According to best practices, tip speed of the last flocculator should be about ______ and operate in the range of _______.

According to best practices, tip speed of the last flocculator should be about ______ and operate in the range of _______.

• A. 0.5 ft/s, 0.3-0.8 ft/s
• B. 1.0 ft/s, 0.9-1.3 ft/s
• C. 1.5 ft/s, 1.0-2.0 ft/s
• D. 2.0 ft/s, 1.5-2.5 ft/s

Answer: (B)

In flocculation, you want mixing to promote collisions and growth of flocs without tearing them apart. The last flocculator should run at about 1.0 ft/sec tip speed, with a practical operating window near 0.9–1.3 ft/sec. This moderate intensity provides enough shear to keep particles colliding and aggregating into larger, settleable flocs, while avoiding the excessive turbulence that can break them apart. The other ranges either under-mix, which slows floc growth, or over-mix, which damages flocs and wastes energy.

In flocculation, you want mixing to promote collisions and growth of flocs without tearing them apart. The last flocculator should run at about 1.0 ft/sec tip speed, with a practical operating window near 0.9–1.3 ft/sec. This moderate intensity provides enough shear to keep particles colliding and aggregating into larger, settleable flocs, while avoiding the excessive turbulence that can break them apart. The other ranges either under-mix, which slows floc growth, or over-mix, which damages flocs and wastes energy.