박지원 Ji Won Park , 정세영 Se Young Jeong , 정준서 Jun Seo Chung , 허준성 Jun Seong Heo , 윤선원 Seon Won Yoon , 김상엽 Sang Yeob Kim , 왕수현 Su Hyeon Wang , 탁지현 Ji Hyeon Tak , 맹승규 Sung Kyu Maeng

DOI:10.15681/KSWE.2025.41.1.1 Vol.41(No.1) 1-9, 2025

In South Korea, the consumption of direct tap water remains low due to public concerns about its safety. Factors contributing to these concerns include aging water pipes, biofilm formation, and the accumulation of particles, such as manganese hydroxide. These issues compromise water quality by releasing impurities and promoting microbial growth, particularly through biofilms that are resistant to chlorine disinfectants. To address these problems, this study investigated the physical and biological characteristics of loose deposits collected from filtration devices in the drinking water distribution systems of three schools (A, B, and C) in S City. We utilized techniques such as inductively coupled plasma atomic emission spectroscopy (ICP-OES), particle size analysis, and fluorescence-excitation emission matrix (EEM) to analyze the chemical and biological characteristics of the filtered materials. Microbial activity was assessed through adenosine triphosphate (ATP), total cell count (TCC), and heterotrophic plate count (HPC) analyses. The results revealed varying levels of contamination and microbial activity within the loose deposits, with School B exhibiting the highest turbidity and microbial presence, followed by Schools C and A. Additionally, many bacteria found within the loose deposits were often unculturable. These findings indicate a strong relationship between biofilm formation and loose deposits, highlighting the need for improved physical filtration methods to complement existing disinfection processes.

Aging pipes, Biofilm, Drinking water, Distribution systems, Loose deposit

정병환 Byung-hwan Jeong , 장영호 Young-ho Jang , 김태영 Tae-young Kim , 강진영 Jin-young Kang , 김연진 Yeon-jin Kim , 황찬원 Chan-won Hwang

DOI:10.15681/KSWE.2025.41.1.10 Vol.41(No.1) 10-17, 2025

This study presents a reliable improvement plan for the Ministry of Environment’s notice by analyzing the concentration and water consumption of sewage in buildings that frequently violate discharge standards. These include Chinese and Korean restaurants, factories, and logistics centers classified as low-load generating facilities, as well as pensions and training centers, which show significant fluctuations in sewage generation over time. The biochemical oxygen demand (BOD) concentration in sewage from Chinese restaurants ranged from 1458.8 to 1550.0 mg/L, which is 2.7 to 2.8 times higher than the regulatory standard of 550 mg/L. In comparison, sewage from Korean restaurants had BOD concentrations between 1135.1 and 1206.0 mg/L, which is 3.4 to 3.7 times above the standard of 330 mg/L. The nutrient salts (total nitrogen and total phosphorus) in sewage from high-load restaurants measured 43.1 mg/L and 7.0 mg/L, respectively, representing 39.2% and 70.4% of the concentrations recommended in the Water Pollution Control Guidelines. Additionally, it was found that the sewage treatment capacity at logistics centers equipped with unmanned automation facilities was overestimated by 388% compared to actual water usage. In contrast, accommodations such as pensions exhibited varying sewage generation based on the day of the week and season. For instance, water usage on Saturdays was 4.9 times higher than on weekdays (Monday to Thursday), while usage at training centers was 0.3 times lower on weekends. Given the significant variation in sewage volume and concentration based on the building's purpose, it is recommended that sewage treatment facility designs fully consider site-specific conditions when calculating load capacity.

Notification value, Sewage quantity calculation, Sewage treatment facilities, Water pollution control guidelines

이도건 Dogeon Lee , 공동수 Dongsoo Kong , 박배경 Baekyung Park , 박성애 Sung-ae Park , 차윤경 Yoonkyung Cha

DOI:10.15681/KSWE.2025.41.1.18 Vol.41(No.1) 18-29, 2025

The Benthic Macroinvertebrate Index (BMI) is used to assess water quality and the health of aquatic ecosystems in South Korea. In the current BMI grade system, the grades were classified based on the relationships between the BMI and three water quality variables (BOD5, TSS, and TP) using the past data. However, BMI values are also influenced by numerical environmental factors in addition to water quality, and the relationships between BMI and environmental factors may change in the long-term perspective. This study applied multivariate regression tree (MRT) analysis to classify BMI into five grades using a broader range of environmental variables, including hydrometeorological data and recent ecological information. The results of the MRT-based analysis, along with the relative importance of environmental variables, were compared with the current BMI grade system. Significant differences were observed in the split points derived from MRT analysis and the current system. Notably, flow velocity, a factor overlooked in the current grading framework, emerged as a critical determinant, displaying clearer distinctions between grades. Additionally, predictions of BMI grades using random forest models based on MRT analysis showed slightly better performance than predictions using the current system. These findings highlight the need to incorporate a wider range of environmental factors into the BMI grading framework to improve its accuracy and adaptability for assessing water quality and aquatic ecosystem health, particularly in the context of long-term environmental changes.

