Olive mill effluent depuration by ozonation and Fenton processes enhanced by iron wastes

The aim of the present work was to compare the potential of iron industry wastes to enhance ozone and hydrogen peroxide action on the degradation of olive mill wastewaters (OMWs). The results attained show a higher efficiency for ozonation using a lower catalyst load. Nevertheless, Fenton's process led to a larger amount of chemical oxidation demand (COD) removed per mole of oxidant applied. It was concluded that hydroxyl radicals are responsible for the pollutant abatement. High eco-toxicity decay was observed after the treatments. Furthermore, a preliminary analysis of the iron shavings' stability was made by reusing it in two feed-batch trials. It was concluded that while activity was maintained for Fenton's, a decrease of about 20% was verified for catalytic ozonation. Comparing these results with the ones obtained for the same processes applied to an actual OMW, a lower percentage of COD abatement was achieved. However, when reporting the amount of COD removed per mole of oxidant used, the difference between effluents are not so high. This should be taken into account when deciding which process should be implemented at an industrial scale. With the outcomes of this research it was possible to conclude that integrating waste management with wastewater treatment was feasible.