Assessment of trihalomethanes formation during the treatment of surface water in coastal areas

Abstract

With the impact of global climate change, saline intrusion into surface water in coastal areas has become a major issue. The water treatment using surface water in these areas has to deal with double issue including organic matters and salinity. This paper evaluated the trihalomethanes (THMs) formation during the treatment of surface water at pilot scale using different disinfection dose and at different salinity levels. The initial results revealed that Chloroform and Bromoform were all met the standard for domestic water at any residual chlorine concentrations, however, Bromodichloromethane and Dibromochloromethane compounds were all found higher than the acceptable values when the residual chlorine concentrations were greater than 0.4 and 0.8 mg/L, respectively. In addition, the higher salinity, the higher values of THMs were obtained. With the impact of salt intrusion, the presence of Br^- was more available in the river which increased the chances of forming Bromodichloromethane and Dibromochloromethane substances. As a result, it is recommended to control completely organic matters in the treated water before using chlorination for disinfection, when employing surface water in coastal areas.