SUSTAINABLE CULTIVATION OF OLIVE TREES BY REUSING OLIVE MILL WASTES AFTER EFFECTIVE CO-COMPOSTING TREATMENT PROCESSES

Summary

All olives’ treatment processes (olives, olive oil, olive wooden residue) produce liquid and solid wastes, which are considered toxic. The treatment of these wastes by using conventional technologies (aerobic/anaerobic biological treatment, incineration, gasification ect) proved to be neither technically nor cost effective. This fact treats the olive oil production by complete cease due to the serious environmental problems caused. The proposed technology includes the detoxification of wastewater by Fenton oxidation reactions and following their utilization by biological treatment methods. The latter is achieved by the implementation of anaerobic digestion process on the oxidized wastewater and the consequent methane production and by co-composting the oxidized or/and anaerobic digested wastewater with solid wastes (olive mill wooden residue, leaves, branches ect.), leading to the production of a high quality soil conditioner. The biogas produced could be utilized for in situ thermal and electrical energy production. The two biological processes used (anaerobic digestion and composting) are ideal combined, since the anaerobic digested wastewaters are totally used in composting process, while the excess thermal energy produced by biogas utilization can accelerate the aerobic biological processes resulting in a high quality biological fertilizer. The proposed technology is effective and simple to be implemented. Wastewaters derive either from two or three phase olive mill could be treated. This technology can be implemented either in one olive mill scale or in central wastewater treatment plants. The proposed technology can not only effectively face the serious environmental problems caused by olive mill wastewater disposal, but it poses new perspectives in olive trees cultivation and olive oil and its by-products market.