Why I Like Filter Presses

I like filter presses because they are easy to use, efficient, and cheap to own and operate. (You can skip the rest of the article. hehe)

Here are some benefits:

  • Potentially enormous filtration capacity
  • Easily scalable up or down
  • Large flow rates
  • Can filter an array of solutions
  • Temperature range and stability
  • Closed Loop
  • Low Operating Expenses (lower than lenticular)
  • CGMP Compliance
  • Easy to use, with little training required

Recently I spoke to two customers with wild consumables cost. One had a maple syrup press from a industry "guru" and was spending $4k a month on filter paper. The other was using lenticular and was spending $8k a month on modules. Insane I tell ya, but lets back up a bit. Yes Lenticular can be awesome and has its uses, and presses with paper have their uses too.

There are many types of presses with all sorts of designs and accessories. What we recommend for botanicals is set up for ease of use, closed loop gasketed to prevent leaks, and most importantly we recommend a press that does not use filter paper. We find that paper is  an unnecessary expense.

I like filter presses because when using the right press, correctly, you can filter enormous volumes of solution down to a fine particle size. You can achieve this without filter paper, instead using the principal of depth filtration. In this process the filter cake layers themselves do the filtration, and the thicker the cake, the better filtration tends to be. Although filter aides are used in this process, the cost is typically negligible and far less than using depth filter sheets or lab filter paper.

A filter press can thus achieve surface filtration, depth filtration, and use the electrokinetic forces of attraction from the adsorbents and filter aides you decide to use. This is similar to lenticular, but in a press you have the freedom to use a larger pool of adsorbents and at higher rates and at far lower costs.

The operation itself of these machines is straightforward. One person can operate a press, even the large presses. In fact, the bigger the press, usually the more automated it is. Cleanup is a breeze, especially once you dial in the precoat process.

The operation remains closed loop which prevents evaporation and keeps you GMP compliant, and on gasketed presses leaks are not a concern. The plastics used in these systems help maintain thermal stability, so cold solutions remain cold. And finally, presses allow you to wash your filter cake with clean solvent, and blow dry the cake with compressed air to recover the solvent.

I believe the bad perception some customers have may come from companies pushing the wrong technology or poor quality to achieve filtration. When the equipment doesn't function correctly it gets blasted on social media. I also see companies strongly promoting technologies that use lots of consumables, like Lenticular, making all kinds of claims that simply are untrue or deceitful half-truths. They portray a filter press like an infomercial, where the press is a terrible machine.

Filter presses are a great option to do most if not all filtration steps of the modern extraction lab, as they can do pre-filtration of particles, remove lipids and fats from winterized streams, and remove adsorbents such as carbon and bleaching clay. They also pair great with OSN Systems. They are a great tool to create clean miscella ready for a downstream process.