The Biosolutions Bulletin

When biology entered the paper mill

• Novonesis • Season 13 • Episode 1

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Paper has been part of our lives for centuries, carrying everything from love letters to laws, poetry and packaging.

Paper is one of the world’s oldest materials — and one of its next frontiers for sustainable innovation. As mills face rising pressure to cut water use, energy, and emissions, biosolutions are emerging as game changers helping make papermaking cleaner and more efficient. 

This audio article is part of The Biosolutions Bulletin. For the text version of this article and to get The Biosolutions Bulletin delivered monthly directly to your inbox, please go to: https://www.novonesis.com/en/biosolutions-bulletin

Paper has been part of our lives for centuries, carrying everything from love letters to laws, poetry and packaging. 

Paper is one of the world’s oldest materials — and one of its next frontiers for sustainable innovation. As mills face rising pressure to cut water use, energy, and emissions, biosolutions are emerging as game changers helping make papermaking cleaner and more efficient. To see why that matters, it helps to first understand paper itself: how it’s made, and why we still produce so much of it. So, in this epsiode of the Biosolutions Bulletin by Novonesis you will learn about the story of paper and why it still matters. 

With the digital revolution, it would be easy to think that paper is slowly disappearing. Yet the world keeps making it, even in staggering quantities. Far from fading, the paper industry remains one of the most active manufacturing sectors on Earth.  

Factories worldwide produce about 401 million tonnes of paper annually— enough to circle the Earth’s equator in stacked sheets many times or print nearly half a trillion copies of Tolstoy’s 1,500-page whopper, War and Peace. While essential to modern life, papermaking remains a resource-intensive process, requiring considerable inputs of water, wood, chemicals, heat, and energy. It is one of the more energy-demanding industries, contributing around 2% to global carbon emissions. 

Yet paper has advantages — it is recyclable and increasingly replacing plastic in packaging and daily products. In the U.S., 72% of paper is recycled; in Europe, 69%. The challenge is making this recyclable material more sustainable and reducing its production impact. This is where biosolutions come in. But first, let’s look closer at how pulp and paper are made—and why demand remains so high. 

Why Are We Producing So Much Paper? 

When was your last online purchase—this week, or even today? From clothes to electronics, make-up and shoes, almost everything we buy arrives in cartons, or corrugated packaging, made from layers of strong paper called paperboard.  

In 2023, 64% of all paper produced — 259 million tonnes of the 401 million tonnes worldwide — went into wrapping and packaging, far surpassing printing and writing paper, which accounted for 18% (73 million tonnes). Household and sanitary products made up 10% (41 million tonnes). 

This represents a major shift over the past two decades. At the start of the millennium, printing and writing paper made up about 43% of total production, while packaging accounted for roughly 57%. Since then, the share of paper used for packaging has grown significantly, driving the overall 24% increase in total paper production and establishing packaging as the dominant segment of the industry. 

Behind this vast range of paper products lies one fascinating process: the ancient art and science of turning wood into paper. 

How Is Paper Made? 

At its core, paper is made of fibers. Just as cotton fibers are woven together to form the clothes we wear, fibers from trees are pressed together to form paper. So, the first step in making paper is to extract these fibers from wood: Freshly cut tree trunks are first stripped of their bark, broken down into small chips, and then turned into a pulpy mixture.  

This is done through mechanical or chemical processes, both designed to separate the wood’s fibers by removing a natural binding material called lignin. Lignin acts like glue inside trees, holding cellulose fibers together and giving wood its strength and rigidity. Once lignin is removed, the free cellulose fibers can be used to make paper. In mills that use recycled paper, the process is similar: The used paper is mixed with water to make pulp again and then follows the same journey as fibers from trees.

Mechanical Pulping: Fiber by Force 

In this method, wood chips are ground by rotating plates or grinders. The idea is simple: apply enough pressure to physically separate the fibers. The resulting pulp keeps most of its lignin, making it darker and more prone to yellowing, but it is cheaper and yields more pulp per log. Mechanical pulp is commonly used for newsprint, magazines, and cardboard, where cost and volume matter more than brightness or durability. 

Chemical Pulping: Fiber by Chemistry 

For high-quality paper, mills use chemical pulping, most commonly the so-called Kraft process — named after the German word for “strength”, a nod to the durability of the paper it produces. In this method, wood chips are cooked in pressurized digesters with a solution of water, sodium hydroxide, and sodium sulphide, which dissolves lignin and frees the cellulose fibers. The process produces a light, strong pulp that can be bleached for high-grade paper. 

Bleaching 

Bleaching is essential for white or high-brightness papers like writing paper and tissue. Chemicals such as chlorine dioxide and hydrogen peroxide remove residual lignin, turning the pulp from brown to white. For packaging materials, bleaching is often skipped since brightness matters less. 

