Valorization of Agricultural Waste: Theoretical Estimation and Experimental Biomethane Yield from Cashew Nut Hulls

Biomethane potential production from cashew nut\r\nhulls, an agricultural waste, was carried out using old and fresh hulls as\r\nsubstrates. Samples were taken from old hulls (around 8 years old) and fresh\r\nhulls produced in cashew scale transformation units at Bobo Dioulasso/Burkina\r\nFaso. Physicochemical parameters showed that cashew hulls can be a good candidate for anaerobic\r\ndigestion. But high acidity, total phenols and lignin tenor could be a\r\nconstraint for anaerobic bacteria. Theoretical biochemical methane potential\r\nshowed high value of 666.937 CH4 L. (Kg VS)-1 and 526.206 CH4 L. (Kg VS)-1 for crushed fresh and powdered old hulls, respectively.\r\nExperimental biochemical methane potential showed significantly low potential\r\nof 1.982 CH4 L. (Kg\r\nVM)-1 and 46.840 CH4 L. (Kg VM)-1 for fresh and hold hulls, respectively. Pretreatment for\r\noptimization, chemical composition and co-digestion system must be expected for\r\na better anaerobic digestion performance.