Abstract
During leachate recirculation, a bioreactor landfill will experience more rapid and complete settlement, which is mainly attributed to the weight of municipal solid waste (MSW) and its biodegradation. The settlement of MSW may cause the decrease of void ratio of MSW, which will influence the permeability of MSW and the leachate quantity that can be held in bioreactor landfills. In this study, a new one-dimensional model of leachate recirculation using infiltration pond is developed. The new method is not only capable of describing leachate flow considering the effect of MSW settlement, but also accounting separately leachate flow in saturated and unsaturated zones. Moreover, the effects of operating parameters are evaluated with a parametric study. The analyzing results show that the influence depth of leachate recirculation considering the effect of MSW settlement is smaller than the value without considering the effect. The influence depth and leachate recirculation volume increase with the increase of infiltration pond pressure head and MSW void ratio. This indicates that the field compaction of MSW has a great influence on the leachate recirculation.
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Abbreviations
- a :
-
McDougall’s model calculation parameter
- A :
-
Elagroudy’s model calculation parameter
- b :
-
McDougall’s model calculation parameter
- B :
-
Elagroudy’s model calculation parameter
- C r :
-
Compression coefficient of MSW
- C(h p):
-
Specific moisture capacity
- D(h p):
-
Diffusion coefficient
- e :
-
Void ratio of MSW
- e 0 :
-
Initial void ratio of MSW
- g :
-
Acceleration of gravity
- H :
-
Total pressure head
- H a :
-
Infiltration pond pressure head
- h p :
-
Pressure head
- h p0 :
-
Initial pressure head
- K(h p):
-
Unsaturated hydraulic conductivity of MSW
- K(h p) x :
-
Unsaturated hydraulic conductivity of MSW in the x direction
- K(h p) y :
-
Unsaturated hydraulic conductivity of MSW in the y direction
- K(h p) z :
-
Unsaturated hydraulic conductivity of MSW in the z direction
- K sat :
-
Saturated hydraulic conductivity of MSW
- K x :
-
Saturated hydraulic conductivity of MSW in the x direction
- K y :
-
Saturated hydraulic conductivity of MSW in the y direction
- K z :
-
Saturated hydraulic conductivity of MSW in the z direction
- k(h p)r :
-
Relative permeability
- L :
-
Depth of waste
- m v :
-
Waste compression coefficient
- m :
-
Van Genuchten parameter related to pore size distribution
- n :
-
Porosity of MSW
- p :
-
Water pressure
- t :
-
Time
- Δt :
-
Time increment
- V :
-
Volume of MSW
- V 1 :
-
Volume of leachate
- v x :
-
Flow rate in the x direction
- v y :
-
Flow rate in the y direction
- v z :
-
Flow rate in the z direction
- α :
-
Van Genuchten parameter related to air entry pressure
- β :
-
Water compression coefficient
- θ :
-
Volumetric water content
- θ r :
-
Residual water content
- θ s :
-
Saturated water content
- Θ:
-
Effective saturation
- μ s :
-
Specific storage
- φ :
-
Constant equals to 0 when h p ≥ 0 and 1 when h p < 0
- ρ :
-
Density of fluid
- σ′:
-
Effective stress
- σ c :
-
Pre-consolidation stress
- ω :
-
Constant equals to 1 when h p ≥ 0 and 0 when h p < 0
- γ :
-
Unit weight of MSW
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Acknowledgments
Much of the work described in this paper was supported by the National Natural Science Foundation of China under Grant Nos. 41072201, 41172245 and 41222021, the National Basic Research Program of China (973 Program) under Grant No. 2012CB719803, the Program for New Century Excellent Talents in University under Grant No. NCET-13-0421, and the Fundamental Research Funds for the Central Universities. The writers would like to greatly acknowledge all these financial supports and express the most sincere gratitude.
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Feng, SJ., Zhang, X. & Cao, BY. Leachate recirculation in bioreactor landfills considering the effect of MSW settlement on hydraulic properties. Environ Earth Sci 72, 2315–2323 (2014). https://doi.org/10.1007/s12665-014-3140-x
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DOI: https://doi.org/10.1007/s12665-014-3140-x