Characterization of Gas Transport Pathways in an Aerated Landfill Using In-Situ Measurement Techniques
S.P. Scott (TU Delft - Civil Engineering & Geosciences)
J. Gebert – Mentor (TU Delft - Geo-engineering)
Timo J. Heimovaara – Graduation committee member (TU Delft - Resource Engineering)
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Abstract
Low-pressure aeration is a sustainable landfill management technique in which atmospheric air is introduced to the waste body with the aim of promoting aerobic respiration and thereby speeding up waste stabilization. This strategy has been implemented at Braambergen, a pilot landfill in the Netherlands, for several years. Landfill operators and regulators are eager to determine the efficacy of this intervention. In this thesis, several novel testing methods were implemented to characterize the gas flow properties of the pilot landfill and evaluate the significance of preferential pathways, which are considered a limiting factor in landfill aeration. The test methods were also evaluated for their utility in landfill monitoring.
Pressure field tests (PFTs) were used in combination with two gas flow models to quantify the gas permeability of the waste body. Partitioning gas tracer tests (PGTTs) were used to evaluate the saturation of the waste body. Additionally, a dual porosity model was applied to estimate the immobile gas fraction, gas velocity, dispersion coefficient, and mass transfer rate. Finally, gas push-pull tests (GPPTs) were used to calculate the oxygen consumption rate.
The results showed that PFTs could be used to estimate gas permeability anisotropy and monitor the high-permeability pathways, but the method did not capture the differences between aerobic and anaerobic regions of the waste body. PGTTs seemed to better represent these differences, but there were major problems with the quality of the data and the applicability of the dual porosity model. If these issues are resolved, the method could be of great use to landfill operators. GPPTs were successfully used to estimate respiration rates,
but the methodology needs improvement. Not enough successful GPPTs were performed to determine their relationship to other test methods.