Following pilot scale trials in comparison with polysulphone and polypropylene membranes, alpha aluminium oxide ceramic membranes were selected for the cross flow filter system installed in 1988 at the DAB brewery in Dortmund, Germany, for recovering beer from spent yeast. The fully automatic system is rinsed with hot water after each filtering operation, which can take from 5 to 65 (average 17) hours depending on the yeast filterability, and given a full CIP treatment once a week. The recovered beer is blended into the whirlpool wort. Concentrations of up to 3% have proved to be organoleptically and analytically undetectable in the finished beer. Neither chemical nor microbiological contaminants have been found in the recovered beer up to the time of writing, nor have any processing problems been experienced. A comparison of the costs of the equipment and the value of the recovered beer shows that such a system can be expected to pay for itself in 3 years or less.
Keywords : beer cross flow filter membrane recovery yeast