FILTRATION & CLARIFICATION Flashcards
What is the definition of filtration?
Retaining the solid particles, suspended in a liquid, by passage through a porous wall which constitutes a filter
What type of filtration do you use for ions?
Reverse osmosis
Electro dialyse
What type of filtration do you use for molecules?
Nano filtration
What type of filtration do you use for colloïdes?
Ultra filtration
What kind of filtration do you use for bacteria?
Micro filtration
What kind of filtration do you use for yeast?
General filtration
What kind of filtration do you use for regular size (?) particles
Screening
What is the difference between ‘front’ and ‘tangential’ sieving?
Front: Vertical flow of liquid towards the membrane
Tangential: Cross-flow of liquid parallel of the membrane
Which kind of ‘flow’ has depth filtration? (front/tangential)
Only front
What is them main pro of tangential filtering?
The membrane get less clogged due to the tangentially movement of the liquid
In what (3) ways can there be interception in the membrane during depth filtration?
Interception
Sedimentation
Adsorbtion
What is specific about a volumetric pomp?
It has a ‘by-pass’ valve that regulates the flow and pressure
What is the definition of porosity (%)?
The empty volume of a filter compared to it’s total volume
What is the definition of a pore diameter
The diameter of the holes in the filter
What is the definition of permeability?
The more or less easy it is for a liquid to pass the filter. High permeability allows easy flow through. Low permeability less easy flow, earlier clogged.
Name 3 examples of types of rough filtration
Alluvial filter (earth)
Hollow frame press filter
Press filter
Name two examples of fine filtration
Membrane filter
Lenticullary filter
(= the ones prior to botteling)
Name two types of must/lees filteration
Lees filter
Vacuum rotary filter
What kind of filter is earth filtration? (front/tangential)
Rough filtration
Front sieve (vertical flow)
What kind of filter is earth filtration? (front/tangential)
Rough filtration
Front sieve (vertical flow)
Which type of filter uses ‘single-celled algae shell’?
Earth filtration - diatomaceous earth or kieselguhr
Do you use perlite instead of diatomaceous earth for filtration for a very cloudy must?
Perlite has a higher permeability
Rough filtration due to high permeability
For what do you use a press filter?
For must and wine lees
What types of methods can be used to extract must lees? (4)
Cold setteling
Flottation
Centrifugation
Dried matter (?)
Which method of extracting must lees will remove the most part of the lees? (?)
Cold settling
Name 4 advantages of horizontal support
Excellent cake hold
Stop and restart possible
Filtering to the end
Cakes in pasty shapes
Name 4 disadvantages of horizontal support
Surface/volume divided by 2
Very high
More delicate cleaning
More sophisticated to handle
Name two types of cellulose filtration
Plate and frame filter
Lenticular filter
What do we mean by polyfiltration?
A press filter with 2 or more filter cycles
Reducing time and oxidation
What are the three ‘levels’ of filtration with plate filtration?
Degreasing (most coarse)
Clarifying
Sterilizing
What is the maximum amount of viable germs/L in dry white after filtration? And in wine with rs?
Dry white: 100 germs per L
White with rs: 10 germs per L
What size um will remove all microorganisms and some macro molecules?
0,2um
Where is a membrane filter used for?
Sterile filtration.
at 90C (Noelle edit = 90C is cleaning temperature, not filtration temp)
What kind of membranes do we have? (4)
Plan membrane
Spiral membrane
Hollow fibers
Ceramic tubular
What do a spiral and plan membrane have in common?
They are both layered.
Only difference is that a spiral membrane is twisted
What do we mean by the back flush system?
You backflush when you have a clogged filter or when you want to clean. Not every filter (like lenticular) is suitable.
What options do you have when your filter is clogged? (4)
Back flush
renewal
Rinse
Cleaning in place
In what case do you choose for sterile filtration?
When you want complete stability
For a wine with short shelf life
Wine aimed for supermarkets and export
What could be arguments for coarse or no filtration?
Wine aimed for long ageing
Tradition
Why is a frontal sieve filtration the best for sterile filtration
How does pressure relate to the density of the liquid?
The higher the density the higher the pressure
What do we mean by pre-coating?
The little layer of clean earth you need to prepare the filter surface with in order to protect it and make it more easy to clean
How many hours do we count for the gross lees?
24 hours
What is the micron size for sterile filtration?
0,65um officially
0,45um to be sure
0,20 sterile sterile
What is the consequence of waiting between filtering without cleaning
Tannin react with polysaccharides and form bigger particles causing quicker clogging
Which principles do you need to take into consideration with depth filtration? (3)
The flow
The capacity
The pressure
What is the principle of alluvial filtration process?
The solide particles are caught in the earth matrix. Less clogging but increasing pressure.
Name what is removed at the different pore sizes: 0,2-0,8um, 0,65um, 0,45um, 0,2um
0,2-0,8um = yeast
0,65um = yeast and bacteria
0,45 um = all micro-organism (seen as sterile)
0,2um all micro-organism and some macro molecules
What the main feature of crossflow in relation with backflush?
Constant backflush during ongoing process. Avoids clogging.
What is the principal of depth filtration
Interception
Sedimentation
Absorption Zeta Potential
