Abstract: The purpose of this study is to observe the effectiveness of coagulation-floculation by of the aluminum sulphate on the removal of organic compounds based on phenolic (phenol and pyrogallol). Trials were conducted on the one hand on synthetic solutions of organic compounds distilled water enriched by ions of magnesium and calcium introduced in various form (CaCl2,2H2O ; CaSO4,2H2O ; CaCO3 ; MgCl2,6H2O ; MgSO4,7H2O), and on the other hand with Algerian drilling waters of different physicochemical characteristics. The addition of minerals seems to improve the yields of elimination of phenolic compounds tested and have an effect on the optimal pH range of coagulation. An application of this process of mineralized waters (water drilling) leads to improved yields compared with distilled water. The experimental results showed that the process efficiency depends on the number and position of phenolic groups on molecules. The main mechanisms would be either a physical adsorption,an exchange of ligand or complexation on the floc surface of aluminum hydroxide.