The overall objective of this research was to characterize and provide morphological analyses of low-pressure membranes comparing clean and fouled membranes. Atomic force microscopy shows that a clean PES membrane is relatively smooth while a clean regenerated cellulose membrane is rough. Fouled UF membrane in AFM image analysis demonstrated that the roughness increased for the smooth PES membrane and decreased for the rough YM membrane demonstrating evidence of surface coverage. Both clean membranes have been visualized by field emission scanning electron microscopy (FESEM). Image analysis of scanning electron microscopy (SEM) applied to MF membranes provides explanations of fouling mechanisms associated with reduced pore size, pore blockage, and/or surface (gel layer) coverage. Images obtained with SEM and FESEM for each membrane have been quantified with porosity, pore density, mean pore radius and pore size distribution using an image processing program. Includes tables, figures.