Horizontal trench system effects on leachate recirculation in bioreactor landfills

Horizontal trenches (HTs) are constructed during the waste filling for leachate recirculation in bioreactor landfills. Leachate distribution depends on HT configuration (i.e., spacing between successive HTs), leachate injection rate, modes of injection, and hydraulic properties and MSW heterogeneity...

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Bibliographic Details
Published in:Geomechanics and geoengineering : an international journal 2017-04, Vol.12 (2), p.115-136
Main Authors: Reddy, Krishna R., Kulkarni, Hanumanth S., Giri, Rajiv K., Khire, Milind V.
Format: Article
Language:English
Subjects:
bioreactor landfills
Computational fluid dynamics
Fluid flow
Heat treatment
Heterogeneity
horizontal trenches
Hydraulics
Landfills
leachate recirculation
Leachates
moisture distribution
municipal solid waste
pore gas pressure
pore water pressure
Trenches
two-phase flow
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Summary:Horizontal trenches (HTs) are constructed during the waste filling for leachate recirculation in bioreactor landfills. Leachate distribution depends on HT configuration (i.e., spacing between successive HTs), leachate injection rate, modes of injection, and hydraulic properties and MSW heterogeneity. Presently, the effects of these variables on the moisture distribution have not been studied systematically. This study provides a systematic evaluation of the effect of the HTs variables on the moisture distribution and pore fluid pressures. A two-phase flow model is used to model a bioreactor landfill having an HT leachate injection system. It quantifies the effects of the unsaturated hydraulic properties and MSW heterogeneity, trench configuration, leachate injection flux, and mode of injection on hydraulic behaviour. The results show that unsaturated hydraulic conductivity and MSW heterogeneity significantly shape the zone of influence and excess pore pressures. Under heterogeneous-anisotropic conditions, the leachate migrates more laterally and the developed pore-pressures are lower than for homogeneous MSW. A closely-spaced, multi-level, staggered HT system is found to provide uniform and adequate moisture distribution in MSW. An intermittent mode of injection that alternates between the shallow and deep trenches with a higher leachate injection flow rate is found to be effective to control the excess pore pressures.
ISSN:1748-6025
1748-6033
DOI:10.1080/17486025.2016.1181793