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ON-SITE LEES
FILTRATION
Technoquip has been filtering lees in the Californian wine industry for the past
14 years. Recently VA Filtration bought Technoquip to add LEES FILTRATION
to its array of mobile services offered. Please note that this service is
only available in California at present.
WHY
SHOULD YOU CONSIDER FILTERING YOUR LEES?
Many people
dispose of their lees believing to be of no value. That is where you are
wrong! Have a look at the following example (very rough estimate):
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10 000
gallons of sauvignon blanc juice at $1.00/gallon picked, crushed
and in tank.
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This 10 000
gallons produces say 5% lees equating to 500 gallons.
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500 gallons of
lees contains approximately 80% juice i.e. 400 gallons recovered at say
$675.00.
-
Let us assume
that you can get $3.00/gallon for the finished wine, then this recovered juice
would be worth $1200.00
-
Take into
account the money you would have wasted if you sent the lees to waste i.e.
$500.00 for purchasing, picking and crushing.
-
Do the math and
voila, you have generated $1 025.00 out of a waste product or 3.5% profit!
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If this product
happens to be a higher end wine and sold by bottle, then the profits would be
even higher!
You have to ask
yourself one question - If you saw a cellar worker running 400 gallons of wine
down the drain during a shift, would you get upset? If you answered yes to
this question, then why would you not consider recovering your lees?
BUT
LEES FILTERED WINE IS OF LOWER QUALITY!
We have heard
this often, but this is not strictly true in all cases. If the lees are
kept cool, gassed and sulfured after the wine or juice has been racked off, the
recovered product can be of a very good quality. It is only if the lees
are left for too long and then filtered that the quality deteriorates and the
wine can be subject to bacteria spoilage or any other problem you can think of.
We can do volumes as low as 250 gallons at a time if required.
HOW
DOES THE ROTARY DRUM VACUUM FILTER WORK?
There are two
known ways of filtering the really thick settled solids found at the bottom of
tanks or drums. i.e. vacuum filtration (rotary drum vacuum filter) or pressure
filtration (filter press). We use vacuum filtration. The process
itself works as follows:
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A rotating
stainless steel drum having a screen on the outside and vacuum on the inside
is first coated using diatomaceous earth to approximately 50 mm (2 inches)
thick. This becomes the filter media that traps the solids while
allowing the wine or juice to pass through to the inside of the drum.
The layer of D.E. is held to the drum via a pressure differential between
the inside of the drum (partial vacuum) and atmospheric pressure on the
outside of the D.E. If the vacuum fails, the filter cake falls away
from the drum - ugly!
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The wine is
then fed to a trough located underneath the drum, through which approximately
15% of the surface of the D.E. on the drum rotates at any one time. By way
of pressure differential (i.e. higher pressure on the outside of the D.E. than
on the inside of the drum) the fluid (wine or juice) will make its way to the
inside of the drum through the tiny open pores within the layer of D.E. As
this occurs, the solids, being larger than the pore size between the D.E.
particles, are trapped in these pores blocking the fluid path and decreasing the
filtration rate. In order for the filtration to continue, this surface
requires unblocking i.e. the filtration media requires renewal.
-
The surface of
the D.E. is renewed using a knife which scrapes away the layer of suspended
solids trapped on the surface. At the same time, a very thin layer of D.e.
is scraped off leaving a fresh surface for filtration purposes. As the
drum rotates this procedure is repeated on a continuous basis resulting in a
fresh layer of D.E. being exposed to the lees. Since the layer of D.E. on
the drum is 50mm (2 inches) thick, it can be renewed continuously until such a
time as it has all been scraped off. The scraped off solids fall into a
bin for disposing of at a later stage.
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Once there is
no more filter media on the drum, the D.E. is simply replaced allowing
filtration to continue.
WHAT DOES TECHNOQUIP OFFER?
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Cost
effective means of recovering your wine or juice from lees that can
potentially put money in your pocket.
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2 x rotary drum
vacuum filters (1 x 4m2 and 1 x 10 m2)
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Superb on site
service.
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Years of
experience in mobile wine filtration.
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