Evaluation of tree leaf properties for potential biogas production

Tree leaves constitute a significant portion of municipal biowaste. One of the most effective ways to utilize them is as a substrate for biogas production. While studies on the anaerobic digestion of leaves exist, they typically focus on single species, with limited physical and chemical analyses. This study aimed to evaluate the chemical and physical properties of leaves from 11 different tree species and assess their biogas production efficiency and energy potential. Biogas production assessment was performed in lab-scale reactors. The novelty in this research lies in the extensive sample set (leaves from 11 tree species), and the in-depth physicochemical characterization alongside biogas productivity assessments. The results indicate substantial variation in the physical and chemical properties of the analyzed leaves, leading to significant differences in biogas yield and fermentation time. The least efficient (Plane tree leaves) produced 63.69 m³ of biogas per megagram of organic matter (m³/Mg ODM), whereas the most efficient (Birch leaves) yielded 189.15 m³/Mg ODM - a nearly 300 % difference. On an industrial scale, the energy potential of using tree leaves in municipal biogas plants translates to an electricity output ranging from 253.94 to 754.18 kWh per ton of fresh leaf mass. These findings suggest that select tree species offer viable potential as supplementary feedstocks for municipal biogas production.