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

Options

A. I will slow down the rate of degradation of organic matter
B. The center of flocs will become anoxic, which would cause death of bacteria and eventually breakage of flocs
C. Flocs would increase in size an anaerobic bacterial would grow around flocs
D. Protozoa would grow in large numbers

Answer

B

Explanation

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.