Can’t watch the video at work, but I suspect the video is about coagualtion & flocculation. The resin is coagulated from disolved resin particles into suspended resin-alum complex particles too heavy to remain suspended in solution, which is why a small-scale settling pond works.

It’d might be a bit quicker/easier to put it through a filter or series of paper filters. Nothing crazy. Even a coffee filter should get most of it. Micron scale filters aren’t terribly expensive but clog quickly, so it’s best to run a coarser filter to get most of the big chucks first. Granted, not sure how long the coagulation process takes versus the flocculation process. If the coagualtion process is slow but the flocculation process is fast, filters probably won’t save much time. Though they may make cleanup easier.

Eventually, the IPA will be diluted with water from the aqueous alum solution (I assume he’s using an aqueous solution as alum is barely to not alchohol soluable). There’s the salt trick to separate the azeotrope, but I haven’t personally tried it.

Lots of work, but still better than those guys who distill the dirty IPA with non-explosion proof apparatuses. shudders in OSHA