Plant-wide modeling and optimization of a large-scale WWTP using BioWin’s ASDM model

In this paper, a plant-wide model has been created for an Egyptian WWTP located in Cairo, namely the Gabal El-Asfar, using BioWin 5.3 software. The model has been created according to the Good Modeling Practice protocol where design reports, effluent analysis, and historical data have been collected - along with various site visits and a detailed sampling campaign. The collected data was used to acquire the necessary analysis for wastewater characterization and model calibration. The wastewater has been characterized and the model has been calibrated according to STOWA protocol for calibration. Then, the model has been dynamically validated using the analysis acquired over an entire year. The model’s accuracy was acceptable and therefore was created to perform optimization studies. Multiple operational scenarios were simulated to achieve the highest effluent quality with nitrogen removal, as the plant currently is not able to perform nitrification-denitrification. Different DO concentrations, RAS flows, SRTs and consequently WAS flows were varied to optimize the nitrogen removal. It was found that nitrification and denitrification percentages of 94 and 62.4%, respectively, could be achieved easily without modifying the WWTP’s configuration or unit capacities. This was achieved by increasing the SRT from 2.7 to 7 days, while converting some compartments of the aeration tank from aerobic to anoxic. Sludge and water lines were both included in to assess the effect of any change in the operating conditions on all components of the plant including sludge units.