Pretreatment includes lake destratification, control of algae, debris removal, presedimentation, aeration, ________, and activated carbon adsorption.

Pretreatment includes lake destratification, control of algae, debris removal, presedimentation, aeration, ________, and activated carbon adsorption.

• A. filtration
• B. chlorination
• C. coagulation
• D. chemical oxidation

Answer: (D)

Chemical oxidation is used in pretreatment to reduce and transform substances that would burden downstream treatment, like color, taste and odor compounds, and certain metals or organics. By applying an oxidant (such as permanganate, ozone, or chlorine dioxide), these contaminants are broken down into forms that are easier to remove later on. This prepares the water for subsequent steps, especially activated carbon adsorption, by making the organics more amenable to adsorption and helping prevent carbon fouling. In other words, oxidation cleans up stubborn constituents so subsequent processes—carbon adsorption and filtration—work more efficiently. Filtration and chlorination serve different roles later in the treatment sequence, while coagulation is another pretreatment step but not the oxidizing action emphasized here.

Chemical oxidation is used in pretreatment to reduce and transform substances that would burden downstream treatment, like color, taste and odor compounds, and certain metals or organics. By applying an oxidant (such as permanganate, ozone, or chlorine dioxide), these contaminants are broken down into forms that are easier to remove later on. This prepares the water for subsequent steps, especially activated carbon adsorption, by making the organics more amenable to adsorption and helping prevent carbon fouling. In other words, oxidation cleans up stubborn constituents so subsequent processes—carbon adsorption and filtration—work more efficiently. Filtration and chlorination serve different roles later in the treatment sequence, while coagulation is another pretreatment step but not the oxidizing action emphasized here.