394687 - Optimal Placement and Operation of Booster Chlorination Stations using an Advection-Dispersion Multi-Species Reactive Transport Model
Wednesday, June 6
2:00 PM - 3:30 PM
Location: Lakeshore C
Pratim Biswas, St. Louis, MO – Washington University in St. Louis
Chlorine is widely adopted by water supply utilities as the disinfecting agent of choice for drinking water treatment. A sufficient residual concentration is typically maintained in the distribution system to prevent microbial recontamination of the treated water as it transports through the pipes of the network. However, applying large doses of the disinfectant at the treatment point has traditionally been associated with several issues, including taste and odor problems near the source locations and high DBP levels at the far ends of the distribution network. As an alternative, booster chlorination can be implemented to overcome these hurdles by injecting the disinfectant at multiple locations with smaller, more distributed, doses. Finding the optimal design and operation of booster chlorination stations has been addressed by multiple previous studies, with the majority of these studies only accounting for chlorine decay. Recent studies have highlighted the importance of incorporating DBPs formation either in the constraints based on regulatory levels, or in the formulation of the objective function to minimize their concentrations. To model DBP formation kinetics, advection-based multi-species water quality models, e.g. EPANET-MSX, were typically implemented. Nevertheless, these models do not account for dispersion as a solute transport mechanism, and are hence not capable of accurately simulating constituent transport in low-flow pipes and dead-end zones. These zones are particularly known to be responsible for most of the water quality degradation in the system due to extended residence times, and therefore require a special modeling approach. In this study, we developed a multi-species reactive-transport model that considers both advective and dispersive transport mechanisms as well as the spatiotemporal variations in the flow-demands. The model will be used to explore the booster chlorination optimization problem. The effect of including dispersive transport in the low-flow pipes on the optimal placement and operation of the boosters is discussed.