Abstract: “Activated sludge process control is a major challenge to plant operators given the need for correct balance of parameters to achieve plant optimum conditions. A good example is a correct Mixed Liquor Suspended Solids (MLSS) balance necessary to retain the Food to Microbe (F/M) ratio within the desired range. In this regard, mathematical models play an important role in assisting plant process control. Thus, a research on a full scale activated sludge nutrient removal plant was carried out in Harare, Zimbabwe at Firle Sewage Treatment Works (FSTW) Unit 4. The main objective was to investigate opportunities for optimizing nutrient removal through the use of BioWin Simulator. This paper presents the results of calibration, simulation and validation of the BioWin modeling tool for optimum nutrient removal from a study carried out during the period 2012 to 2015 at FSTW. BioWin Simulator is complex because it attempts to simulate simultaneously biological processes of different organisms in”

Keywords: Activated Sludge, BioWin Simulator, Full-scale calibration, Nutrient removal, Validation