Modeling of Anaerobic Digestion of Food Industry Wastes in Different Bioreactor Types

Abstract

In the present study, modeling of the anaerobic digestion of food industry waste is examined. A very simple model was developed, assuming that the organic matter (in terms of COD) is composed of a hardly and an easily biodegradable COD fraction, which are consumed through different Monod kinetics towards methane production. Biochemical methane potential tests and continuous stirred tank experiments were carried out and used to estimate the values of the main kinetic parameters. In the sequel, the kinetic model is used to predict the behavior of a periodic anaerobic baffled reactor (PABR), also fed with the same waste. Only a single new parameter, the biomass retention factor is added in order to model the behavior of the high-rate reactor. Despite the structural and operational differences of the two anaerobic digesters, the simple model was able to satisfactorily predict methane production and COD consumption of both bioreactors over a wide range of operating conditions. Thus, the proposed modeling approach can be valuable in describing the behavior of different anaerobic digesters, using a minimal number of kinetic variables and kinetic/stoichiometric parameters.