revealed that MWCNT 13 enriched hydrolytic and acidogenic bacteria, including Clostridium spp., Levilinea saccharolytica, and Terrisporobacter mayombei. Further, the archaeal genera Methanobacterium spp. and Methanothrix soehngenii were dominant under this condition, reflecting active hydrogenotrophic and acetoclastic methanogenesis. These results suggest that moderate MWCNT supplementation enhances microbial synergy and diversifies methanogenic pathways, ultimately improving the efficiency of methane production from SM.

Key Words

Anaerobic digestion, Swine manure, Multi-walled carbon nanotubes (MWCNT), Methane production, Microbial community structure

김서현 Seo Hyeon Kim , 문동훈 Dong Hun Moon , 이영진 Young Jin Lee , 박정훈 Jeong-hun Park

DOI:10.9786/kswm.2025.42.4.211

Abstract

The escalating volume of waste in modern society is rapidly depleting landfill capacity. With the 2030 direct landfill ban approaching, constructing additional incineration plants is inevitable in several regions, including the Seoul metropolitan area. However, local opposition complicates the facility site selection process, as the “Not In My Backyard” (NIMBY) phenomenon impedes essential waste management facilities. This study examines the current state of the NIMBY phenomenon regarding waste management facilities in South Korea by investigating official reports from the Ministry of Environment and local governments, government policy cases, and recent strategies addressing NIMBY responses. In the Seoul metropolitan area, NIMBY reactions are predominantly observed. Similarly, cities like Gwangju, Daegu, and Sejong have experienced delays in incinerator construction due to local opposition. Analyzing these cases revealed that successful strategies include underground facility designs, improved communication, and facility conversion to tourist sites, while failures often resulted from insufficient early engagement with residents and financial disputes among local governments. To mitigate opposition, recent designs often feature resident-friendly amenities or underground constructions. Considering these findings, an effective solution could be underground incinerator designs with surface areas developed into tourist and community facilities. Additionally, preemptive institutional measures are needed to address NIMBY opposition to incinerator construction.

Key Words

Waste disposal facilities, Waste management, Incineration facilities, Direct Landfill Ban Act, NIMBY Phenomenon