Solid waste laboratory samples homogeneity influence on analytical determination

The paper presents the influence of solid waste laboratory samples homogeneity on the
determinations quality of calorific value and carbon content.
Laboratory tests were conducted for a sample of mixed solid wastes (biomass, textile, plastic).
The waste laboratory sample was prepared for physico-chemical characterisation by using basic
methods, mass and particle size-reduction of components. Particle size-reduction of components
was carried out using two laboratory mills: Retsch Rotor Beater Mill SR 300, and Retsch Vibratory
Disc Mill RS 200. Laboratory sample was prepared in two versions. In the first version (V1)
particles size reduction took place by passing a 2 mm sieve through the rotor beater mill Retsch
SR 300. The plastic component of the waste was not fully integrated into the sample. In the
second version (V2) the waste sample obtained in the first version was first pulverized in the
Retsch Vibratory Mill RS 200, followed by a comminution of the particles to diameters passing a
0,5 mm sieve through the Rotor Beater Mill Retsch SR 300. In the second version the sample
was visibly homogeneous.
Laboratory sample homogeneity influence was highlighted by determining calorific value and
carbon content of the waste sample prepared in the two versions.
Following laboratory tests the results for carbon content and calorific value were within the
repeatability limits imposed by the standardized methods for the second laboratory sample
version.