Separator's Digest 2009/1 min. - GEA Westfalia Separator Group

The ceramic membrane in
cross-flow filtration is the
most efficient method of
juice filtration.
Avoiding retentate
Membrane technology is suitable for maximum concentration of the solids in the
retentate, thereby reducing the overall retentate volume.
The quantity of retentate is reduced if decanters are used for juicing
in normal processing. In principle, this use of centrifugal technology
with decanters features the lowest trub level. However, the solids
content can also be reduced to a minimum with a separator for
clarifying the juice. This means that the quantity of trub, which
forms the subsequent retentate, is limited right from the very
beginning.
In the next stage, the process of continuing this idea for reducing
the general volume of retentate results in maximum concentration
of the solids in the retentate. Polymer and ceramic membranes are
suitable for this purpose, with system-related differences. A ceramic
membrane is much more stable with regard to pressure, and is thus
able to provide a retentate with a solids content of up to 90 percent
(by volume). Compared with a plastic membrane, the concentration
factor is thus three times as high. Such a high concentration of
the solids requires no further treatment of the retentate. A ceramic
membrane in cross-flow filtration is thus the most efficient method
used for juice filtration. The use of decanters and ceramic filtration
is therefore always recommended for a new installation or
whenever an existing operation is extended.
Solids content reduced by a centrifuge
upstream of filtration
Diafiltration is the simplest way to achieve an additional benefit
from the retentate, in order to generate a profit from waste costs.
In many areas, it is better known as desweetening. At the end of
the filtration stage, water instead of turbid juice is added to
the filtration cycle. The cost-effectiveness of desweetening must be
determined for each individual case. Process engineering measures
enable the filtration cycles to be extended and thus the number of
cleaning and diafiltration runs to be reduced.
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Separator’s Digest 1 | 2009
GEA Westfalia Separator Process