The application of Anaerobic Digestion Model No. 1 for the optimization of biogas production from maize silage, pig manure, cattle manure, and digestate in a full-scale biogas plant

Abstract

The main aim of this study was to evaluate the applicability of a mathematical model based on Anaerobic Digestion Model No. 1 (ADM1) for optimizing biogas production during a two-stage anaerobic digestion process in a full-scale biogas plant. Biogas production was analyzed in two variants. Variant I involved two decision variables: the proportion of the gaseous phase in the total volume of each digester within a preset limit of 0.05 to 0.95. Four decision variables were adopted in variant II: total digester volume during the first and second stage of anaerobic digestion, and the proportion of the gaseous phase in each digester. Digester volume was set at 10–1000 m3 for the primary digester, and at 300–5000 m3 for the secondary digester. The proportion of the gaseous phase was also set within the range of 0.05–0.95. Optimal digester volume (131 m3 for the primary digester and 5000 m3 for the secondary digester) and the optimal proportions of the gaseous phase in total digester volume (0.35 and 0.05, respectively) were generated by the modified ADM1xp model. The modeled parameters predicted a 67% increase in methane yields in a two-stage anaerobic digestion process (acidogenesis and methanogenesis).