Geotechnical properties of municipal solid waste at different phases of biodegradation

Journal Article · Tue Nov 15 00:00:00 EST 2011 · Waste Management

DOI:https://doi.org/10.1016/j.wasman.2011.06.002· OSTI ID:21578431

Hettiarachchi, Hiroshan ^[1]; Gangathulasi, Janardhanan ^[2]

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1. Department of Civil Engineering, Lawrence Technological University, 21000 West Ten Mile Road, Southfield, MI 48075 (United States)
2. Department of Civil and Materials Engineering, University of Illinois at Chicago, 842 West Taylor Street, Chicago, IL 60607 (United States)

Highlights: > Degraded synthetic municipal solid waste (MSW) anaerobically in controlled bench-scale reactors. > Performed laboratory tests to determine geotechnical properties of MSW at different phases of degradation. > Hydraulic conductivity decreased by two orders of magnitude due to degradation. > Compression ratio reduced from 0.34 for initial fresh waste to 0.15 for the mostly degraded waste. > Friction angle reduced, but cohesion increased with degradation. - Abstract: This paper presents the results of laboratory investigation conducted to determine the variation of geotechnical properties of synthetic municipal solid waste (MSW) at different phases of degradation. Synthetic MSW samples were prepared based on the composition of MSW generated in the United States and were degraded in bioreactors with leachate recirculation. Degradation of the synthetic MSW was quantified based on the gas composition and organic content, and the samples exhumed from the bioreactor cells at different phases of degradation were tested for the geotechnical properties. Hydraulic conductivity, compressibility and shear strength of initial and degraded synthetic MSW were all determined at constant initial moisture content of 50% on wet weight basis. Hydraulic conductivity of synthetic MSW was reduced by two orders of magnitude due to degradation. Compression ratio was reduced from 0.34 for initial fresh waste to 0.15 for the mostly degraded waste. Direct shear tests showed that the fresh and degraded synthetic MSW exhibited continuous strength gain with increase in horizontal deformation, with the cohesion increased from 1 kPa for fresh MSW to 16-40 kPa for degraded MSW and the friction angle decreased from 35{sup o} for fresh MSW to 28{sup o} for degraded MSW. During the triaxial tests under CU condition, the total strength parameters, cohesion and friction angle, were found to vary from 21 to 57 kPa and 1{sup o} to 9{sup o}, respectively, while the effective strength parameters, cohesion and friction angle varied from 18 to 56 kPa and from 1{sup o} to 11{sup o}, respectively. Similar to direct shear test results, as the waste degrades an increase in cohesion and slight decrease in friction angle was observed. Decreased friction angle and increased cohesion with increased degradation is believed to be due to the highly cohesive nature of the synthetic MSW. Variation of synthetic MSW properties from this study also suggests that significant changes in geotechnical properties of MSW can occur due to enhanced degradation induced by leachate recirculation.

• OSTI ID: 21578431
• Journal Information: Waste Management, Vol. 31, Issue 11; Other Information: DOI: 10.1016/j.wasman.2011.06.002; PII: S0956-053X(11)00267-4; Copyright (c) 2011 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0956-053X
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
BIODEGRADATION
BIOREACTORS
COMPRESSIBILITY
COMPRESSION RATIO
HYDRAULIC CONDUCTIVITY
MOISTURE
MUNICIPAL WASTES
SANITARY LANDFILLS
SHEAR PROPERTIES
SOLID WASTES
WEIGHT
CHEMICAL REACTIONS
DECOMPOSITION
DIMENSIONLESS NUMBERS
MANAGEMENT
MECHANICAL PROPERTIES
WASTE DISPOSAL
WASTE MANAGEMENT
WASTES