FTIR spectra of the fouled membranes are shown in Fig. 9. The
main absorption bands in Fig. 9A and B were in the vicinity of
1631 cm1 (CQO stretching of amide I, quinone, and ketones),
1563 cm1 (N–H deformation, C–N stretching of amide II and
symmetric stretching of COO–), and 1078 cm1 (C–O stretching of
polysaccharides). The band in the vicinity of 1400 cm1 could be
due to aliphatic C–H deformation, C–O stretching or O–H deformation
of phenol. The band in the range 600–800 cm1 could be
representative of aromatic compounds. These results suggest that
the constituents of the membrane fouling matter included proteins,
polysaccharides, and aliphatic and aromatic compounds
derived from organic or microbial matter. Fig. 9C, which represents
the pilot plant module from the 7th element showed a weaker
shift than the previous membranes at the vicinity of 1078 cm1
(C–O stretching of polysaccharides) and at 1563 cm1 (N–H
deformationþC–N stretching of amide II) protein contents. As
expected, the samples collected from the first module (and from
the entrance to the module, in the case of the pilot plant
autopsies) suffered the most from organic and biological foulants.
The FTIR results indicate that the first module acted as a “pretreatment”
stage for the entire train and therefore it was the most
fouled in the commercial and in the pilot plants.