Mathematical Analysis and Update of ADM1 Model for Biomethane Production by Anaerobic Digestion

Stefano Bertacchi,Paola Branduardi,Aki Sorsa,Mika Ruusunen,Anu Sirviö

doi:10.3390/fermentation7040237

Stefano Bertacchi, Paola Branduardi + Show 3 more

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https://doi.org/10.3390/fermentation7040237

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Journal: Fermentation	Publication Date: Oct 21, 2021
Citations: 12	License type: CC BY 4.0

Affiliation: University of Milano-Bicocca, University of Oulu

Abstract

Biomethane is a renewable product that can directly substitute its fossil counterpart, although its synthesis from residual biomasses has some hurdles. Because of the complex nature of both biomasses and the microbial consortia involved, innovative approaches such as mathematical modeling can be deployed to support possible improvements. The goal of this study is two-fold, as we aimed to modify a part of the Anaerobic Digestion Model No. 1 (ADM1), describing biomethane production from activated sludge, matching with its actual microbial nature, and to use the model for identifying relevant parameters to improve biomethane production. Firstly, thermodynamic analysis was performed, highlighting the direct route from glucose to biomethane as the most favorable. Then, by using MATLAB® and Simulink Toolbox, we discovered that the model fails to predict the microbiological behavior of the system. The structure of the ADM1 model was then modified by adding substrate consumption yields in equations describing microbial growth, to better reflect the consortium behavior. The updated model was tested by modifying several parameters: the coefficient of decomposition was identified to increase biomethane production. Approaching mathematical models from a microbiological point of view can lead to further improvement of the models themselves. Furthermore, this work represents additional evidence of the importance of informatics tools, such as bioprocess simulations to foster biomethane role in bioeconomy.

Highlights

At the end of the first decade of 21st century, the European Union (EU) RenewableEnergy Directive 2009/28/EC required that by 2020, each member state had to rely on renewable energy for 20% of the total needs and 10% for transport alone [1]
The goal of the present work is to update this model with observations from the The goal of the present work is to update this model with observations from the mimicrobiological nature of the process, and to evaluate which industrially relevant pacrobiological nature of the process, and to evaluate which industrially relevant parameters rameters could impact the most on the final production of biomethane by the simulated microbial consortium
We use a simplified version of the Anaerobic Digestion Model No. 1 (ADM1) model, were hydrogenotrophic methanogens were omitted considering their lower impact on biomethane production if compared to acetoclastic methanogens [10]

Summary

Introduction

At the end of the first decade of 21st century, the European Union (EU) RenewableEnergy Directive 2009/28/EC required that by 2020, each member state had to rely on renewable energy for 20% of the total needs and 10% for transport alone [1]. Namely methane (CH4 ), is a prominent target to be substituted with renewable alternatives, as it is still widely used in the EU for industrial, domestic, and transport sectors. Biogas is a blend of mainly CH4 and CO2 : it can be deployed directly as a source of energy, but the presence of the already fully oxidized CO2 reduces the overall calorific value. For this reason, several “upgrading” processes exist, aimed at purifying biomethane from biogas, to expand its use to domestic and transport sectors via injection into the conventional pipelines [3,4]

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