Soilfood, a Finnish circular economy company, is processing the fibre-based side streams generated in the production of paperboard from manufacturer Metsä Board, into various soil improvement fibres for local farms. Soilfood has previously used these side streams from Metsä Board's board mills at Kemi and Äänekoski. Now the cooperation has been extended to the Tako mill, located in the centre of Tampere.

Re-use of surplus material

Metsä Board's cooperation with Soilfood started with a research project initiated in 2015 by the Natural Resources Institute Finland. The study looked at how wood-based fibre sludge had the ability to reduce erosion and nutrients leaching from fields to water bodies. The large-scale use of side streams is part of a new circular economy approach, where raw materials are kept in use as long as possible and existing materials are re-used.

The two companies are also working together to develop other new solutions for the beneficial use of existing production side streams. "Our goal is to have zero landfill waste from the processes of our paperboard mills after 2030. Currently, more than 99 per cent of our production side streams are used either as materials or energy. Metsä Board wants to focus on its core competence as a producer of fresh fibre paperboard, but at the same time seek more opportunities for promoting the circular economy. That's why partners like Soilfood are important to us," says Mika Leino, Metsä Group's Vice President Environment.

From fibre sludge to farm soil

Soilfood collects fibre sludge from the Tako mill on a weekly basis. "The unique location of the Tako mill in the centre of Tampere brings with it special challenges as there are no large storage areas on the grounds of the mill," says Jaakko Ikonen, VP of Tako Board Mill.

Eljas Jokinen, Managing Director of Soilfood, explains about the journey of the side streams; "Soilfood takes on the responsibility of handling the side stream from its point of origin. In practice, the side stream must be mobilised almost as soon as it is generated. The number of loads varies according to the mill's production schedules and volumes. The products Soilfood processes from Tako's fibre-rich side stream are then transported to farmers in the surrounding area as soil improvement products."

In agricultural use, these soil improvement fibres both increase soils organic matter content and improve its water retention capacity. At the same time, nutrients of wood are returned to the soil. The fibres also reduce the environmental impact of farming by increasing soil carbon stocks and reducing the leaching of nutrients into water bodies*.

* Rasa, K, Pennanen, T, Peltoniemi, K, et al. Pulp and paper mill sludges decrease soil erodibility. J. Environ. Qual. 2021; 50: 172- 184. https://doi.org/10.1002/jeq2.20170

Link to photos (https://databank.metsagroup.com/l/KBhswDwXfjc-)