A circular clarifier with a diameter of 50 feet and a depth of 10 feet treats a flow of 2 MGD, what is the detention time in hours?

To determine the detention time in a circular clarifier, you first need to calculate the volume of the clarifier in gallons and then relate that volume to the flow rate, which is given in million gallons per day (MGD).

The volume of a circular clarifier can be calculated using the formula for the volume of a cylinder:

Volume (V) = π × r² × h

Where:

• r is the radius (in feet)

• h is the depth (in feet)

Given that the diameter is 50 feet, the radius will be half of that, which is 25 feet. The depth of the clarifier is 10 feet. Plugging these values into the formula:

V = π × (25)² × (10)

= π × 625 × 10

≈ 1963.5 cubic feet.

Next, we need to convert cubic feet to gallons. There are 7.48 gallons in one cubic foot, so:

Volume in gallons = 1963.5 cubic feet × 7.48 gallons/cubic foot ≈ 14,694 gallons.

Now, to find the detention time (DT), we use the formula:

Detention Time (hours) = Volume (g