The B.O.D. method has been widely used to assess both the degree of organic bio-oxidisable pollution and the consumption of oxygen by the micro-organisms responsible for the degredation of the pollution. Although the B.O.D. method is being applied as an international standard, it has a great number of shortcomings which are fundamental to this technique. These have already been discussed in detail by ETTINGER (1956), WUHRMANN (1958) and LENHARD (1962a).
More recently, GAMESON et al. (1958) proposed the introduction of 'ultimate oxygen demand' (U.O.D.), 'as a measure of the total polluting capacity of a waste'. These authors stated that the U.O.D. figure is of great value in calculating the effect of a sewage effluent on the distribution of dissolved oxygen. On the presumption that only the organic carbonaceous matter and reduced nitrogen compounds such as ammonium salts and nitrites can produce a biochemical oxygen demand, it was suggested that the U.O.D. should be calculated from the organic carbon, the ammoniacal and organic-nitrogen and the nitrous-nitrogen, as determined chemically, in the following way: U.O.D. = 2.67 (organic carbon) + 4.57 (NH,+ -N + organic nitrogen) + 1.14 (nitrous nitrogen). The factors were derived from stoichiometrical considerations with regard to the amount of 0, required by weight to oxidise carbon, NH&* -N and NO, -N to CO2 and NO,-. These factors are based further on the assumption that biological degradation is a complete aerobic oxidation which can be expressed in simple chemical reactions and also that the complete oxidation of carbon proceeds by a respiratory quotient of unity.
Fats, carbohydrates and proteins which form normal constituents