In this work, three different types of impurities: soybean oil, surfactant and diatomaceous earth were doped to simulate the impurities in wastewaters issued from edible oil refinery plant. The effects of the impurities on the oxygen transfer rate were investigated in an electroflotation cell. The volumetric mass transfer coefficient was studied for a batch mode involving different values of the current density for different impurities concentrations. The capacity of oxygenation and the corrective alpha factor were also studied. Models which relate the volumetric mass transfer coefficient to the current density and the concentration of the impurities were established. The results showed that the presence of impurities significantly reduce the volumetric mass transfer coefficient K(L)a.