Fouling in beer clarification using polyethersulfone hollow fiber membranes

Hollow fiber microfiltration membranes holds promise for cost-effective concentration in beer clarification, however, membrane fouling issues still hinder its practical application. The fouling phenomenon during beer clarification is a complex process influenced by multiple organic foulants, yet the underlying mechanisms, particularly the interactions between membrane-foulant and coexisting foulant components, remain poorly understood. In this work, fouling mechanisms were investigated based on the fractional components in beer using polyethersulfone (PES) hollow fiber microfiltration membranes, with fouling behavior analyzed through the Hermia model. The results indicated that membrane-foulant interactions are relatively weak, and the adsorption of components onto the membrane surface plays a negligible role in fouling. However, under dynamic filtration conditions, fouling severity was significantly enhanced. For single components, yeast cells predominantly accumulated at the membrane surface, forming a distinct cake layer. In contrast, smaller molecular-sized components (proteins, polysaccharides, and tannins) primarily penetrated the membrane's internal pore channels, leading to pore blocking. Furthermore, the polysaccharides and tannins are easier to form aggregates with other components in the mixture, and the addition of casein further enhanced aggregate formation. These aggregates exhibited a greater impact on fouling mechanisms compared to single components, with the fouling behavior of simulated mixtures transitioning to intermediate blocking models. Importantly, these observations are consistent with results from actual beer fermentation, suggesting that membrane fouling occurs through a combination of pore blocking and cake layer formation mechanisms.