Impact of temperature on immediate and secondary compression of MSW with high and low food contents

Abstract

Landfills in developing countries usually show municipal solid wastes (MSW) with large amount of food wastes, extraordinarily high moisture contents, and high internal temperatures. Because of these specific characteristics, significant post-closure settlements in landfills with high food waste are expected over time. This paper focused on the assessment of temperature impact on immediate and secondary compression behaviors of MSW with large contents of food, water, and plastic, comparatively to an aged low food content waste. A compression test was developed having a temperature-control system. The immediate compression index (C'_c) of HFWC samples was found to be higher than those of low food waste content (LFWC) owing to the soft behavior of food content, although immediate compression was 15-30% of total strains for HFWC wastes, while for LFWC samples it was 80% of total strains. Mechanical creep was also greater in HFWC owing to the soft behavior of the wet food components intensified by temperature increases. Mechanical creep of LFWC samples was attributed to the deformation of large parcel of soft plastics, also accelerated by temperature. The HFWC waste showed a first dominant phase of biocompression with an intense and rapid biological degradation, and a second phase characterized by reduced biological activity. Temperatures higher and high compression stresses are required to provide significant impact on biocompression index magnitudes. Overall, the compressibility of high food content wastes has shown to be significantly higher and the temperature impact led to twice total settlements of the MSW with low organic content.

Keywords: Biocompression; Food waste; Landfill; Municipal solid waste; Settlement; Temperature.