Biochemical processes at wastewater treatment plant are complex, nonlinear, time varying and multivariable. Moreover, relationships between processes are very strong. One of the most important issues is exerting proper control over dissolved oxygen levels during nitrification phase. This parameter has a very large impact on activity of microorganisms in activated sludge and on quality of pollution removal processes. Oxygen is supplied by aeration system which consists of many nonlinear elements (blowers, pipes, diffusers). In this paper, the sequencing batch reactor is applied and modelled. Also, the aeration system is modelled. Those models are validated based on real data sets. The adaptive control system with anti-windup filter is proposed and designed for tracking the reference trajectory of dissolved oxygen. Furthermore, the reference trajectory of dissolved oxygen is generated by the supervisory controller using NH4 measurements. Simulation results of control system are calculated for a case study plant located in Swarzewo, Northern Poland.

The wastewater treatment plant can be considered as a dynamic large scale complex system, in which the most important control parameter is the dissolved oxygen concentration in the aerobic zone. The air is supplied to this zone by the aeration system. In the paper, both the sequencing batch reactor and the aeration system are modelled and used as plant of control performed by the cascade nonlinear adaptive control system extended by the anti-windup filter. The effect of certain parameters of the adaptive controller on the quality of control is analysed. Simulation results based on real data recorded in the case study plant are included.