Characterization and monitoring of subsurface contamination from Olive Oil Mills’ waste waters using Electrical Resistivity Tomography

This work describes the efficiency and ability of Electrical Resistivity Tomography (ERT) to map and monitor the subsurface contamination caused by the wastes created during the production of olive oil. The spatial distribution and temporal variation of these wastes are investigated through an integrated methodological flowchart composed of numerical modeling tests and field data collected from an active waste disposal site. An Olive Oil Mills’ Wastes (OOMW) real site was chosen to monitor the subsurface flow of the wastes that are disposed of in an artificial pond for 1.5 years. Synthetic modeling was used to simulate and reconstruct the movement of the OOMW as a conductive target within a layered resistive medium. The results of the ERT data show a high degree of correlation between published ERT, geochemical, and IP geophysical results. This indicates that ERT can be a powerful tool for mapping and monitoring the byproducts of the olive oil industry, in the form of subsurface contamination, as demonstrated by the synthetic modeling. The electrical signature of the OOMW was also verified through the identification of in situ wastes within an excavation trench along the monitoring ERT line. The results show that ERT can be used as a stand-alone tool to characterize the subsurface pollution in OOMW sites.