Characterization of Waste Density Via Microgravity and Settlement Analysis

Optimizing the utilization of landfill airspace and production of biogas for use as an energy source relies on an understanding of the compaction, settlement, and stabilization of waste over time. A higher degree of compaction reduces the landfill footprint; however, this may not provide the optimal conditions for bacteria development and waste stabilization. This thesis reports on a research project that pilots the use of repeated microgravity surveys to map the density of waste over time In a bioreactor landfill.;The density values obtained from the microgravity surveys were 1.35 ± 0.31 g/cm3 in the first waste slab, 1.44 ± 0.22 g/cm 3 and 1.20 ± 0.25 g/cm3 in the second waste slab in the northeast and southwest ends of the cell respectively, and 1.15 ± 0.28 g/cm3 and 1.12 ± 0.15 g/cm3 in the third waste slab in the northeast and southwest ends of the cell respectively. These results agreed best with the densities computed from the landfill operation data in the first slab (within 3%), and deviated later in the study (within 22% in the third slab, in the northeast end).;Over the duration of 3 years, five microgravity surveys were conducted on a new cell at a bioreactor landfill in Sainte-Sophie, Quebec, Canada, as it was gradually filled with waste up to a height of 25 m. After each survey, waste density values were extracted by comparing with previous data from lower elevations. For an accurate density computation, a settlement model was applied in order to estimate the degree to which waste had been compacted over time. This model was derived from settlement data recorded by sensors buried at various elevations throughout the waste column.