Question

Differentiable between primary sludge and activated sludge.

Answer 1

PRIMARY SLUDGE	ACTIVATED SLUDGE
Formed during primary treatment of sludge.	Formed during secondary sewage treatment.
It does not contain floes of decomposer microbes.	Floes of decomposer microbes present.
No aeration is required.	It requires aeration.
Very little decomposition occurs during the formation of primary sludge.	During the formation of activated sludge, a lot of decomposition occurs.