Fuzzy predictive control for nitrogen removal in biological wastewater treatment

Whenever the carbon/nitrogen ratio of a domestic wastewater is too low, full denitrification is difficult to obtain and an additional source of organic carbon has to be provided. Since loading conditions may vary appreciably over the diurnal cycle, depending on the weather and sewage conditions, dosing should be controlled by an adaptive regulator to keep into account the time-varying process dynamics. A fuzzy predictive controller is proposed in this paper and its performance is tested through numerical simulations. The new aspects brought forward are the use of an improved model for denitrification, the use of benchmark (i.e. thoroughly tested and standardised) input files and the conclusion about regulator performance in overall plant performance, in terms of carbon saving and discharge compliance.