Reverse Osmosis

What is Reverse Osmosis?

A separation process that uses applied pressure to force solvent through a semi-permeable membrane from the concentrated side to the dilute side — the reverse of how osmosis would proceed naturally on its own. It's the working principle behind most modern desalination and water purification, filtering out salts and contaminants that can't pass through the membrane.

The five clues

Engineerdle #72 described Reverse Osmosis with five clues, revealed one at a time from hardest to most direct. Each clue points at a different property of the concept.

1. 01A separation process that runs directly against a natural tendency.
2. 02It forces a solvent through a membrane from the concentrated side to the dilute side.
3. 03That's backward from how osmosis would normally proceed on its own.
4. 04High pressure is what makes it happen against the natural gradient.
5. 05A separation process using pressure to force solvent through a semi-permeable membrane, against the natural osmotic gradient.