Activated carbon treatment in water treatment is used for which purpose?

• A. Adsorbs organic contaminants and odors; used for taste/odor control and removal of certain organics and solvents.
• B. Primarily removes dissolved salts to soften water.
• C. Kills bacteria through disinfection.
• D. Increases color and turbidity.

Answer: (D)

Activated carbon treatment relies on adsorption to remove organic contaminants and odors from water. The activated carbon has a highly porous structure with a huge surface area, which attracts and holds many organic molecules—especially those that cause taste and odor, as well as certain solvents, pesticides, and disinfection-byproduct precursors. That’s why it’s particularly effective for improving taste and odor and for removing some dissolved organics before or during treatment.

It doesn’t serve to remove dissolved salts or minerals, so it isn’t used for softening or desalination. It also isn’t a disinfection step, so it doesn’t kill bacteria—that role is filled by chlorine, chloramines, UV, or other disinfectants. And it won’t increase color or turbidity; in fact, it can help reduce color by removing colored organics, while turbidity (suspended particles) is addressed by coagulation and filtration.