Rough beer filterability in industrial powder-filters and lab-scale dead-end and crossflow filtration apparatuses

Abstract

Rough beer clarification in large-sized breweries is mainly carried out using powder filters. In this work, it was attempted to explain why two rough beer samples yielded quite different filtrate volumes (~965 vs. 2,068 hL) from industrial-scale powder filters coated with equal doses of filter-aids of the same nominal permeability, but of different lots. By resorting to a bench-top dead-end filtration apparatus, the above 50% reduction in beer filterability was attributed to the lots used, the permeability of the corresponding filter cakes slightly varying from ~0.19 to 0.25 Darcy. When using a bench-top plant equipped with a 0.8-µm ceramic tubular membrane operating under constant values of the transmembrane pressure difference (3.73 bar), feed superficial velocity (6 m.s-1), and temperature (1.5 °C), the volumes of permeate recovered, as well as the limiting and average permeation fluxes, were not statistically different. Thus, membrane clarification of rough beer may overcome the intrinsic variation in the particle size distribution of commercially available filter-aids of the same nominal permeability.