# GATE Questions & Answers of Primary, Secondary and tertiary treatment of wastewater

## What is the Weightage of Primary, Secondary and tertiary treatment of wastewater in GATE Exam?

Total 3 Questions have been asked from Primary, Secondary and tertiary treatment of wastewater topic of Water and Waste Water subject in previous GATE papers. Average marks 1.67.

The spherical grit particles , having a radius of 0.01 mm and specific garvity of 3.0, need to be separated in a settling chamber. It is given that

$\bullet$ g = 9.81 m/s2

$\bullet$ the density of the liquid in the settling chamber - 1000 kg/m3

$\bullet$ the kinematic viscosity of the liquid in the settling chamber = 10-6m2/s

Assuming laminar condition , the settling velocity (in mm/s, up to one decimal place) is ___________