Simulação de controle de temperatura em biorreator de leito empacotado de fermentação em estado sólido para produção de enzimas para biocombustíveis

Abstract

Studies on solid state fermentation (SSF) have gained prominence in recent years due to their potential to produce enzymes for biofuels using agro-industrial solid waste, fitting into the biorefinery concept. Despite its advantages, SSF still faces challenges and limitations such as the formation of thermal gradients in packed bed bioreactors, which are the most suitable models for filamentous fungi, microorganisms that are better adapted to this type of bioprocess. Given this context, the objective of this work was to propose thermal control strategies to prevent or mitigate overheating in these bioreactors. To achieve this, one-dimensional pseudo-homogeneous energy transfer equations in porous media arranged in packed beds were used to model different aeration schemes and operational conditions, with the aid of MATLAB software. The strategies evaluated included varying the inlet air temperature and flow rate, as well as modifying the aeration configuration by implementing central or bidirectional aeration compared to the traditional unidirectional axial aeration model. The proposed schemes were simulated in a case study involving the production of cellulase, an enzyme of great interest to the biofuels sector, by two fungi: Myceliophthora thermophila I-1D3b (thermophilic) and Aspergillus niger (mesophilic). In addition to the proposed strategies, simulation results from the literature involving flow direction reversal aeration were compared with experimental data from a packed bed bioreactor using this same type of aeration. All the strategies tested showed promise in reducing overheating in the bed, based on the simulation results obtained in MATLAB. It was concluded that these alternatives have potential for experimental implementation, with particular emphasis on the modifications in aeration configuration, which showed greater efficiency in reducing overheating. This contributed to better fungal growth, especially for temperature-sensitive microorganisms such as A. niger.