Model predictive control of biological nitrogen removal via partial nitrification at low carbon/nitrogen (C/N) ratio

• Model predictive control for partial nitrification was developed.
• Aeration and carbon source addition can be saved by MPC.
• Partial and complete nitrification control can be switched by using different set-point value for DO.

The shortage of easily degradable carbon source in the denitrification process limits the biological nitrogen removal efficiency. Partial nitrification has shown to be an attractive technology due its savings in aeration and external carbon source addition cost in the biological nitrogen removal. In this article, a model predictive control method was proposed to optimize the aeration and the external carbon source addition under the disturbance of influent flow rate and nitrogen load. The results indicated that 56% saving in external carbon source addition and 26% saving in aeration cost can be achieved by the model predictive control method applied in the partial nitrification, in comparison to the complete nitrification.