Abstract

The aim of the joint project is the practical prototype testing and demonstration of an innovative, economically and technically viable process chain for thermal sewage sludge utilization with phosphorus recycling and product usage for the model region "Middle German Tri-border region". It is to be shown on a technically relevant scale that marketable fertilizer products can be produced from sewage sludge in a consistently good quality and quantity. The fertilizer can be utilized both regionally and, if necessary, nationally.

Regional thermal utilization is a core element of the application strategy. In order to avoid the problems often encountered with large centralized plants, such as high transport volumes and a lack of heat suppliers, an approach with decentralized sewage sludge incineration plants with lower capacity and upstream drying is to be pursued in DreiSATS in the future.

The separation/reduction of heavy metals is possible directly during incineration as well as in the P-recycling process of the ashes. This results in a high product safety independent of the properties of the input sludge while also allowing enough flexibility to adjust the technical and economical optimum of the process control.

The aim of the concept is the regional and sustainable recycling of the produced sewage sludge, a pollutant sink and the closing of regional nutrient cycles with the lowest possible transport costs.

Focus of work

• Characterization of sewage sludge, sewage sludge ashes and alternative input materials
• Combustion tests with the pilot plant dust firing to determine process parameters
• In-situ modification and hot gas filtration for heavy metal separation in the dust firing
• Ash evaluation and site-specific recipe development for P-recycling and fertilizer granulate production
• Conception, planning and construction of a pilot plant for P-recycling
• Testing of the entire process chain as well as evaluation and testing of fertilizer products
• Development of the Geoinformation System (GIS)-based software tool for the planning of an economic, regional P-recycling concept

Main work packages

Exploitation strategy

After project completion, the project partners will have access to novel technologies as well as a flexibly applicable process chain, which, compared to the currently applied processes, has a significantly improved energy and material efficiency as well as a much broader range of input materials. Based on the above-mentioned prospects of success and the realization of the political goals in Germany and the European Union, it is assumed that the technologies and services (disposal) to be developed within the project for the processing of sewage sludge into fertilizer products will find broad application. In order to achieve the highest possible economic exploitation of the project results, current norms and standards will be considered during the development and used as a benchmark for the development of the process concept. These include the requirements of the safety regulations, the choice of materials and the necessary quality of the final product.