Polynomialized model for critical DO deficit

The existing DO sag models of Streater-Phelps have become obsolete in the present day context of polluted streams in which a part of the BOD removal necessarily takes place through sedimentation. The Streater Phelps models do not consider this aspect. Bhargava's theoretically derived model for the critical DO deficit rests on an almost linear removal of the settleable BOD and an exponential decay of non-settleable BOD. However, the Bhargava's model has two independent but complex expressions, one each for times less than and greater than the transition time. A polynomialized form of Bhargava's models for critical DO deficit has been developed as a single expression and universally applicable without any regard to the transition time. Unlike, the Streater-Phelps or Bhargava models, the presented polynomial form of Bhargava models, for critical DO deficit has an additional advantage of evaluating the critical dissolved oxygen deficit concentrations directly and without first determining the time of occurrence of such a deficit. The material presented would thus add to the exiting literature on the subject.