Civil Engineering - Waste Water Engineering - Discussion

Biochemical Oxygen Demand (BOD, also called Biological Oxygen Demand) is the amount of dissolved oxygen needed (i.e. Demanded) by aerobic biological organisms to break down organic material present in a given water sample at certain temperature over a specific time period. The BOD value is most commonly expressed in milligrams of oxygen consumed per litre of the sample during 5 days of incubation at 20°C and is often used as a surrogate of the degree of organic pollution of water.

Not BOD cause it is asking consumed. So dissolved oxygen is the right answer. To take out BOD we need initial DO and final DO consumed by the bacteria. And they are asking.

"The amount of oxygen consumed by the aerobic bacterias which cause the aerobic biological decomposition of sewage is known".

The amount of oxygen consumed by the aerobic bacterias which cause the aerobic biological decomposition of sewage, is known. Bio-Chemical Oxygen Demand (B.O.D.)

So, the correct answer is B.O.D. i.e Option A.

BOD is only for the organic material in sewage not for total sewage. For sewage it is the total oxygen consumed which is more than the BOD.

So the answer is DO.

D is correct because the question mentions the consumed oxygen by the aerobic bacteria.

Yes @jay Given answer is correct.

Because here, it says the amount of oxygen consumed.

The Amount of oxygen required to decompose a bacteria by aerobic process called BOD.

Key word for this is "needed=BOD" and "consumed = DO".

I also agree, option A is correct.

I think the right answer is BOD.