The mitigation of membrane fouling due to the mechanical scouring behavior of granular activated carbon (GAC) particles of diameters ranging from 0.9 to 4.6 mm was studied using a GAC tangential shear-membrane filtration cell, wherein GAC was directed to scour the membrane surface by a magnetic stirrer placed 10 mm above the membrane. Two membrane pore sizes (namely, 0.1 and 0.45 mu m), two permeate fluxes (namely, an above and below-threshold flux) and two operation modes (namely, continuous and intermittent filtration) were investigated. Results indicated that: (1) GAC marginally improved threshold flux values, with the benefits more significant for the larger-pore membrane; (2) For continuous filtration, the presence of GAC reduced the cake layer resistance, but increased the irreversible resistance; (3) For intermittent filtration, GAC was surprisingly less effective in reducing cake layer resistance compared to continuous filtration for the smaller-pore membrane, but did not increase the irreversible fouling resistance; (4) Both threshold flux antifouling layer resistance were independent of GAC particle diameter, which contradicts the inertial lift model and thereby affirms the dominance of the mechanical scouring behavior studied here; (5) A model developed, based on momentum transfer between the GAC particle and foulant, provided a mechanistic understanding. (C) 2015 Elsevier B.V. All rights reserved.