Drained sewage has biological oxygen demand `(BOD)`:

Drained sewage has BDO

What is biological oxygen demand ?

BOD (biological oxygen demand) is

BOD (biological oxygen demand) is

Biological oxygen demand (BOD) is a measure of

Explain the process of secondary treatment given to the primary effluent up to the point it shows significant change in the level of biological oxygen demand (BOD) in it.