Development and calibration of a model for biohydrogen production from organic waste

Existing models for H-2 production are capable of predicting digester failure caused by a specific disturbance. However, they are based on studies using simple sugars, while it is known that H-2 production and fermentation kinetics vary with the composition and characteristics of the substrate used. Because the behaviour of biological processes may differ significantly when the digesting material is a complex matrix, such as organic waste, the aim of this study was to develop and calibrate a mathematical model for the prediction of hydrogen production on the basis of the results obtained from a laboratory scale experimental study using source-selected organic waste. The calibration was carried out for the most important kinetic parameters in mesophilic anaerobic digestion processes and also served as a sensitivity analysis for the influence of both the specific growth rate (mu(max) and the half velocity constant (k(s)), both of which are strongly dependant on the substrate used. High values of mu(max) led to a shorter lag-time and to an overestimate of the cumulative final H-2 production relative to the experimentally measured production. Additionally, high values of k(s) associated with amino acid and sugar fermentation corresponded to a lower rate of substrate consumption and to a greater lag-time for growth of hydrogen-producing microorganisms. In this case, a lower final H-2 production was predicted than that which was experimentally observed. Because the model development and calibration provided useful information concerning the role of the kinetic constants in the analysis of a fermentative H-2 production process from organic wastes, they may also represent a good foundation for the analysis of fermentative H-2 production from organic waste for pilot and full-scale applications. (C) 2013 Elsevier Ltd. All rights reserved.