Olive mill wastewater (OMW), generated by the oil extraction industry, represents a severe environmental problem due to its highly polluting organic load arising from polyphenol content with low biodegradability. However, with its more than 30 phenolic compounds, OMW is also regarded as a potent source of natural antioxidants. Consequently, during recent years, various reports have appeared in the literature following such benefit. In this article, patent publications between the years 2005 and 2009 for the recovery of phenolic antioxidants from OMW and olive processing solid by-products are reviewed: solvent extraction and membrane separations individually or integrated with some other separation and concentration procedures, such as centrifugation, chromatographic separation and evaporation are the fundamental processes described. In the publications reviewed, hydroxytyrosol, tyrosol, oleuropein and phenolic acids, which possess more powerful antioxidant properties than other phenolic compounds in OMW, are given the most prominence for their recovery. The interest in membrane technologies in processing olive oil by-products indicates that the future direction of the processes for the recovery of antioxidants from OMW is presumably toward the utilization of membranes in a sequential design.
Olive mill wastewater, olive vegetation water, olive processing by-products, phenolic antioxidants, hydroxytyrosol, recovery of polyphenols
Ankara University Faculty of Engineering, Department of Chemical Engineering, 06100 Tandogan Ankara Turkey.