Electrolytic treatment method of Olive Mill Waste Water, during which, olive mill waste water passes through grids of specific gaps (3, 4, 5), and then is subjected to flotation with Nitrogen, which through an appropriate porous ceramic diffuser device enters the waste water stream with a specific diameter range of bubbles and where the residual oil floats and it is removed by a surface scraper; then, the oil free olive mill waste water is made saline by being mixed with brine which derives from the discharge of a reverse osmosis unit, or which has been prepared from water and NaCl; then, the oil free saline olive mill waste water passes through a special type flotation clarification unit (16, 17, 18, 19), where chemicals are injected at different stages in the treatment of the oil free saline olive mill waste water, while the pH and the quantity of the injected chemicals are controlled by a PLC; at this point, the flotation of solids included in the aforementioned waste water is achieved by injecting air with specific diameter range bubbles, through a nano-bubble production pump and a suitable porous ceramic diffuser device and the floating solids removal is being done by a first surface scrapper and a second surface scraper; afterwards, the oil free saline olive mill waste water passes through self-cleaning filtering units of specific gaps (37, 38, 39, 42, 43, 44) and is then forwarded for electrolysis by non-sacrificial anode electrode such as a Dimension Stable Anode, or sacrificial anode electrode, where the oil free saline olive mill waste water is electrolyzed with a specific minimum intensity of direct current per cm 2 of anode, for a specific period; then, the de- oxidation of the electrolyzed and saline olive mill waste water takes place within a predetermined period, afterwards, the waste water passes through an activated carbon filter of specific volume in relation to flow, and then the waste water is lead to the reverse osmosis, wherein the brine discharge of the reverse osmosis returns in the treatment process of the oil free olive mill waste water. then is subjected to flotation with Nitrogen, which through an appropriate porous ceramic diffuser device enters the waste water stream with a specific diameter range of bubbles and where the residual oil floats and it is removed by a surface scraper; then, the oil free olive mill waste water is made saline by being mixed with brine which derives from the discharge of a reverse osmosis unit, or which has been prepared from water and NaCl; then, the oil free saline olive mill waste water passes through a special type flotation clarification unit (16, 17, 18, 19), where chemicals are injected at different stages in the treatment of the oil free saline olive mill waste water, while the pH and the quantity of the injected chemicals are controlled by a PLC; at this point, the flotation of solids included in the aforementioned waste water is achieved by injecting air with specific diameter range bubbles, through a nano-bubble production pump and a suitable porous ceramic diffuser device and the floating solids removal is being done by a first surface scrapper and a second surface scraper; afterwards, the oil free saline olive mill waste water passes through self-cleaning filtering units of specific gaps (37, 38, 39, 42, 43, 44) and is then forwarded for electrolysis by non-sacrificial anode electrode such as a Dimension Stable Anode, or sacrificial anode electrode, where the oil free saline olive mill waste water is electrolyzed with a specific minimum intensity of direct current per cm 2 of anode, for a specific period; then, the de- oxidation of the electrolyzed and saline olive mill waste water takes place within a predetermined period, afterwards, the waste water passes through an activated carbon filter of specific volume in relation to flow, and then the waste water is lead to the reverse osmosis, wherein the brine discharge of the reverse osmosis returns in the treatment process of the oil free olive mill waste water.