Structure

The material flows in the planned integrated solution are recorded and balanced qualitatively and quantitatively. This balance ultimately serves as a dimensioning basis for the implementation of P-recovery. In addition, the dynamic disposal situation caused by different ash deliveries and qualities is to be recorded in order to identify the necessary flexibility and efficiency of the P recycling process (WP 1.1, 1.2). Parallel to this, input paths of the relevant heavy metals in conurbations are to be investigated (WP 1.3). Recommendations for action to reduce these inputs will be developed and, if necessary, included in the assessment of P recycling in an ecological balance sheet.

The PHOS4green process completely refines the KSA added to the process into a P-rich fertiliser with the lowest possible amount of by-products or residues. Heavy metal removal has not been possible with this process so far. The challenge of the project is to remove the heavy metals relevant under fertiliser legislation from the CRSA in a target-oriented manner and at the same time to keep the accumulation of residues and the associated recycling and disposal costs as low as possible. The ash components remaining after the removal of heavy metals will continue to be refined into a fertiliser. AP 2 is divided into three main areas of work for the differentiated investigation, adaptation and optimisation of the process engineering modules for phosphorus recovery. AP 2.1 and 2.2 differ significantly in the scale to be investigated. Thus, the basic suitability of heavy metal removal is being investigated on a laboratory scale (WP 2.1), and the dimensioning basis and optimisation for the large-scale implementation planned in WP 2.3 are being investigated on a semi-industrial scale (WP 2.2).

Parallel to the technological issues in WP 2, ecological (WP 3.2) and economic (WP 3.3) aspects for the planned P-recycling and for the integration of heavy metal depletion are considered in WP 3. The assessment also includes the measures developed in WP 1 to reduce the input of heavy metals into the wastewater network and takes into account the recovery of the produced recyclate and the resulting residual materials (WP 3.1).

In addition to the clarification of the overriding legal issues regarding P-recycling, the organisational form of the network must also be worked out. Particular challenges arise from the different private and public law forms of organisation of the project partners, the pilot character of the project with regard to phosphorus recovery and the intended cooperation across federal states. The aim of the legal support is to create a network that strikes an appropriate balance of interests between the partners in the municipal economy (which are financed by fees) and the companies involved in the recycling industry.

On the basis of the collaborative P-recycling solution developed for the Rhine-Main area, the results obtained in the course of the project and the challenges to be overcome in the design of (mixed private- and public-law) collaborative projects will be transferred in the form of a guideline into a widely applicable and practicable tool that supports the preparation, design and implementation of possible P-recycling collaborative projects (WP T.1). In addition, the results of the further development of the PHOS4green technology with regard to the sewage sludge ashes that can now be used and the flexibility of the process with regard to potential limit value tightening are summarised and evaluated in an assessment of potential (WP T.2).