Booster chlorination for managing disinfectant residuals

Booster chlorination is an approach to residual maintenance in which chlorine is applied at strategic locations within the distribution system. Situations in which booster chlorination may be most effective for maintaining a residual are explained informally in the context of a conceptual distribution system. To form the basis of a quantitative analysis of booster chlorination, experiments simulated chlorine decay under booster conditions. These experiments suggested a conceptual model for bulk chlorine decay, which is used to analyze an example representing a header pipe serving two distinct zones in a distribution system. The chlorine mass savings associated with booster chlorination in this example are derived and used to show the influence of flow rates, residence times, and decay kinetics on the effectiveness of booster chlorination. The role of booster chlorination is also discussed as part of coordinated treatment efforts meant to manage the risks associated with biological regrowth and disinfection by-products.