Modelling, optimisation and control of full-scale co-digestion biomethane plants

To match the growing demand for biomethane production, anaerobic digestors need an optimal management of the input diet, and the said diet must not be constrained to a single substrate - that is, co-digestion is required. Co-digestion is far more complicated to govern than single-substrate digestion, and constitutes a very hard challenge for the instrumentation and control equipment typically installed aboard full-scale plants. We propose a solution based on offline trajectory optimisation with the aid of a complex first-principle digestor model extended to embrace the co-digestion of complex substrates, followed by online control with a purpose-specific scheme to mitigate the risk of inhibition. We show simulation results and some preliminary tests on a pilot plant.