A dual-permeability hydro-biodegradation model for leachate recirculation and settlement in bioreactor landfills.

A dual-permeability hydro-biodegradation model is developed to describe the leachate flow in municipal solid waste (MSW) and predict the long-term settlement induced by biodegradation in bioreactor landfills. The model is verified against Hydrus-1D and a recirculation experiment conducted in a full-scale landfill. Preferential flow and mass transfer between fissure and matrix can be reasonably modeled by the proposed model. A higher recirculation flow rate can speed up the stabilization process of landfill. However, too much recirculation leachate is not economical and environmental friendly. A stabilization speed index and a leachate utilization index are adopted to evaluate the stabilization speed of bioreactor landfill and utilization rate of leachate, respectively, and the optimal recirculation flow rate is estimated. A flow rate of q = 5 × 10-5-5 × 10-4 m/h (equivalent to recirculation intensity of Q = 15-150 L/tonwaste/year) is recommended for recirculation, which has been verified by the field data in numerous bioreactor landfills.

The use of electrical resistivity tomography and borehole to characterize leachate distribution in Laogang landfill, China.

Leachate is a polluting liquid which may cause harmful effects on human health or the environment without a tightly control manner. The leachate management is an important part of the design and operation of bioreactor landfills. To detect the leachate distribution in Laogang Landfill, China, the measurement of electrical resistivity tomography (ERT) was carried out in three areas with different ages. ERT method proved to be an effective non-invasive geophysical method in bioreactor landfills, and the physical properties of waste samples obtained by boreholes were tested in a laboratory. The correlation between the resistivity and the moisture content was described by Archie's law. The result shows that the moisture content of fresh waste is inhomogeneous, while that of aged waste increases with depth. A pseudo 3D model of the moisture content was proposed to improve the understanding of leachate distribution and exhibit the accuracy of the ERT method.