AMPHORE (implementation phase) – Regional Sewage-Sludge Ash Management and Phosphorus Recycling for a Metropolitan Area

Phosphorus recovery from wastewater, sewage sludge and sewage sludge ash is one of the major future topics in water management. Even before the EU Commission classified phosphorus as a critical raw material, there were attempts to recover this vital, non-substitutable commodity from wastewater or waste streams. Germany has meanwhile defined legal requirements with the amendment of the Sewage Sludge Ordinance (AbfKlärV), which includes the obligation to recover phosphorus from sewage sludge and sludge ash as of 2029. In order to support the German water industry in the implementation of this task, the BMBF support measure "Regional Phosphorus Recycling" (RePhoR) was launched within the framework of the funding programme "Research for Sustainable Development (FONA3)"

One of seven implementation projects within the RePhoR funding measure is the research project "Regional Sewage Sludge Ash Management and Phosphorus Recycling for a Conurbation (AMPHORE)" under the leadership of the Ruhrverband, Essen. A large proportion of the sewage sludge in NRW and in particular of the water associations involved in the project, is already being incinerated in mono-incineration plants with the production of energy; the ashes are then deposited or used in the construction industry. The partners from the water industry and science of the AMPHORE project are working on prospectively recovering phosphorus in the form of phosphoric acid and making it available for regional companies.

The aim of the project partners is to develop a common regional approach for the implementation of phosphorus recovery. They examine whether the operation of large, central plants or smaller, regionally distributed plants is economically and ecologically viable. Also, the organisational and legal constraints necessary for this will be considered. For this purpose, the ISA develops a sewage sludge and sewage sludge ash management. A material flow model is created based on an extensive database of collected and measured data. The sewage sludge and sludge ash are examined for their composition and analysed regarding their suitability for various phosphorus recovery processes.

Based on this, scenarios are developed that feed the sewage sludge to the available combustion lines according to their quality, thereby the resulting ash can be subjected to the best possible phosphorus recovery process. In the project the ISA is also supporting the preparations for construction and operation of a demonstration plant for phosphorus recovery from sewage sludge ash. The demonstration plant with a throughput of up to 1,000 t of sewage sludge ash per year will be built in Bottrop during the first phase of the project and its operational optimisation will subsequently be scientifically monitored by the ISA.