Question

Which of the following order is correct regarding the thickness of layer of the materials used in the mixed media filter?

(a) Anthracite coal < Sand > Garnet sand

(b) Anthracite coal > Sand > Garnet sand

(c) Anthracite coal = Sand = Garnet sand

(d) Anthracite coal < Sand < Garnet sand

This question was posed to me in homework.

My question comes from Dual Media and Mixed Media Filter topic in section Filtration of Environmental Engineering

Answer 1

Right option is (b) Anthracite coal > Sand > Garnet sand

To elaborate: Anthracite coal has a thickness of 45 cm, sand has a thickness of 22.5cm and Garnet sand has a thickness of 7.5 cm. So, coal has highest, sand has medium and Garnet sand has a lower thickness of layer between them.