BEER CLARIFICATION BY CROSS-FLOW MICROFILTRATION - FOULING MECHANISMSAND FLUX ENHANCEMENT

An experimental study of beer microfiltration has been carried out on ceramic membranes with the eventual aim of carrying this process throu gh to the commercial scale. Enhancement of surface hydrodynamics throu gh flow pulsation had little impact on flux suggesting that pore block ing by in-depth adsorption/deposition was the dominant factor and this was indeed found to be so. The nature of the foulants has been determ ined by studying the filtration rates of beer treated with various enz ymes which degrade potential foulant species. Specific classes of carb ohydrates and minerals have been identified as foulants. In particular , pentosans (carbohydrates composed of 5 numbered sugar rings) make a major contribution. A multi-stage backflush programme was developed an d optimized in an attempt to achieve maximum pore clearance with minim al use of permeate and time. Moreover, when backflush (BF) was employe d, staged increases in trans-membrane pressure had a more positive imp act on flux improvement. The effect of membrane pore size on product q uality and flux was also investigated in this work. Use of the BF prog ramme achieved a flux improvement of 400%.