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

Standard filtration

Answer 2

“primary” or “rough” filtration; uses a filter aid. Removes solid particles, chill haze, yeast, some bacteria

Question 3

Sterile filtration

Answer 3

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

Question 4

Stabilizing filtration

Answer 4

Uses stabilizing agents to remove haze precursors (proteins and polyphenols

Question 5

Candle filter

Answer 5

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

Question 6

Leaf filter

Answer 6

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

Question 7

Plate and frame filter

Answer 7

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 8

Sheet filter

Answer 8

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

Question 9

Lenticular filter (sheet/membrane filter)

Answer 9

Filter modules shaped like lentils contain internal separators and are stacked on 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 10

Crossflow filter (membrane/sieve filter)

Answer 10

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

Question 11

Diatomaceous earth, kieselguhr

Answer 11

Filter aid used for precoat and body feed. Fossilized remains of diatoms (single celled organisms)

Question 12

Cellulose

Answer 12

Filter aid that can be mixed with precoat or body feed. Made from purified plant fibers.

Question 13

Perlite

Answer 13

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

Question 14

Silica

Answer 14

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