https://doi.org/10.15681/KSWE.2026.42.1.1

장서진(Seojin Jang) ; 이승연(Seungyeon Lee) ; 강민석(Minseok Kang) ; 이승기(Seunggi Lee) ; 서유진(Yu-Jin Seo) ; 신재돈(Jaedon Shin) ; 윤영건(Younggun Yoon) ; 조민(Min Cho)

Pathogenic microorganisms that persist on hydrophobic surfaces in agricultural environments present a significant sanitation challenge. Materials like Velcro can serve as reservoirs for bacteria and hinder the effectiveness of disinfectants. This issue is particularly critical in reusable equipment and high-contact areas, where microbial colonization can lead to recurrent contamination. This study evaluated the disinfection performance against Escherichia coli O157:H7 and methicillin-resistant Staphylococcus aureus (MRSA) inoculated onto Velcro surfaces. The disinfection methods tested included low-frequency ultrasound (<40 kHz), Tween 80 surfactant, and free available chlorine (FAC), applied individually and in combination. While FAC alone rapidly inactivated E. coli in aqueous suspension (over 4-log reduction within seconds), it demonstrated limited effectiveness against MRSA and bacteria strongly adhered to Velcro (less than 2-log reduction). However, pretreatment with either Tween 80 or ultrasound improved FAC penetration into the Velcro structure, enhancing bacterial inactivation. The combination of both pretreatments achieved greater than 4-log reduction for E. coli and approximately 1.6-log reduction for MRSA under the tested conditions. Surface analyses, including contact angle measurements and FT-IR, confirmed increased hydrophilicity without altering the chemical integrity of Velcro. These findings indicate that integrating physical and chemical pretreatments can address accessibility barriers on complex hydrophobic materials, thereby enhancing chlorine-based disinfection. This combined strategy offers a practical solution for agricultural and food production environments where conventional methods often struggle to achieve reliable pathogen control.

https://doi.org/10.15681/KSWE.2026.42.1.14

김진평(Jinpyeong Kim) ; 가이레아마르(Amar Gaire) ; 박민서(Min Seo Park) ; 박상준(Sang Jun Park) ; 홍석범(Seok Beom Hong) ; 조민(Min Cho) ; 윤영건(Younggun Yoon) ; 신재돈(Jaedon Shin)

Benzoic acid derivatives (BADs) are increasingly found in natural waters used for drinking and agriculture, raising concerns about their transformation into disinfection byproducts (DBPs) during oxidative treatment and their potential allelopathic effects that can hinder plant growth. This study systematically evaluated the degradation of two representative BADs: para-aminobenzoic acid (p-ABA) and para-chlorobenzoic acid (p-CBA), using ferrate(VI) [Fe(VI)] under controlled and environmentally relevant conditions. The results indicated that Fe(VI) effectively degraded p-ABA, while p-CBA showed negligible reactivity due to differences in their electron density and substituent effects. For p-ABA, the apparent second-order rate constants (kapp) under compound-excess conditions ranged from 78 to 1,692 M-1s-1 at pH 6?8. In contrast, under Fe(VI)-excess conditions, kapp’ values ranged from 180 to 625 M-1s-1, with degradation rates influenced by the Fe(VI) dosage. A tentative degradation pathway was proposed, based on existing literature, suggesting the initial formation of an aniline radical cation, which may then transform into nitro- or azo-derivatives that are structurally persistent and could pose environmental risks. Experiments conducted with natural river water from the Nakdong River in Korea showed greater removal of p-ABA than predicted by phosphate-buffered models. This indicates that dissolved organic matter and other background constituents can enhance degradation through secondary reactive species such as Fe(IV) and Fe(V), or through alternative pathways. The observed >95% removal at Fe(VI)≥0.5 mg Fe/mg DOC highlights the effectiveness of Fe(VI) oxidation in complex water matrices. These findings enhance the understanding of Fe(VI)-based oxidation, provide insights for optimizing treatment processes under realistic conditions, and underscore its potential as a selective and sustainable strategy for treating BADs in drinking water and agricultural reuse systems

https://doi.org/10.15681/KSWE.2026.42.1.28

이서홍(Seohong Lee) ; 김신호(sinho Kim) ; 배지한(jihan Bae) ; 이광언(gwangeon Lee) ; 이민서(minseo Lee) ; 최영지(youngji Choi) ; 김설빈(seolbin Kim) ; 안지현(jihyeon An) ; 정진영(jinyoung Jung) ; 최대희(daehee Cho)

