Booster chlorination for managing disinfectant residuals

Booster chlorination is an approach to residual maintenance in which chlori ne is applied at strategic locations within the distribution system. Situat ions in which booster chlorination may be most effective for maintaining a residual are explained informally in the context of a conceptual distributi on system. To form the basis of a quantitative analysis of booster chlorina tion, 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 b ooster chlorination in this example are derived and used to show the influe nce of flow rates, residence times, and decay kinetics on the effectiveness of booster chlorination. The role of booster chlorination is also discusse d as part of coordinated treatment efforts meant to manage the risks associ ated with biological regrowth and disinfection by-products.