I’m sure you’ve all seen the claims and implementations of carbon filters in our society. My question is: how do these (usually) fist sized objects really dechlorinate (for example) hundreds (or thousands) of gallons of water over a period of months without becoming completely ineffective or reintroducing the previously extracted contaminates?
As a rough rule, activated carbon can hold something like its dry weight in contaminants. It depends. The stronger an affinity something has for carbon, the more easily it is held. The cooler the carbon is, the more it can hold, and you can re-heat the carbon to drive stuff off.
I’m more familiar with carbon in air cleaning, and don’t even happen to know whether chlorine is one of the things it will catch. I think it’s better at catching things that are larger than chlorine, for example extracting gasoline from water after an underground tank leak.
Activated carbon also causes ozone to revert to O2, but it doesn’t absorb it. It just catalyzes the change.
The effectiveness and capacity of granular activated carbon(GAC) is based on what your using it for the size and the strength of charge that contaminate carries. GAC has a positive charge and a huge surface area do to its pores nature. A gram of GAC has a surface area of over over 1500sf. The particles it is attracting are very small and in very small numbers compared to the water.
You can taste chlorine in water at as little as 1 part per million. The amount present in most water supplies is very low. Chlorine particles are very small and stack neatly on GAC so it is very easy for GAC to pull and hold them.
Other contaminates, such as sulfur, eat up GAC’s capacity much faster due to their size and shape. GAC can absorb one ton of chlorine for every pound of sulfur. So if that was the main thing your trying to take out it you’d want to look at other options.
Think of the carbon like a magnet. Run a bunch of BB’s by it and it will attract and hold them indefinitely. Once it’s picked up enough BB’s or it is too coated with them for the magnet’s charge to reach further BB’s it simply stops attracting new ones but will hold the ones it already has. It does not release them back.
If only one in a million of those BB’s is steel and the rest are plastic it takes an awful lot of BB’s going by for it to become to coated to attract new ones.
Some water supplies can exhaust a standard cartridge carbon filter in a week others could take a year or more. It is recommended you change the filter as needed or at least every 6 months. GAC is an attractive place for bacteria to grow the 6 month mark where experts agree a bacteria count could begin to be unhealthy.