How is cardboard recycled? A step-by-step explanation

Even though you come into contact with it every day, the question of how is cardboard recycled is probably not something you consider often. Yet cardboard (and paper-based packaging) has one of the highest recycling rates in the UK.

So, how is cardboard recycled?

Cardboard recycling involves a 6-step process. These steps are collection, sorting, shredding and pulping, filtering, finishing, and converting back into corrugated board. It is possible to recycle cardboard more than 20 times before the fibres become too weak. Over 70% of the cardboard used in the UK is recycled.

This guide provides you with an overview of the complete cardboard recycling process. It also covers limitations, differences between virgin and recycled fibres, and the business advantages of using recyclable (and recycled) cardboard packaging.

You may also find this article on Packaging Waste Regulations helpful, as it covers government recycling targets alongside details of whether your business has any legal obligations.

The first (and perhaps obvious) stage is collecting the waste corrugated material. Collections may be from consumers’ kerbside bins or industrial agreements with manufacturers that generate large volumes of waste material.

Usually, they are measured and transported to recycling facilities, which are commonly part of paper mills.

The next stage is to sort the different materials.

Firstly, any cardboard coated or waxed (i.e. for food contact) is separated and undergoes a separate, specialised recycling process.

Sorting of the remaining material separates corrugated cardboard and what is known as “boxboard” – thinner material with no fluting used for items such as cereal boxes.

This sorting is crucial as the different materials are ultimately used to manufacture various grades of material by the paper mills/recycler.

After sorting the material, the next step is to shred it and then pulp it.

Once shredded into fine pieces, the process mixes the cardboard, water and chemicals that break down the fibres in the paper. This process turns it into a slurry-type substance.

This “pulp” is blended with new or virgin pulp that usually comes from wood chips. Doing this helps the substance to become firmer and solidified, as well as helping to regulate the strength of the new material.

The pulp material passes through a wide variety of filters. Firstly this eliminates foreign objects such as tape or glue. A centrifuge process removes contaminants such as plastics and metal staples. Plastics float on top whilst metals sink to the bottom.

The following process is removing all the inks from the pulp using chemicals, effectively cleaning the pulp for the final processing stage.

After this, it is possible to store the pulp for use at a later date. Doing this may require adding extra water to the pulp before being finished into sheets or rolls of paper.

The cleaned pulp is spread out to dry on a flat conveyor and heated cylindrical surfaces. As the pulp dries, excess water is also pressed out. The process effectively forms long rolls of solid sheets from the fibres.

Pressing the sheet through rollers also helps to turn the sheet into something starting to resemble paper. At this stage, adding additional layers to the cardboard is possible, depending on how thick it needs to be.

Ultimately this process produces large reels of brown paper (weighing several tonnes) that can be cut to size as required.

It is possible to use the sheets of paper produced as outer liners of the corrugated material or the fluting, depending on the grade produced.

The material can then be turned into corrugated cardboard by the paper mill and sold directly to packaging manufacturers. Alternatively, selling in paper form to other companies who convert the papers into various materials is possible.

You can see further information regarding the cardboard manufacturing process here.

There is a wide range of reasons why recycling cardboard helps the environment.

Firstly, estimates indicate that overall energy savings of between 25% and 50% when using recycled cardboard rather than virgin material.

Secondly, recycled cardboard uses between 70% and 100% less virgin material (it is commonplace to add some virgin material to recycled products during manufacturing).

Thirdly, water consumption is reduced by up to 99%.

And finally, there are considerable emission reductions in manufacturing recycled cardboard in the UK by not importing materials from overseas. The UK cannot sustainably produce enough wood for the amount of paper and cardboard produced yearly, but recycling the material already within the economy circumvents this issue.

Virgin and recycled fibres are common terms when discussing the recycling of papers and corrugated cardboard.

But what do these mean?

Virgin fibres are effectively pulp obtained by a chemical process which removes lignin (a class of complex organic polymers that form necessary structural materials in the support tissues of vascular plants) from wood. Effectively, it is making paper from wood.

Recycled fibres refer to pulp from recycled material – essentially cardboard packaging or papers previously used but recovered for recycling.

But which is better for the environment?

Many people believe virgin fibres have an increased environmental impact as they involve deforestation.

However, this is not strictly true. Careful management and replanting mean forests become a renewable source of material and net oxygen producer. The only major drawback of virgin fibres is the requirement for more process water treatment.

Recycled fibres actually take more fossil energy to process. Virgin fibres are also typically added to recycled fibres – they are reusable for around 20 times before becoming too weak. After this, the fibres are so small that they wash out during the process.

Using recycled fibres does help reduce landfills, using the existing material to its full potential. It also allows the use of virgin fibres in applications where their properties are specifically required.

However, it is vital to provide a balanced argument. Specific scenarios exist where recyclable packaging, such as corrugated cardboard, is counterproductive and less sustainable than non-recyclable packaging.

For example, plastic totes, such as those manufactured from Correx®, are often better than a single-trip cardboard alternative if part of a closed-loop supply chain. Compared to expendable packaging, their longevity means considerably fewer containers are required.

Using a smaller number of containers reduces overall material use, minimises transit costs through the required additional deliveries, and less energy consumption used in manufacturing.

Another area where recyclable corrugated alone isn’t always suitable is for exceptionally valuable or fragile items.

You must also consider the damaged items’ environmental (and monetary) costs. If a product breaks in transit, it is typically sent to a landfill. There is a requirement for additional energy and material in manufacturing replacements. Plus, the further transport to return and redeliver the item.

As well as the environmental impact, however, it also significantly impacts your business. Written off stock, unhappy customers who are less likely to purchase from you again, as well as a negative impact on your brand and business reputation.

Finally, there are always some products that aren’t suited to transit in corrugated packaging. Even with specialist coatings, certain oily or moist products will degrade the corrugated material, rendering it ineffective.

Food produce is likely to spoil quicker, leading to increased food waste in landfill. It can also make the material unsuitable for recycling (e.g., pizza boxes being too greasy).

How your business can benefit from recyclable packaging

Although cardboard packaging is not suitable for every application, it has many advantages to using it where possible.

As well as the environmental benefits – including the reduction in your organisation’s carbon footprint – using easily recyclable packaging often leads to better consumer perception of your brand and business.

Equally, it can allow you to position your brand in a specific market. Ultimately there is the potential for increased sales amongst particular demographics.

And customers that can easily recycle your packaging typically report higher satisfaction levels.