Filtration

Question 1

Darcy’s law

Answer 1

Law governing filtration:
Flow rate is determined by viscosity, filter bed permeability, area of filtration, pressure differential, and bed depth.

Question 2

Filtration mechanism: sieving

Answer 2

The filter has pores in its surface that allow beer to pass through solid particles larger then the pores are trapped on the surface of the filter

Question 3

Filtration mechanism: depth filtration

Answer 3

The filter contains channels or pathways; these channels allow liquid to pass, but trap particles.

Question 4

Filtration mechanism: adsorption

Answer 4

The filter contains channels, which allow liquid to pass while solid particles adhere to the filter material.

Question 5

Standard filtration

Answer 5

Primary or rough filtration; uses a filter aid.
Removed solid particles, chill haze, yeast, some bacteria

Question 6

Sterile filtration

Answer 6

Polishing filtration; removes beer spoiling organisms (eg yeast or bacteria) to numbers insufficient for growth

Question 7

Stabilising filtration

Answer 7

Used stabilising agents to remove haze precursors (proteins and polyphenols)

Question 8

Diatomaceous earth

Answer 8

Filter aid used for pre coat and body feed. Fossilised remains of diatoms (single called organisms)
Most commonly used

Question 9

Cellulose

Answer 9

Filter aid that can be mixed with precise it body feed. Made from purified plant fibres

Question 10

Perlite

Answer 10

Filter aid used primarily for precoat. Made from ground volcanic rock

Question 11

Silica

Answer 11

Filter did typically mixed with other aids and used as body feed. Very fine powders derived from sodium silicates

Question 12

Candle filter

Answer 12

Depth/ adsorption; cluster of tubes with tons of tiny holes. Filter aid powder is added and coats are he candles and their holes. Rough beer is pumped through the vessel, and particles stick to the powder.

Question 13

Lead filter

Answer 13

Depth: adsorption; plates/leaves made of fine stainless mesh arranged in a line and pre coated with filter powder aid. Rough beer is pumped through, and particles stick to the powder.

Question 14

Plate and frame filter

Answer 14

Depth/ adsorption; frames with a filter plate made of stainless mesh and covered with a filter sheet covered in filter powder aid. Rough beer is pumped through, and particles stick to the powder.

Question 15

Sheet filter

Answer 15

Plates separated by a porous material, sometimes coated with filter aid are prepped with hot liquor and must be cooled and purged if O2 before running rough beer.

Question 16

Lenticular filter (sheet/membrane filter)

Answer 16

Filter modules shaped like lentils contain internal separators and are stacked in top of each other within the vessel. Porous internal separators allow beer to pass through and solids are retained. Filter aids can be used or not.

Question 17

Crossflow filter (membrane/ sieve filter)

Answer 17

Does not use filter aids. Beer flows alongside filter rather then through it. Differential pressure allows beer to continue to flow while particles are caught in the membrane. Long lifespan, no powders, low effluent waste.