Question

2. Filtration of a beer containing a protease
We have a broth of Bacillus subtilis for producing the enzyme protease. To separate the biomass, Celatom, a filter aid has been added 1.3 times the biomass, which yield a beer containing 3.6 % by weight of solids. The viscosity of the beer is 6.6 cP. With a Buchner funnel 5 cm in diameter attached to an aspirtator, it is found that 100 ml of the broth can be filtered in 24 min. previous studies with this type of beer have had a compressible cake with s equal to 0.67.
We now feed to filter 300 litre of this material in one of the pilot plant’s plate and frame filter presses. This frame has 15 frames each of area 3520 cm2. The spacing between these frames can be made large. This is an advantage, because we can then filter all the beer without emptying the press and hence reduce the risk of contamination. The resistance of filters themselves is much smaller than the filter cake. The total pressure drop which can be used is 65 psi.
How long will it take to filter this beer at 50 psi?
How long will it take at half the pressure drop?​

Answer 1

Answer:

The efficiency of separating wort from the mash is highly dependent on the large molecules dissolved in the liquid. The high-molecular-weight molecules are present in various cereal grains, but in different amounts and ratios. For example barley, oats and sorghum have more than twice as much β-glucan as xylans, while it is the opposite with wheat and rye.

β-glucans and arabinoxylans create high wort viscosity, which dramatically reduces the speed of mash filtration. They stick to filter aids and filter membranes. They also stick to starch molecules, making them less available for enzymatic degradation. That can result in a lower brewhouse yield or cause haze.­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­