Characterization and fouling properties of exopolysaccharide produced by Klebsiella oxytoca

Klebsiella oxytoca produced a type of exopolysaccharide (EPS) with the average molecular weight (Mw) of 116,018 Da and the average size of 260 nm. The EPS monosaccharide components contained rhamnose, fucose, arabinose, xylose, mannose, galactose and glucose and the molar ratio among them was 0.033:0.0411:0.0147:0.0051:0.2393:0.0986:0.1304. Typical EPS absorption peaks in FT-IR spectrum and pseudoplastic properties were also revealed. The polyvinylidenefluoride (PVDF) membrane showed a relatively larger flux decline resulted from the EPS fouling. The EPS filtration was dominated by more than one mechanism at the beginning phase and mainly by the cake formation at the later phase for both membranes. The pore blocking resistance had a predominant contribution to the filtration resistance and the cake resistance played a secondary role for both the membranes. The EPS adsorption resulted in a weak membrane fouling. The PVDF membrane exhibited a larger adsorption resistance than the polypropylene (PP) membrane.