## 3 Results
The highest absorptivity of all the examined materials was observed in the granulometric category below 0.5 mm in Miscanthus grass. Miscanthus also exhibited a good pelletising ability, as may be seen in Figure 7a,b, which also shows lavender of the same grain size of 0.5-1 mm. In order to verify the absorptivity of the material, the free-fall drop test was carried out. The purpose of the test was to assess the ability of the material to sustain in the form of a compact unit after the application of water drops. The figure clearly shows that lavender did not exhibit any pelletising ability as the grains did not amalgamate after water was applied and did not form a compact unit. The behaviour of lavender with the grain size of 0.5-1 mm was almost hydrophobic. This test confirmed the test of capillary water absorption in which lavender exhibited the worst absorptivity in all grain size categories. Results of the test of the absorptivity of wood biomass consisting of pine and oak sawdust are documented in Figures 8 and 9. Figure 8: Wetting of pine sawdust at granulometric compositions: **(a)** Under 0.5 mm; **(b)** 0.5–1 mm; **(c)** 1–2 mm. Figure 7: Green pellet of Miscanthus sinensis **(a)**; Green pellet of Lavandula angustifolia **(b)**. Wood biomass was also subjected to absorptivity testing carried out by applying the free-fall drop test, at the granulometry of 0.5-1 mm (Figure 10a,b). The Figures clearly show that in the experiment the pine and oak sawdust formed only a few compact pellets, while oak sawdust exhibited better absorptivity and better grain amalgamation. This test confirmed the results of the absorptivity test at which the maximum values of the height of absorption were low at the given fraction of 0.5-1 mm and with the given type of the used liquid (cold water). Pine sawdust absorptivity values were much diversified with different types of liquids. Moreover, at a fraction of 0.5-1 mm and 1-2 mm and with the use of cold water, there was almost zero absorption. In this case, wetting was only achieved when tensile and a soap solution were used. Figure 10: (a): Green pellet of Scots pine;10 (b): Green pellet of English oak. Figure 9: Wetting of oak sawdust at granulometric compositions: (a) Under 0.5 mm; (b) 0.5–1 mm; (c) 1–2 mm. In the case of English oak, at the granulometry of 0.5-1 mm, the best absorptivity values were observed, amounting to 26 mm. A higher value was also observed at a fraction of 1-2 mm--in particular 20 mm. Compared to pine sawdust, oak sawdust was absorptive in all selected grain size categories. As for oak sawdust, the lowest absorptivity value of 5 mm was observed at a fraction of 1-2 mm. Plant biomass (Miscanthus sinensis) exhibited the highest absorptivity at a fraction below 0.5 mm; with lavender, the highest value in this category was 14 mm (when tensile was used as the medium); with other liquids, the maximum value was 10-15 mm in the grain size category below 0.5 mm. The absorptivity curves for Miscanthus grass in the granulometry category below 0.5 mm were very similar to those of lavender, but the maximum value achieved was 34 mm. In terms of the used liquid medium, tensile was the most suitable liquid for pelletisation; warm water and a soap solution were, in some cases, more efficient, depending on the granulometric composition and the type of the used biomass. The least satisfactory results have been observed with the use of cold water. The study also brought a conclusion that the best absorptivity, out of the selected types of biomass, was observed in Miscanthus, and the behaviours of oak and pine sawdust were very similar in terms of absorption. Nevertheless, oak sawdust exhibited slightly better absorptivity than pine sawdust. These lower values of absorption identified for pine and oak sawdust may be attributed to their structure. Pine wood has a fine porous structure consisting of thin-walled tubular cells called tracheids. The lengths of longitudinal tracheids were approximately 3 to 5 micrometers and their diameters ranged from approximately 20 to 80 micrometers.