Question

Separation of solid wastes of different densities is done by

• A. Air classifiers
• B. Screens
• C. Shredders
• D. Magnetic devices

Hint:

Common waste separation methods: \[ \boxed{ \begin{aligned} \text{Screens} &\rightarrow \text{Size separation}\\ \text{Magnetic separators} &\rightarrow \text{Ferrous metals}\\ \text{Air classifiers} &\rightarrow \text{Density separation} \end{aligned} } \]

Answer 1

The Correct Option is A

Step 1: List the common waste separation devices.
Screens separate waste by size, magnetic devices pull out ferrous metal, shredders reduce size rather than separate, and air classifiers use a moving air stream.
Step 2: See how an air classifier works.
Shredded waste is dropped through a rising column of air, light, low density material such as paper and plastic gets carried upward while denser material like glass and metal falls against the airflow.
Step 3: Match the property being used.
Since the separation happens purely because of density and drag differences in the air stream, this is the job of an air classifier.
\[ \boxed{\text{Air classifiers}} \]