A Distiller’s Guide to

Optimal Filtration

Nathan Kreel, PhD

Gusmer Enterprises

Service with Knowledge®

Why Filter Distilled Spirits?

Clarity

Chill Proofing

Color/Flavor Adjustment

Contamination Risks (Liqueurs)

Where and What is Finishing?

Mashing → Fermentation → Distillation

→ Aging → Finishing → Bottling

• Finishing

– Dumping the barrels

– Filtering (coarse filtration)

– Cutting / Proofing - Modifying / Stabilizing

– Filtering (prior to bottling)

Finishing… What Might You Face?

Instabilities (What’s in your soup?)

Batch to Batch Variations

Formulated Products

What’s In Your Soup?

Fermented Beverages Are Complex Systems

• Substrate (Grain / Fruit / Vegetable) – Sugars / Carbohydrates / Proteins / Phenolics / Acids / Salts /

Enzyme Systems / Plus Many More Compounds

• Introduce Yeast/Bacteria → Ferment – Alcohols / Fats / Lipids / Glycerol / Sugars / Acids / Esters,

Aldehydes and other Metabolites / Plus Many More Compounds

Spirits are mostly ethanol, but compounds carry over (congeners)

or are added during additional processing

Instabilities

Equilibrium Reactions / Solubility

A + B ↔ C

Solute/Solvent ↔ Saturation

System in Equilibrium + Change = Could shift

reactions and create instabilities

– Triggers • Shift in solvent system (alcohol solubility)

• Shift in pH

• Shift in temperature

• Reactive compounds (i.e. dissolved oxygen, blending)

• Time (age)

Batch to Batch Variations

(in non-formulated products)

Small Scale or Craft Programs – may embrace

variations…up to a point

Large Scale Program – may require more

consistency

– Bottling Specifications for Color / Flavor / Aroma / Clarity (or

Turbidity)

• Turbidity specification is typically < 1 NTU (nephelometer turbidity units –

measures light scatter)

• May require color, flavor, aroma additives to meet specifications

• May require fining to remove color, flavor, aroma, or stabilize

• May consider blending similar products

Formulated and Specialty Products

• Ready to Drink Cocktails / Extractions / Liqueurs – Risk for Post Bottling Fermentations

• Low alcohol levels (<15% by volume)

• Residual sugars

• Higher pH levels (2.5 – 3.9 more stable, 4.0 to 4.9 moderately stable, above

5.0 less stable)

• May need to consider sterile filtration and/or preservative systems

– Potential for Instabilities

• Colorings, Flavorings, Aroma… Natural and Artificial Compounds

Correcting Instabilities and Variations

• General Debris and Turbidity – Filtration

• Fatty Acid / Alcohol Solubility – Chill Filtration

• Color, Flavor, Aroma Reduction – Loose Carbon or Carbon

impregnated filters

• Pectin (fruit extracts, fruit concentrates) – Enzymes

• Protein (fruit extracts, fruit concentrates) – Bentonite (pH

dependent), Silica Gels

• Phenolic / Color Stabilization (fruit, grains) – Gelatins, PVPP, Casein

Filtration Still A Necessity

Most of these processing steps will require some

type of filtration… but which filters are best for

spirits applications?

Where Filtration Occurs, Grain Receiving

Hammer Mill

Slurry / Mix tank

Liquifaction tank Fermentation tanks

Beerwell

Distillation

Ethanol Storage

Whole Stillage Tank (Feed)

Decanter

Centrifuge

DDGS (Feed)

Dryer

Wetcake (Feed)

Thin Stillage

Evaporators

Backset

Syrup

Barrel Aging

Pre-Bottling Holding Tanks

Standard/Polish

Filtration

Coarse

Filtration

Final (Bottling) Filtration

Blending Tanks

Chill Tanks

Coarse Filters in a Distillery

• Bag Filters • Housings ~ $1,000

• Polyester Felt Bags ~ $10

each

• Limited retention and “dirt

loading” capacity

• In-line Strainers • Housings ~ $600 - $1,000

• Over screens ~ $200

• Limited retention and “dirt

loading” capacity

Application: Dumping – Coarse filtration to remove any

barrel char or general debris

Types of Filter Media for Standard Filtration

DEPTH FILTER SHEETS

All Cellulose

DE Containing

Carbon Containing

SYNTHETIC CARTRIDGES

Nominal rating

Absolute rating

LOOSE POWDER

Carbon

Diatomaceous Earth

LENTICULAR STACKS

All Cellulose

DE Containing

Carbon Containing

And Associating Hardware…

DEPTH FILTER SHEETS

SYNTHETIC CARTRIDGES

LOOSE POWDER

LENTICULAR STACKS

What Type is Right for You?

