Abstract:This study employed coagulation-sedimentation-submerged microfiltration membrane process to treat raw water from Taihu Lake and investigated the variation of hydrophilicity/hydrophobicity and molecular weight (MW) of organic matter along this treatment process. The organic component of chemical cleaning water was also analyzed to confirm the main material composition causing the membrane fouling. Coagulation pretreatment could effectively remove organics with hydrophilic macromolecules responsible only for reversible fouling, but showed less effective in removing the mid- and low-MW organic matters responsible for irreversible fouling. In addition, three dimensional excitation-emission matrix (3DEEM) fluorescence spectra exhibited that the two regions closely related to membrane fouling were: λex=230nm/λem=330~350nm (RegionⅠ) and λex=280nm/λem=300~350nm (Region Ⅳ). The corresponding organic foulants in the two regions were extracellular protein-like organics and soluble microbial products (SMP), which were responsible for irreversible fouling.