The fluid flow through a spacer-filled disk-type membrane module was investigated using a computational fluid dynamics (CFD) technique. The properties of fluid flow through a membrane module depend on its geometry, in this case, the collection-tube size and the spacer thickness. This study focused on the influence of the geometry of the membrane module on the volumetric flow rate, permeate flux and the distribution of permeation rates in a spacer-filled disk-type membrane module. The numerical results showed that there were variations in the volumetric flow rate and permeation rates with differences in construction. The optimum permeate flux occurred with a collection-tube size of 15-20 mm and a spacer thickness of 0.75-1.00 mm. An understanding of the microscopic fluid flow in a membrane module based on CFD analysis could improve the design of collection tubes and spacers to enhance module performance and facilitate the construction of new designs. (C) 2011 Elsevier B.V. All rights reserved.