From the user who throws a container to the yellow container to the plant that gives the material new life, going through artificial intelligence, a sophisticated chain of actions promotes a more sustainable model
Society is increasingly aware of the environmental impact of its waste and, therefore, of the importance of recycling. The circular economy is postulated as the most sustainable production modelensuring endless new uses of resources thanks to reuse and recycling.
In this way, a chain is created that goes from the user who throws away a container to the yellow container, passing through the garbage collection service, the sorting plant and, finally, the recycling facilityin charge of turning waste into raw material to create new objects.
One of the more than 420 facilities approved by Ecoembes, located in Alcal de Guadara (Seville), opens its doors to us so that we can learn in detail about the processes that these selected containers follow until they become raw material again. TO Recycled The Network Trucks loaded with bales arrive every day with previously selected plastic containers. Specifically, these containers are those deposited in the yellow container, where each citizen deposits in 2021 18,8 kilos on average, the equivalent of lowering the bag of containers once every four days.
The volume that they manage in these facilities is such that, every hour, two and a half tons are processed, explains Felipe Pardooperations director of Reciclados La Red. “The material comes from solid urban waste treatment plants, mainly high density polyethylene (HDPE), although also improper, hence the need for a classification in these same facilities”, adds Pardo. Containers such as bottles of shampoo, bleach, milk or cleaning products domestic
Everything arrives in large bales from packaging selection plants, where they are broken down by type thanks to a optical separator which detects their wavelength and selects them. These bales are opened and introduced into a belt that goes through all the phases for the treatment of the material. Next, the containers pass through a large cylinder where impurities are removedallowing them to arrive separately to the next process.
On this occasion, a large number of boats of the same color and shape attract attention, occupying part of the conveyor belt. Pardo clarifies that these are containers with manufacturing defects that the company itself has had to discard. Its magenta pink stands out from the amalgamation of different colors that advance by a chain of different machines and processes.
As a result, at the end of its journey through these facilities, all these containers will end up converted into HDPE pellets, some small lentil-shaped balls pied. Before, a meticulous selection separates the aluminum that may have stuck to the containers and some other inappropriate material that has slipped through. They can be container labels or the typical metallic colored cover that some containers have to prevent their interior from spilling.
after, until three types of optical separators are dividing and selecting the containers discharges of the bales to the conveyor belt. “The first optic separates polyethylene from unsuitable materials and the other two are in charge of separating the colors. White, yellow, blue, green, natural, and the rest that is for black,” says Pardo.
This system is able to recognize the color of the container thanks to the training of an artificial intelligence which, in milliseconds, marks the color and sends the order to a compressed air system that separates the object from the rest. The objective is to achieve a pellet of a uniform color, making it easier, for example, for the resulting yellow pellets to serve as raw material to create yellow containers. “We achieve a lower consumption of dyeswhich represents both an economic and an environmental benefit”, underlines Pardo from the facilities.
Once divided, the different groups each go through a double crushing and washing process, to eliminate all the impurities and remains of the material that these containers once housed. In fact, like HDPE is less dense than water, during washing, impurities such as paper, labels, glue, remains of other plastics or organic remains that may remain are separated by flotation. In addition, all the water used is reused, making the process more sustainable and efficient.
The remaining material is then centrifuged and subjected to a current of air that removes all moisture. It is then crushed again to turn the plastic into flakes. That’s when it comes into play the extruder for graining plastic. The flakes enter through a funnel into a cylinder, in which the material begins to heat up until it becomes a liquid.
A spindle, similar to a large screw, pushes the substance to the end of the machine, where it is cut while still soft and the pieces are solidified with cold water. This is how the pellets are obtained and the generation of dust and loss of material is avoided. These are launched by a pneumatic installation, by means of an electric fan, to a deposit where the remains of humidity will be eliminated.
These little lentils are the raw material with which new containers, pipes or any polyethylene object will be created high density blown Here the batches of these pellets are also analyzed, analyzing characteristics such as fluidity, density or ashes, to ensure the homogeneous quality of the product that will become new objects. Then the next life of the containers deposited in the yellow container begins.
Circular Economy Series carried out in collaboration with the organization Ecoembes.
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