Comparison between empirical formulae and a first order kinetic model for modelling trialomethanes formation in water systems

Chlorination is the most widely used method for disinfection of drinking water, being very effective and relative inexpensive. However there are concerns about the formation of chlorination by-product, such as trihalomethanes (THMs), since the chronic exposure to them may pose risks to human health. For striking a balance between protection from microbiological risks and the risks connected to byproducts, it is necessary to maintain throughout the distribution system free chlorine residual above a minimum value and the THMs concentration below a maximum level. For these reasons it is very important to be able to correctly reproduce THMs formation in water distribution systems. In literature many models for predicting THMs formation, based on empirical relationships, have been proposed. In this work 18 literature empirical models have been selected for investigating their reliability in real situations through the application to a real water supply system in Southern Lazio (Italy). The comparison of the performances of such models furnishes interesting observations. The predictions of the empirical models are also compared with the results obtained using a simple first order kinetic model, calibrated using measured data.