Dear readers,
a recent study by Hagel & Schütt (2024) sparked inspirational discussions between Willem van Veen (WvV) of inDUfed and Leo Goeyens (LG) of IBE-BVI Group. Their questions formed the basis for in-depth discussion, which led to this article.
Numerous questions came from LG, while responses were offered by WvV. Where viewpoints diverged, we noted it. They hope you all enjoy your reading.
A clear definition of packaging to start with!
Packaging an item goes beyond just putting it in a box or wrapping it in a plastic film. Packaging serves several purposes, including
̶ protection: every packaging should safeguard the packed product during handling, storage, and transportation;
̶ identification: packaging helps identify the packed product, its brand, its contents, its properties, and various other details, since a lot of this is mandatory information that must be communicated;
̶ convenience: packaging should make it easier for consumers to handle, store, and use the packaged product (for example, special boxes that allow us to spread just the right amount of chocolate sprinkles on our sandwich);
̶ attractiveness: packaging can increase brand awareness and appeal to potential purchasers; and
̶ economy: every packaging should simplify storage, handling and transportation.
How do we make paper? What do we need to manufacture it?
Paper is crafted from defibrated cellulose fibres which can be derived from plants and algae, natural and renewable resources. These plentiful and renewable fibres eliminate the need for laboratory-synthesised cellulose. In reality, paper can be made from a variety of plant sources, such as wood chips, sawmill waste, agricultural leftovers, straw, grasses, and even rags, without requiring significant portions of trees or other vegetation. Currently, it is predominantly manufactured using wood fibres that are reused multiple times.
The paper industry is actively exploring alternative fibers to reduce reliance on traditional wood sources. Researchers are investigating various non-wood fibers such as bamboo, hemp, flax, and agricultural residues like bagasse and wheat straw. WvV acknowledges that creating paper may seem simple, but it is in fact quite complex due to the vast differences in cellulose fibres from various sources, such as eucalyptus, pine, bagasse, wheat straw, and grass. These plants can provide virgin fibres, but there are some operational and financial requirements that must be met: cost efficiency, availability and scalability, technical criteria as well as compatibility with the main resource. You can read more about these conditions in this article. Obviously, wastepaper and cardboard can also be used. Paper recycling is very advanced, but it is still gaining attention. We should be aware, though, that paper recycling is complex, and requires a smooth chain of operations.
Several pulping techniques are available. How does one proceed?
The primary components of wood are cellulose, hemicellulose, and lignin. Cellulose gives plants their tensile strength, hemicellulose connects cellulose fibres and chains, and lignin serves as a cement that hardens the wood structure. Furthermore, wood consists of various organic compounds such as tannins, resins, waxes, and minerals, which do not contribute to papermaking processes (Zhang et al. 2022).
Cellulose is the key raw material for paper, leading to a significant focus on the pulping process. According to WvV, there are three main categories of pulping: chemical, mechanical, and recycled. In chemical pulping, chemicals and heat are used to dissolve lignin and separate the fibres, producing excess green energy that is generally used in the drying section of the paper machine. Mechanical pulping breaks down raw materials into individual fibres, eliminating the need for harsh chemicals. This approach is more material efficient, resulting in high-quality papers that retain their natural lignin content. Paper produced using the chemical process tends to be stronger and less prone to discolouration, since the lignin has been removed. The process of recycling pulp involves the use of previously used paper and cardboard, which may be deinked by froth flotation, by the injection of gas, or by adding dispersants to remove ink and other undesirable substances. This approach provides a sustainable and eco-friendly source of raw material.
How large are our needs? Is it possible to replace all virgin fibres with recycled ones?
Modern plants can efficiently handle large volumes of input materials, with 500 000 tons being typical. This requires some 60 to 100 trucks per day, highlighting the substantial logistical demands. While this may appear overwhelming to those unfamiliar with the industry, it is actually feasible and manageable.
High-quality paper products, including writing paper as well as high-end toilet paper, have historically been made from virgin fibres, primarily derived from wood. However, due to ecological concerns, more stringent regulations on forest management are being implemented, and as a result, alternative materials, such as straw, bagasse, and post-consumer paper, are now being explored as potential substitutes. However, these alternatives are not a full replacement for virgin fibres, as recycling degrades the fibre quality, requiring the addition of new fibres.
Before using alternative fibres, several prerequisites must be considered. Are there sufficient quantities of these materials available? Are the techniques and the fibres themselves compatible with the current recycling system? And can they perform their intended functions?
