About Paper Recycling
Paper is well known for its recycling potential, and is often seen as the recycling industry’s biggest success story. Paper lends itself to be broken down back to cellulose fibers, which can be used as building blocks for the production of recycled paper. These cellulose fibers can however not be recycled endlessly. During the recycling process, the fibers are shortened, until ultimately they become too short to apply in new paper products. Theoretically, the same fibers can be recycled up to 6 or 7 times before fiber properties have diminished to such extend that they cannot be used for paper anymore. These short cellulose fibers end up in what is called paper sludge.
Cellulose fibers are a major source of organic material. In some countries, paper sludge is still used as a soil amendment to improve soil fertility. This may seem like a perfect solution, but besides short cellulose fibers, paper sludge contains (residues of) inks, minerals, adhesives, coatings and several other undefined chemicals. These additives were never designed for return to the biosphere. An alternative use for paper sludge, is “thermal recycling” or incineration. “Waste-to-energy” seems a viable option. However, due to these contaminants, the flue gases produced through incineration need to be purified, and the remaining ashes cannot be used as fertilizer for soils. Additionally, the same contaminants can wind up in recycled paper products. These chemicals do not only lead to contamination of paper sludge. Contaminants may also end up in recycled paper products, like food packaging, where they leak from the paper into the product, forming a hazard for human health.
From a Cradle to Cradle® perspective, the use scenario of a material is crucial: in the conventional paper making process paper fibers cannot be recycled endlessly and can therefore not be considered technical nutrients. Thus, the paper making process has to be optimized in such a way that fibers can be re-used as often as possible until they become unsuitable for paper, cardboard or tissue, and then serve as valuable biological nutrients for soil amendment and/or energy generation. The by-products from the paper recycling process (e.g. from de-inking) can be designed to be safe for humans and the environment.
There is still a great potential to optimize our paper making industries, starting at re-thinking what the exact use scenario of our paper products is. Successful implementation of the paper cascade is closely correlated with the materials each actor in the supply chain adds to the cellulose fiber. It is therefore important that all actors align their activities to come to positively defined process and final product.