Ease of Use

HIGHEST

LOWEST

Solids Capacity (per ft2)

LOOSE POWDER

(bodyfeed)

DEPTH FILTER SHEETS =

LENTICULAR STACKS

SYNTHETIC CARTRIDGES

SYNTHETIC CARTRIDGES fast install, consistent, drip-free, storable

LENTICULAR STACKS fast install, consistent, drip-free, short storage

DEPTH FILTER SHEETS med. install, consistent, drips, short storage

LOOSE POWDER slow install, inconsistent, drip-free, no storage

Depth Filters (either sheets or stacks) are most common in distilling

Standard Polish Filters in a Distillery • Filter Press – Filter

Sheet Media – 40 cm Filter Press ~ $6,000

– 40 cm Filter Sheet Media ~

$1.65 per sheet

– Wide range of porosity and

retention rates available (0.3 to

20 microns nominal retention)

– Excellent retention and “dirt

loading” capacity

– Best economics

• Application: All general

filtration applications for

Spirits production – Coarse to polished filtration

Standard Polish Filters in a Distillery

• Lenticular Cartridge

Filters – Housings ~ $3,500 to $7,000

– Cartridges ~ $125 each

– Wide range of porosity and

retention rates available (0.3 to

20 microns nominal retention)

– Excellent retention and “dirt

loading” capacity

• Application: All general

filtration applications for

Spirits production – Coarse to polished filtration

Lenticular Cartridge vs. Sheets

Same Filter Media - Different Form

Pros & Cons - Lenticular vs. Sheets Lenticular Cartridges

– Full range of filter media

– Easy to load

– Small footprint

– No Dripping

– Sealed (more sanitary)

– More expensive per

square foot of filter media

– Low holdup volume

Filter Sheets

– Full range of filter media

– Takes more time to load

– Larger footprint

– Drips

– Exposed edges of filter

media (less sanitary)

– Less expensive per

square foot of filter media

Filter Sheet Raw Materials

Cellulose Fibers Diatomaceous Earth (DE)

+ Resin (Binder)

Filtration – Types of Filter Media

https://youtu.be/ZMphfbtHyqM

Filter Sheet Demonstration

1) Some particles are too large to enter the filter & remain trapped on the surface

2) Some particles enter the filter’s interior and become trapped in the intricate network

3) If charged, some particles are attracted to the charge & become trapped

Filter Sheet Mechanisms

Gusmer Filter Sheet Grades

1700 series 1900 series

CSF series

Sheets:

• 60x60cm sheet = ~59x59cm active sheet = 3481cm2 = 3.75 ft2

• 40x40cm sheet = 1.64 ft2

• 20x20cm sheet = 0.4 ft2

Lenticular Stacks:

Area provided by Manufacturer

Example: Gusmer’s 12” 16 cell stack = 17.7 ft2 each

Synthetic Cartridges:

Area provided by Manufacturer

Example: Millipore’s Bevigard 10” cartridge = 7.5 ft2 each

Filtration Prep – Calculating Surface Area

Sheet Area (ft2/sheet) x # of Sheets =

Filter Area (ft2)

Filter Area (ft2) x Rec. Flow Rate (gpm/ft2)*=

Total Flow (gpm) * Manufacturers provide a recommended flow rate range based on pore size

Filtration Prep – Calculating Flow Rate

Example:

1,000gal of spirit will be filtered through thirteen 40 x 40 cm sheets (polishing filter grade). How fast can I filter?

• Filter area = 1.64 ft2 active area/sheet X 13 sheets =

21.3 ft2 total filter area

• Flow Rate = 16 gal/hr/ft2* X 21.3 ft2 = 341 gal/hr =

5.7 gal/min flow rate

*note: manufacturer rec. 8-24 gal/hr/ft2 for polishing grades

• Time needed for Filtration = 1,000gal ÷ 341 gal/hr =

2.9 hrs total filtration time

Filtration Prep – Calculating Flow Rate

Filtration Start-up – Filter Press 1. Inspect press gaskets & plates for cracks

2. Carefully load sheets into press:

• Cockled surface should face inlet plate

• Media edges should be visible around plate

• Ensure media is not pinched in gaskets

3. Tighten press ~50% and begin recirculating spirit or H2O to

equilibrate (close outlet vent once press is filled)

