Investigating the effect of compression on solute transport through degrading municipal solid waste

• Published in: Waste management (Elmsford) 2014-11, Vol.34 (11), p.2196-2208
• Main Authors: Woodman, N.D., Rees-White, T.C., Stringfellow, A.M., Beaven, R.P., Hudson, A.P.
• Format: Article
• Language: English
• Subjects: Applied sciences; Breakthrough curve; BROMIDES; Compressing; COMPRESSION; Compressive stress; Conservative; Degradation; DEUTERIUM; Diffusion; Diffusion barriers; Environmental Monitoring; Exact sciences and technology; General treatment and storage processes; GEOSCIENCES; HYDRAULIC CONDUCTIVITY; LIQUID FLOW; LITHIUM; MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; MBT; Models, Theoretical; MSW; MUNICIPAL WASTES; Obstructions; Other wastes and particular components of wastes; PERMEABILITY; Pollution; POROSITY; Pressure; SANITARY LANDFILLS; Solid Waste - analysis; Solid waste management; SOLID WASTES; Tracer; Tracers; Urban and domestic wastes; Wastes; Water Pollutants, Chemical - chemistry
• ISSN: 0956-053X; 1879-2456
• DOI: 10.1016/j.wasman.2014.06.022

•The influence of compression on MSW flushing was evaluated using 13 tracer tests.•Compression has little effect on solute diffusion times in MSW.•Lithium tracer was conservative in non-degrading waste but not in degrading waste.•Bromide tracer was conservative, but deuterium was not. The effect of applied compression on the nature of liquid flow and hence the movement of contaminants within municipal solid waste was examined by means of thirteen tracer tests conducted on five separate waste samples. The conservative nature of bromide, lithium and deuterium tracers was evaluated and linked to the presence of degradation in the sample. Lithium and deuterium tracers were non-conservative in the presence of degradation, whereas the bromide remained effectively conservative under all conditions. Solute diffusion times into and out of less mobile blocks of waste were compared for each test under the assumption of dominantly dual-porosity flow. Despite the fact that hydraulic conductivity changed strongly with applied stress, the block diffusion times were found to be much less sensitive to compression. A simple conceptual model, whereby flow is dominated by sub-parallel low permeability obstructions which define predominantly horizontally aligned less mobile zones, is able to explain this result. Compression tends to narrow the gap between the obstructions, but not significantly alter the horizontal length scale. Irrespective of knowledge of the true flow pattern, these results show that simple models of solute flushing from landfill which do not include depth dependent changes in solute transport parameters are justified.