Effects of Olive Mill Wastewater on Soil Physical and Hydraulic Properties: a Review

Although olive mill wastewater (OMW) is a significant environmental hazard because of its high organic load, antimicrobial properties, and phytotoxicity, it is produced in vast quantities during a short time (2–3 months). Several studies acknowledged that these wastes have a substantial fertilizer value for sustainable agricultural practices when the controlled land application is used due to the vast range of plant nutrients and high organic matter content that improve soil properties and water retention. The composition of OMW varies according to cultivation practices, olive variety and maturity, and olive mill process. OMW’s treatment and land application have been investigated to find suitable treatment and reuse methods. The treatments of OMW include physiochemical, chemical, biophysical, and biological techniques and controlled land application, either treated or untreated OMW. Although the effects of OMW application on soil fertility and chemical properties have been intensively investigated, we are aware of few studies on its impact on soil physical and hydraulic properties. This paper reviews the effects of OMW land application on soil aggregate stability and structural stability, penetration resistance, saturated hydraulic conductivity, infiltration rate, soil water retention, and soil water repellency.