In this study, the growth of biofouling layer on the FO membrane
surface in OMBRs was in-situ investigated using multiple
fluorescence labeling and CLSM. The CLSM images of aand
b-D-glucopyranose polysaccharides, proteins and total
cells were obtained by staining with the fluorescent probes of
ConA, CW, FITC and SYTO 63, respectively, and their structural
parameters were computed by the softwares of PHLIP
and Image J. The following conclusions could be drawn:
(1) b-D-Glucopyranose polysaccharides were easier to deposit
on the FO membrane surface compared to a-Dglucopyranose
polysaccharides. The biovolume of b-Dglucopyranose
polysaccharides significantly increased
during the growth of biofouling layer, and that of proteins
dramatically increased from the 3rd to the 8th day
and then leveled off. However, the a-D-glucopyranose
polysaccharides and total cells decreased after their
increase from the 3rd to the 8th day.
(2) Except for the dominant role of microorganisms in the
initial formation of fouling layer, microorganisms were
seldom detected on the upper fouling layer after 3 days.
Furthermore, EPS was much more abundant than
microorganism according to the intensity variations
with the distance of biofouling layer. These results
indicated the significant role of EPS in the formation and
development of biofouling layer.
(3) The development of biofouling layer on the FO membrane
surface in OMBRs could be divided into three
stages. In stage 1, the free EPS including polysaccharides
and proteins firstly deposited on the FO membrane
surface, and then cells embedded in a matrix of EPS to
form clusters. After the initial formation of the
biofouling layer, the clusters of EPS and microorganisms
dramatically increased on the FO membrane surface,
resulting in the quick growth of biofouling layer. However,
when the operating time of the OMBR further
extended, the increase of EPS and microorganisms
became slowly, and some of them were easy to detach
from the biofouling layer.