In the filtration stage, in contrast to sand, granular activated carbon (GAC) is an absorbent. It is generally used for water purification.
The adsorptive capacity of activated makes it ideal for removing a variety of contaminants from water, air, liquids and gases.
The EPA, and most state-based departments of health, consider adsorption by activated carbon to be the best available technology for the removal of many organic materials in surface water including:
Disinfection byproducts (DBPs) associated with chlorine and alternative disinfectants
Endocrine-disrupting compounds, pharmaceuticals and personal care products
Taste and odor-causing compounds
Organic materials and other naturally occurring matter