An integral part of flow equalization is ___.

• A. Aeration
• B. Filtration
• C. Mixing
• D. Settling

Answer: (C)

Flow equalization aims to smooth out fluctuations in wastewater inflow so downstream processes receive a steady, predictable feed. Mixing in the equalization basin is essential because it keeps solids and pollutants distributed evenly, preventing settling in layers and ensuring the entire basin shares the same concentration. This uniformity makes the discharged flow representative of average conditions, which improves control and stability for the rest of the treatment train. While aeration can be used in some systems for odor control or to keep solids in suspension, it isn’t the defining element of equalization. Filtration and settling are downstream treatment steps, not the mixing action that characterizes the equalization stage.