Recycling: types of processes and applications

When we talk about recycling, what comes to your mind? We often think of colorful waste bins and the selective collection where we separate recyclable materials that will be processed to become new products. But what is the definition of recycling?

According to the National Policy for Solid Waste, recycling can be defined as “the process of transformation of solid waste that involves the alteration of its physical, physical-chemical, or biological properties with a focus on transformation into inputs or new products, observing the conditions and standards established by the competent bodies of the Sisnama and, if applicable, of the SNVS and Suasa”.

What we don’t know is what happens after we deposit the recyclable materials into each of the bins and the different types of processes that can be used to treat these materials.

And how are these processes classified?

Currently, the most used recycling techniques are primary and secondary and that much has been researched in order to develop tertiary and quaternary recycling mechanisms.

Learn about the main recycling process classifications:

1) Primary recycling: The process which occurs within the company producing the waste, and when recycled, this waste generates the same product or products with a similar application. As an example, process trims or products with specification problems that are reused within the process of the producing company itself. This technique is also known as re-extrusion, being normally used for industrial waste, which is cleaned (Al-Salem, Lettieri, & Baeyens, 2009).

2) Secondary recycling: Uses post-consumption waste as raw material. Waste discarded by a given consumer or industry, after its use, is recovered and processed in order to manufacture new products, which do not necessarily have the same purpose as the original product. Secondary recycling processes involve washing and grinding the received materials. Secondary recycling is mostly known as mechanical recycling (Al-Salem et al., 2009).

3) Tertiary recycling: is the one that uses thermochemical methods to process the materials, organic or non-organic, which will be molecularly disintegrated and transformed into new products. In many cases products that can no longer be processed by primary or secondary recycling due to the degradation of the material, undergo tertiary recycling processes. The resulting materials are normally used as primary materials, fuels or are co-processed with other materials. In the case of plastics, tertiary recycling allows the production of naphtha or monomers, which are further processed to produce new plastics.  Tertiary recycling is also known as advanced recycling (Al-Salem et al., 2009).

4) Quaternary recycling: like tertiary recycling, Quaternary recycling can use any type of material and is used for the purpose of recovering these materials energetically. That is, they are processed in order to transform these materials into products of high energy value, which can be used for energy generation. Quaternary recycling is known as energy recycling (Al-Salem et al., 2009).

As we discuss recycling, consider: Do you know if you know how to identify recyclable and recycled products and the difference between them?

When a package is identified as recyclable, it means that it can be sent to the recycling processes and that it does not contain raw materials that prevent its recyclability. On the other hand, packaging identified as recycled, reveals that the material used for its production comes from other recycled packages.

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