Treatment sludge offers opportunities for the reuse or recycling of micronutrients

The goal of the TKI project ‘Micronutrients in the resource loop’ is to contribute to closing the micronutrient resource loop in the Dutch food system. The focus is on both the direct and indirect reuse of these substances. In the direct reuse the process occurs via the residual streams that contain these micronutrients. Indirect reuse focuses on the recovery of the substances after the residual streams have been treated.

Project approach

The project is mapping the nutrient streams and concentrations of these substances. It is also investigating the availability of micronutrients for plant growth and, lastly, it is developing value chains for recycled micronutrients.

Sugar-beet chain as case study

The project took the sugar-beet chain as its first case study. This study has now been completed and is the subject of a report. The investigation began by mapping the position of micronutrients in the entire production chain, including the residual streams. Then an examination was made of solution paths to increasing the circularity of the micronutrient stream and/or improving the reuse of residual streams.

Treatment sludge offers the best possibilities

The key conclusion is that the treatment sludge offers the best possibilities for further enhancing the reuse/recycling of micronutrients in the sugar-beet chain. The existing legal provisions however are an obstacle to this recycling. A modification of the status of treatment sludge from agro-food processing is necessary, so that the sludge can be used as a fertiliser in the agricultural sector.