Adding Value to Olive Oil Production Through Waste and Wastewater Treatment and Valorisation: The Case of Greece

Abstract

Nowadays, an increasing trend towards olive oil production is observed globally. The extraction of olive oil is mostly implemented through three-phase or two-phase centrifuge systems. Olive pomace, derived as a by-product of olive oil processing, constitutes a raw material for olive–pomace oil production. The operation of olive oil mills and olive–pomace industries has been connected with the generation of heavily polluted wastewater and solid waste. The present paper aims at investigating the current treatment methods and techniques applied for the management of the wastewater and solid waste generated by olive oil (including olive–pomace oil) production in Greece. Aiming at adding value to the Greek olive production process, international practices applied for solid waste and wastewater treatment as well as potential valorisation options are reviewed within this paper. The results reveal that there is room for improvement in wastewater treatment in Greece, since the currently applied method, i.e. oil removal, neutralisation, sedimentation and evaporation in open lagoons, comprises only a basic—level treatment technique. Concerning solid waste management, attention must be paid to the use of sludge produced from the evaporation ponds, since its application as soil improver without appropriate treatment may entail diverse toxic effects to soils. Regarding solid waste valorisation, pomace handling is thoroughly exploited in Greece, since it is utilised for the production of olive–pomace oil and pomace wood. Other valorisation opportunities, identified in the literature, include production of biomolecules as well as cosmetic products, dyes, construction materials and water decontamination sorbents. However, more work is needed in order to maximise the economic feasibility and applicability of such practices.