Odor control is considered a type of preliminary treatment.

• A. False
• B. Never
• C. Sometimes
• D. True

Answer: (D)

Odor control is addressed early because odors originate at the point where wastewater first enters the plant. By controlling odors at the headworks, screening, and grit removal areas, you protect workers, reduce corrosion and nuisance emissions, and keep downstream processes functioning smoothly. This aligns with preliminary treatment’s goal of preparing the wastewater for the main treatment by removing solids and stabilizing flow. So, odor control is considered a type of preliminary treatment.