Plating wastewater is characterized by high concentrations of cyanide (CN), heavy metals, and refractory organics, which complicates its treatment using conventional biological methods. This study assesses the feasibility of co-treating pre-treated plating wastewater with industrial effluent at a centralized treatment plant within a national industrial complex. To facilitate effective treatment, a nine-step advanced pre-treatment system was implemented, incorporating cyanide oxidation, chemical treatment, and advanced oxidation processes (AOPs). Following pre-treatment, the effluent was mixed with industrial wastewater and processed in a lab-scale anaerobic-anoxic-oxic (A2/O) bioreactor. The primary focus of the research was to determine the optimal mixing ratio and to evaluate the use of alternative external carbon sources to enhance nitrogen removal efficiency. Experimental results identified an optimal mixing ratio of 2:1, industrial to plating wastewater, which complied with legal effluent water quality standards. Notably, the use of a recovered carbon source (RCS), consisting of a glycerol-methanol mixture, significantly improved nitrogen removal efficiency compared to traditional methanol. The specific denitrification rate (SDNR) with RCS was approximately 3.1 times higher than that achieved with methanol, highlighting its effectiveness as an electron donor. Furthermore, key water quality indicators, including Total Nitrogen (TN), Total Organic Carbon (TOC), and Biochemical Oxygen Demand (BOD5), remained within legal limits. This study concludes that pre-treating plating wastewater allows for successful co-treatment with industrial effluent, offering a technically and economically viable strategy for integrated wastewater management.

https://doi.org/10.15681/KSWE.2026.42.1.36

최재영(Jaeyoung Choi) ; 김지민(Jimin Kim) ; 류건영(Gunyoung Ryu) ; 오희경(Heekyong Oh)

Per- and polyfluoroalkyl substances(PFAS) are commonly used across various industries due to their stable structure. However, these characteristics make PFAS challenging to degrade and remove. This study investigated the use of biomass-derived activated carbon(AC) as an alternative to coal-based AC for PFAS removal during water treatment. The adsorption capacities of coal, bamboo, and coconut-based AC were evaluated in relation to their characteristics, including iodine number, zeta-potential, surface area, and pore volume. Coal-based AC demonstrated the highest PFAS adsorption capacity(6.02?6.11 μg/g), regardless of chain length. In contrast, bamboo-based AC had the lowest adsorption capacity(3.53?5.7 μg/g) due to strong negative zeta-potential, which resulted in electrostatic repulsion, particularly for short-chains. Coconut-based AC showed better adsorption than bamboo, but long-chain PFAS caused pore-blocking in the AC micropores, disrupting the adsorption. As Bamboo-based AC is effective at removing long-chains, a mixture of bamboo-coconut AC in a 1:2 ratio can reduce pore-blocking, thereby increasing the adsorption than using alone. A rapid small-scale column test was conducted using the optimal bamboo-coconut AC mixture, applying influent of each PFAS concentrations normally at 10 ng/L, and high concentration at 625 ng/L. During the second high-concentration injection(27.2k BV), PFBA reached its breakthrough point, surpassing the concentration of influent. Initially, short-chains were removed more effectively than long-chains; however, around 15.5k and 34k BV, the removal efficiency of long-chains surpassed that of short chains. The results indicate that the combination of AC types enhances the removal of PFSAs and long-chains, but additional research is necessary to improve the removal of short-chains.

https://doi.org/10.15681/KSWE.2026.42.1.47

안종호(Jongho Ahn) ; 최미경(Mikyong Choi) ; 이태환(Taehwan Lee) ; 정세웅(Sewoong Chung)

