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The use of waste-derived paste as daily cover materials for enhancing geo-environmental performance of sanitary landfills

Authors Ng, Kelvin Tsun Wai
Issue Date 2008
Summary The use of earth materials as daily covers in sanitary landfills not only consumes valuable landfill space, but also creates a series of technical and operating issues. Column tests were conducted to study fines migration from traditional soil covers. Moisture content at compaction, cover thickness, and soil-waste interface were the most influential parameters on fines migration. The sizes of migratory fines were in the range of 4–140 μm. The majority of migratory fines migrated during first permeations, representing 64–86% of the total mass of fines. Seeping velocity was believed to be responsible for the detachment and transportation processes. An innovative synthetic paste of waste tire chips and paper sludge was, therefore, developed for landfill daily cover applications. The engineering properties and behaviours of the proposed paste were studied through a series of laboratory tests. When compared to traditional soil covers, the paste was: (i) 2–3 times lighter in weight; (ii) at least two orders of magnitude more impermeable; and (iii) comparable in shear resistance. The shear strength of the paste was considerably higher than the parent materials. The reinforcing mechanisms were examined and quantified, suggesting an optimal of tire chips in the paste of about 55%. The environmental benefits of the paste were demonstrated using column tests. An equilibrium deterministic transport model was used to fit the transport parameters from the breakthrough curves of Pb. Analysis of the effluent concentrations displayed retardation effect in all cases, with fitted retardation factors from 19.9 to 59.0. Early arrivals of solute were observed unexpectedly in columns with high paper sludge content and might be attributed to the presence of non-uniform flow. It is believed that a set of operational, mechanical and environmental benefits can be obtained by using the proposed paste. Engineering significances of the work are included.
Note Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2008
Language English
Format Thesis
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