Reverse Osmosis: Getting The Concentrations Right

Some people demand that the food they eat and the water they drink are clean and pure. After all, some, especially those who are undergoing dialysis treatments, wouldn't want to ingest anything that could harm them.

Likewise, some industrial processes require the liquids they use to have certain levels of concentration and purity. The boiler water in power plants has to be free of contaminants and other corrosive substances, as a way of keeping the machinery free from damage.

Around the world, people need their liquids and substances to be pure or highly-concentrated. How do you think this is achieved?

One way is through the process of reverse osmosis or RO. Here, substances are made to flow through a semipermeable membrane with pores big enough for liquids to pass, but small enough to trap particles as tiny as ions and molecules.

Before anything else though, what is reverse osmosis the reverse of?

Osmosis is the natural process where the solvents in mixtures flow from spaces where solute concentration is low through a membrane to another space where solute concentration is high. This is how the cells in plants, animals and humans get the substances needed for survival.

Reverse osmosis, likewise, involves the flowing of solvents through a membrane, except that these substances run from a space of high solute concentration to one that is of low solute concentration. This process can only occur where external pressure is applied to such an extent that the natural flow is countered.

The most common application of reverse osmosis is in the purification and treatment of water. As people living in far-flung communities don't have ready access to potable water, reverse osmosis filtering units are used to clean water from rivers or springs. Likewise, RO filters are used to desalinate sea water enough to make it drinkable.

Many people in the world require substances to be concentrated at certain levels. Reverse osmosis gives these people what they need.