Non-recyclable materials: what are they and what to do

Non-recyclable materials are those made up of substances that are difficult to separate and whose benefits of the recycling process do not outweigh the costs. The large volume of disposal of this type of waste has become a environmental problem, given the delay in decomposition and the chemical and biological effects on the ecosystem. To solve this question, it is necessary to reduce, reuse and, when neither of the two options is possible, proper disposal is essential to reduce environmental impacts.

They exist three types of recycling: chemical, mechanical and energy – this can be an alternative for some of these residues that cannot be recycled through conventional processes (chemical or mechanical).

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List of non-recyclable materials

• Non-recyclable papers: carbon paper, photography, paper towels, toilet paper, used napkins, paper metallized, adhesives, labels, plasticized or coated papers with paraffin, cellophane, vegetal paper.
  
• Non-recyclable glass:
  medicine or chemical bottles, toxic reagent bottles, ceramics, lamps, mirrors, crystals and flat tempered glass.
  
• Non-recyclable plastics: metallized packaging, cellophane-type plastics, thermoset plastics (used in the electronics industry) and acrylics.
  
• Non-recyclable metals: steel sponge, paper clips and chemical packaging cans (paints, medicines, pesticides).

Why can some materials not be recycled?

Some materials are not recyclable as the benefits of the recycling process do not outweigh the costs.

There are two reasons for not carrying out conventional recycling (chemical or mechanical) of an inorganic material. The first one is due to the relatively small volume material to carry out recycling. In the case of plastic bags, candy wrappers, paper clips, among others, there is not a considerable volume of each to justify the process.

The second reason is the substances hard to separate, as in the case of mirrors, which are made of a layer of silver nitrate (which allows the glass reflect images) and dark paint to protect that surface. For this mixture that forms the mirror, there is no efficient technology to separate it and enable recycling.

Another type of non-recyclable material is contaminated, such as drug or chemical packaging, napkins, paper towels and other types of paper that are discarded wet, greasy. It is impossible to recycle this type of material because there is no practical and efficient process for cleaning and separation and because, in some cases, the final volume and benefits do not justify the process.

See too: How long does a material take to decompose?

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What to do with non-recyclable materials?

• Waste reduction

The ideal is to use as little material as possible that is not recyclable, replacing it with another product that fulfills the same function and causes minors environmental impacts. The use of ecobags or ecological bags, for example, was encouraged in order to reduce the use and disposal of plastic bags. At ecobags they are made of fabric, are more resistant and can be reused over and over again. Furthermore, the fabric, when discarded, is a less offensive type of waste than the thousands of plastic bags.

At ecobags are an alternative to replace the use of plastic bags.

• reuse

There are many creative ideas to add value to materials that are not recyclable, such as mirrors, which can be used in decorative items, for example. It is very important to try to reuse this type of material before disposing.

Reuse of broken mirror to add value to a clay vase.

• proper disposal

For those residues where it is not possible to reduce or reuse, the ideal is to make the correct disposal for prevent the spread of this garbage,which, in most cases, takes a long time to decompose and disappear from the environment, becoming a serious problem for the environment and for those who live there.

Read too: 10 attitudes that can save the planet

Types of recycling

Illustrative image of the stages of the processes that the recycled material goes through.

Before talking about the types of recycling, let's explain the difference between recycle and reuse. In recycling, a physical-chemical transformation of the material takes place so that it can be used again for other purposes or even for the same. In reuse, the material undergoes physical changes, being cut, kneaded, sanded, glued, and sanitized to be then reused.

• Chemical recycling: the transformation of the final product into raw material takes place, which can be reapplied in the manufacture of several new elements. In the case of plastic, for example, depolymerization occurs, which is the transformation of a polymer in monomer or in a polymer smaller than the original. This type of process takes place with the use of high temperatures or chemical reagents, factors that vary according to the type of product and expected reaction.
  
• Mechanical recycling: consists of crushing, cleaning and reprocessing waste of a certain class (plastic, metal, glass etc.) to reuse them in the manufacture of new materials with the same characteristics chemical. In this case, the material undergoes physical changes through grinding and melting at high temperatures, but it maintains the chemical characteristics of the original compound.
  
• energy recycling: process that transforms urban garbage in electrical and thermal energy. This type of recycling is for materials that cannot undergo mechanical or chemical recycling, such as disposable plastics, napkins, cellophane, among others. Energy recycling is the reuse of heat capacity of materials and brings great benefits not only in obtaining energy as a final product, but also in the disposal of waste, as the process drastically reduces the volume of solid waste. In addition, what remains from the incineration can still be used to manufacture building materials, such as bricks and tiles.

By Laysa Bernardes Marques de Araújo
Chemistry teacher

Would you like to reference this text in a school or academic work? Look:

ARAúJO, Laysa Bernardes Marques de. "Non-recyclable materials"; Brazil School. Available in: https://brasilescola.uol.com.br/quimica/materiais-que-nao-sao-reciclaveis.htm. Accessed on June 28, 2021.