Select the correct statement regarding activated sludge formed during secondary sewage treatment.

Q. In one method of sewage treatment, the sewage flows into a _______ tank in which anaerobic bacteria decompose the waste.

Q. Assertion: A major part of the activated sludge is pumped into large tanks called anaerobic sludge digesters.
Reason: During anaerobic digestion, the anaerobic bacteria digest the organisms present in the primary sludge.

Q. After secondary treatment, a part of activated sludge is passed back to aeration tank as inoculum while most of the part of activated sludge passed to

Q. During secondary sewage treatment,
Flocs from the settling tank are sent for their digestion
Only a part of it is sent as inoculum in the aeration tank
Then the aeration tank is agitated where this inoculum multiplies for the development of flocs

I have a doubt,
Can we not transfer all the flocs from the sediment tank to the aviation tank and not just the small inoculum? Because now even if we don't agitate the aeration tank but allow the flocs in the aeration tank to break down the sewage the same process would occur in the aeration tank in a much less time and we would also be saving the energy spent in the agitation of aeration tank.

Q. Study the given differences between primary sludge and activated sludge and select the incorrect ones.

	Primary Sludge	Activated sludge
(i)	It is sludge formed during primary sewage treatment.	It is sludge formed during secondary sewage treatment.
(ii)	It possesses flocs of decomposer microbes.	It does not possess flocs of decomposer microbes.
(iii)	It does not require aeration.	Formation of activated sludge requires aeration.
(iv)	A lot of decomposition occurs during formation of primary sludge.	Very little decomposition occurs during formation of activated sludge.