Advanced monitoring and control of anaerobic wastewater treatment plants: software sensors and controllers for an anaerobic digester

A mass balanced based model representing the dynamical behaviour of anaerob ic digester has served as a basis for the design of software sensors for th e concentration of inorganic carbon, alkalinity and volatile fatty acids. T he predictions of the sensors are class to the actual off liner measurement s. The model has also been used to design a model-based adaptive linearizin g controller and a fuzzy controller whose objective is to regulate the, rat io of the intermediate alkalinity over the total alkalinity below some desi red value (0.3) under which the process is assumed to remain in stable cond itions and avoid VFA accumulation. Both controllers were calibrated via ext ensive numerical simulations and implemented. The controllers proved succes sful in maintaining the ratio of TA over PA below 0.3, even in presence of large variations of the organic load.