Fouling of organic microfiltration membranes by wine constituents: importance, relative impact of wine polysccharides and polyphenols and incidence of membrane properties

Abstract

Microfiltration experiments, along with biochemical analyses and scanning electron microscopy observations, were used to investigate the ability of wine soluble constituents to foul organic cross-flow microfiltration membranes, to weight the respective impact of polysaccharides and polyphenols and to determine the incidence of membrane surface polarity in fouling. Three organic membranes were used, presenting similar rated average pore size and differing by their pore size distribution and their polarity. Though much smaller than the membrane average pore size, wine polysaccharides and polyphenols induced sharp flux declines within the first minutes of the process that could not be attributed to adsorption alone. Results suggested that flux losses were related to the aggregation of wine constituents at the pore entrance and on the membrane surface, induced by permeation fluxes. On the whole, polysaccharides had a higher impact on membrane permeability than polyphenols. Due to its strong incidence on polyphenol deposition, membrane polarity had a large impact on the building of the fouling deposit. However, the amounts of deposited polysaccharides and polyphenols alone could not account for the differences observed between membranes in terms of fluxes. Considering the mechanism proposed for membrane fouling (interactions between wine constituents) these differences were well explained by the differences in the pore size distribution of the three membranes.