Surface Loading Rate Surface Settling Rate and Surface Overflow Rate

The surface loading rate is the number of gallons of wastewater passing over 1 ft2 of tank per day. This can be used to compare actual conditions with design. Plant designs generally use a surface loading rate of 300 to 1200 gpd/ft2. Other terms used synonymously with surface loading rate are surface settling rate and surface overflow rate.

Surface Settling Rate (gpd/ft2) =-Flow (gpd)-2 (13.1)

Settling Tank Area (ft2)

Problem: A settling tank is 120 ft in diameter, and flow to the unit is 4.5 MGD. What is the surface loading rate in gpd/ft2?


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  • rollo
    What is surface loading.?
    8 months ago

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