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.