Understanding leachate flow in municipal solid waste landfills by combining time-lapse ERT and subsurface flow modelling – Part II: Constraint methodology of hydrodynamic models

• Published in: Waste management (Elmsford) Vol. 55; pp. 176 - 190
• Main Authors: Audebert, M., Oxarango, L., Duquennoi, C., Touze-Foltz, N., Forquet, N., Clément, R.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 01.09.2016; Elsevier
• Subjects: Biodegradation, Environmental; Bioreactors; Computational fluid dynamics; Electrical resistivity tomography; Electricity; Environmental Sciences; Fluid flow; Hydrodynamic parameters; Hydrodynamics; Infiltration; Landfills; Leachate flow; Leachates; Mathematical models; Methodology; Models, Theoretical; Municipal solid waste; Refuse Disposal - methods; Solid Waste; Waste Disposal Facilities; Wastes; Water Movements; Water Pollutants, Chemical - analysis; Leachate flow; Electrical resistivity tomography; Hydrodynamic parameters; Landfills; Municipal solid waste; HYDRODYNAMIC PARAMETERS; ELECTRICAL RESISTIVITY TOMOGRAPHY; LEACHATE FLOW; MUNICIPAL SOLID WASTE; METHODE ERT
• ISSN: 0956-053X; 1879-2456
• DOI: 10.1016/j.wasman.2016.04.005

•A new constraint methodology of hydrodynamic models.•Single and dual continuum approaches.•Hydrodynamic parameters. Leachate recirculation is a key process in the operation of municipal solid waste landfills as bioreactors. To ensure optimal water content distribution, bioreactor operators need tools to design leachate injection systems. Prediction of leachate flow by subsurface flow modelling could provide useful information for the design of such systems. However, hydrodynamic models require additional data to constrain them and to assess hydrodynamic parameters. Electrical resistivity tomography (ERT) is a suitable method to study leachate infiltration at the landfill scale. It can provide spatially distributed information which is useful for constraining hydrodynamic models. However, this geophysical method does not allow ERT users to directly measure water content in waste. The MICS (multiple inversions and clustering strategy) methodology was proposed to delineate the infiltration area precisely during time-lapse ERT survey in order to avoid the use of empirical petrophysical relationships, which are not adapted to a heterogeneous medium such as waste. The infiltration shapes and hydrodynamic information extracted with MICS were used to constrain hydrodynamic models in assessing parameters. The constraint methodology developed in this paper was tested on two hydrodynamic models: an equilibrium model where, flow within the waste medium is estimated using a single continuum approach and a non-equilibrium model where flow is estimated using a dual continuum approach. The latter represents leachate flows into fractures. Finally, this methodology provides insight to identify the advantages and limitations of hydrodynamic models. Furthermore, we suggest an explanation for the large volume detected by MICS when a small volume of leachate is injected.