4. Once edges of sheet are wet, tighten press snugly

5. Begin Filtration

Filtration Flow Diagram (top view)

Filtration Flow Diagram (top view)

Clean Plates

Outlet

Dirty Plates

Inlet Closed

Outlet

Filtration Start-up – Lenticular Stack 1. Inspect gaskets/ O-ring (media base & housing base)

2. Place stack(s) on center post & hand-tighten locking assembly

3. Close dome and seal

4. Open top vent & fill housing (with spirit or H2O)

5. Close vent & flush/recirculate to equilibrate

6. Begin Filtration

Application / Flow Rates / ∆P

Application Filter Grades Recommended

Flow Rates

g/hr/sqft

Max. Flow Rates

g/hr/sqft

Max. Diff.

Pressure

Coarse Filtration 1925-1940 24 to 32 30 to 40 45

Polish/Clarifying

Filtration

1945-1960 8 to 24 20 to 30 45

Sterile Prep./Pre-

Membrane Filtration

1965-1975 3 to 12 10 to 15 21

Application Guide

Efficiency dependent on processing conditions (flow

rate, differential pressures, particle type, etc.) – Lower flow rates allow for better retention

– Lower differential pressures allow for better retention

Important Filtration Parameters

Flow Rate

Follow the Manufacturer’s recommended limits

• Filter grade (↓ pore size = ↓ flow rate)

• Surface area (gpm/ft2, ↑ ft2 = ↑ gpm)

Differential Pressure

Follow the Manufacturer’s recommended limit

• Differential Pressure (psid) = inlet psi – outlet psi

• Filter Run psid = psid @ finish – psid @ start

Pressure differential is higher resulting in less throughput at excessively high flow rate

Turbidity breakthrough is higher & more erratic at excessively high flow rate

Excessive Pressure can also cause

Turbidity breakthrough!

Filtration Run – CONSISTENCY

Consistent products improve filtration consistency

• If variability is expected in the product, may be best to

add a “safety factor” by increasing filter area

Consistent preparation improves filtration consistency

• If chilling, chill to the same temp every time

• If dosing carbon:

• dose at the same rate (lb/gal) every time (or adjust

filter area accordingly)

• provide the same contact time

• provide the same level of agitation every time

Potential Outcomes – Optimal (Ideal Scenario)

Filtration Results:

Pressure increased throughout batch filtration but didn’t hit terminal psid

Resulting Product:

Achieved product target (clarity or color)

Fully utilized filter sheets

based on achieving

pressure differential and

maintaining color spec

Sheets not underutilized,

not throwing away

unused material, sized

appropriately

Potential Outcomes – Under Utilized Filtration Results:

Minimal pressure rise throughout batch filtration

Potential Outcomes – Under Utilized Filtration Results:

Minimal pressure rise throughout batch filtration

Optimization Options (to fully utilize filter):

• If flow rate is NOT a bottleneck: – Use fewer filter sheets & reduced flow rate accordingly

• If flow rate IS a bottleneck: – Filter a larger volume of product through the sheets

Under utilized sheets, throwing away capacity. Instead, use fewer sheets, slow down

flow rate. For larger producers, continue using sheets with similar batch material

This situation is all about saving $$$

Potential Outcomes – Over Worked Filtration Results:

Terminal pressure hit midway through batch filtration, requiring shut down to change out filter media.

Potential Outcomes – Over Worked Filtration Results:

Terminal pressure hit midway through batch filtration, requiring shut down to change out filter media.

Optimization Option:

• Use more sheets & increase flow rate accordingly if desired

Undersized system – all about time

saving

Then again, time is $$$

Filtration Shut-down

Reasons to shut-down filtration:

• Batch filtration completed

• Terminal differential pressure reached – DO NOT EXCEED!

Maximizing yield:

Gently push out fluid remaining in the press/housing using gas

(air, nitrogen, CO2, etc.)

• Use low pressure (normally a few psi) to keep pressure and

flow rate below normal operating conditions

• Where to apply the gas:

• For stacks/cartridges – apply gas at top vent/gauge port

• For presses – apply gas at regular inlet

Cheat Sheet for Optimal Filtration • Calculate the appropriate flow rate based on Manufacturer’s

recommendations

• Product and preparation consistency will improve filtration

consistency

• Check your gaskets/O-rings!

