The production of olive oil are concentrated in the countries around the Mediterranean see: Espagne, Portugal, Italia, Greece, Torque, Tunisia and Marco. These countries represent more that 90% of the world production. The wastewaters issue to olive oil industry are charged out of polluting matters which produce a negative impact on the natural medium and especially the reserves of water and the production of drinking water. The wastewaters of olive oil industry are obtained after triturating of olives. These wastewaters are black colouring (brown dark), odorous liquids and characterized by the presence of a large quantity of polyphenols. These wastewaters contain 7 to 15% of organic matter in weight %. This fraction is primarily made up of glucids, proteins, vitamins, phenolic compounds and polyphenols. These wastewaters contain also mineral fraction around 2% of the dry matter. This mineral fraction is primarily made up of phosphates, chlorides, sulphates, calcium, magnesium and potassium. The biological oxygen demand (DBO_5) and the chemical oxygen demand (COD) are, according to the method of triturating, up to 60 g/l and 160 g/l respectively. The pH of these wastewaters is close to 5. Several methods of treatment, such as biological treatments, coupled or not with a physical pre-treatment, was developed. Treatment of wastewaters from olive oil industry was already performed by hydrothermal oxidation. Hydrothermal oxidation combines pressure and temperature like activators of reaction. The hydrothermal oxidation process leads to non-toxic end product. The organic matter (CHO) is converted in CO_2 and H_2O exclusively.
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