Advanced oxidation technologies for the treatment and detoxification of olive mill wastewater: a general review

Olive oil production has an economic importance for Mediterranean countries, ensuring employment opportunities and export earnings. The crushing units produce two types of residues, one solid (pomace) and the other liquid, called olive mill wastewater (OMW). This by-product has adverse effects on the olive oil sector and particularly on the quality of waters into which they are discharged. Hence, there is a critical need to orient the scientific research toward the treatment of this hazardous waste. Several techniques have been proposed and developed for OMW management. However, the advanced oxidation processes (AOP) remain the most advantageous with high treatment efficiencies. This trend allowed achieving a significant detoxification of OMW. A considerable amount of effort has been expanded to provide detailed and critical reviews on the use of this alternative technology in the treatment of water and wastewaters. Regrettably most, if not all, of these review papers were not focused mainly on OMW application. This paper aims to highlight the ancient and recent progress of various types of oxidation techniques for OMW treatment. Moreover, principles, advantages, limitations, and efficiencies of each method are presented, to gain a more scientific understanding of the most feasible approach regarding the treatment of this harmful residue.