• Follow Manufacturer instructions for start-up

• Monitor flow rate, pressure & product targets during filtration

• Do NOT exceed recommended pressure before termination

• In any of these scenarios, if NTU spec is higher than desire,

need to consider a tighter sheet

Filter Press Troubleshooting Symptom Underlying Issue Root Cause Solution

Leakage

Poor seal at the

gasket

Worn or cracked

gaskets

Replace gaskets; use operator manual or contact the

supplier to determine thickness

Incorrect gasket size Replace gaskets with gaskets that are the correct

thickness (see above)

Poor seal around the

media

Insufficient filter press

tightening

If unable to properly tighten the press by hand, a

“cheater” bar or hydraulic closure can be used

Misaligned sheets Take your time and carefully align each sheet while

dressing the press to ensure proper sealing

Missing guide rods Short-term: carefully hold sheets while tightening press

Long-term: purchase replacement rods

Incorrect operating

parameters

High pressure or

excessive flow rate

Follow filter sheet product literature for proper

operating conditions of grade in use

Unexpected

short life

Filter sheets placed

backwards

Gradient density in

opposite direction

Always face the cockled side of the sheet towards the

plate with an un-gasketed inlet port

Incorrect operating

parameters

High pressure or

excessive flow rate

Follow filter sheet product literature for proper

operating conditions of grade in use

Unexpected

breakthrough

Incorrect operating

parameters

High pressure or

excessive flow rate

Follow filter sheet product literature for proper

operating conditions of grade in use

Stack (Lenticular) Filter Troubleshooting Symptom Underlying Issue Root Cause Solution

Unexpected

breakthrough

Stack filter has ruptured

Unintended back-pressure

(most common cause)

Always install a quick acting check

valve at the exit of the housing

Improper storage

(rare)

Never remove wet stacks from housing

for storage, if needed, store in closed

housing

Fluid is bypassing the

media

Missing stack gasket

(most common cause)

Always check each stack to ensure it

has its end gaskets while installing

Center post not properly sealed

(rare)

Follow literature instructions to hand

tighten the follower assembly, this is

sufficient for a proper seal

Incorrect operating

parameters

High pressure or excessive flow

rate

Follow filter sheet product literature for

proper operating conditions of grade in

use

Leakage at base of

the housing

Housing is not properly

sealed

Torn or misaligned o-ring at

housing base

(most common cause)

Always inspect the o-ring before use

and replace if damaged. Make sure o-

ring is properly seated in its grove and

housing bolts are snug

Housing base bolts are not

properly tightened

(rare)

Follow housing literature instructions to

hand tighten the base bolts, a wrench

or “cheater” bar can also be used if

necessary depending on the housing

model

Filtration with Synthetic (PVDF or PES)

• Depth Filter Media – Thick matrix of gradient density

media (Fiber, DE, resin) in which

the filtration occurs on the surface

and interior of the matrix

– High “dirt loading” capacity

– Nominal micron rating (0.5 to 20

microns)

– Appropriate for most Spirits

applications

• Surface Filter Media – A thin matrix of media (PVDF or

PES) in which the filtration occurs

mostly on the surface

– Low “dirt loading” capacity

– Absolute micron rating (0.45

microns)

– Membrane filter – appropriate for

aseptic “sterile” filtration of

beverages

Bottling Line Filters in a Distillery • Cartridge Filters

– Housing ~ $1,500 to $3,000

– Cartridges ~ $125

– Better retention and “dirt loading”

capacity

– Wide range of micron options,

filter media choices and cartridge

sizes

Filtration Start-up – Synthetic Cartridge

1. Inspect O-rings (cartridges & housing base)

2. Install cartridges in housing

3. Close dome & seal

4. Open top vent & fill housing (with spirit or H2O)

5. Close vent & flush/recirculate to equilibrate

6. Begin Filtration

Finally, Please remember…

– Coarse Standard/Polish Final(Bottling)…not the opposite

direction…this DOES NOT WORK!

– FILTRATION in your process potentially will require the most attention!

You can vary the setup…

– Cartridge filters and housing can be used for coarse filtration

– Lenticular and Sheet filters can be used for coarse filtration or bottling

Work with your supplier to determine what works best for you

Questions?

Thank You! Nathan Kreel, PhD

Distilling Industry Specialist

Technical Sales Representative, Southeast US

240-810-2650

nkreel@gusmerenterprises.com

www.gusmerdistilling.com

Service with Knowledge®