Question

What is the best water purification method?

Answer 1

Water purification method:

1. It is a technique to remove chemical contaminants (pollutant and toxic), biological contaminants (bacteria, fungi, viruses), suspended solids, and gases.
2. There are different methods to purify the water: physical method (filtration), chemical method (reverse osmosis), and biological method (activated carbon).
3. The best method for water purification is reverse osmosis.
4. Reverse osmosis consists of four units.
5. Polypropylene filter that removes the 50 microns pore size impurities.
6. Polypropylene filter which removes 1 to 5 microns pore size impurities.
7. Activated carbon removes the small molecular gases like oxygen, chlorine, carbon dioxide, and ozone.
8. Ion-exchange column purifies and softens the water by using a cation exchanger that removes the calcium and magnesium ions and polyvalent metals.

The detailed description of reverse osmosis is shown below:

1. The water is filtered through a semipermeable membrane at $10-12\mathrm{bar}$.
2. The water is flowing from the high concentration region to the low concentration region.
3. This method removes the foreign particles which are in the range of $0.001-0.0001\mathrm{\mu m}$ that includes sodium ions, salt hardness, and small molecules of dye.
4. This method retains the high molecular weight contaminants and allows the low molecular weight contaminants like carbon dioxide, oxygen, and chlorine.
5. The $20-500\mathrm{nm}$ impurities size can not pass through the membrane such as microorganisms and viruses.