1 What is the purpose of primary sedimentation, and how are units sized? 2 A treatment plant has…

1 What is the purpose of primary
sedimentation, and how are units sized?

2 A treatment plant has three primary
clarifiers at 60 ft in diameter with side water depths of 9 ft. The

inboard weirs are set at 54 ft. The
average daily flow is 4.6 mgd and the peak flow is 8.7 mgd. Calculate the

overflow rates, detention time, and weir
loading. Using the calculations, are the clarifiers adequately sized? What are
the overflow rates with one unit out of service?

3 A primary clarifier is 65 ft in
diameter and receives a peak flow of 1.2 mgd containing 230 mg/l TSS.

Calculate the overflow rate,

1 What is the purpose of primary
sedimentation, and how are units sized?

2 A treatment plant has three primary
clarifiers at 60 ft in diameter with side water depths of 9 ft. The

inboard weirs are set at 54 ft. The
average daily flow is 4.6 mgd and the peak flow is 8.7 mgd. Calculate the

overflow rates, detention time, and weir
loading. Using the calculations, are the clarifiers adequately sized? What are
the overflow rates with one unit out of service?

3 A primary clarifier is 65 ft in
diameter and receives a peak flow of 1.2 mgd containing 230 mg/l TSS.

Calculate the overflow rate, and based on
the information in the text, estimate the percentage of TSS

removal and effluent TSS concentration.
If ferric and polymer are added to improve primary removal,

what is the estimated removal and
effluent TSS concentration.