A variable rate coefficient chlorine decay model

Chlorine is the most widely used water disinfectant in the world. As a result, optimal chlorine usage is essential for both human and environmental health. Chlorine decay models can be used to predict residual concentrations in water distribution networks and optimize chlorine dosing. However, the coefficients of current chlorine decay models are often dependent on the loading conditions and are therefore impractical for day-to-day water distribution network modeling purposes and chlorine dosing optimization studies. This study proposes and assesses a novel numerical chlorine decay model with four parameters that are independent of the loading conditions for a given water sample. The model is based on kinetic equations derived from the rate law for concurrent bimolecular second order reactions with chlorine and will be referred to as the variable rate coefficient (VRC) chlorine decay model. The performance of the proposed model is compared with another model reported in the literature, and the VRC model is also assessed for reliability with data sets that are omitted during model calibration. The VRC model is consistently found to be in agreement with the experimental data.