Chlorine Demand and TTHM Formation Kinetics: A Second-Order Model

Abstract

Much effort has been expended in attempting to develop mathematical models for chlorine demand in water and wastewater. Most of these efforts have centered around the use of first-order functions or modifications of first-order functions. Recently there has also been interest in characterizing the formation of total trihalomethanes. These efforts have taken on new meaning because of the importance of maintaining chlorine residuals for microbial protection and concerns over the formation of trihalomethanes in drinking water distribution systems. This paper applies second-order kinetics to describe both of these relationships, using data collected from a recent collaborative study between the EPA and the American Water Works Association Research Foundation. It demonstrates that TTHM formation can be characterized as a function of chlorine demand.