The Ultimate Guide to Paper Recycling Process

Each year, over 400 million metric tons of paper and cardboard are produced globally, with over half of production originating from China, the United States, and Japan.

In 2016, Americans alone consumed 70 million metric tons of paper a year or approximately 514 pounds per person

The United Kingdom’s maximum consumption rate of nearly 13 million metric tons was reached in the year 2000 and has steadily decreased to a rate of 9.1 million metric tons or 305 pounds per person in 2015.

Most of this paper can be recycled, which is the process of reprocessing waste paper for reuse.

Paper is one of the most easily recycled materials, however, the paper eventually reaches a point where it can no longer be recycled due to the progressive shortening of fibres each time it is recycled.

Waste papers are gathered from:

Paper Mill Scraps

Discarded paper waste after consumer use – for example: old newspapers, magazines, white printer paper, cardboard, and packaging papers

Each metric ton (1,000 kilograms) of recycled paper can save approximately:

19 trees that can absorb 127 kilograms of carbon dioxide from the atmosphere each year

1,500 liters of oil

2.68 cubic meters of landfill space

4,400 kilowatts of energy

29,000 liters of water

Paper Recycling Process

Whether you recycle your own paper or recycle paper on an industrial scale, the process is essentially the same.

However, steps may be added or omitted in some cases, depending on the quality of the recovered paper, with thin lightweight newspaper requiring fewer steps than thick cardboard boxes.

Additional steps can also be added to remove a greater number of contaminants in paper such as bisphenol A, phthalates, phenols, mineral oils, polychlorinated biphenyls (PCBs) and toxic metals.

1. Collection

Recycling begins with individual users (homes, businesses, universities, industrial manufacturers) that collect and store paper waste in bins. Recyclers and paper merchants collect this paper and combine it together in a large recycling container.

2. Sorting and Transportation

After collection, the paper is measured and graded for quality. Waste paper with similar qualities are combined since they have similar amounts of fibre which can be extracted from the pulp. The paper is then hauled to paper mill recycling facilities.

Upon arrival at the recycling facility, the quantity and quality (cleanliness and type) of the paper is measured and a purchase contract is issued to the recycler.

These measurements of paper quality are also used to determine whether the type of waste paper is accepted or rejected; some recyclers accept mixed grades of recovered paper, while others only accept the preferred quality of waste paper grades.

Once accepted by the recycling facility, the recovered paper is then further sorted based on its surface treatment and structure.

For instance, very thin lightweight paper such as newspapers are sorted separately from thick paper materials such as paper folders.

This sorting is important because different grades of paper material are produced based on the materials being recovered.

3. Shredding and Pulping

After sorting, the paper is then shredded to break down the material into small bits. After the material in finely shredded, a large amount of water is added along with other chemicals such as hydrogen peroxide, sodium hydroxide, and sodium silicate to break down and separate the fibers of the paper.

The resultant slurry solution, known as pulp, has an oatmeal consistency and is the raw material used to make paper. This process of transforming the recovered paper materials to pulp is known as pulping.

The pulp is then passed through a series of screens, and a centrifuge-like process to remove larger contaminants such as paper clips, staples, tape, and plastic films that were included in the recovered paper.

4. Floatation Tank / De-inking

After removing larger contaminants, pulp is added to a flotation tank where chemicals and air bubbles remove dyes and inks to enhance the purity and whiteness of the product.

Hydrogen peroxide, and other whitening agents may be added to further enhance the whiteness if a white color is desired as the product. This step continually bleaches the pulp until it is ready for the final processing stage.

Dyes are sometimes added to create colored products, and in some cases a small amount of blue and black dye are added to create a bright white printing paper. Brown paper pulp, such as paper pulp used to make paper towels, is not bleached.

The pulp, which is now 99 percent water and one percent fiber at this stage, may be combined with pulp made from new materials to enhance its properties, and is then pumped over onto a paper machine.

5. Drying / Finishing for Reuse

The pulp is then passed over rollers that press out excess water, or a vibrating machine to create a product made of 50 percent water and 50 percent fiber. The pulp can be used alone or additional virgin wood fiber can be added to the pulp to give the paper extra strength or smoothness.

If coated paper is desired for smooth printing, a coating mixture may be applied to the paper near the end of the paper-making process or after the process is completed.

Next, the sheets pass through steam heated rollers, at temperatures as high as 130 degrees Fahrenheit to form long rolls of continuous sheets of flattened paper. A single roll of this paper can be as wide as 30 feet and weigh up to 27 metric tons.

At this stage, coatings such as potato starch are sometimes added to the paper to keep ink from spreading like it does when writing on tissue paper. The ends of the roll are then trimmed and recycled to make new pulp.

The resulting paper roll is then shortened into smaller sections and sent to various manufacturers that use paper to make their product, such as newspaper printing, wrapping paper, printing paper, and blown-in cellulose insulation.

Unfortunately, there is a limit to how much recovered paper can be recycled. During the paper recycling process, the individual paper fibers are shortened more and more each time they are recycled, and generally have a maximum limit of 7 times that they can be recycled. Such “end of the line” paper products include products like cardboard egg cartons that can no longer be recycled.

The best way to dispose of these products in an environmentally-friendly way is to compost them.