Calibration of kinetic constant for predicting trihalomethanes formation in water distribution networks.

Chlorination is the most widely used method for disinfection of drinking water, but there is concern about the presence in treated water of trihalomethanes (THM), formed as a by-product of chlorine decay. In fact, they are potentially carcinogenic for humans and many countries have established maximum acceptable THM levels. Therefore, it is very important to have models able to predict both THM and chlorine residual levels in water distribution networks. The application to real water systems of many predictive methods proposed in literature presents difficulties and in many cases do not furnishes good results. The paper presents a method for calibrating the reaction constants of both a first and a second order kinetic model, adopted for simulating simultaneously chlorine decay and trihalomethanes formation in water distribution networks. The procedure is applied using data collected on a real water system: the Aurunci-Valcanneto aqueduct in Southern Lazio (Italy).The results furnish indication on the effectivness of the application of such approach to real world situations.