Ansa Palojärvi and Tapio Salo: Soil health benefits from food industry residues

The concept of the circular bioeconomy is attracting growing attention to biomass use as a basis for renewable resources. The EU Bioeconomy strategy has five goals: i) ensuring food and nutrition security, ii) managing natural resources sustainably, iii) reducing dependence on non-renewable, unsustainable resources, iv) limiting and adapting to climate change, and v) strengthening European competitiveness and creating jobs.

Food industry residues are a valuable raw material, containing ingredients like nutrients, trace elements, and organic matter. EU studies have estimated that food processing waste contributes between 12% and 41% of the total amount of food waste. On average, 5% of raw materials in the food industry end up as waste. It has high valorisation potential duo to large, homogeneous biomass amounts, but if not correctly handled, landfill deposition may cause greenhouse gas emissions and eutrophication.

In Finland, approximately 400 000 tonnes of side streams are formed in the food industry annually, corresponding approximately 8 000 tonnes of nitrogen and 800 tonnes phosphorus. It is less than 10% of the total use of mineral fertilizers annually but could be locally important.

Arable soils in the EU are subject to severe degradation. Soils are healthy when they are in good chemical, biological, and physical condition, and thus able to continuously provide their important ecosystem services, such as food and biomass production. An estimated 60–70% of EU soils are unhealthy. 12.7% of Europe is affected by moderate to high erosion, causing an estimated loss of agricultural production of €1.25 billion per year. Meanwhile, organic carbon stocks in cropland topsoil are declining, further accelerating global climate change. The use of recycled fertiliser products would contribute to reducing dependence on mineral fertilisers and improving soil health. An important goal is to reduce GHG emissions, both within value chains and through the replacement of mineral- and fossil-based fertilisers.

The EU Horizon-funded DeliSoil project (www.delisoil.eu), coordinated by the Natural Resources Institute of Finland (Luke), is contributing to the EU’s Mission “A Soil Deal for Europe” by improving the sustainability of food systems and enhancing soil health. This will be achieved through the development of improved recycling and processing solutions for food industry residues.

Various processing technologies are available for non-edible food waste. These can be based on biological, chemical, or physical treatment processes, or combinations thereof. These processes can, for example, degrade organic matter, reduce water content, and bind, release or separate nutrients. The end-products could be used as organic matter -rich soil improvers, such as digestate from anaerobic digestation (AD), biochar or compost, with demonstrated improvements in soil health metrics, crop yields, and environmental sustainability.

To achieve this, guidance on actions and priorities is needed to overcome challenges and trade-offs associated with these technologies, such as potential biological or chemical risks, storage, and transport. These efforts must take into account social, legislative, economic, and environmental barriers to encourage widespread adoption.

The adoption of integrated value chains has been identified as one of the most promising pathways to accelerate the food industry’s transition to a circular bioeconomy, i.e., achieving a zero-waste goal and enhancing the economic and environmental sustainability of the food production chain. Cascading use of biomass follows a downward movement in the bio-based value pyramid, progressing from higher- to lower-value biomass applications (the so-called waste hierarchy). The goal of EU fertiliser legislation (2019/1009) is to promote nutrient recycling, so it is important to determine whether additional legislative requirements are needed to minimise risks and promote the use of these products.

The DeliSoil project will perform a comprehensive evaluation of the circularity of the technological approaches. The assessment includes several key aspects: the technological feasibility of the processes, the agronomic potential of the resulting products, and the broader environmental and socioeconomic sustainability impacts of the applied technologies. By addressing these dimensions, the project aims to ensure that the proposed solutions not only function effectively but also align with the principles of the circular economy. Processing and recycling solutions for side-streams from the food processing industry have the potential to promote industrial sustainability as part of the local value chains, improve nutrient self-sufficiency in agriculture, enhance soil health and contribute to mitigating adverse environmental impacts while better controlling nutrient flows into the Baltic Sea.