Refining 

Refining is a crucial stage where wood fibers gain the strength and flexibility that define paper quality. After pulping and bleaching, the stiff fibers are gently worked until they become soft and able to bond.  

It’s a bit like preparing flour for baking. You cannot make a cake or flatbread directly from whole wheat; you must grind it to the right consistency first. Refining does something similar: it adjusts the fiber texture so that the final paper feels just right. 

At the microscopic level, refining pushes water into the fiber cell walls and exposes tiny fibrils that help fibers interlock, creating a denser, smoother sheet. The process must be carefully balanced: too little refining leaves paper weak, too much shortens fibers and reduces strength. Each paper type has its own balance — soft for tissues, strong for cardboard. 

Pressing 

Once the wood is turned into pulp, it enters the paper machine — a massive system that turns watery pulp into solid paper. In the paper machine, the watery pulp is compacted between large rollers to remove water and form a uniform sheet. This pressing stage forces out moisture and bonds the fibers more tightly — much like wringing out a damp towel. The process must be balanced: removing more water reduces later drying energy, but too much can weaken the fibers. About 35% of moisture is usually retained to keep the sheet pliable and strong for the final transformation into paper. 

Drying 

After pressing, the sheet feels firm but still damp. To become the crisp, dry paper we know, it enters the dryer section of the paper machine — its final and largest part. Here, the sheet passes over steam-heated cylinders that gradually evaporate moisture until only 5–10% remains, just enough to keep fibers stable. Drying is the most energy-intensive step, using about 70% of the total energy in papermaking, which is why efficient pressing is so important. Beyond removing water, drying gives paper its familiar texture, stiffness, and light crackle. 

What began as a soggy web of fibers now emerges as a continuous ribbon of paper, ready to be rolled and cut.

Let's take a moment for some fun facts:

  1. Paper Came First, Books Took 700 Years to Catch Up 
    Paper was invented around the year 150. However, the first printed book on record, the Diamond Sutra — a Chinese translation of a Sanskrit Buddhist text, was published only in the year 868. That’s a 700-year “writer’s block”! Johannes Gutenberg’s printing press came another 600 years later, in the 15th century, proving the world had paper long before it had paperbacks.  
  2. Before Trees, There Were Rags 
    Long before trees became the main source of paper, Europeans were turning old clothes into pages. By the 13th century, the town of Fabriano in Italy was home to thriving paper mills that used worn-out garments collected by rag pickers as raw material. The mills sorted, washed, and softened the fabrics before breaking them down into fibers, transforming old cloth into fresh paper. Fabriano’s papermakers also introduced another first: the watermark, a clever signature pressed into the pulp to mark authenticity and craftsmanship.  
  3. Pulp Fiction Was Paper First, Not a Movie 
    Before it was a Tarantino classic, “pulp fiction” referred to the cheap, rough paper used for early 20th-century magazines. Printed on low-grade wood pulp, these stories were filled with fast-paced adventures, crime, and intrigue. Cheap to buy and thrilling to read, they defined popular entertainment long before television and film took over.  
  4. The Secret Life of Paper  
    Paper may look blank, but it holds memories of its making. Under a forensic microscope, its fibers, fillers, and chemical traces reveal where it came from — even how old it is. Watermarks and surface textures act like invisible signatures, letting investigators trace forgeries and uncover a document’s true origins. In the right hands, paper can give up secrets no ink ever could. 

Mitigating the Costs of Heat, Water, and Energy 

It is remarkable to think how far papermaking has come. From its origins in ancient China nearly two thousand years ago to the vast industrial mills that now run day and night across the world, the craft has become faster, bigger, and more precise.

Yet at its heart, almost nothing has changed. It is still about freeing fibers from wood, mixing them with water, and pressing them into sheets — the same dance of fiber and fluid that ancient craftsmen once performed by hand. 

For all its progress, the paper industry has relied on the same fundamental process for centuries. Machines have grown mightier, but the principles remain untouched. And so do the costs. Every sheet of paper and every carton carries a hidden burden: the immense use of chemicals, heat, water, and energy. These give paper its strength and smoothness, but also its heavy environmental footprint. 

Now, as the world demands cleaner production and lower emissions, papermaking stands at a turning point. The next leap forward will not come from steel and steam, but from something natural and organic: biosolutions.  

Biosolutions in the form of enzymes help paper mills get more from every tree while using less energy, heat, chemicals, and water. They also help mills recover and reuse fibers from recycled paper more effectively and efficiently.  

In the article [When Biology Entered the Paper Mill], we will explore how these biosolutions are transforming paper mills across the world — making production more sustainable, recycling more effective, and every sheet of paper a little kinder to the planet.  

Thank you for listening. This audio article is part of the Biosolutions bulletin by Novonesis. For the text version of this article and to receive the monthly Biosolutions bulletin directly in your inbox, go to: https://www.novonesis.com/biosolutions-bulletin.