What process is described by the term adsorption in water treatment?

The term adsorption in water treatment specifically refers to the process where contaminants attach themselves to the surface of a solid medium. This is a fundamental mechanism used in various water treatment processes, including activated carbon filtration, where impurities in the water adhere to the surface of carbon particles. The effectiveness of adsorption depends on several factors, such as the characteristics of the adsorbent material, the nature and concentration of the contaminants, and the environmental conditions.

This process differs significantly from others like dissolution, where contaminants would become part of the liquid phase, or evaporation, which involves a change from liquid to gas. Chemical neutralization, on the other hand, involves a chemical reaction to eliminate contaminants but does not describe the physical adherence of substances to a surface. Thus, the correct answer highlights the essential nature of adsorption as a surface phenomenon in the context of water treatment practices.