4 January 2016

GATE Questions

GATE 2006

Low COD to BOD ratio of an organic pollutant represents

(A) Low biodegradability of the pollutant
(B) Presence of free oxygen for aerobic decomposition
(C) High biodegradability of the pollutant
(D) High arsenic in the pollutant

Answer: (C) High biodegradability of the pollutant

·         BOD (Biochemical oxyen demand) - The amount of oxygen required by micro-organisms to degrade the organic matter.
·         COD (Chemical Oxygen Demnad) - In this process , Use of strong chemical agent (such as potassium dichromate) is used to degrade both the organic as well as inorganic matter present in the wastewater samples.

·         COD values are always higher than the BOD values. Because COD includes both biodegradbale and non-biodegradable substances whereas BOD contains only bio-degradable.

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