Reduced streamflow not only stresses freshwater ecosystems but is also closely associated with rising river water temperatures. When low-flow conditions coincide with elevated water temperatures, their combined effects can create complex risks for the health of these ecosystems and for water resource management. However, previous studies have mainly used univariate analyses, examining extreme low-flow or high-temperature events separately. This approach limits the ability to quantify the likelihood of joint extreme events involving interrelated variables. To overcome this limitation, this study employs Copula-based bivariate joint modeling to estimate the conditional exceedance probability of concurrent low-flow and high-temperature events. Monthly streamflow and water temperature data from three upstream sites in the Nakdong River basin were analyzed. For each variable, seven theoretical distributions were tested, and the optimal marginal distribution was chosen using the Kolmogorov-Smirnov test. Subsequently, copulas were fitted, and the best model for each site and month was identified based on the Akaike Information Criterion. The results revealed a significant sensitivity of water temperature to changes in streamflow during specific months and locations, suggesting that thermal response characteristics may vary with spatiotemporal conditions. The proposed Copula-based joint probability modeling approach effectively captures the dependency structure between streamflow and water temperature, offering a solid foundation for high-temperature risk assessment and aiding hydrology-based policy and decision-making amid increasing climate variability.

https://doi.org/10.15681/KSWE.2026.42.1.57

손예지(Yeji Shon) ; 이채림(Chaelim Lee) ; 김상단(Sangdan Kim)

Turbidity, mainly caused by suspended sediments (SS), significantly impacts river ecosystems by reducing populations of sensitive taxa while promoting tolerant species. Traditional biological indices, such as species richness, the Benthic Macroinvertebrates Index (BMI), and the Benthic Macroinvertebrates Streambed Index (BMSI), may not adequately capture the cumulative and long-term effects of turbidity. To address this gap, we created the Turbidity Sensitivity Index for Benthic Macroinvertebrates (TSI-BM) specifically for the upper Soyang River Dam in the North Han River basin. We defined turbidity exposure as the cumulative SS concentration over six months, reflecting long-term stress rather than short-term variations. We analyzed correlations between cumulative exposure and 255 taxa within the groups Ephemeroptera, Plecoptera, and Trichoptera (EPT) to classify species into four sensitivity categories. Sensitive groups (A and B) were weighted to calculate TSI-BM, which represents the proportion of sensitive taxa scores within a community. TSI-BM demonstrated strong and consistent negative correlations with turbidity exposure (Spearman's ρ ? ?0.46, p < 0.001), outperforming conventional indices. It effectively captured spatial variations among sites and seasonal differences, proving to be a robust diagnostic tool. These findings suggest that TSI-BM integrates species-specific sensitivity with cumulative stressor exposure, offering a stressor-specific and ecologically relevant metric for turbidity assessment. Beyond enhancing the ecological evaluation of sediment stress, TSI-BM provides a practical framework for biomonitoring and managing river ecosystems amid changing hydrological conditions and land-use pressures.

https://doi.org/10.15681/KSWE.2026.42.1.65

이준영(Junyoung Lee) ; 신안국(Ankook Shin) ; 김찬겸(Changyeom Kim) ; 위선민(Sunmin We) ; 정연지(Yeonji Jeong) ; 진영규(Youngkyu Jin) ; 이동준(Dongjun Lee) ; 한정호(Jeongho Han) ; 임경재(Kyoung Jae Lim)

Efficient irrigation water management is essential for sustainable agricultural practices in paddy-dominant irrigation districts, where reservoir releases and conveyance losses significantly impact field-scale ponding. This study developed a field-scale Environmental Protection Agency (EPA) Storm Water Management Model (SWMM) framework to improve the spatial resolution and hydro-hydraulic fidelity of irrigation and water delivery processes. Its performance was compared with a conventional lateral-scale model in the Baekma Reservoir watershed, a standard test basin designated by the Korea Rural Community Corporation (KRC). The field-scale SWMM was parameterized using field survey data and GIS-derived information that reflected plot-level irrigation demand, canal network connectivity, and operational constraints. Model performance was assessed against observed canal water levels using the coefficient of determination (R²) and Nash?Sutcliffe efficiency (NSE). The field-scale models accurately replicated upstream stage dynamics, achieving statistically significant agreement (p < 0.05), which indicates a reliable representation of inflow and upper-network hydraulics. However, simulation accuracy diminished in downstream reaches, primarily due to the lack of water-gate operation data and incomplete downstream boundary condition specifications. These factors may disrupt hydraulic continuity and introduce uncertainty in delivery timing. Despite these limitations, the field-scale model effectively captured the spatial heterogeneity of irrigation distribution and maintained continuity in downstream supply, highlighting a clear imbalance with reduced irrigation in lower reaches. Many downstream paddy fields struggled to maintain the target ponding depth and were classified as insufficient for ponding maintenance.

