Ncert Exercises & Solutions

What would happen if oxygen availability to activated sludge flocs is reduced?

1.	It will slow down the rate of degradation of organic matter.
2.	The center of flocs will become anoxic, which would cause death of bacteria and eventually breakage of flocs.
3.	Floes would increase in size as anaerobic bacteria would grow around floes.
4.	Protozoa would grow in large numbers.

(b) Activated sludge microorganisms need oxygen as they oxidise wastes to obtain energy

for growth. Insufficient oxygen will slow down or kill off aerobic microorganisms, make facultative

organisms work less efficiently and ultimately lead to the breakage of flocs.

it will also result in the production of the foul-smelling byproducts of anaerobic decomposition. So,

sufficient oxygen must always be maintained in the aeration tank to ensure complete waste

stabilisation.