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A Guide to Botanicals Filtration

Last updated: 6/2021

Applies to: Producers looking to filter ethanol-based botanical extracts. It details the steps involved, discusses equipment and media choices, and provides options for filtration setups depending on batch size and throughput.

BACKGROUND

While botanicals filtration is a newer market category, many of the same tried and true applications, techniques and solutions can be applied that have been around for decades. Filtration equipment and media options for ethanol-based botanical extracts can seem overwhelming at first glance. The options laid out below are based on the real-world trials and tribulations of Scott Labs' suppliers and customers, and our quest for continually improving the efficiency and filtrate quality of many gallons of precious extracts. Find here our recommendations for filtration steps, equipment, media, and setup.

PROCESS

1. REMOVAL OF PLANT MATERIAL (Bag Filtration):

The first consideration in the filtration of botanical extracts is removal of plant material. With the goal of achieving a brightly polished product, this step is important for two reasons:

  • It decreases the load on the main depth filter.
  • It allows a more efficient depth filtration and prevents premature blinding of the filter with plant material.

How you complete this step depends on your extraction equipment. If not already included as part of your extraction setup, we recommend a sanitary bag filter housing loaded with 5µ welded (not stitched) felt polypropylene bags, though it is possible to use bags as tight as 1µ. This bag filter can either be placed directly in-line with the extractor on the way to a holding tank or it can be placed in-line between the extractor and lenticular housing. The bag can be emptied periodically and reused. Our bag filter housings are available in standard size #2 which houses bags that are 32” long by 7” in diameter.

This step takes care of picking up residual plant material that may have made it through the extractor. It prevents suspended solids from prematurely clogging the lenticular filter in the next step and increases long-term process efficiency. After the removal of plant material, we recommend a depth filtration using a lenticular setup.

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2. BRIGHT POLISH (Depth Filtration):

This step is with the intent of removing lipids and colloids that can’t be removed by the first step for a bright polish. We recommend using a lenticular housing loaded with SupraDISC II (SDII) media. The industry standard grade of media typically used in this step is K100 grade (1µ) but depending on the nature of your filtration you can also filter coarser (K250 2.5µ) or tighter (EK1 0.35µ). Please note that it is not possible to mix grades in the same housing. The size housing and quantity of modules used depends on your average batch size and whether this volume changes over time. See the next section for tips on sizing your lenticular housing or feel free to contact us.

3. AROMA AND FLAVOR ADJUSTMENT (Carbon Filtration):

A carbon filtration is recommended after completing the bright polish. A carbon filter is a contained carbon treatment that adjusts color and flavor but is not considered a depth filter in the traditional sense of the word. Please note that it is not recommended to skip the bright polish step (K100, K150, K200 or K250) or the carbon media may be prematurely inundated with suspended solids. The same lenticular housing as used above can be used for a carbon filtration step by switching out the SupraDISC II media for AKS4 carbon embedded media.

PRO TIP: When filtering at subzero temperatures, it is important to tighten the lenticular hold down device until the spring is compressed all the way and then turn back between half a turn to two turns to make sure the lenticular pack stays compressed when it shrinks during cold contact.

LENTICULAR HOUSING SIZE CONSIDERATIONS

Depending on your throughput and frequency of filtration, your setup to complete these steps may vary. The size of lenticular housings are classified by:

  • Diameter (12 or 16 inches)
  • Height in terms of modules (1, 2, 3 or 4)

The larger diameter and larger height modules are the most flexible: 16” housings can use both 12” and 16” media, and taller housings can use any number of modules by simply changing out the center post. For example: if batch sizes are projected to start small but you’d like to leave room for growth in production, you may consider a 16” 4-high housing for the most flexibility. For small batch filtration, where a 12” SUPRAdisc II has too much surface area for the volume you’re needing to filter (< 40 gallons), consider the SUPRApak S housing and media system (contact us for info). It is also worth nothing that lenticular filter housings also come in split dome format which makes mid-run media change-outs easy.

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BATCH SIZE EFFECT ON FILTRATION SETUP

WHAT IF I NEED MORE THAN ONE LENTICULAR HOUSING?

When working with large batch sizes and high frequency of filtration, it is a good idea to add a second lenticular housing. This housing can be used one of two ways:

  • In-line with the first lenticular
  • Exclusively to house AKS4 carbon media (dedicated housing for carbon media)

Having a dedicated housing for carbon media can be advantageous if it works for your process. Placing it in-line with the first two depth filtration steps allows you to avoid switching out regular lenticular media for carbon modules and allows you to perform the flavor and color adjustment in the same pass as the bright polish.

A NOTE ON CARTRIDGES

As mentioned above, you can achieve this by adding another lenticular housing loaded with the AKS4 modules (12” or 16”). Alternatively, you could also achieve this with a ScottCart Cartridge Housing loaded with ScottCart Carbon cartridges. This is another option for quality carbon embedded media that can handle higher pressure differentials than the AKS4 media and lenticular housings. ScottCart Carbon cartridges also have little chance of carbon blow-by due to the protective spun polypropylene layers in the construction.

Just as lenticular housings are flexible in terms of sizing, so are cartridge housings. They can be a housing for a single cartridge, or multiple rounds such as 3, 5, 6, 7, 12 or 24-round depending on the desired flow rate. Positions in the cartridge housing can also be plugged if you prefer to use fewer cartridges in a larger housing. This will allow for growth as batch sizes or flow rates increase over time.

LAYOUT OPTIONS FOR FILTRATION CHAINS:

Considering the options discussed above, here is a summary of optional layouts for different filtration chains depending on your budget, flow rates and potential growth.

First, ask yourself the following questions to help define your production needs: What is your batch size? Do you have clear quality metrics on output? Do you have time and labor constraints? Then, choose the setup that will be best for your operation:

  • SMALL BATCH = 2-pass System with 1 Lenticular Filter:
    • (1) First Pass: bag filter to lenticular filter with SupraDISC II media of appropriate bright polish grade to tank.
    • Switch lenticular filter media from bright polish to carbon AKS4 media.
    • (2) Second Pass: tank to lenticular filter with AKS4 carbon media to new tank.
  • LARGER, MORE CONTINUOUS PRODUCTION = 2 Dedicated Lenticular Filters:
    • Bag filter to lenticular filter 1 with SDII of appropriate bright polish grade to lenticular filter 2 with AKS4.
  • LARGER PRODUCTIONS OPTIMIZING QUALITY = Dedicated Lenticular and Dedicated Cartridge:
    • Bag filter to lenticular filter with SDII of appropriate bright polish grade to ScottCart cartridge housing with carbon cartridges.