BIOCHEMICAL OXYGEN DEMAND—ITS CHEMICAL REACTION, MATHEMATICAL INTERPRETATION AND METHODOLOGY

Abstract

ANY one who studies water pollution and industrial effluents comes across
the ever important three words—^Biochemical Oxygen Demand, which means
the amount of oxygen, in mg., taken up by 1 litre of the sample (usually
diluted with sufficient well-oxygenated tap-water or synthetic dilution water
made by aerating the distilled water and adding the nutrient salts) or the
quantity of dissolved oxygen required to effect stabihsation by aerobic bacterial
action that portion of the dissolved organic matter which can be oxidised in
5 days at 20° C. It has been observed that in India, Germany and U.S.A.
' the usual practice is to do B.O.D, tests at 20° C. (68° F.) but in England most
of the B.O.D. experiments are done at 18-3° C. (65° F.) even though this is
giving way to 20° C. rapidly. But in practice and interpretation the experiment
is not so simple as that. In the present paper a comprehensive attempt
to explain the basic methodology, chemistry and kinetics involved in B.O.D.
experiment will be made.