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ePaper created 2014-05-07, 13:23:14 | version 1.30.01
Initial situation The expansion of the bioeconomy simultaneously accompa- nied by a worldwide growing need for food has resulted in an ever-greater demand for fertilizers. However, the supply of fertilizers is increasingly limited, due to the high primary energy consumption for the production of synthetic nitrogen fertilizers, for example. In addition, now that the available phosphorus resources no longer have a high degree of purity, the exploitation and processing costs are rising as well. A way out of this situation in terms of sustainability is offered by the recycling of the basic nutritional elements phosphorus (P), nitrogen (N) and potassium (K). To achieve this, the nutrients have to be recovered from the material cycles of industrial production, food production, municipal wastewater and also from the bioenergetic recycling or the processing of renew- able resources. Nutrients management by closing material cycles The recovery of nutrients is of vital importance for a sustain- able nutrients management that will continue to be viable in the future. The Fraunhofer IGB is working on the development and implementation of sustainable cost-efficient technologies and strategies for integrated resource management. The main emphasis is on the development of new technologies for the recovery of nutrients from wastewater and organic residual matter such as liquid manure, fermentation residues and in- dustrial residues, for example, from the food industry. Our methodology includes the standardized characterization and evaluation of various solid and liquid residues with the prospect of recovering nutrients. Depending on the material characteristics of the initial substrate, we develop new, spe- cific processing technologies to achieve the highest possible recovery rates. In our subsequent downstream production processes, the nutrients are precipitated or pelletized in such a way that they can be marketed as a fully fledged, specific product to be utilized in various agricultural sectors. Fertilizers can be manufactured and offered for sale both in solid and liquid form. We offer the possibility of developing customized product formulations, manufacturing sample amounts and characterizing them accordingly. Electrochemical process for the recovery of magnesium- ammonium-phosphate The Fraunhofer IGB has developed and patented a new elec- trochemical process for the recovery of ammonium (NH4 + ) and phosphate (PO4 3– ) from wastewater. Here NH4 + and PO4 3– are precipitated as struvite (magnesium-ammonium-phosphate, MAP, MgNH4PO4*6 H2O) using a magnesium electrode. Our process has the advantages that no chemicals such as MgCl2 or NaOH have to be added, and that only a low consumption of energy is required (70 Wh / m3 wastewater). The electrochemical process was successfully demonstrated with an electrolytic cell using various approaches to testing, such as batch and continuous processes in addition to varying ion concentrations (20 – 500 mg / l PO4-P and 100 – 1500 mg / l NH4-N). A pilot plant is available with a throughput volume of 1 m3 / h wastewater for trials at various locations with different feed streams, for example, to wastewater treatment plants. 112 CLOSING MATERIAL CYCLES TO ACHIEVE SUSTAINABLE PRODUCTION OF FERTILIZERS AND SOIL CONDITIONERS Jennifer Bilbao M.Sc., Dipl.-Ing. (FH) Daniel Frank ENVIRONMENT 1 2