Modelling and structure-tailored control of biogas plants fed on agro-food residues

The problem addressed in this paper is the efficient operation of anaerobic digesters for biogas production. We improve the generality of a literature model (the AMOCO) to account for two hydrolysis steps. We introduce an LFT-based parameter identification technique, ans demonstrate the achievable match improvements by validating the model versus experimental data from bench scale reactors fed on corn and cattle manure. We finally propose an innovative scheme for methane production rate control, tailored to the observed dynamic structure of the process, and based on a cascade structure having VFA concentration as the inner variable. A simulation campaign on the model aligned to experimental data, shows that this scheme improves control quality over the state of the art, yet preserving simplicity and ease of tuning-a true necessity for field acceptance.