Olive oil is tasty and healthy. However, liquid and solid waste materials are created during the production process that contains polyphenols. These aromatic compounds are of natural origin, but that is one of the reasons why waste products from the olive oil industry have a considerable negative environmental impact.
For this reason, the waste must be disposed of in a complicated process. Partners from research and industry examined how to utilize the residues in the “En-X-Olive” project, which is sponsored by the EU. The idea is to first extract usable substances to use them as natural antioxidants in the cosmetics or foodstuffs industry. The remaining biomass should be utilized to create energy.
Scientists from the Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB in Stuttgart are checking to see if the wastes are suitable for providing biogas. Initial laboratory-scale checks show that the liquids as well as the solid residues provide valuable energy. The residual wastes were fermented using a process developed at IGB during which the substrates are mixed optimally in the reactors during the fermentation process.
Up to 720 liters of biogas were created from solid waste within 20 to 30 days per kilogram of organic dry substances, depending on the composition of the respective waste portion. For the liquid wastes, the researchers were able to prove 680 to 980 liters of biogas per kilogram of organic dry substances within 10 days. A traditional biogas facility with corn silage provides 680 liters of biogas per kilogram of organic dry substances. Even the fermentation residues can be utilized, for example, as organic fertilizer.
Source: Fraunhofer Institute