The microbiological safety of drinking water is an important public health matter. Even if the content of viruses in drinking water is very low, it can pose a threat to human health. The photocatalytic membrane reactor (PMR) is a hybrid reactor in which photocatalysis is coupled with a membrane process, and is a promising technology to inactivate viruses and other microorganisms. In this study, the virus removal efficiency and mechanism in an integrated PMR system was evaluated. Bacteriophage f2 (mean size of 25 +/- 1 nm), which is similar in size to the human enteric virus, was used as the model virus. The influences of filtration flux and permeation mode were tested with a continuous flow. The optimum operating conditions of PMR were determined to be intermittent suction mode with 40 L/(m(2) h) or greater of the filtration flux. PMR removed more than 5 log of phage f2 on average after 24 h of continuous operation (f2 in feed tank was 5.22 log). The f2 was primarily inactivated during the photocatalysis process, and the membrane served mainly as a barrier. The mechanism of f2 inactivation during photocatalysis process was investigated. Among the three kinds of reactive oxygen species (ROS), the hydroxyl radicals ((OH)-O-center dot) was important for the inactivation of f2, which was collected through the reaction of electron vacancy - "hole" (h(+)) and H2O. Compared with h(+), electron (e(-)) showed a stronger inactivation effect of f2. (C) 2015 Elsevier B.V. All rights reserved.