Facility location model for booster disinfection of water supply networks

Secondary or postdisinfection is widely used to maintain protective levels of disinfectant within water distribution systems. In contrast to conventional methods that apply disinfectant only at the treatment works, booster disinfection reapplies disinfectant at strategic locations within the distribution system to compensate for the losses that occur as it decays over time. Building on the writers' previous work, this paper addresses the problem of locating disinfectant booster stations that minimize the dosage required to maintain residuals throughout the supply network, and introduces a useful parameterization for disinfectant source types. The model is related to the general fixed-charge facility location problem and is formulated as a mixed integer linear programming problem. Results for an example network show that disinfectant dosage savings are achieveable with the adoption of booster disinfection, and that the rate of savings decreases as the number of booster stations utilized increased. Furthermore, booster disinfection may provide a more even distribution of disinfectant concentrations, throughout the network, and has the potential to reduce aggregate exposure of the population to chlorine (and its by-products) while simultaneously improving residual coverage in the periphery of the distribution system.