Plastic Sorting
The plastic from separate waste collection is transported to sorting centers.
The first step is to remove irrelevant objects from the plastic material, such as large items, non-plastics and non-recyclable plastics. Very obvious items (suitcases, pipes, chairs, umbrellas) can be removed before entering the facility. Otherwise the bags are opened mechanically and the waste is spread out on a conveyor belt to be checked and to remove any further extraneous items. Only some objects are sent to the dump; others (such as fruit boxes, films or straps) are collected with their own type of plastic.
After the extraneous items have been removed, the material is separated by size. This second step first eliminates the smallest and lightest pieces. A rotating sorter removes the small, light pieces and divides large bottles from containers for liquids (bottles for water, soft drinks, detergent, etc.). A second sorter refines the separation between flat items (films) and “hollow” ones (bottles, tins, cans).
This step mostly yields a mix of films.
After the small, light pieces and the films have been removed from the material, it moves on to the third step in which PET is separated from metals and other bottles. Metals are extracted from the flow of material using magnets and an induced current is used for non-ferrous metals (aluminum). An initial optical detector separates PET bottles from other containers. During this phase, metals (iron and aluminum), high-density polyethylene (HDPE) and low-density polyethylene (LDPE) are collected.
All that is now left is a mix of PET bottles. In the fourth step, PET is sorted by color using an optical detector.
This stage divides the material into colored, blue and transparent PET.
The sorting centers produce pressed bales of the following materials: transparent (colorless) PET, blue PET, multicolored PET, metals (iron, aluminum), mixed polyolefins, mixed films, HDPE-LDPE, PE/PP (plastic boxes and crates).
On average, one ton of collected material will produce 270 kg of PET from liquid containers, 100 kg of PE from flexible packaging, 90 kg of HDPE from detergent bottles, 20 kg PE/PP from produce crates and 220 kg of mixed plastics.
