Pore Size of Coffee Filter Materials

Average pore size range for coffee filters is from 5 to 100 microns.

Is there a catch here,? I thought charcoal was the accepted solution, or doesn't it deal with arsenic?

Charcoal is an acceptable method for removal of organics. Arsenic is metallic and is adsorbed onto certain iron oxides (eg: rusty nails, or iron ore fines). Controlled packaging of iron oxides in such filter packets could provide a means to remove arsenic and simultaneously filter the water of pathogens if the filter paper were of appropriate size to remove the biologicals (typically ~1-2 microns). Similarly, any other adsorbent could be packaged for removal of other pollutants.

Currently, P&G has marketed an emergency system for water purification (that comes in packets) to remove bioloical pathogens. I believe it is called PUR and I think it uses appropriate quantities of Calcium Hypochlorite and an iron based coagulant to treat the water.

I am looking at what might be done to remove chemicals and trace hazardous metals from contaminated water often used in poor villages. This would be a way for providing a more "controlled" or guaranteed means for arsenic (or other materials) treatment of the water and would be simple to produce at low cost.

Arsenic in groundwater is frequent found in a reduced state as a cation associated with sulfur anions, e.g. sulfide. This is a soluble form. By oxidizing it to anionic form and reacting it with certain metals, Iron is a good example, it precipitate out the arsenic to form a metal arsenic precipitate. This can form on the surface of the metal or in solution.