This study investigated the performance and mechanisms of a novel pilot-scale bio-diatomite dynamic membrane reactor (BDDMR) for slightly polluted surface water treatment in continuous-flow mode. The results revealed that the pilot-scale BDDMR was very effective at reducing particle number and removing turbidity, chemical oxygen demand (CODMn). UV absorbance at 254 nm (UV254), NH3-N and trihalomethane formation potential (THMFP) with a hydraulic retention time of 8 h. The transmembrane pressure (TMP) of the dynamic membrane was invariant for each selected flux, i.e., 30 L/m(2) h, 50 1./m(2) h and 80 L/m(2) h, in the early filtration stage and rose quickly to 4.5 kPa in the final stage of the operation period. Based on the results of the three-dimensional excitation and emission matrix fluorescence spectroscopy (3D-EEM) observation, the aromatic protein-like substance in the influent was removed effectively. In addition to suspended solid separation, the BDDMR could partially remove a MW 1000-3200 Da of dissolved organic matter (DOM). Three individual effects responsible for removing pollutants were investigated. The polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) was also used to verify the shift of microbial communities in the mixed liquor. (C) 2011 Elsevier B.V. All rights reserved.