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Jun 08, 2022 View:

Different Use For Reverse Osmosis Filter

I visited a sugar house recently and the owner showed me around and explained the basics of making maple syrup. One thing I find VERY fascinating is his use of an RO filter system between the sap collection and the final cooker. He takes his sap (which needs to boil down roughly 40:1 to make maple) and runs it through an RO system to strip out water so his initial cook is now only a 5:1 or so. Essentially, he eliminates up to 90% of the water that would be put in his cooker with an RO system.

This got me thinking about a lautered wash and the possibility of mirroring the same process. If an 8% ABV wash was put through an RO system, would the RO strip out alcohol as well? Or would it just take water? I'm not too familiar with how they work on that molecular level. I cruised this forum and a couple others but couldn't find any answers.

The end goal of my thinking is: if you can use an RO system to strip even 50% of residual water before filling your still for the first run, you'll be much more efficient. Any thoughts?


Something conceptually similar is used in the wine world, basically the permeate is mostly water, alcohol, and some acids and all other components of the wine/wash are left behind. The permeate is then distilling or disposed of. I've had distillate produced in this process and it has very little character but I am sure is useful for things.  but the systems are designed to remove alcohol, rather than remove water. Alcohol is larger than water so maybe it is possible to alter the equipment to target water removal rather than water + alcohol.


Reply:20 hours ago, JustAndy said:

That is interesting, what I tasted was 177 proof neutral grape spirit for fortifying wine, so a different objective. What is the abv of the permeate you get? 


Permeate usually around 5.7%abv  I double (alembic) distill to about 68% (136 pr) then cut to 60% and barrel age, or to 40% as a clear spirit.

Late heart/tails cut brings across a lot more grape notes