Disinfection
of water by chlorine produces a number of halogenated disinfection by-products
(DBPs). Trihalomethanes (THMs) and haloacetic acids (HAAs) are the domin0ant
species found in finished drinking water. Several toxicological studies shown
some disinfection by-products (DBPs), including certain (THMs) and (HAAs), to
be carcinogenic in laboratory animals. Due to all these potential problems
associated with the formation of disinfection by-products (DBPs) during the
free chlorination of drinking water have been well documented and due to the
health risks associated with them, the US Environmental Protection Agency
(USEPA) began regulating the levels of these disinfection by-products (DBPs) in
finished drinking water in 1979.  Many
researchers suggested different procedures in order to minimize the
concentrations of the formed DBPs. These procedures based upon the decreasing
of the natural organic matter (NOM) in the raw water e.g. ultrafiltration
(UF)–nanofiltration (NF) combined membrane process which showed better removal
efficiency of NOM. Another studies suggested usage of another disinfectants
e.g. ozone.  This study aimed to minimize
the concentrations of the (DBPs) via the optimization of the added chlorine
dose which complies with the microbiological requirements. Also the effect of
temperature on the formed DBPs was studied. The results showed that the
concentrations of the various (DBPs) are inversely proportional with the
temperature. Also this study suggested another procedure to calculate the most
suitable chlorine dose.