Molecular Size Distribution of Dissolved Organic Matter in Water of the Pearl River and Thrihalomethane Formation Characteristics with Chlorine and Chlorine Dioxide Treatments

River water sample from Guangzhou section of the Pearl River to investigate soluble fractions and formations of trihalomethane (THM) after chlorine and chlorine dioxide treatments was collected. The water sample was passed through Amicon super( registered ) YC-05, YM-1, YM-3, YM-10, YM-30, YM-100, and ZM-500 series membranes after a pre-treatment. The molecular weight distribution and the specific ultra-violet absorbance (SUVA-254) of each fraction obtained from membrane were analyzed and were further disinfected with chlorine and chlorine dioxide. The THMs concentration and SUVA-254 increased gradually as the molecular weight of the obtained fractions reduced. Between the two disinfection processes tested, chlorine dioxide produced less THMs than chlorine.