Performance of Various Kinetic Models for Chlorine Decay

A number of computer packages have been developed for modeling chlorine decay in water distribution networks. However, there is uncertainty as to the kinetic model that they should use for the decay mechanism. This paper explores the performance of six different kinetic models for the decay of free chlorine in over 200 bulk water samples from a number of different sources. The paper also presents the results of surveying the longitudinal decay profile of free chlorine in two in situ pipe stretches. It concludes that, for network modeling purposes, it is generally reasonable to assume first-order kinetics for bulk and overall decay.