Geophysical Time-lapse Monitoring of Leachate Recirculation in a Bioreactor Landfill

This work deals with the time-lapse geoelectrical monitoring of leachate re-circulation inside a municipal solid waste landfill. The studied landfill is exploited as an anaerobic bioreactor, and leachate is re-circulated in order to maintain constant and high moisture content within the waste. The goal of leachate injection is to ensure optimal conditions for the anaerobic bacteria to rapidly degrade the organic fraction of the waste. The main objective of this study is to evaluate the electrical behavior of the wastes, for estimating the moisture content dynamics during time. Electrical resistivity tomography (ERT) and self potential (SP) methods have been applied both on surface electrodes installed on the top of the landfill and along borehole which have been installed for cross-hole measurements. Both the methods helped in locating the zones affected by the leachate flow, but ERT measurements suffered from anomalous long-term polarization phenomena. On the other hand, SP measurements were in good accordance with the injected leachate volumes, and they can be useful for helping numerical modeling of the leachate flow within the waste mass.