A standard garbage bag that any Spanish household placed in the yellow container should be made up, solely and exclusively, of plastic containers, cans and cartons. The reality is that that bag often contains other types of waste that should not be there.
“The concept that is most difficult for citizens to understand is the packaging. People have conceptualized yellow as the container for cans and plastics, with which any metallic or plastic element tends to be associated with having to go into the yellow container,” explains Fernando Martín, coordinator of the Waste Knowledge area. Ecoembes.
We would be talking about waste related to household items, buckets, tapers… which could be considered those errors due to ignorance; but also others such as glass, cardboard, textiles or organic matter.
This unwanted waste is called improper and its presence in the yellow container varies depending on the area of Spain that is analyzed. “There are places where the percentage of inappropriate waste in the selective collection of light packaging is below 20% and there are places where it is above 30%,” says Martín.
It cannot be generalized or said that there is a standard garbage bag that describes how Spanish society as a whole recycles. Its composition depends on the region and its consumption patterns, socioeconomic factors, whether they are urban or rural population centers, the type of housing, the time of year…
This knowledge of society’s recycling patterns is possible thanks to the analysis or characterization work that Ecoembes carries out in 97 sorting plants in the country, those places where household packaging is classified by material before being sent to the recycling plants where they will be transformed into raw materials.
A millimeter sampling job
Characterization is an “analytical process that allows you to know the composition of the waste” that citizens have thrown into the yellow container, explains Martín. These controls, which are carried out using random samples, take place when said waste enters the selection plants.
The process lasts between five and eight hours and begins with the collection truck dumping the waste on what is known as the unloading yard of the sorting plants. At that moment, they are homogenized, that is, turned over with an excavator shovel to mix them in such a way that the sample to be worked on is as representative as possible.
Of the average 2,000 kilos that a collection vehicle usually transports, approximately half are taken and, after a new homogenization, they are divided into four piles of more or less similar volume (quartering). Two opposite rooms are chosen at random, the other two are rejected and the process is repeated until 250 kilos of waste are left, which will be the ones analyzed.
Ecoembes has about 60 teams of two people each, that is, about 120 workers dedicated to it nationwide. In 2023, more than 7,700 characterizations of selective collection entries for light packaging were carried out throughout the country.
These characterizations are not random: they are based on a standard sampling methodology and are iterative. “We do a sampling campaign for a year and when we have the year closed, we will be able to do an analysis of what the variability of the results is like for each of the collection management units. This will help us calculate the number of samples that we will have to do for the next sample period,” says Martín.
What does a characterization tell us and what do we do with it?
The characterization allows us to analyze in detail which waste reaches the selection plants and in what proportion. To do this, those 250 kilos selected are classified into 33 fractions, according to the type of material from which they are made.
Eleven of them correspond to containers – polyethylene, polypropylene, film, steel, aluminum, beverage cardboard, etc. – and the remaining 22 correspond to improper waste – textiles, pruning remains, glass, etc. – that should not be there. entered the yellow container. The quantities of each of them are also determined.
With this data, Martín explains that it is possible to “provide information upstream, towards the collection management unit, about the composition of the waste that can be used to take improvement actions; and downstream, to the selection plant, because the plant needs to be sized to obtain efficient performance.”
And Ecoembes makes all this data available to local entities so that they know the result of selective collection in their municipalities; and develops awareness campaigns together with public administrations adapted to the needs of each area. In addition, they also serve to understand consumer trends and analyze whether it is easy for citizens to associate the different packaging and materials available with their corresponding container.
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