Co-digestion and food waste AD: BioWin modelling to optimise OLR and HRT on the Avonmouth food waste digesters

In this study, a model for anaerobic digestion of food waste was developed using BioWin 4.1 simulator software. Substrate characteristics were determined by laboratory analysis and steady state simulation. Kinetic parameters were identified by running dynamic simulations. Input data for calibration and validation was collected from a large-scale food waste digestion plant in the UK. The model predictions showed a high degree of agreement in terms of biogas production, COD and VS reduction, and ammonia and VFAs concentrations. The model was used to investigate how the process responds to various changes in the operating conditions including increasing organic loading rate (OLR) or decreasing HRT. The results show that the current 20-25 days HRT could be decreased by 10% without risking process stability and reducing the efficiency of the anaerobic digestion, and hence throughput and biogas production could be increased.