Difference between surface loading rate and surface overflow rate of sedimentation tanks

Question

Can anyone please explain to me the difference between surface loading rate and surface overflow rate when used during the design calculations of sedimentation tanks in water treatment plants?

Answer 1

I'm not 100% familiar with english terms of art. However, according to this document, they are the same:

The surface loading rate is a hydraulic loading factor expressed in terms of flow per surface area. This factor is also referred to as the “surface settling rate” or “surface overflow rate.” [...] Typical values of surface loading rates for primary clarifiers are 600 to 1,000 gallons per day per square foot.