How do Water Filters Work?

Question

as in brita (basically, tap water) filters? what kind of components do they use exactly?

Answer 1

Generally they contain Granules of Activated Carbon and Ion Exchange Resin (Zeolites).

The Charcoal is an 'Adsorbent' which holds molecules of other substances on the surface area of the molecules of Carbon.

The carbon Adsorbs Chlorine, and organic material, thereby improving the taste. The Ion Exchange Resin removes the temporary hardness by picking up the Calcium and Magnesium Ions and replaces them with Sodium Ions

The system also significantly reduces levels of metals such as Lead, Aluminium and Copper .

The growth of Bacteria is also prevented by an inhibitor.

Answer 2

Reverse osmosis (RO) is a separation process that uses pressure to force a solution through a membrane that retains the solute on one side and allows the pure solvent to pass to the other side. More formally, it is the process of forcing a solvent from a region of high solute concentration through a membrane to a region of low solute concentration by applying a pressure in excess of the osmotic pressure. This is the reverse of the normal osmosis process, which is the natural movement of solvent from an area of low solute concentration, through a membrane, to an area of high solute concentration when no external pressure is applied. The membrane here is semipermeable, meaning it allows the passage of solvent but not of solute.

The membranes used for reverse osmosis have a dense barrier layer in the polymer matrix where most separation occurs. In most cases the membrane is designed to allow only water to pass through this dense layer while preventing the passage of solutes (such as salt ions). This process requires that a high pressure be exerted on the high concentration side of the membrane, usually 2 to 17 bar (30 to 250 psi) for fresh and brackish water, and 40 to 70 bar (600 to 1000 psi) for seawater, which has around 24 bar (350 psi) natural osmotic pressure which must be overcome.

Answer 3

Most home-use water filters use a substance called Granulated Active Carbon.

Basically its plain carbon that is processed to make it very porous (lots of holes). This exposes a large amount of surface area for the carbon to react with incoming impurities and absorb them.

The sites listed below should help.

Peter

How Your Electronics Work

http://www.howyourelectronicswork.com