The work is to be conducted by two institutions. Middle East Technical University will operate laboratory scale batch anaerobic reactors for the digestion of poultry manure and wastewater treatment plant sludge mixtures in different ratios, and conduct struvite precipitation experiments in both solid and fluid phases of digestion residues. The resulting products will be examined using microscope and X-ray diffraction techniques. Additionally, the concentrations of N, P, Mg and other significant metals will be determined so that a mass balance can be prepared. In the first phase of the project the University of Stuttgart will conduct struvite precipitation experiments in synthesised digestion liquor in order to understand the system and determine the mechanisms. Meanwhile, the results will be transferred onto a chemical model together with the chemical data from the analyses of the partner institution to estimate the potential reactions in the investigated complex type of process waters. The modelling phase will be followed by a short verification phase applying struvite formation on real digestion residues. The resulting products are also to be examined as mentioned above. Results are to allow the determination of critical concentrations of metals which influence the struvite formation.
The cooperation intends to support at least two research assistants or graduate students for scientific research during the planned project. A close collaboration is expected to be performed by visits from both institutions, enabling an ambilateral exchange of experience.