The use of geomembrane as a remediation towards a sustainable OMWW landfilling: Case study of Agareb site in Sfax, Tunisia

Abstract

In Tunisia, olive mill wastewater (OMWW) locally named ‘margine’ constitutes a serious problem due to its huge amount, of about one million ton per year, and the high pollutant load resulting in the excessive chemical oxygen demand (COD) values and the presence of phytotoxic and antibacterial polyphenols. The most common treatment of OMWW was storage in evaporation ponds which are authorized but uncontrolled. Thus, it represents a potential contamination source of natural resources (air, soil and water) via infiltration. This study aims at a critically analysing the OMWW storage management on the site of Agareb in Sfax, Tunisia. The data relating to the OMWW production highlights that it exceeds its storage capacity due to the uncomplete OMWW evaporation. The geotechnical investigations confirmed the spread of OMWW through and below the storage basins. Furthermore, multiple slope sliding has been observed within embankments separating the OMWW storage basins. Faced with this alarming situation, the assessment of the incorporation of geomembrane is analysed in order to ensure the sustainability of OMWW landfilling. The slope stability analysis based on limit-equilibrium method (LEM) using Midas-Soil works software was investigated. The use of geomembrane can secure the slope stability and limit OMWW infiltrations in the landfill body and sub-soils in the studied site.