Question

Detention time for a circular tank is given by _______

(a) t = D (D + 0.785H) /Q

(b) t = D (0.1D + 0.785H) /Q

(c) t = D2 (0.01D + 0.785H)

(d) t = D2 (0.01D + 0.785H) /Q

I had been asked this question in unit test.

Query is from Design Elements of Sedimentation topic in section Sedimentation of Environmental Engineering

Answer 1

Right answer is (d) t = D2 (0.01D + 0.785H) /Q

To explain: Detention time for a circular tank is given by t = D2 (0.01D + 0.785H) /Q where D is the diameter of the tank, H is the vertical depth of wall and Q is the discharge rate.