An investigation on parameters for modeling THMs formation

Reactions between natural organic matter (NOM) and chlorine during disinfecting drinking water form trihalomethanes (THMs) and other chlorinated by products (CBPs), some of which are possible carcinogen to human health. A number of models have been developed to predict THMs formation since the discovery of THMs in drinking waters. A fraction of these models used a total of 22 different parameters while individual models used 3 to 8 parameters. Some existing models incorporated more than one parameter from total organic carbon (TOC), dissolved organic carbon (DOC) and UV absorption capacity at 254 nm (UV₂₅₄), while all of these three characterize NOM in water; thus, there exist a possibility of illconditioned coefficient estimation. This paper presents the results of an experimental investigation on different parameters from four water supply systems in Newfoundland, Canada. Strong correlations were found among total organic carbon (TOC), dissolved organic carbon (DOC) and UV absorption capacity at 254 nm (UV₂₅₄). This study along with the past studies identified pH, temperature and reaction time as significant for THMs formation; however, some existing models ignored these parameters. Although these models have good performance in predicting THMs formation in respective environmental conditions, some models might suffer weakness from mathematical point of view; thus needs to be carefully applied. This study recommends using one parameter from TOC, DOC and UV₂₅₄ and chlorine dose, pH, temperature and reaction time for future modeling.