Biological Oxygen Demand (BOD) differs from Chemical Oxygen Demand (COD), on what grounds?

1. BOD is the amount of dissolved oxygen demanded by aerobic biological organisms to break down organic material present in a given water sample at certain temperature.
2. COD is a measurement of the oxygen required to oxidize only the soluble organic matter in water.

Which of the statements given above is/are correct?
a) 1 only
b) 2 only
c) Both 1 and 2
d) Neither 1 nor 2

Ans- [A]

Explanation– Biochemical Oxygen Demand or BOD  is a measure of the amount of dissolved oxygen required for the aerobic bacteria to assimilate and oxidize the organic components present in water or waste water at a certain temperature. Higher the BOD value, higher the organic pollution in water.

Chemical Oxygen Demand or COD is a measure of the capacity of water to consume oxygen during the decomposition of organic matter and the oxidation of inorganic chemicals such as ammonia and nitrite. Statement 2 is thus wrong.