Verfahren zur Gewinnung von Sekundärphosphaten aus flüssigen Stoffströmen und deren Einfluss auf die deutsche Phosphorbilanz

Phosphorus is a chemical element and essential for humans, fauna und flora. Phosphorus is not substitutable and in addition finite. Its chemical compounds rank among those material flows of our planet, which are extensive affected by industrial production and consumption. Phosphorus is available at natural mineral deposits in the form of phosphate ore and is to be mined. The worldwide phosphorus reserve has a limited range. The composition of the phosphate ore is significant for its utilisation: the main part of the phosphate deposits are enriched with heavy metals due to their genesis which handicaps the utilisation. The price of phosphorus is extremely insecure, because it is not a global trade price, but it is based upon bilateral trade agreements. Germany possesses no own phosphate deposits and is totally reliant on phosphate imports. In the presented dissertation a phosphorus balance for Germany is generated in order to get a general idea of human activities and the resultant phosphorus mass flows. Twelve relevant process units are identified. Six of them belong to the industrial and three to the agricultural sector. Two units are related to waste and waste water treatment. The twelfth process unit is made by the German domestic households. To complete the balance three units are defined outside of the balance envelope: the import of phosphoric mass flows as well as the export represent relevant quantities of the balance as well as the hydrosphere. Additionally to the process units five store units are defined: the storage of phosphorus in the soil and in humans, long-living products, waste of the fertiliser industry and landfills. Altogether 28 mass flows are identified, whereof several of them are to subdivide. The phosphorus balance illustrates, that annually approx. 536,000 Mg P/a are imported into the balance envelope. The agricultural production plants receive a proportion of 35.6% of this in the form of fertiliser and forage, closely followed by the phosphorus production industry with a proportion of 34.9%. With a proportion of 24.4% the food processing industry is the third largest recipient. At the same time this industry sector exports the major phosphorus quantity with 59.7% of all phosphorus exports. Further relevant export oriented sectors are the phosphorus working industry (11.8%) and the fertiliser industry (8.7%). The phosphorus export amounts to approx. 233,500 Mg P/a and the input to the hydrosphere to 33,000 Mg P/a. Consequently 262,000 Mg P/a remain in the balance envelope and represent the store units considering the balance vagueness. Over the past years research about phosphorus recovery has been intensified. In this dissertation recovery processes from liquid media, which at least are in the final design and development stages, are listed and compared. Against the background of the generated phosphorus balance mass flows is identified and quantified, which either are considered for phosphorus recovery or can be diminished by diverse measures. Subsequently the phosphorus balance is examined once again in consideration of the phosphorus recovery processes, which are nominated as particularly suitable for phosphorus recycling. Apart from the qualitative rating of the relevant phosphorus recovery mass flows each recycling potential is quantified and their impact on the mass flows of the phosphorus balance is evaluated. It is illustrated by a future scenario that Germany is able to to become more and more independent from phosphorus imports due to efficient phosphorus recovery systems and several saving measures as a first step. The suggested phosphorus recovering systems would lead to a circuitry of approx. 36,000 Mg P/a within the balance envelope. Realising the drafted phosphorus recycling measures the imports of mineral fertilisers could be decreased by 50%. This would lead to an annual reduction of the total German imports of 6.6%. Furthermore the input to the hydrosphere could be decreased by 38%. That would make an important contribution to the correction of the water bodies quality with regard to the realisation of the EU Water Framework Directive. The drafted double strategy of avoidance and substitution of phosphorus quantities based on fully developed technologies can initiate the beginning of an increasing German independence of the international phosphorus market. Furthermore the implementation of nationwide phosphorus recovery systems would be a pioneer work that could strengthen the German leading role in the environmental technology sector. The phosphorus recycling processes are nearly completely developed and ready for large-scale applications. Their implementation currently runs hesitantly, but the knowledge of the finiteness of the phosphorus resources and its general importance for life must lead to sustainable action and reasonable behaviour within all relevant social groups