Combined treatment of olive mill wastewater by multi-soil-layering ecotechnology and adsorption on activated carbon/lime

The main objective of this work was to evaluate the ability of the multi-soil-layering (MSL) combined with adsorption, using two adsorbents: activated carbon and lime, for the treatment of olive mill wastewater (OMW). We have studied the influence of different physicochemical parameters, such as the type of adsorbents, the mass of the adsorbent, the dilution factor, the temperature, and the pH. This study has shown that the discoloration rate of OMW by activated carbon is more important in comparison to lime. Optimization of treatment parameters with activated carbon (pH = 2, T = 298 K, dilution factor = 5, mass (CA) = 5.5 g) allowed a 92% chemical oxygen demand reduction, 100% polyphenols reduction and almost a total discoloration of the effluent. Adsorption isotherm study shows that the adsorption on activated carbon is heterogeneous and in multilayer, and also that the adsorption sites have different interaction energies. Therefore, the process of MSL combined with adsorption on activated carbon could be a good option for the treatment of OMW