Where normal osmosis is the passive diffusion of a solute (water molecules) from an area of low solvent (mineral molecules) to high solvent levels through a selectively permeable membrane, reverse osmosis forces water molecules through a selectively permeable membrane through the use of an artificially raised hydrostatic pressure, requiring the active release of energy (such as pumps). In doing so, the small water molecules are forced through the small pores of the selectively permeable membranes, while the larger mineral molecules, such as salt are trapped in the filter and remain behind, thus leaving only clean drinking water on the other side of the selectively permeable membrane.
What are the benefits of Reverse Osmosis?
The benefits of reverse osmosis is the potential to produce clean, drinkable, water from the ocean during periods of severe draught, or in countries like Malta that have very little natural water supplies.
What are the cons of Reverse Osmosis?
1. The downside of reverse osmosis is the fact that this is not a passive movement of water through diffusion and requires the expenditure of large amounts of energy.
2. While reverse osmosis does remove all large mineral molecules, small bacteria (which are molecularly smaller than water molecules) are able to freely pass through the selectively permeable membrane, requiring desalinated water to have further refinement and treatment before it is drinkable by human beings.
3. Reverse osmosis also wastes large amounts of water during the process.
If you would like to learn more about osmosis, please review my what is osmosis page.
If you would like more examples of osmosis, please review my examples of osmosis page.