Comparison of pyrolysis and anaerobic digestion processes for wheat straw biomass

Due to the growing interest in using biomass as a renewable energy source, this study presents a comparative analysis between two prominent biomass conversion technologies—anaerobic digestion and biomass pyrolysis—focused on wheat straw biomass. The objective of this study is to evaluate and compare the efficiency, energy output, and environmental impact. Anaerobic digestion was performed under mesophilic conditions (35 ± 0.5 °C) using the biochemical methanogenic potential (BMP) methodology. Pyrolysis was conducted through thermogravimetric analysis (TGA) to determine the thermal behaviour and kinetic parameters of the biomass. Biogas production led to better energetic results as high methane yields of over 11 mL CH₄ g⁻¹ VS were obtained. Additionally, the integration of both processes was considered by subjecting digestate from anaerobic digestion to pyrolysis process. Key findings demonstrate that the activation energy ( Ea ) for wheat straw ranged from 166.49 to 176.42 kJ·mol −1 across different kinetic methods, indicating its suitability for pyrolysis. In contrast, digestates exhibited significantly lower activation energies, with 1-week, 2-weeks, and 3-weeks digestates showing ranges of 53.27–60.79 kJ·mol −1 , 38.69–46.86 kJ·mol −1 , and 46.29–72.34 kJ·mol −1 , respectively. These results suggest that anaerobic digestion not only produces biogas but also yields a byproduct with potential for efficient pyrolytic conversion suggesting opportunities for integrated waste management and renewable energy production systems.