High-rate upflow anaerobic sludge blanket bioreactor for the treatment of olive mill effluents: Laboratory and pilot scale systems investigation

Olive mill effluents are amongst the most prominent waste streams produced in Mediterranean countries, with their uncontrolled disposal in soil, without any prior treatment, having significant environmental and social effects. Anaerobic digestion has been extensively studied for the treatment of various waste streams, from industrial waste to agricultural and livestock residues. Some of the major advantages of anaerobic digestion relate to energy and soil fertilizer production. The scope of this work was the experimental optimization of the organic loading rate of anaerobic UASB digesters processing olive mill wastewater effluents. The optimization procedure was performed in a laboratory and a pilot scale set-up. The results showed that the maximum organic loading rate that could be applied to such a system was 5-6 gCOD/LR/d, without the need for any pretreatment. Moreover, it was exhibited that the large period of inoculum acclimatization to the olive mill effluents improved the phenols degradation inside the reactor, which reached 59%.

Automated summary

Olive mill effluents are a significant waste stream in Mediterranean countries and their uncontrolled disposal without treatment has adverse environmental and social impacts. Anaerobic digestion has been extensively researched for treating various waste streams, and its advantages include energy and fertilizer production. This study optimized the organic loading rate of anaerobic UASB digesters processing olive mill effluents, reaching a maximum of 5-6 gCOD/LR/d without pretreatment. The acclimatization of inoculum to the effluents also improved phenols degradation inside the reactor to 59%.