Question

_______ is the velocity at which the solid matter in sewage remained in suspended form.

(a) Settling velocity

(b) Self cleansing velocity

(c) Mean velocity

(d) Non Scouring velocity

The question was asked during an interview.

This intriguing question comes from Minimum and Maximum Velocity of Flow topic in chapter Hydraulic Design of Sewers of Environmental Engineering

Answer 1

The correct option is (b) Self cleansing velocity

To explain I would say: Self cleansing velocity is the minimum velocity, which is required to keep the solid particles in suspended form otherwise they will settle and result in clogging.