Environmental risk assessment of soil contamination from olive mill wastewater using electrical resistivity tomography

Olive mill wastewater (OMW) produced during the process of olive oil extraction has been commonly stored in evaporation basins. It constitutes a serious threat to environment because of the presence of polyphenols concentration and high chemical oxygen demand values. In this work, the electrical resistivity tomography (ERT) is applied to appraise soil contamination potential within the vicinity of the OMW evaporation pond in Ben Aoun village in Sidi Bouzid region, Tunisia. For this purpose, three of surface ERT profile lines were carried around the evaporation pond in the Ben Aoun region based on historical information about site exploitation and their accessibility. The interpreted resistivity showed a low resistivity anomaly (< 5 Ωm), indicating the OMW plume spread from evaporation pond. The ERT results revealed also that the OMW infiltration reaches upright to 48 m in depth. In hindsight, the ERT monitoring could be a helpful tool for detecting both the infiltration and distribution of the OMW.