Bringing clarity to complexity
Begins Timo Kanerva, Environmental Director, Metsä Group, “Side streams are a complicated topic. For the general public, I think the terminology and concepts are not the easiest ones to understand. But, right from the outset, if we want to make things a little clearer, we can take the whole side stream umbrella and then we can divide it into three different sections: bioproducts, by-products and waste.”
The term ‘side stream’ is a very wide definition that basically includes everything that comes out of a mill that is not the main product (wood pulp). With the bioproduct mill concept we have learned to realise that some of these side streams, such as tall oil and turpentine, are in fact valuable products themselves and are part of the bioproduct portfolio on the global market. Other side streams are more or less valuable as products, raw materials or in renewable energy production. A very small share of the side streams is currently waste, and its share is constantly decreasing as new end uses are created.
Inclusion / exclusion
We arrive at the materials that are classified as genuine side streams and waste, substances derived from the production of wood pulp. These are by-products with lower value which are used in the fertiliser industry, for example. Ash from the power plants can be used as a fertiliser or soil improvement agent. Also lime and lime dust are derived from the chemical recycling process of the pulp mill and have some commercial value.”
In addition to those previously mentioned materials, there are other notable by-products too. Screening fibre fractions, for example, are certain parts of wood that come from the pulp mill that have been rejected, while sandy bark is from the wood yards where bark is being cleaned and contains sand and impurities within it. De-inking sludge comes from the recycling process of recovered paper. From that process, the fibre itself continues to further uses and the rest, such as kaolin and other coating materials create the de-inking sludge, which in the circular economy can today be utilised in many ways. These are by-products that are no longer defined as waste, but still remain of fairly low commercial value. That said, nearly all of them have ‘real-world uses’ and are able to increasingly contribute to the circular economy, depending on what kind of side streams they are.
“We can take the whole side-stream umbrella and then we can divide it into three different sections: bioproducts, by-products and waste.” adds Kanerva, “We are developing the utilisation of these side streams all the time and the market in this respect is very interesting. Furthermore, the value of it is growing as globally there is more interest in using recycled materials as part of circular economy. As a result, we are trying to make it more valuable and high-quality and many things are happening in that area.”
A growing market
Explains Sanna Pulkkinen, Development Manager, Metsä Group, “With regards to side streams viewed from an economic perspective, on the company level, we are looking at an overall figure in the many tens of millions of euros. This is the magnitude and value of side streams at the moment. Most of the turnover on side streams comes from biochemicals, such as tall oil and turpentine. But, if you are talking about the less valuable side streams, there is a potential for that to grow and to become a real business as well.”
Adds Kanerva, “Many of these materials such as ash and lime dust were considered waste ten years ago and were simply taken to the landfill. Now we are talking about large fractions of the material streams that are now no longer considered as waste. They are by-products and they are becoming more and more valuable raw materials, or fertilisers for agriculture to use instead of conventional fertilisers from fossil sources. It is a very big cultural change, as well as a big change in this industry. Within the next 5-10 years this area will develop much further.”
Currently, around 94% of Metsä Group’s production side streams are utilised. These side streams fall into five categories: energy utilisation, material utilisation, fertilising and soil improvement, and industrial use.