Fouling potentials of polysaccharides in membrane bioreactors (MBRs) assessed by lectin affinity chromatography

In this study, the fouling potentials of polysaccharides contained in mixed liquor suspension in a membrane bioreactor (MBR) treating municipal wastewater were investigated using lectin affinity chromatography. This investigation was carried out with different membranes to assess the effects of membrane materials on fouling potentials of polysaccharides. In lectin affinity chromatography, some polysaccharides with high affinity to the lectin in the column can be retained in the column. The fouling potentials of the retained polysaccharides were evaluated by dead-end filtration test. Degree of reduction in fouling potential differed considerably when different lectins were used in affinity chromatography indicating that fouling potentials of polysaccharide differed depending on types of polysaccharide. Trends in the reduction of fouling potential were different depending on membrane materials. Characteristics of the organic matter associated with polysaccharides removed by lectins were investigated by means of excitation-emission matrices (EEM). The results of EEM analysis indicate that the characteristics of the organic matter eluted from different lectins were different as long as elution reagents for the lectin were different. Characteristics of the organic matter eluted from the lectins which have the same elution reagent were similar in terms of shapes of EEM fluorescence spectra. However, the trends in reduction of fouling potentials could not be explained by the characteristics of organic matter assessed by EEM analysis. On the basis of the results obtained in this study, it can be concluded that characteristics of membrane and structures or properties of sugar chain would play an important role in determining fouling potentials.