Membrane bioreactor (MBR) systems are an established technology for the domestic and industrial wastewater treatment, but efficient fouling reduction by air sparging remains an operating problem and design rules still are of a purely empirical nature. Therefore, many modeling approaches have been proposed to solve these operating problems and increase the process efficiency. Several experimental and computational studies have been done to access more efficient separation in different membrane application. Recently, computational fluid dynamics (CFD) has been widely used for hydrodynamic simulation of fluid on the membrane surface and pores, modeling mass transfer rate and further predicting the fouling layer. It provides a method for finding the most effective design features at fundamental level. Especially CFD has been preferred to simulate the fouling problem in MBR systems because these systems have highly energy dependent technologies due to air sparging to control fouling. However, designing and optimization of submerged MBRs can be done through CFD simulations and mathematical modeling. This paper aims to summarize both effective design and optimized parameters of submerged MBRs using flat sheet and hollow fiber membranes considering the CFD studies in literature.