Global trends toward more stringent regulation of effluent quality resulting from the treatment of wastewater has lead to increased interest in the application of advanced control techniques in nutrient removal processing. Auckland's primary wastewater treatment facility, the Mangere Wastewater Treatment Plant, employs a suspended growth biological treatment process for the purpose of ammonia removal. The wide range of operating conditions experienced at the facility in combination with process non-linearities, transportation delays and measurement uncertainty result in complicated control system requirements. This paper analyses the dynamic behaviour of the system in respect to the associated aeration requirements through the formulation of a system model and investigation of sophisticated control strategies.

The objective of this work was to minimise the compressed air required to control the rate of ammonia removal in the wastewater bioreactors. In order to do this a reduced nonlinear dynamic model based on the International Association on Water Quality (IAWQ) activated sludge model No. 3 was developed, expressing the nitrification kinetics and hydraulic dynamics of the system. From this model a steady state representation of the plant was derived and simulated for various load characteristics experienced at the facility, and as a result an optimal load profile was developed for the compressed air distribution to the four aerobic zones.