| With the increasing municipal wastewater loads, people pay more attentions to the municipal wastewater treatment, so it is the requirement that we develop more efficient procedures for wastewater treatment plants to meet the stricter requirements on effluent quality and economics. The activated sludge process has been extensively utilized for the secondary treatment of industrial and municipal wastewater. The aim of this thesis is primarily to propose and illustrate methods for modeling and control of activated sludge processes, develop a simulator for the activated sludge process, in order to possibly strength the users' knowledge for different process plants and the control strategies, and possibly improve process efficiency.The first part of the thesis introduces the activated sludge model No.l (ASM1), and illustrates the representative method, the characters of the water quality and the different components in detail.The second part of the thesis includes a derivation of reduced order models for the activated sludge process. Firstly, the paper introduces the derivation of time-varying linear state-space models for the anoxic part and the aerobic part. Secondly, by integrating the anoxic part model with the aerobic part model, we can get the resulting models - a time-varying bilinear state-space model for the activated sludge prenitrification system. Finally, we simply introduce a settler model under the ideal condition.In the third part, a MATLAB-GUI (graph user interface) based computer simulator of the activated sludge process is developed. An overview of its functions and applications, the algorithms and procedure of simulation are given.Finally, three representative control strategies, such as the control of external carbon flow rate, the supervision control of the DO process and the control of internal recirculation flow rate, are used in the simulator under different weather conditions, in order to analysis the practicability and feasibility of the simulator.
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