Activated carbon in water treatment works primarily through which process?

Activated carbon in water treatment is primarily effective through the process of adsorption. This technique involves the adherence of molecules from a fluid (like water) to the surface of a solid (the activated carbon). The highly porous structure of activated carbon increases its surface area significantly, providing more sites for contaminants to adhere to, which allows it to effectively remove various organic compounds, chlorine, and other impurities from water.

Adsorption is distinct from absorption, where one substance completely penetrates another. Instead, in adsorption, the contaminants remain on the surface of the activated carbon rather than being absorbed into its structure. This characteristic is crucial for water treatment, as it enables the efficient removal of unwanted substances while allowing the treated water to continue flowing.

Filtration refers to the physical removal of particles from water via a physical barrier, which is not the primary function of activated carbon. Coagulation involves the aggregation of particles to form larger clusters (flocs) that can be removed, and while it is an important step in water treatment processes, it does not directly involve the properties of activated carbon. Thus, the choice of adsorption accurately describes the fundamental mechanism through which activated carbon operates in water treatment systems.