Page 5 - mobile Workbook-chapter 2
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2.3 Density
Density (specific weight) is defined as the weight of a material per unit volume (kg/m3, lb/ft3).
Density is a useful parameter in waste characterization as it provides information for predicting
storage volume, including as-discarded at a residence or commercial facility, after compaction in
a collection truck, and after compaction within a landfill cell. Density of raw, uncompacted SW will
vary as a function of composition, moisture content, physical shape, and degree of compaction.
Moisture will replace the air occurring in voids, thus increasing density until it becomes saturated.
[2]. Range in density of some wastes (kg/m3): uncompacted (60 - 120), baled waste (470 - 900),
compacted in collection truck (300 - 400), compacted in landfill (300 - 890) [5].
Fig 2.4: Some types of solid waste
If materials have different densities are expressed in terms of their weight fraction, the equation
for calculating the bulk density:
ρ (a+b) = M a +M b where Ma, Mb: the mass of A, B : bulk density of A, B
M a
⁄ + M b ⁄ a, b
ρ a ρ b
The degree of volume reduction that occurs as a result of waste compaction: r = V /V
d
c
where Vc: volume of compacted waste, Vd: volume of discarded waste
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