Pyrophos, FHNW School of Life Sciences

Phosphorus is a finite yet essential raw material, which in Switzerland is imported entirely in the form of mineral fertilisers. At the same time, large quantities of phosphorus accumulate in high concentrations in sewage sludge. Due to numerous legislative changes, sewage sludge disposal will largely shift to phosphorus recovery in the coming years.

In the project, sewage sludge is mixed with potassium in an alkali pyrolysis process and treated thermochemically under reducing conditions. This results in the formation of phosphate phases that are completely available to plants and the separation of heavy metals via the gas phase. The FHNW is working with the technology provider CTU, which is active in the field of thermal processes and would like to market the process once it has been developed. In addition to AVA as the wastewater association and potential plant operator, the project partner Landor, Switzerland's largest fertiliser company and purchaser of the product, now represents the entire value chain in the project.

The following work is planned:

• The process will be demonstrated on a large scale in a fluidised bed.
• Agronomic efficiency will be continuously monitored.
• The full-scale plant for the Altenrhein site will be designed and its economic viability will be examined in detail as part of a preliminary project.
• A sales and logistics concept for the product will be developed, a detailed estimate of operating costs will be made, and the cost efficiency and environmental impact of the process will be compared with reference processes.