Paper recycling

Paper is the most recycled material in the world. We recycle more paper than plastic, glass and aluminum combined. In some countries, where recycling is still not very wide-spread, people still recycle paper. Recycling 1 kilogram of white (printing or copier) paper saves slightly more than 2 kilograms of wood. At the same time recycling 1 kg of gray paper (i.e. paper used for printing newspapers) saves about 1 kg of wood. On many sources you can find a relation of kilograms of recycled paper with the amount of saved trees. This comparison is, however, rather meaningful. Tree sizes vary significantly, therefore, such a comparison can result in very different outcomes. It has, however, been estimated that recycling half of the paper currently used by humanity, would save around 81,000 km² of forestland [1].

Paper recycling

What can recycled paper turn into?

Have you ever heard the following phrase: “Paper has seven generations”? This phrase refers to the amount of times it can be recycled. The quality of paper is defined by the length of its fibers. The longer the fibers – the higher the quality (or grade). Usually, the more times the paper has undergone the recycling procedure – the shorter its fibers. Therefore, a general “rule of thumb” is: the grayer the paper – the more recycling cycles it has been through. For example, newspapers and paper-towels represent the lower grades, since they usually make use of recycled paper. White paper for the printers is, on the other hand, usually of the highest quality – not yet recycled at all. After five to seven recycling cycles, the fibers become too short to make new paper and addition of new fibers is necessary to create paper.

One of the most popular usages of recycled paper is pulp or molded fiber packaging. However, various other usages of scrap or recycled paper exist. Among them the previously mentioned newspapers and paper towels, as well as egg cartons or grocery bags.

Recycling procedure.

The process of paper recycling consists of several stages.

  1. The first stage is paper collection. The biggest amount comes in a form of used paper from the consumers. However, paper trimmings from the manufactures also end up in the recycling process. Furthermore, some paper is discarded after it left the production site  but before it reaches the customer. That paper usually ends up collected for recycling as well.
  2. The second stage is sorting the paper according to its grade. As discussed above, the length of the fibers defines the grade of the paper.
  3. After sorting comes storing in the recycling facility or “recycling mill”.
  4. Consequently, some chemicals are added to the paper to remove the leftover admixtures. These admixtures can include aluminum, ink and other contaminants.
  5. Then special machines cut the paper into small pieces and heat these pieces up. This breaks paper down further into fibers. The resulting mixture has the name of pulp, or slurry. Dedicated screens then remove any impurities that may still be in the mixture. Then the mixture is cleaned, de-inked, bleached, and more water is added to it.




[1] EarthWorks Group. 1990. “The Recycler’s Handbook”. Berkeley, CA: The EarthWorks Press