Integrated modelling of anaerobic digestion process chain for scenario assessment

Abstract

Anaerobic digestion (AD) expansion as a renewable energy source offers environmental benefits, such as reducing mineral fertilizer use and preserving soil organic matter. However, poor AD performance can cause greenhouse gas emissions and nutrient loss, impacting efficiency. To address this, an innovative AD process chain (ADPC) model was developed to dynamically simulate biogas production, organic matter bioaccessibility, digestate phase separation, storage, and soil application, focusing on carbon and nitrogen dynamics. Evaluated against 5 lab-scale experiments and C/N soil dynamics without specific calibration, the model accurately reproduced trends (bias: 11% for biogas, r²: 0.78 for soil N dynamics), despite discrepancies in digestate carbon speciation and soil C dynamics, emphasizing the importance of calibrating feedstock biodegradability and hydrolysis parameters to enhance accuracy. Additionally, feedstock seasonality scenarios demonstrated the importance of dynamic modeling in predicting agronomic digestate fate positioning ADPC as a valuable tool for scenario testing considering both energy and agronomic valorization.