Management of Olive Oil Mill Wastewater in Morocco

With over one million hectares of 998,000 ha, the olive tree is the most crucial permanent crop in Morocco. Production, which reached 1,559,000 tonnes for the 2017–2018 campaign, has averaged around 1.2 million tonnes over the past ten years, ranking the country 5th for olive producers after Spain, Greece, Italy, and Turkey. Olive growing is one of the most developed crops in Morocco. Concerning the development of this olive growing and the increased demands of the internal and external markets for olive oil, the olive industry has also experienced significant development in the country, thus causing a significant discharge of liquid residues loaded with toxic elements. The oil mill wastewater problem for Morocco is that the olive crushing units, whether traditional or modern, are concentrated in the most critical area in terms of water resources. The impacts of wastewater from olive oil mills on surface water, groundwater in particular, on drinking water production downstream of the city of Fes have been widely studied. The results showed that wastewater is heavily loaded with oils, trace metals, polyphenols, detergents, etc. The cost of producing drinking water from Oued Sebou becomes increasingly crucial during the olive growing period due to the discharge of olive oil mill wastewater directly discharged into Oued Sebou. To minimize the impacts, the Moroccan government has encouraged olive growers to use two-phase machines allowing the production of oils without producing margins and avoiding the use of conventional systems (press), which produce effluents heavily loaded with oils, and grease compared to the discharges produced by two or three-phase machines. In this work, we studied the different methods of managing vegetable waters produced during the olive growing period in Morocco, the impacts on the environment, the treatment of rejects the valuation of olive oil mill wastewater as raw materials for the production of several products (activated carbon, cosmetic products, detergents such as the extraction of polyphenols, production of compost with a view to sustainable development). The olive oil mill wastewater produced is currently stored in large tanks to be evaporated naturally. However, this technique is too slow and does not allow a sound reduction in pollution. In addition, it is more advantageous during storage to scrape off the oils that rise at the interface at least twice to three times a week (two to three months). This technique has shown that natural flotation would considerably impact reducing oil pollution. In Morocco, different techniques are currently used to reduce the impacts of olive oil mill wastewater on the environment in particular: