Gardening

Paper recycling: process and environmental benefits

Of the total urban waste , paper and cardboard account for between 16% and 25%, of which up to 70% can be recovered. They mostly come from magazines and newspapers, food packaging, cardboard boxes, high-quality paper used in printing and reproduction, and mixed paper.

Most paper is made from trees , although in the past it was also obtained from other plants, including cotton, hemp from which a high-quality cellulose is extracted, fern, garlic, onion or nettle. The global paper industry consumes around 4 billion trees each year, mainly pine and eucalyptus . By recycling paper and cardboard, it is possible to extend the life of cellulose fibers, a natural resource that comes from wood.

For recycling , it is very important that the paper is collected separately from other waste, to avoid staining and contamination, which will make recycling very difficult or impossible. Used paper is recovered for recycling through industrial collection (in companies, publishers and printers and large commercial areas), and municipal collection (through the blue containers for household paper, through collection «Door to door» of small businesses, and through collections in offices, schools and buildings of public bodies and institutions).

In the blue container we can put newspapers, magazines, shoe boxes, cereal boxes, paper rolls, books, egg cartons, brochures, folios, envelopes, all kinds of cardboard and paper packaging.

The paper and cardboard are collected, separated and later mixed with water to be converted into pulp . The lower quality pulp is used to make cardboard boxes. Impurities and some inks are removed from the better quality pulp to make recycled paper for printing and writing. In other cases, the recycled fiber is mixed with new pulp to make paper products with a percentage of recycled material .

Waste paper can be shredded and recycled multiple times. However, with each cycle 15% to 20% of the fibers become too small to be used. In addition, it is estimated that around 19% of the paper we use cannot be recovered for recycling because we keep it, as can happen with books, photographs or documents, or due to its use as happens with toilet and sanitary paper or with the cigarette paper. That is why it is necessary to permanently inject a certain amount of virgin fiber into the process.

The recycled paper of long fiber pulp (such as office paper) has greater flexibility to recycling as it can be used to produce new paper products using either long or short fibers. Paper recovered with short cellulose fibers (such as newspapers) can only be recycled into other products that use short cellulose fibers. For this reason, long fiber recovered paper is generally of higher value than short fiber coated paper.

The Spanish paper industry uses 1.8 million tons of virgin fiber and 5.1 million tons of recovered fiber as raw material.

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paper making process The manufacture of recycled paper consists of the following stages or phases

  • Selective collection of used paper in special containers.
  • Purification of used paper pulp by filtering and centrifuging, to eliminate possible particles of non-fiber elements such as sands, lacquers, wires, ropes, etc.
  • Ink separation by flotation. To do this, the paste is immersed in soapy water (surfactants) in a tank, also called a pulper or mixing tub, and air is injected to cause the appearance of bubbles. The ink forms a colloidal suspension and the foam is made to float together with the ink, allowing it to be mechanically separated. Later, the ink is transferred to landfills , where it is incinerated using its own heat energy.
  • Dried and pressed . The pulp obtained, which usually contains 42% fiber, follows the same process as cellulose of primary origin to obtain paper. In other words, it dries at 120 ° C, while it is pressed and stretched to give it the final shape and texture.

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Improvements in environmental impact

If recycled paper manufacturing processes are compared to making paper from virgin chemical pulp, the following improvements in environmental impact can be noted:

  • The consumption of wood is reduced , which favors the development of forest masses and reduces the costs of felling, transport and handling.
  • It is possible to reduce primary energy consumption , whose savings can reach 60%.
  • Reduction of water consumption by just over 85%.
  • Reduction of the mass of urban waste in landfills. In high-income countries this reduction reaches 30%. For every 700 kg of recovered paper, we save the space equivalent to a car in the landfill and avoid emissions equivalent to a trip of more than 3,700 km by car.

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 Types of paper

On the market there are virgin fiber papers , recycled fiber papers and a mixture of both. The use of virgin fiber or recycled fiber in the composition of a paper depends on the characteristics of the final product, which, in turn, are determined by its application.

The ecological role is one that in its production have taken steps to reduce environmental pollution by using natural resources, energy, air emissions, waste disposal, etc. Recycled paper may not be ecological if it has a polluting production process , sometimes the treatments of inks composed of varnishes, oils, solvents, pigments and other compounds, can generate negative impacts on the environment.

Depending on how the whiteness of the paper has been obtained, they can be  elemental chlorine free (ECF) using chlorine dioxide with chemicals without chlorine, or totally chlorine free (TCF) using oxygen, oxygen peroxide (hydrogen peroxide) or ozone, completely eliminating the use of chlorine. Both options have a much lower environmental impact than the process in which chlorine gas was used as a bleaching agent, a powerful water pollutant that, when reacting with wood molecules, generates substances such as organochlorines, which affect the immune system of the mammals.

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