Future Trends in Olive Industry Waste Management: A Literature Review

Abstract

AbstractOlive oil is one of the major features of the Mediterranean diet signifying healthy nutritional practices of both ancient and modern times. It is an exceptional food and contains several components beneficial for wellbeing and well-being. Olive oil, as well as the olive tree leaves are rich in oleuropein. During maturation of the fruit and the leaves, oleuropein is broken down to hydroxytyrosol and elenolic acid that are valuable components. These are antioxidants that strengthen the immune system. Oil mills use different technologies and consume a lot of water and energy. Depending on the technology, along with the main product line, side-streams such as cakes, pomace, kernel, and different types of olive mill wastewaters are generated. Wastes are also generated from subsequent treatment facilities for pomace oil and soap production. Captured oils are reclaimed and refined if possible. Only part of the beneficial chemicals such as polyphenols in the olive fruit is retained in the olive oil phase and a substantial part goes into the waste streams. More than fifty different valuable phenolics and other organic compounds have been identified in olive mill wastewaters. Pomace contains another good portion of polyphenols depending on the extraction technology. These chemicals need to be processed or removed from wastewaters by pretreatment for easier environmental management as the wastes are not acceptable to the receiving environmental media, and moreover they inhibit waste treatment. Integrated with this treatment, biotechnological conversions, or recovery of pure ingredients from the wastes are advisable to produce valuable raw materials for food, energy, agriculture, and pharmaceutical sectors. With the rising of 3R (reduce, reuse, recycle) trends, conservation of water and energy has become an issue in the olive industry. This strategy extends from preservation of these resources to enrichment of the beneficial ingredients in the product oil and reclamation of chemicals from olive by-products and wastes. Another option is adding wastes into adjusted cultures as substrates for biomass production and use the products in food, energy, and fertilizer industries. Innovative, and revised conversion technologies are needed for treatment, reuse, and reclamation of these chemicals from by-product and waste streams. There is a high number of scientific publications to address these more challenging goals. In this article new trends for stand-alone or integrated methods of waste treatment/pretreatment in management schemes for olive agro-industry with waste minimization, bioconversion and recovery/purification of beneficial chemicals are evaluated. Among the options, biotechnology of producing fuel, food, animal feed, pharmaceuticals, and fertilizers is especially important. These are being discussed for development of a profile leading to future research interests in view of the big number of published scientific research related to olive agro-industry.KeywordsOlive productsOlive waste treatmentOlive industry material side-streamsBiotechnology of olive wastesAgricultural uses of olive wastesTreatment of olive oil mill wastesTreatment of table olive wastesWaste minimization in olive industryBiorefinery of olive industry wastes