Characterisation of municipal solid waste physical properties and their evolution with age

Abstract

This paper presents results of the physical characterisation of municipal solid waste (MSW) through laboratory and in situ tests, as well as by a monitoring system. The physical parameters of MSW characterised are: particle size distribution, geometry and classification of the waste, moisture and organic matter content, unit weight, and temperatures of the landfilled waste. The results are part of research carried out in the Sto Tirso landfill (in the north of Portugal) between 2001 and 2007. The results obtained from different analysis methods are compared. The influence of the average age of the deposited MSW and of the landfill phase (construction and post-construction) on the parameters is also presented. Regression models are presented for the decay of total and degradable organic matter, and for the influence of overburden stress on MSW unit weight, plus correlations obtained between some of the analysed parameters.

Municipal solid waste shear strength parameters defined through laboratorial and in situ tests

“…Further, the tensile strength of these fibrous materials should decrease with elapsed time due to decomposition processes (Singh and Sharma, 2008), which is in agreement with the gradual degradation observed of the surface of the thin plastics in the older samples. Moreover, the amount of granular materials and the density of the waste tend to increase with age (Gomes and Lopes, 2011b), which should also contribute to an increase in friction strength. This behavior is comparable with that reported by Zhan et al (2008) in the Suzhou landfill (China), where the same type of changes in shear strength parameters with the aging of the waste (a decrease in the cohesion and an increase in the friction angle) occurred.…”

“…The results (omitting the higher values) were corrected for the number of rods and the diameter of the hole, N 60 , which represents the blow count obtained at 60% of the hammer's theoretical free fall energy on the rods, using the corrective factors proposed by Skempton (1986). N 60 values were then corrected for the effect of the effective vertical stress, N 1(60) (determined by the leachate height in each borehole and the in situ unit weight of the waste; Gomes and Lopes, 2011b). The evolution of N 60 values with depth is presented in Figure 12, which shows a slight increase with depth, just like the results of Gonzalez (1995), Carvalho (1999) The histogram of the relative frequency of the N 1(60) values ( Figure 13) shows that the majority of the N 1(60) values are in the range 4-25 at station A, 4-30 at station B, and 4-35 at station C; this suggests a slight increase in the higher values of N 1(60) (between 25 and 40) with the aging of the waste.…”

Editorial

“…Such an approach could potentially result in a change in the standard way we characterise soils. The second paper, by Gomes and Lopes (2012), looks at municipal solid waste (MSW) from a landfill in Portugal. Characterisation includes laboratory testing of samples (particle size distribution, unit weight, moisture and organic content).…”

Effects of Waste Placement Practices on the Engineering Response of Municipal Solid Waste

“…The organic content of MSW is one of the most important physical properties of MSW because it has been demonstrated to influence other physical and mechanical properties of MSW including methane potential (Barlaz et al 1989;Eleazer et al 1997;Demirbas 2006), temperature (Yesiller et al 2011), absorption capacity (Zornberg et al 1999), unit weight Gomes and Lopes 2012);…”

“…used to obtain the same outcome as oven drying at 105°C (e.g. Reddy et al 2009a;Gomes and Lopes 2012). The percent by mass of each waste category (i.e., residential, commercial, and self-delivered) was determined using the tonnage records which was then used to calculate an average moisture content by means of a weighted average.…”