Question

4. What is the purpose of "secondary treatment" in sewage system?​

Answer 1

Explanation:

Secondary treatment is the removal of biodegradable organic matter (in solution or suspension) from sewage or similar kinds of wastewater.

Answer 2

$\huge{\mathfrak{\underline{\red{Answer}}}}$

The secondary treatment is important because the biological or organic wastes that are still present in the clarified water are removed.

_____________________________

Hope it helps! :)