Trihalomethane formation in chlorinated drinking water: A kinetic model

Aquatic humic and fulvic acids are the main trihalomethane (THM) precursors formed during surface water chlorination. The plot of THM concentration against humic substance levels is a "convex"-shape, suggesting that a multi-step reaction occurs. In the first step, organochlorine intermediates are produced, and, in the second step, these are converted to THM. A mechanistic model, based on the reaction of chlorine with model compounds, is used to derive kinetic equations for THM formation as a function of the precursor and chlorine concentrations under controlled pH and temperature conditions. This paper describes the application of this model and the correlation between calculated THM levels and experimentally measured values.