Abstract：A pilot-scale ultrafiltration membrane plant was set up for treating Luanhe River water with flocculating and precipitation process of waterworks. The aim is to investigate the variation and characteristics of natural organic matter and disinfection byproducts formation potential in the whole process in winter. The results show that dissolved organic matter (DOM), UV 254 , trihalomethanes formation potential (THMsFP) and haloacetic acids formation potential (HAAsFP) of Luanhe River water were mainly distributed in the range of molecular weight (MW) <1 kDa, so were the membrane feed water and treated water by membrane. Specific UV absorbance, specific THMsFP and specific HAAsFP have the maximal value in the MW fraction of 1-3 kDa, except that specific UV absorbance of membrane feed water is in the range of 3-10 kDa; DOM of membrane backwash water is mainly distributed in the range of MW>30 kDa and MW<1 kDa. It is the DOM in water backwashing in up way that made significant contribution to the higher dissolved organic carbon content in membrane backwash water. However, UV 254 , THMsFP and HAAsFP were mainly distributed in the range of MW<1 kDa. The highest concentrations of specific THMsFP and specific HAAsFP appeared in the MW fraction of 3-10 kDa. CHCl 3 was the major THMs species during MBW chlorination and occupied more than 60% of the total THMsFP. Dichloroacetic acid and trichloroacetic acid were the main components in HAAsFP. The concentration of THMsFP and HAAsFP in MBW was influenced by operation period.The polluted water sources and enhancement of water quality requirements lead to the fact that the traditional treatment process cannot meet the stringent drinking water standards. The ultrafiltration (UF) membrane is regarded as a substitute of traditional drinking water treatment process for its efficient retention of particles and viruses in water [1] . The research on the distribution and characterization of natural organic matter (NOM) and disinfection byproducts formation potential (DBPFP) arouses special attention [2,3] . Variation in the amount and nature of NOM, especially with respect to changes in the aromatic carbon content, has become significant factors for designing water treatment strategies [4] . NOM in water not only produces chromaticity, turbidity and eutrophication, but also produces disinfection byproducts(DBPs), and many of them have been proved to be carcinogenic [5] . At present, most researches regarding the occurrence of chlorinated DBPs in drinking water are on trihalomethanes (THMs) formation and evolution [6] , and a few are on haloacetic acids (HAAs). In order to better remove NOM in the UF process, membrane filtration can be combined with other unit processes, such as coagulation, precipitation and adsorption [7] . Research on the characteristics of NOM in the combined process and the role in forming DBPFP may shed light on more effective solutions to controlling NOM and decreasing DBPs in the treatment process during the period of low temperature and low turbid...

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The objectives of this study were implemented to investigate the haloacetic acids formation potential (HAAFP) in drinking water treatment and determine the reduction of haloacetic acids (HAAs) during preozonation. This full-scale examination was conducted with Luan River water. Two preoxidation methods were performed, prechlorination and preozonation. HAAFP and HAA species were analyzed. The investigation indicated that 33.25% of HAAFP was removed during preozonation. Study on the distribution of HAA species showed a significant reduction during preozonation, 21.52% of DCAA, 66.20% of TCAA and 42.59% of DBAA was removed, respectively. The result suggested that preozonation process is effective to reduce HAAs generation during the treatment. In the final effluent, the total removal rate of HAAFP was 67.79%. Materials and methods Source water characterization.In this full-scale study, raw water was from the Luan River. In winter, the water is characterized by low temperature and turbidity.Treatment processes. This study was carried out in a water supply plant in Tianjin. The processes were preoxidation (preozonation or prechlorination), coagulation, clarification, filtration and final disinfection, presented in Fig. 1. About 1.0 mg/L of ozone or chlorine were added during preoxidation. The contact time was controlled at three minutes [11].