Mathematical models for the kinetics of methane production via the anaerobic co-digestion of biomass waste

Abstract

Unsuitable disposal of organic agrifood waste has had a serious impact on the environment, so processes and tools that enable products of value to be generated from this waste and promote its use need to be created. This research presents the study and comparative evaluation of 5 kinetic models of methane production from the anaerobic co-digestion of biomass waste, such as cattle and horse manure, tripe, and whey in experimental prototype reactors. Based on this biochemical methane potential method anaerobic co-digestion experiments were carried out using hermetic reactors at room temperature that are monitored for 70 consecutive days. The models used to describe the kinetics of experimental methane production were: a) first order kinetic, b) cone, c) modified logistics, d) modified Gompertz and e) modified Richards. The maximum methane production rate and phase lag duration were determined, as well as the accumulated methane production potential. The residual sum of squares and the correlation coefficient were compared to identify the mathematical model that best describes the phenomenon. Modelling the kinetics of anaerobic digestion in a suitable manner is important for designing digesters and predicting the behaviour of anaerobic systems, as well as optimising and scaling real fermenters. It was shown that there is potential to produce biogas from the AcoD of the tested waste.