https://doi.org/10.15681/KSWE.2026.42.1.77

하지원(Jiwon Ha) ; 윤여정(Yeojeong Yun) ; 김성진(Sungjin Kim) ; 정세웅(Sewoong Chung)

This study explores optimal intake strategies for harnessing deep water from Lake Soyang as a sustainable thermal resource for cooling data centers. The primary focus is on maintaining a stable intake temperature (≤7°C) while minimizing turbidity. We utilized the CE-QUAL-W2 model, calibrated for the wet year 2022 and validated for the dry year 2016, to simulate the temperature and turbidity of intake water under various scenarios and to identify the optimal intake depth. During calibration, we applied cooling water intake scenarios (S0-S3), which were subsequently replicated as S4-S7 for the validation period. Scenario S0 represents the current condition, where hydropower releases are solely supplied through the penstock outlet (EL. 130.0-150.0 m). Scenario S1 assumes an additional intake of 2.79 m³/s of cooling water through the same outlet. Scenarios S2 and S3 assume the same discharge volume, but selectively withdrawn at EL. 130.0 m and EL. 120.0 m, respectively. Results indicated that the current outlet withdrawal (S1 and S5) exceeded the 7°C cooling criterion for over 179 days in 2022 and 161 days in 2016. In contrast, selective withdrawal from 20 m below the current outlet (S3 and S7) consistently maintained target temperatures of ≤7°C. Additionally, maximum turbidity was reduced by approximately 60% and 38% compared to S1 and S5, respectively. This study highlights the significant impact of intake depth on cooling efficiency and water quality for data center cooling. The findings contribute to the optimization of deep-water intake strategies and the prediction of water quality impacts for thermal energy utilization projects in multipurpose dams across Korea.

https://doi.org/10.15681/KSWE.2026.42.1.92

장수헌(Su-Heon Jang) ; 박성직(Seong-Jik Park)

Inland waters constitute dynamic biogeochemical hotspots within the global carbon and nitrogen cycles and are now recognized as substantial sources of greenhouse gas emissions (GHG). This review synthesizes current knowledge of the production, transformation, and emission pathways of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) across diverse aquatic environments including rivers, lakes, reservoirs, ponds, wetlands, and estuaries. CO2 emissions are primarily driven by microbial respiration, organic matter decomposition, and external inputs of dissolved inorganic and organic carbon. CH4 arises predominantly from anaerobic methanogenesis and is partly offset by aerobic or anaerobic oxidation, while its efflux occurs via diffusion, ebullition, and plant-mediated transport. N2O is generated through nitrification, nitrifier denitrification, and incomplete denitrification, though under specific physicochemical conditions inland waters may also function as net sinks. Emission magnitudes are strongly modulated by climatic forcing, hydrological dynamics, nutrient enrichment, oxygen availability, and land-use practices. A critical appraisal of monitoring techniques is also presented. The headspace method provides cost-effective and scalable estimates but underrepresents transient fluxes. Chambers directly capture both diffusive and ebullitive emissions yet remain spatially constrained. Bubble traps are particularly suited to quantifying ebullition-dominated CH4 fluxes, though their irregularity limits extrapolation. Eddy covariance offers continuous, ecosystem-scale flux measurements but entails high technical and financial demands. Modeling approaches facilitate spatially explicit and long-term assessments, but estimates remain sensitive to input data and underlying assumptions. Integrated methodological frameworks combining field observations, process-based modeling, and remote sensing are essential for advancing Monitoring?Reporting?Verification (MRV) systems.