Flow Equalization in preliminary treatment is used to...

• A. Aeration
• B. Remove oil and grease
• C. Remove grit via sedimentation
• D. Ensure flow is the same throughout the system

Answer: (D)

Flow equalization is used to smooth out fluctuations in flow before treatment. In preliminary treatment, influent flow can vary dramatically, especially with storm events or daily usage patterns. An equalization basin stores excess flow during peaks and releases it at a steadier rate, creating a more uniform hydraulic load for downstream units. This helps protect pumps from shock loads, keeps primary and subsequent treatment processes operating more predictably, and improves consistency in chemical dosing and settling performance. It doesn’t perform aeration, oil and grease removal, or grit removal—those are handled by other pretreatment steps. The result is a more uniform flow through the system.