In Tunisia, oil extraction industry generates high amount of two by-products: an aqueous effluent (Olive Mill WasteWater) and a solid residue (Olive Mill Solid Waste). Two recovery pathways (thermal and physicochemical) were performed to reduce these wastes. Firstly, a combined process which includes impregnation on low-cost renewable absorbents and an energetic recovery via combustion was studied. Olive Mill Solid Waste (OMSW) and sawdust were chosen as absorbent of OMWW. During combustion tests, carbon balance increases with temperature increasing followed by an increase of CO and VOC emissions. Nevertheless, it was necessary to increase the residence time of gas in order to reduce the unburned compounds in the exhaust. This process may be a promising issue to reduce OMWW environmental impact. The mixture of OMSW/ OMWW with mass ratio of OMWW close to 28%wt shows a similar behaviour to original OMSW under inert and oxidative atmospheres. It seems that the use of this mixture of OMSW/OMWW may be a solution for Tunisia since the resource is abundant and may increase farm yields. The physico-chemical way of OMSW recovery focused on the removal of nickel and copper from wastewaters. The trapping of these metals in the ash reveals that nickel and copper are low volatilized. Moreover, these metals are not soluble during leaching. Consequently, their transfer to the atmosphere and the environment is minimal.