Aquatic ecosystem, Benthic macroinvertebrates, Benthic Macroinvertebrates Index (BMI), Multivariate regression tree (MRT), Random forest, Variable importance index

강보미 Bomi Kang , 공동수 Dongsoo Kong

DOI:10.15681/KSWE.2025.41.1.30 Vol.41(No.1) 30-53, 2025

This study developed a Benthic Macroinvertebrate Lithophility Index (BMLI) to assess relationships between benthic macroinvertebrate communities and streambed substrate types, providing an advanced tool for evaluating stream physical microhabitats. Lithophilic valency, lithophilic value, and indicator weight value for 632 benthic macroinvertebrate taxa were revised using a dataset of 40,038 sampling units collected from 3,354 sites in South Korea from 2008 to 2023. BMLI could refine the classification of streambed substrates to enhance the accuracy and applicability of biological assessments, unlike previously developed Benthic Macroinvertebrate Streambed Index (BMSI), which classifies substrates into ten categories based on Shepard’s (1954) method, BMLI adapts Cummins’ (1962) five category classification to address over- or under-representation of certain substrate types. Among tested metrics, lithophilic values based on the average abundance of individuals were found to be more reliable and effective indicators than other approaches. BMLI demonstrated a highly significant correlation with streambed substrate types (determination coefficient, R² > 0.6), with slightly higher coefficients than BMSI. Assessment classes of BMLI could reflect physical characteristics of various streambed substrates, allowing for detailed biological assessments across diverse microhabitat conditions. However, further studies are required to refine its applicability across different environmental factors. Future research should integrate additional microhabitat parameters, including water temperature, flow velocity, and depth, to enhance the robustness of the index. These improvements would facilitate a more comprehensive assessment of species distributions, functional guilds, and community diversity, thereby strengthening the framework for ecological evaluation.

Benthic macroinvertebrates, BMLI, Lithophility, Physical microhabitat, Streambed

이규연 Kyuyeon Lee , 차지연 Ji-yeon Cha , 이은주 Eun-ju Lee , 이승철 Seung-cheol Lee , 손승우 Seungwoo Son , 김성환 Sunghwan Kim , 김현준 Xuanjun Jin , 최준원 Joon Weon Choi , 오능환 Neung-hwan Oh

DOI:10.15681/KSWE.2025.41.1.54 Vol.41(No.1) 54-69, 2025

The composition of stream water is the result of various biogeochemical reactions occurring within watersheds. Since 64% of South Korea is covered by forests, studying the components of forest streams is essential to understand the biogeochemical cycling in terrestrial ecosystems. Dissolved organic matter (DOM) is a key subject both in carbon cycle and aquatic ecosystem management. We analyzed stream water practically every month (excluding winter) at the V-notch weir of Mt. Jeombong, the national long-term ecological research site, from 2019 to 2023 when it did not rain. The stream water had no significant seasonal variation, and the concentration of dissolved organic carbon (DOC) was generally low (mean: 1.2 mg L^-1). The mean SUVA₂₅₄, stable carbon isotope ratio, radiocarbon isotope ratio, sum of lignin phenols (Λ₈), aromatic carbon ratio using 1H NMR analysis, lignin-like substance ratio, and tannin-like substance ratio of the stream water were 3.6 L mg^-1 m^-1, -27.0‰, 13.7‰, 1.27 mg/(100 mg of organic carbon), 6.1%, 78.0%, and 13.3%, respectively. The results demonstrate that recently photosynthesized unsaturated organic compounds from dominant C3 plants (angiosperms) in the watershed, can be the main components of stream DOM regardless of the season under near baseflow conditions. However, when snow and ice melted in spring and flowed through the soil layer into the stream, DOC concentration and lignin phenol content increased, indicating the strong role of hydrology on stream DOM dynamics. The results indicate that employing multiple advanced techniques is crucial for understanding changes in DOM quality within Korea’s forest ecosystems.

Biogeochemistry, Carbon, Dissolved organic carbon, Forest stream, Isotopes, KLTER