Technical Bulletin No. 0506: Time Variable Modeling of ASB Systems and Examination of an Aerator Control Strategy

The objectives of this study were to (a) examine the predictive capability of the NCASI model using time varying inputs and (b) use the model to provide a rational basis for determining the time varying aeration level required to maintain a consistent effluent BOD concentration over a twelve month period. To achieve the former objective, the NCASI ASB model was applied, in its time variable mode, to simulate day by day process performance at two mills over a three year period. The simulated effluent BOD concentrations were compared with measured BOD concentrations in graphical displays accompanied by tabular summaries of the model’s accuracy in predicting observed elevated effluent BOD levels.