Addition of media to bag filter during 3-stage filtration - effective at increasing duration between filter changes?

Apologies for what feels like a really dumb question. Been out of the industry for the last ~year and a half, taking a much-needed break - and now back in, but the finding the knowledge previously attained doesn’t feel anything like riding a bicycle. Finding myself needing to re-learn a bunch/re-remember.

But - Just recently came on to help a crude manufacturing lab. They have 4 in-line bag-filters setup in housing, and we’re going from a first/basic filtration (pull out mud, etc) into a 50 micron, into a 10 micron, into a 1 micron at the end. One of the issues we’re grappling with is the duration of time between filter changes, as the filters never seem to last nearly as long as we’d like between changes (3 runs or so).

Currently don’t have any media within the bag filters - but I was thinking, if we were to use diatomaceous earth in say the 50-micron filter (gets clogged the quickest) and activated carbon in the 10 micron filter, would this increase how many runs/our throughput (and reduce how long the filtration takes) we would be able to filter before needing to change them out for fresh filters? There’d be a quality increase with the activated carbon, but really interested in what can ensure our throughput stays consistent for as long as possible before needing to change out filters completely. We’re burning through filters at the moment.

In the back of my mind there’s this thought of “yeah obviously you need media in bag filters” which is why I feel like it’s a dumb question… but would very much appreciate any suggestions!

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I personally find this to be completely useless as the fluid will inevitably just channel through the media. It sounds like you need bigger filters.


I’d ask why is there so much mud in the extraction part in the first place? What type of extraction are you employing? Centrifuge or ?
What is your flow rate>filter capacity? Bag size, temps when filtering etc.
Are you filtering directly after extraction or before evaporation? Winterizing?
I’d love to help as I am dealing with a similar issue atm.


If your bag filter is large enough, you could try:

  1. The first coarse filtration (70μm), the second 25μm, the third 10μm (with activated carbon decolorization), the fourth 1~5μm
  2. Using lower temperature and lower rotation speed for extraction, the extraction time can be slightly increased to reduce the dissolution and dispersion of waxy and heavy triglycerides.
  3. Your idea of adding media to the bag filter is definitely effective. However, if you do not want to waste filler media, you can also try a finer pre-filter, but the filter area of the pre-filter is required to be increased.

FYI, welcome communicate more


If rhe purpose is winterizing, I’d suggest using Activated alumina in your bag filters, and for bonus points you can shove a stainless steel conical mesh filter into the alumina to add more surface area.


Centrifugal cold-ethanol extraction, but I expect the mud issue is tied to much of the material being unmilled, where we mill it in-house - and I’d imagine that a lot of the mud content is picked up because the centrifuge itself lets larger mass through. It all gets picked up by a sintered stainless pre-filter, but it ends up clogging that filter pretty quickly causing a need to change it after every run (at least it’s sintered stainless that can be cleaned).

Temps when filtering = going in at -30C (I would be far happier in terms of quality if we were running lower, but it’s the SOP that was provided in terms of maximizing production throughput/quality), the filters aren’t jacketed, so it’s definitely picking up heat as it travels between filters.

Filtering directly after extraction - closed-loop going from the centrifuge directly into the line of filters.

Not honestly sure what the flow rate/filter capacity is rated at.

Biggest hope was that by using diatomaceous earth or another media, that after the tincture passes through the pre-filter - diatomaceous earth would manage to capture/hold some of the filtered/solid matter before contact with the filter bag itself, in hopes that we could manage more passes before needing to change out the filters.

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We have a little bit of that setup going, in terms of our first filtration being course (not exactly sure what the micron is, but it’s thin sintered stainless - I’d hazard a guess at ~150+μm for course/first filter)

In terms of 3) - any idea what you might suggest in terms of percent of the bag to fill with media? I was thinking ~50-60% or so, leaving a fair bit of headspace.

Interesting - what would the advantages be for activated alumina in winterization? Our material is coming out of the centrifuge already “sort-of” winterized (not really to be honest, we don’t have a separate winterization step but we are extracting at -30C at least rather than room temp. Material definitely needs, IMHO, further winterization)

Edit: Holy hell - activated alumina functions as a dessicant, it seems like that could be incredibly beneficial to have in a bag just to ensure anhydrous tincture as best as we could (and, at that point, hopefully induce some degree of precipitation for waxes)

Honestly - reading about it - it seems like that would be an incredibly helpful addition. Thank you so much for the heads-up! I’d still love to get your general thoughts on its effectiveness


Inevitably, yes, but the goal isn’t so much in ensuring that it never channels through the media - it’s really just in trying to extend the duration/number of runs we can pass through the filters before needing to change them out. If a filter media were capable of allowing us to go 6+ runs rather than 3 before changing due to slowing filtration speed, that would be worthwhile. Trying to hit the balance between production capacity/throughput, cost of labor, expendables, etc

Here’s a search query about alumina and all posts that @Beaker is found discussing. He set the trend, I just followed along. Alumina will keep back a lot of waxes and more importantly keeps it off the filter’s frit.


I don’t think it’s going to do what you want it to do, but you’re welcome to try. I think you’ll find the media itself is just going to be one more thing that obstructs the flow and they may even plug up faster.

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I sent a message. I’m with Carbon Chemistry and
I’d love to be of service.

Hi, You may need to conduct several experiments to determine the loading ratio of the filler in the bag filter. :grinning:

  1. Bag Type
  2. Membrane stack
  3. Membrane stack
  4. Titanium rod filter
    Is like this? You may need to do experiments to determine the loading ratio

My god I wish it were like that, wish we had a membrane stack.

What we have is 4 rudimentary pressure-assisted filter bag housings, with varying micron filter bags.

If you’ve got four of them, why not use two of them with 50um bags and then step down. I.e. split the inlet into two of the four and then use the combined stream to go into filters 3/4.

You would need check valves at the outlet of each stream but in theory it would work quite well.

Edit: And you’d have to change the bags out half as often–I would not recommend adding powder at all.


3-4 runs has been my experience with a 3-stage setup that’s appropriatelt sized. Bag filters are cheap, and you’re going to add a lot of headache trying to play with media. Also, felt bag filters aren’t as effecient as some pleated filter options and you’re likely going have some media getting past that last stage. Shop around your bag filter supplier to get them as cheap as possible. East Coast Filters used to be my go-to.

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