Investigation of organic wastes from Mediterranean plants to produce biogas by anaerobic digestion
Résumé
The University of Corsica is contributing to the research of both efficiency and integration of renewable energy in the main electrical grid. Since 2013, a scientific program concerning the valorization of biomass energy has been developed to investigate the methane potential through the anaerobic digestion process of lignocellulosic resources. In Corsica, due to the clearing brush policy to prevent forest fires, cellulosic wastes are generated. Besides, Corsica is an important producer of essential oil from Mediterranean species thanks to a process generating an important amount of dried vegetation as waste every year.
The aim of this preliminary study on biomass as renewable energy was to characterize and to select the most appropriate substrates for the anaerobic digestion process. Fiber contents and Biochemical Methane Potential (BMP) were performed on five substrates. Heather, rockrose and strawberry tree were chosen as representative of forest fuels. Water distillation residues of laurel and immortelle were considered as natural resource wastes.
On this work, we focus on the three species which had the best BMP. Rockrose, dry residue of immortelle and strawberry tree produced 139, 124 and 87 Nm3 CH4 per grams of volatile solids, respectively. The ratio holocellulose: lignin, thanks to the Van Soest method of fiber determination, was determined for those species: 3.8, 3.4 and 1.7. This parameter is a key factor to take into account for the correlation of the BMP with the compositional characteristics. Further work will be performed on these chosen substrates to optimize the anaerobic digestion process in 15 L-reactors.