NONLINEAR APPROACH FOR THE VFA REGULATION IN AN ANAEROBIC DIGESTER

This paper presents the design and the experimental validation of a nonlinear control approach for the regulation of volatile fatty acids (VFA) in an anaerobic digester. Such an approach is conformed by an output feedback control and an extended Luenberger observer which allows the estimation of the uncertain terms associated to the VFA dynamics (i.e., influent composition and kinetic terms). The nonlinear approach is experimentally validated in a 0.528m3 up-flow fixed-bed anaerobic digester used for the treatment of industrial wine distillery wastewater. The experimental results show that the VFA regulation is achieved in spite of uncertain kinetics, restrictions in the control input and unknown load disturbances.