Degradation of toxic phenolic compounds in olive oil mill wastewater by using the electro-fenton process using different graphite electrodes

In this study, degradation of vanillic acid, coumaric acid and protocatechuic acid, three representative toxic phenolics in olive oil mill?s wastewater were carried out with electrochemically generated Fenton?s reagent (H2O2 + Fe2+) and the strength of various systems having different carbon electrodes, namely carbon felt and borondoped diamond (BDD) and the presence or absence of UV support were compared throughout the degradation processes upto mineralization. It has been demonstrated that all three phenolic compounds were completely reacted with hydroxyl radicals and degradated efficiently by using both carbon felt and BDD as working electrodes, though BDD was found to be more effective when the degradation and mineralization results were normalized with respect to unit surface areas of the working electrodes. In photoelectro-Fenton process, it has been shown that the degradation and mineralization efficiency of the phenolic compounds were enhanced by the effect of UV-A light, especially at the later stages of the degradation processes. It was observed that the effective surface area of the working electrode was the crucial parameter for determining the amount of electrical energy to be spent for mineralizing a certain amount of the phenolic compound such that higher the surface area of the working electrode, less the spent electrical energy during the electrolysis for mineralizing the same amount of the phenolic compound. Key Words: biophenolics, electro-Fenton, carbon felt, BDD, olive oil wastewater.