3.3.2. SEM–EDX analysis of the membrane
Four pieces of the new membrane and the top, middle, and bottom parts of the used membrane (operated under an HRT of 5 d)
were collected for SEM–EDX analysis to investigate the extent of
fouling. The SEM micrograph (data not shown) shows that the fibers of the new membrane were clearly visible and randomly distributed to form the porous structure of the membrane. In contrast,
the three parts of the fouled membrane were observed to be covered with a dense cake layer. A similar phenomenon was reported
by An et al. (2009) to be caused by biofouling on the membrane
surface (Meng et al., 2007).