Booster disinfectant of water supply networks: Multiobjective approach

Booster disinfection is the addition of disinfectant at some critical locations of a water distribution network such that disinfectant residuals are maintained at a level greater than the minimum for public health. Compared to conventional methods that apply disinfectant only at the source, booster disinfection can reduce the total disinfectant dose. The present work investigates the booster facility location and injection scheduling problem in water distribution networks. The problem is formulated as a multiobjective optimization model. The objectives are minimization of the total disinfectant dose and maximization of the volumetric demand within specified residual limits. Multiobjective genetic algorithms are used for solving the problem. The model utilizes the theory of linear superposition in water quality modeling for calculating concentration profiles at network nodes. Unlike previous models, the present multiobjective approach does not require pruning of monitoring nodes to find feasible solutions; all demand nodes are considered as monitoring nodes. Application of the model to an example problem reveals that there is a critical point in the level of constraint satisfaction, after which the disinfectant dosage rate increases significantly in order to satisfy a few remaining constraints.