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ABSTRACT

The first order biochemical oxygen demand (B0D)model developed early this century is still the most widely used model for the prediction of BOD progression as a function of time. Numerous methods are available for the determination of the ultimate BOD and rate constant for deoxygenation which define this model. Evidence suggests that the rate constant varies randomly within a period of time; and, if the rate constant for deoxygenation is assumed to have a normal distribution with constant mean and variance, then it is possible to introduce a third parameter for the definition of BOD progression with better accuracy. Preliminary results indicate that the sum of squares of the differences between the measured and computed values of BOD is significantly reduced when the three-parameter model is used for the prediction of BOD as a function of time.