If I understand your question, you are asking about how to separate cellulase enzyme from a solution/suspension of ethanol, citric acid, __ citrate, cellulose, glucose and brewers yeast (and probably water) to reuse it, and you are wondering if microfiltration will work.
In my professional opinion, not knowing the process conditions nor the slurry parameters but having spent a long time in this field, I'm going to say, no. You won't have any luck doing this and should not waste your time chasing it. There are too many variables that go into filtration design, your cellulase is too small to separate via microfiltration, microfiltration is ridiculously expensive, the process is a beast to operate, your yield would be terrible and last but not least, there's no guarantee any recovered cellulase would be active in your next batch of moonshine. I don't think it can be done nor should be attempted. The filter peddlers might disagree, but I wouldn't do it.
The way cellulase is recovered in industry is by crude filtration of the suspension to remove yeast, followed by precipitation with ammonium sulfate, followed by separation via adsorption (such as chromatography) columns. This paper discusses it. I'm sure if you google you'll find more of the same infohttp://scienceandnature.org/IJSN_Vol6(3)J2015/IJSN-VOL6(3)15-28.pdf
note the words "The sample containing maximum cellulase activity was
selected for further purification by chromatography" under the Chromatographic Technique discussion. What do you read that as? I see it as a problematic purification process.
Anyway and more importantly, when you can buy it from Alibaba for $80/kg (or less in bulk), you need to ask yourself... "self, what business do I want to be in. The business of making moonshine or the business of making cellulase". If the later, you've got some learning to do, some redirecting of resources and some advanced marketing to work on, etc to be competitive in that market. I wouldn't do that either. I'd stick to making bourbon (or whatever it is you're making).