Availability goes beyond quantity; it also encompasses continuity
The manufacture of paper and cardboard occurs continuously, requiring constant access to raw materials. A rough estimate reveals that an average paper mill uses ~1600 tonnes of paper for recycling or ~2900 tonnes of wood per day. Let’s look at the example of straw, which typically comes from wheat and is available during harvest. In other words, it is a material with peak availability for one specific period each year.
Even if there is an abundance of resources, other considerations must be addressed too. Is there enough storage capacity to use these alternative fibres when needed? Moreover, organic fibres will biodegrade, making them useless for paper production processes. Proper storage is therefore important in terms of both preservation and volume. There must be space to store them.
Moreover, it should be noted that this raw material may already be used for other applications. Straw is used in agriculture as bedding for livestock and it is very useful for the organic matter balance of agricultural soils as well as for soil structure and biodiversity.
In an ideal circular economy, it is crucial to utilise resources that offer the greatest sustainable benefit, as long as feasible substitutes exist.
Can we just switch raw materials?
Paper mills usually specialise in producing a particular range of products, such as high-quality paper, packaging paper or cardboard and magazine paper. The manufacturing procedures have been thoroughly optimised, with some facilities using pristine fibres derived from specific woods, and others utilising reprocessed fibres obtained from discarded paper.
As previously mentioned, mechanical pulping involves grinding the fibres to separate them. Each type of wood also has a specific fibre structure. The grinding process is often specifically designed to optimally process the types of wood used so that the fibres are not damaged and as much usable raw material as possible is obtained. In contrast, paper manufacturing using recycled materials relies solely on dissolving the fibres in water, resulting in a homogenous pulp solution. No mechanical defibrillation is necessary. As a result, that raw material is unusable (unless it is purchased as pulp).
In other words, the opening of the fibres is very specific and it is not possible to simply switch to another stream.
Should we not fear for food safety once straw is being used to produce paper bags?
WvV and LG express concerns about the potential dangers associated with using straw as a raw material for food packaging. It is common knowledge that industrial farming relies on pesticides to maximise crop output. Therefore, it can not be ruled out that trace amounts of these chemicals may persist in paper and cardboard products, ultimately finding their way into our daily meals. While limited information is available, this certainly does not imply that there are no issues at hand.
Pesticides are typically intricate blends or cocktails of chemicals, and even modest doses may pose health hazards. It’s important to emphasise that the combined impact, the so-called cocktail effect, of exposure to mixtures can result in adverse effects that surpass the sum of their individual effects (INRA 2020). In light of this, it is imperative to conduct a comprehensive analysis of the migration from straw-based paper, given the legislator’s previous insistence on the necessity for all food packaging to meet certain standards.
Any material that comes into contact with food must meet some requirements. This applies to paper and plastic as well as any other material. Regulation (EC) No. 1935/2004 on materials and articles intended to come into contact with food requires that materials do not release harmful levels of their constituents into foods. The regulation mandates that substances used in food packaging must not alter its taste, scent, or composition in an objectionable manner. Furthermore, businesses involved in food packaging must establish a system to trace food contact materials from production to distribution. In the production processes of paper and board, chemicals are also used, but all in a controlled environment and with compliance to the legislation in mind.
The EU has the authority to establish particular rules for specific materials, such as plastics. Once these rules are implemented, manufacturers using these materials must submit a Declaration of Compliance. In this document, companies must attest to their adherence to all relevant regulations and provide evidence of traceability through labelling and supply chain records.
Never say no to progress, but look before you leap
We should commend all initiatives to limit logging and repurpose agricultural byproducts of little value into more ‘noble’ uses. However, it is important to carefully consider these proposals.
In the paper industry, one fibre cannot simply replace another. The production of paper and board requires high-tech processes that pay attention to both the quality and required quantities of the basic raw materials as well as of the final products.
Furthermore, an evaluation of the fibre origin is recommended. Chemical pollutants frequently exhibit tenacious resistance to degradation and, hence, affect every aspect of life. They can end up in food packaging, then in our diets, and finally in our bodies. High-quality paper and board bulging with unwanted chemicals is to be avoided at all costs.
References
Hagel & Schütt (2024). Reinforcement Fibre Production from Wheat Straw for Wastepaper-Based Packaging Using Steam Refining with Sodium Carbonate. Clean Technologies 6(1), 322-338
INRA (2020). The effect of a cocktail of low-dose pesticides via the diet: initial findings in animals have demonstrated metabolic disturbances. https://www.inrae.fr/en/news/effect-cocktail-low-dose-pesticides-diet-initial-findings-animals-have-demonstrated-metabolic-disturbances
Zhang et al. (2022). Comparison of lignin distribution, structure, and morphology in wheat straw and wood. Industrial Crops and Products, 187, 115432
