Co-Optimization of Valve Placement and Chlorine Dosing in Water Distribution Systems

The primary objective of water distribution systems (WDSs) is to ensure a high-quality water supply. Chlorine, commonly used as a primary disinfectant in WDSs, requires precise control of its concentration to safeguard public health. However, the complex network structure and its highly nonlinear dynamics inherent in a WDS pose significant challenges in chlorine management. This study proposes an optimization approach to tackle these challenges by leveraging different kinds of valves to distribute water flow within the network, thereby realizing both chlorine and pressure management. A simplified chlorine propagation model is introduced, based on which three optimization problems are formulated and solved to compute optimal management strategies. The first one is a nonlinear programming (NLP) which minimizes source dosing across the WDS by an optimal distribution of the water flow in the pipelines, leading to a lower bound for the chlorine management. The second one is a mixed-integer nonlinear programming (MINLP) problem to localize isolation valves (IVs) and achieve a realistic and practical solution. The third one extends the MINLP framework to integrate pressure reducing valves (PRVs), optimizing the placement of both IVs and PRVs to enable a multi-objective approach that minimizes chlorine dosing while regulating the system pressure. The results of a benchmark demonstrate that the integrated use of IVs and PRVs significantly enhances the performance of both chlorine concentration and pressure regulation, offering an efficient solution for WDS management.