Experimental and theoretical assessment of the multi-domain flow behaviour in a waste body during leachate infiltration.

The optimisation of landfill operation is a key challenge for the upcoming years. A promising solution to improve municipal solid waste (MSW) management is the bioreactor technology. A meso-scale (around 1m(3)) experimental set-up was performed to study the effect of moisture control in low density conditions with different leachate injection operations and bioreactor monitoring including the use of a neutron probe. The moisture content distribution evolution demonstrates a multi-domain flow behaviour. A classic van Genuchten-Mualem description of the connected porosity proved insufficient to correctly describe the observed phenomena. A bimodal description of the connected porosity is proposed as solution and a connected/non-connected porosities numerical model was applied to the results. The model explains the experimental results reasonably well.