Denitrification and nitrification processes improvement for avoiding pollutants limits violations in the effluent

© Springer International Publishing Switzerland 2017. In this chapter, different control strategies are applied with the aim of avoiding SNtot,e or SNH,e violations using BSM1 as testing plant. These control strategies are implemented simultaneously with the hierarchical control structure explained in previous chapter, in order to achieve, at the same time, an EQI and OCI reduction. The tuning of both higher level controllers is modified based on the required objective. The controllers applied for the proposed control strategies are divided into two alternatives: functions that relate the inputs and the manipulated variables, and FCs. Therefore, on one hand, an affine function is proposed to eliminate SNtot,e violations and a combination of a linear function with an exponential function to remove SNH,e violations. At the same time, the higher level affine function is applied. On the other hand, two FCs are proposed to avoid SNtot,eand SNH,e violations. The higher level FC is also applied. For the cases of a rain or storm event and for the simultaneous SNtot,e and SNH,e violations removal, an extra control is added based on affine functions, for both alternatives.