Question

What is sludge blanket?

(a) Blanket of waste

(b) Anaerobic digester

(c) Aerobic digester

(d) Simple sludge

I had been asked this question at a job interview.

This interesting question is from Treatment Processes in chapter Effluent Treatment of Bioprocess Engineering

Answer 1

The correct answer is:

(a) Blanket of waste

A sludge blanket refers to a layer of suspended sludge particles that accumulate in certain wastewater treatment processes, such as in sedimentation tanks or clarifiers. In these systems, solids settle to the bottom, and the thicker sludge layer that forms at the bottom of the tank is called the sludge blanket. It plays an important role in separating solids from the treated water.

To clarify the other options:

• Anaerobic digester (b) and aerobic digester (c) are specific types of digesters used to break down organic waste, but they are not directly related to the concept of a sludge blanket.
• Simple sludge (d) is not a specific term used in wastewater treatment and does not describe the "blanket" formed in certain processes.

Therefore, a sludge blanket is indeed a blanket of waste, typically composed of settled solids or suspended particulates in water treatment processes.