탁도 강건성 지수(TRI)를 이용한 정수공정 성능 평가 = Performance Evaluation of Drinking Water Treatment Processes Using a Turbidity Robustness Index(TRI)

다국어 초록 (Multilingual Abstract)

In order to investigate the changes in raw water turbidity according to rainfall, two drinking water treatment plants(DWTPs) located within the Daecheong Dam basin, the largest drinking water source in the central region of Korea, were compared. The DWTP-C takes its raw water from the regulating reservoir downstream of the dam, while the DWTP-S takes its raw water directly from the reservoir itself. In addition, a turbidity robustness index(TRI) was applied to historical operating data in an attempt to highlight specific events and periods when the coagulation and sedimentation processes deviated from normal operating conditions due to the high-turbidity raw water. Also, statistical analyses of the turbidity of settled water were conducted to evaluate how increases in raw water turbidity influence the coagulation and sedimentation processes. From this study, the following conclusions were made.
First, analysis of seven years of data(2018–2024) revealed that, until 2021, the DWTP-S exhibited higher maximum turbidity and earlier peak occurrence compared to the DWTP-C. Since 2023, however, the DWTP-C has shown higher peak turbidity, and the temporal difference in peak occurrence has diminished. Both the annual mean and the 95th percentile turbidity values at the DWTP-C were also higher than those at the DWTP-S, indicating a substantial shift in turbidity behavior between the two plants after 2023.
Second, the TRI was evaluated for the DWTP-C using SCADA-derived settled water turbidity data from 2023 and 2024. The median TRI increased proportionally with increases in raw water turbidity. In particular, during summer seasons with high-turbidity raw water, both the median TRI and its degree of scattering increased markedly, suggesting that the robustness of the coagulation and sedimentation processes is negatively affected during high-turbidity events.
Third, the settled water turbidity at the DWTP-C remained consistently lower than the operational target of 2 NTU. Considering this fact, the target settled water turbidity(Tgoal) was lowered to 0.5 NTU and the TRI was re-estimated. The resulting TRI values exhibited higher medians and improved visibility in the box–whisker plots. This result indicates that applying a lower Tgoal is more appropriate for interpreting TRI in facilities where settled water quality remains consistently favorable throughout the year.
Fourth, statistical analysis of daily mean settled water turbidity at the DWTP-S showed that high-turbidity raw water does affect the performance of the coagulation and sedimentation processes. However, the effect was less distinct than that observed in the TRI results of the DWTP-C.
Lastly, with the turbidity data obtained in this study alone, it was not possible to scientifically verify the hypothesis that the DWTP-C is influenced by the mid-layer high-turbidity raw water formed after heavy rain season in the Daecheong Reservoir. It is anticipated that future studies incorporating measurements of turbidity, dissolved organic carbon(DOC), UV254 absorbance, and molecular weight distribution before and after maximum turbidity events could provide stronger evidence regarding the presence of mid-layer high-turbidity raw water.

Key words : Drinking Water Treatment Plant(DWTP), Performance Evaluation, Coagulation and Sedimentation, Turbidity Robustness Index(TRI), High-turbidity Raw Water

목차 (Table of Contents)

• 목 차 ⅰ
• 표 목 차 ⅲ
• 그림목차 ⅳ
• Ⅰ. 서 론 1
• 1. 연구 배경 및 필요성 1
• 2. 연구 목적 및 내용 2
• Ⅱ. 이론적 배경 3
• 1. 상수도 시스템 3
• 1) 상수도의 역사 3
• 2) 상수도 시스템 4
• 3) 기후변화에 의한 도전 6
• 4) 신종환경유해물질에 의한 도전 7
• 2. 탁도 강건성 지수(Turbidity Robustness Index, TRI) 9
• 1) 탁도 강건성 지수(TRI)의 도입 배경 9
• 2) 탁도 강건성 지수(TRI)의 정의 10
• 3) 수정된 탁도 강건성 지수(TRI) 13
• 4) 입자 강건성 지수(Particle Robutness Index, PRI) 15
• Ⅲ. 연구 내용 및 방법 18
• 1. 연구대상 정수장 18
• 1) 한국수자원공사 C정수장 18
• 2) 대전광역시 S정수장 20
• 3) 연구대상 정수장의 취수원 22
• 2. 연구대상 정수장의 원수 탁도 조사 23
• 3. 탁도 강건성 지수(TRI) 및 침전수 탁도 평가 23
• 1) C정수장 24
• 2) S정수장 24
• Ⅳ. 연구 결과 및 고찰 25
• 1. 강우량에 따른 연구대상 정수장의 원수 탁도 변화 25
• 1) C정수장 25
• 2) S정수장 28
• 3) 강우량에 따른 원수 탁도 변화의 비교 31
• 2. 탁도 강건성 지수(TRI) 및 침전수 탁도 평가 33
• 1) C정수장 33
• 2) S정수장 44
• Ⅴ. 결론 47
• 참고문헌 49
• 영문 초록 52
• 감사의 글 55