Modelling Biogas and H2S in Anaerobic Digestion

Green Economy is the key word of the last two decades. In this context, an important role is covered by anaerobic digestion (AD), treating organic waste fractions to recover both fertilizing elements and energy. Countless biochemical reactions lead to substrate degradation and biogas development. Despite AD has been used for many years, its study from an engineering point of view is quite recent. The reference model ADM1 (Anaerobic Digestion Model No.1), proposed in the late 90’s by IWA (Batstone et al., 2002) to describe and simulate the steady-state digestion of sewage sludges from Wastewater Treatment (WWT) plants, has gone through several adjustments during time. The aim of this work is to improve and extend ADM1 by means of coefficients and equations optimization to better fit various contexts such co-digestion processes. Moreover, provide a description of the complete biokinetic of H2S, main biogas impurity, through the homologation of Fedorovich and Kalyuzhnyi studies (1998), which perfectly address its production from the organic feedstock reduction by means of Sulphur Reducing Bacteria (SRB) bacteria. Introducing the novelty of H2S biological abatement process, whose mechanism spontaneously occurs under microareation condition, also requires the implementation of an inhibition function since O2 will affect methane production. Python™ is the coding language chosen in order to solve a highly stiff ODE system and earlier literatures are the roots of this new model, that has been validated on real data resulting in 0.2%vol. H2S and 2%vol. unreacted O2 release.