A Comparative Study on a Hydraulic and Water-Quality Analysis Method for Determining Rechlorination Injection Points for a Water-Supply Network

Abstract

Water supply facilities are vulnerable to extreme weather events, such as droughts and floods. To establish a sustainable solution that resists accidents and disasters, a distributed system is required. To supply high-quality tap water using the existing water-supply network, rechlorination facilities must be installed to secure residual chlorine at the pipe end. In this study, a process is developed to determine the injection points and dosages of rechlorination using the latest pressure-driven analysis. The method was compared to the results of demand driven analysis methods. The proposed model was applied to P City in Korea to draw results. A detailed evaluation was performed to study how water pressure head and demand-based hydraulic and water quality analysis results impact the injection points and dosages of rechlorination. Thus, the existing demand-based model shows significant spatial deviations in the pressure head in the presence of water pressure drops, which subsequently lead to over-estimation of chlorine injection dosages for maintaining the concentration of residual chlorine. However, the proposed model involves a numerically validated theory and draws more reasonable results for hydraulic, water quality, and rechlorination dosages. The proposed model can be used as a decision-making tool based on hydraulic analysis for the supply of water of a stable quality.

Emerging Issues and Methodologies for Resilient and Robust Water Distribution Systems

“…It was confirmed that a PDA-based solution tends to locate the injection points at an upstream divergence, whereas DDA-based solutions locate them at the end of a branched network. Similar to Yoo et al [2], Lee et al [5] highlighted the importance of a realistic network simulation (PDA) in performing WDS resilience studies that are mostly based on abnormal failure conditions (e.g., low pressure from a pipe break). In future studies, methodologies to minimize the risk originating from having multiple distributed rechlorination facilities (e.g., rechlorination ROB) could be developed to maintain the residual chlorine concentration, even under the failure of a single chlorine injection point.…”

“…While category (3) included visualization methods to represent the system's criticality, category (2) summarized three papers to improve the capacity of WDS to supply customers' demands under earthquakes, a representative catastrophic failure event for resilience. Studies included in themes (4) and (5) proposed novel design methods and monitoring approaches for improving WDS resilience, respectively. The contributions of each study were described in the context of WDS resilience.…”

“…Therefore, implementing efficient early warning systems, maintaining the high preparedness of emergency recovery teams and constructing reliable and rapid two-way communication systems between the supervisory control and data acquisition system (SCADA) and remotely located booster stations could help improve the rapidity [20]. Contributions have been made regarding this topic by Jun and Kwon [1] and Lee et al [5] who developed methods for pressure monitoring and chlorine injection locations, respectively.…”

“…Lee et al [5] proposed an optimal chlorine injection (location and dosage) model to minimize the total mass of chlorine injected per day given the constraints on the residual chlorine concentration and the number of rechlorination facilities to be installed. Optimal solutions were sought by a greedy algorithm with a demand-driven analysis (DDA) and independent PDA for hydraulic and water quality simulations of a network for the constraint check.…”

“…The papers are sorted in the order of publication date (Jun and Kwon [1], Yoo et al [2], Choi and Kim [3], Diao et al [4], Lee at al. [5], Jung et al [6], Lee et al [7], Kim et al [8], Balut et al [9], Lee et al [10], Li et al [11]). Among the 11 papers, Yoo et al [2] received the largest number of full-text views, whereas the abstract of Kim et al [8] was viewed the most often.…”