As environmental awareness increases, more and more attention is given to proper waste separation. What happens to the paper put into a blue waste bin? That is not where it ends up. Actually, that is where it begins a new journey.
For paper to be recycled it is up to us to take the first steps. We have to segregate refuse from materials that can be reused, and separate them into appropriate groups. What waste paper can be recycled? There are a few general principles to follow. First of all, the paper should be dry, clean and free from oil or fat. Any cardboard boxes should be emptied, broken down and flattened out. Do not put paper towels, tissues, wipes, receipts or juice cartons into the blue bin.
What happens to the paper collected in the waste bin?
The first stop on the path to recycling is a sorting plant. The waste paper is delivered there and undergoes selection. Any paper that cannot be recycled, including wet paper, is rejected. A popular myth is that wet paper is rejected by sorting companies as unrecyclable. The actual reason is trivial – paper mills pay for wastepaper by weight and wet paper is heavier, so they do not wish to pay for the water which will eventually evaporate.
At the sorting plant, the paper is also graded according to quality. Then it is pressed into bales and transferred to a paper mill.
At the mill, the paper undergoes a defibering and repulping process. It consists in shredding the paper into small bits, putting them into a large tank and mixing with hot water. This separates cellulose fibres. There is a rotor at the bottom of the tank, separating the fibres from any contaminants (e.g. adhesive tape, staples etc.) that were not removed at earlier stages. The paper is also de-inked, often using chemical agents.
3. Mechanical removal of contaminants
The next step involves removing any contaminants from the cellulose pulp, such as sand or the already mentioned staples or tape residues. In this process, sieves are used and hydrocyclones applying centrifugal force. The pulp is fractioned according to fibre length and further cleaned downstream. When the recycled pulp is completely free from contaminants, it is thickened using special filters and presses.
Recycled paper serves various purposes. If it is intended to be presentable, e.g. used for newspaper printing or as writing or copying paper, it must be de-inked first. If it is to become just wrapping paper or cardboard, this step is skipped.
What is de-inking? Basically, it is removing dyes, ink and adhesives by means of floatation. The process consists in putting the pulp into a floatation tank where air bubbles carry away the dye, ink and glue particles from it, and the resulting froth is then disposed of.
Chemical agents are added to the pulp to ensure that the produced paper is white. Otherwise, the product will be brown.
6. Drying and sheet formation
Finally, the pulp is dried and formed into paper sheets.
It is estimated that paper can be recycled up to 7 times in this manner. However, as you can see, the recycling process is complicated and energy intensive. So, let’s think what we could do not to waste paper. Why don’t we give up paper letters and shift to e-mail entirely. If we really have to print something, do it on both sides of the sheet. And reuse cardboard boxes and packaging.
In one of our previous entries we advised you how to design your book in a greener way, and told you what we do for the environment as a printing company.
We also encourage you to do your bit for waste segregation. After all, it is up to us whether paper gets a new life, or ends up in a landfill.