Parameter identifiability analysis and model fitting of a biological wastewater model

Abstract A biological wastewater treatment plant situated at Duvbacken in Gavle, Sweden is described. A dynamic model based on the Activated Sludge Model No. 2d (ASM2d) is developed in the simulation language Modelica, and is exported from dymola (a Modelica environment) into Matlab. It is of interest to adjust the parameters in the model such that the developed model fits better to experimental data from the Duvbacken plant. In this paper, a systematic approach for parameter identifiability analysis is described. A standard least squares criterion is used in combination with a direct optimization method to calculate the improved parameter estimates, and the adjusted model is validated against experimental data from the industrial plant.