Assessing measurement uncertainty on trihalomethane prediction through kinetic models in water supply systems

Disinfection of drinking water through chlorine is commonly used in many countries for reducing pathogenic infection problems, but it may pose a risk to human health due to the formation of some byproducts, such as trihalomethanes (THMs). For an adequate management of the disinfection process, it is useful to have models capable of simulating THM concentrations in water supply systems. However, a crucial aspect is the reliability of their performances when used on real systems and the knowledge of the uncertainty of their predictions. The objective of the present paper is to investigate the simulation of THM formation through calibrated kinetic models, along with the assessment of the measurement uncertainty on the parameters' estimate and on the model predictions. In particular, a first order, a second order and a two-phase kinetic model are considered, while the effect of measurement uncertainty is mainly investigated through the first order second moment (FOSM) method. The analysis performed on a real case study shows that the three considered models have similar performances in terms of predicted concentrations, which suggests using the simplest first order one. Moreover, the FOSM results reveal that the first order model is also less affected by measurement uncertainty.