Anaerobic digestion of olive oil industry waste with a jacketed reactor heated by an autothermal process

A comprehensive valorization of waste generated from the olive oil manufacturing industry and olive grove pruning was conducted. Anaerobic digestion of the sludge waste from the olive industry was performed in stirred tank reactors under mesophilic conditions to remove volatile solids and to generate biogas. The waste was also treated with an alkali to improve biogas production by reducing the lignin content. The required heating for the anaerobic reactors was supplied by energy valorization of waste biomass from olive prunings through an autothermal process. Good heat transfer in a conical combustor using spouted bed technology was demonstrated by measuring local heat transfer coefficients. Combustion of olive pruning waste in this reactor was highly efficient.