Electrochemical oxidation of olive mill waste waters on Tin Oxide Electrode

Oil mill wastewaters (OMW) are a liquid effluents resulting from the extraction of the olive industry, characterized by their acidic pH ( 5), their red-brown color, Chemical Oxygen Demand may exceed 220 g / L, high phosphorus content that accelerates the growth of algae resulting in eutrophication, high salinity and very large quantity of phenolic compounds ( 8g/L) which cause the destruction of soil microflora and induce toxic effects on plant crops. In addition, this compounds lead to sterilization of soil and the imbalance of the biological interaction between soil s microflora and plants. To treat these liquid wastes, several techniques have been used, but the results are not satisfactory. For this we have chosen the electrochemical process because it is environmental and economic. In this work the electrochemical degradation of olive oil mill wastewater (OMW) was investigated using a Tin dioxide anode SnO₂ in chloride containing solution by cyclic voltammetry and chronopotentiometry. The electrolytic process was detected by the UV–visible spectrometry and the Chemical Oxygen Demand (COD). The influence of current density, time of electrolysis and the concentration of conductive salt were studied. The results obtained show that after only 4 hours of electrolysis, discolouration was reached at 96% with an abatement of COD 73%. The study of the applied current density shows that the best efficiency of the removal of COD reaches a maximum at 100 mA / cm².