Explain why pure o2 injection controlled by DO measurement in pressurised mains maintains fresh sewage?

Question

Explain why pure o2 injection controlled by DO measurement in pressurised mains maintains fresh sewage?

Answer 1

Not sure 100% what u mean, but...

In sewage, controlling the amount of available oxygen is crucial in finding a balance between elimination of organic materials (by bacteria usually) and controlling aerobic organism growth.  

Answer 2

Anaerobic(without oxygen) bacterial decay of sewage produces odors.

Anaerobic (with oxygen) bacterial decay doesn't produce odors.

Injecting Oxygen into the sewer main promotes aerobic vs anaerobic decay