The shape of the filtration media and the production process directly affect the absorption capacity of the granulate and consequently the efficiency of filtration.
Granules in the shape of a pellet (cylinder) do not facilitate such a high degree of compaction as spherical granules, so that the passage of the air flow becomes easier, as preferential streaming is avoided. This implies less loss of pressure. In postharvest applications, especially in transport filters, this difference is very advantageous.
On the other hand, granules in the form of pellets have a greater surface area, which facilitates interaction between the active ingredient and the air to be treated in such a way as to optimise the absorption capacity of the granulate.
Aside from the shape of the granule, another factor to take into account is the production process. In the case of impregnation, the active ingredient remains only on the surface of the pellet (regardless of the shape, whether pellet or sphere), while if the granule is extruded, the active ingredient remains homogeneous in structure, both at the surface and inside the granule. This means that not only is there a greater quantity of the active ingredient, but it is also uniformly distributed throughout the structure of the pellet - surface and
Interior - achieving greater absorption capacities.