The recirculation of a feed solution through a 30-kV electrostatic device changed the zeta-potentials of colloidal particles by ca. 40 mV (from +20 mV to -20 mV) for TiO2 nanoparticles and ca. 6 mV (from -18 mV to -24 mV) for SiO2 nanoparticles. The permeate flux of a 0.1 wt% silica solution at pH 2.6 declined rapidly, probably due to enhanced agglomeration of the colloidal particles with almost zero zeta-potentials, but the decline of permeate flux was distinctly retarded under the influence of electrostatic force at 30 kV. The electrostatic force induced the surface charge of colloidal particles toward more negative values, consequently leading to the retardation of membrane fouling as a result of increased electrostatic repulsion between colloidal particles. The resulting flux decline was fitted by pore-blocking models, indicating that the membrane fouling was caused mainly by a cake layer of foulant nanoparticles.