MATHEMATICAL MODELING AND ANALYSIS OF WASTEWATER TREATMENT PROCESSES

The activated sludge process is the most commonly used biological waste water treatment system. Mathematical modeling of this process is important for improving its treatment efficiency and thus the quality of the effluent released into the receiving water body. These models can help the operator predict the performance of the plant to take cost-effective and timely remedial actions that would ensure consistent treatment efficiency and meeting discharge requirements. However, due to the highly complex and non-linear characteristics of this biological system, mathematical modeling of this treatment process has remained a challenge. The first part of this study is to build fundamental grey-box models to predict the raw influent quality and the preliminary effluent of the plant for any given day using historical data. The thesis is an attempt to model the various waste water treatment processes and validate the model with the historical data available for the Stickney Water Reclamation Plant, Chicago. This model has been further used to analyze the plant on both dry and wet weather conditions. Wastewater treatment processes utilize approximately 3% of the energy consumption in the US. A detailed study of the aeration required for the activated sludge tanks has been performed. The plant has been operated at a far higher aeration compared to the minimum required aeration which has increased the operating costs tremendously. A description of cost reduction by minimizing aeration usage without compromising on the discharge limits has been provided. Finally, storms are one of the biggest challenges faced by the operators in treatment plants. Dynamic simulations of storms have been described using the model to understand and control storm events in a more robust manner.M.S. in Chemical Engineering, May 201