NitroPhos

Industrial Research on Optimized Process Chain of Nutrient Recovery from Digestate with Integrated Biogas Treatment (NitroPhos)

Topic

The high crop yields in Germany are achieved through the use of mineral phosphorus, potassium and nitrogen fertilizers. However, the production of these fertilizers leads to considerable environmental polution both locally in mineral extraction and globally through high carbon dioxide emissions. Digestate from biogas plants is an interesting alternative to mineral fertilizers. In Germany, digestate is highly regionally concentrated, which leads to nutrient surpluses. Due to the high water content, it is difficult to transport the digestate economically, which is why it makes sense to extract the nutrients from the digestate and then concentrate them. In particular, the NuTriSep-process of the company Geltz Umwelttechnologie GmbH is promising, but currently still has a high consumption of chemicals and energy. The process is to be optimized as part of this project. For this purpose, the chemicals used so far will be replaced by the substances ammonia and carbondioxide produced in the biogas process. In addition to the recovery of phosphate salts, the biogas will be purified and the quality of the fermentation residue increased.

Goals

As part of this project, a pilot plant for the recovery of phosphate salts, combined with biogas upgrading to natural gas quality, is being developed in cooperation with the company Geltz Umwelttechnologie. The plant will then be tested at the "Unterer Lindenhof" research site of the University of Hohenheim. In addition, a reactor for energy efficient nitrogen stripping is to be built on a laboratory scale and tested in the laboratory of the state institute.

Tasks of the State Institute

The State Institute is responsible for the experimental optimization of the pilot plant as well as the design, construction and testing of the reactor for nitrogen stripping.