The Role of Mixing in Equalization

Authors:

Paul R. Bradley

J. Y. Oldshue

Mixing Equipment Co., Inc.

This content discusses the design and operation of equalization basins in wastewater treatment, emphasizing their role in stabilizing fluctuations in flow and contaminant concentration. Properly mixed and sized basins can improve effluent quality, reduce operational costs, and minimize the required horsepower for aeration systems. The article also covers considerations for mixer design, baffling, solids management, and material selection to optimize basin performance and achieve consistent treatment results.

Key Learnings

• Properly designed equalization basins stabilize fluctuations in influent flow and contaminant concentration, leading to more consistent effluent quality.
• Hydraulic equalization dampens both flow and concentration variations, while constant-volume basins primarily reduce concentration fluctuations.
• Efficient mixing and baffling are critical to achieve uniform blending and maximize the effectiveness of the basin.
• Appropriate basin sizing and mixer selection can reduce operational horsepower and lower capital and operating costs.
• Solids management, including removal or resuspension, is essential to maintain effective equalization volume.
• Material selection for mixers, supports, and basin liners is important to resist corrosion, abrasion, and chemical effects in industrial waste systems.
• Equalization can reduce system upsets, simplify control systems, and improve the overall stability of physical, chemical, and biological treatment processes.
• Each waste stream must be individually analyzed to determine the most effective equalization approach.
• Using floating or fixed mixers requires proper installation and protection to ensure consistent operation and optimal performance.
• Economic evaluation of basin design and equalization benefits can yield significant savings in power, aeration, and equipment costs.