Legal requirements for digestate as fertilizer in Austria and the European Union compared to actual technical parameters.

Biogas is mainly discussed in the context of renewable energy, digestate is playing a minor role. However, in the upcoming EU Fertilizer Product Regulation digestate as eligible component material is in line with the circular economy action plan. This article discusses the quality of raw digestate based on analysis data from Austrian biogas plants regarding to the current Austrian as well as the European fertilizer regulatory framework. Therefore, a survey among Austrian biogas plant operators for results of digestate analysis and substrate input and energy output is used. The results show, that the legislative framework applies to a minimum of 1.5 million tonnes of digestate. Austrian digestate is of high quality with regards to the nutrient content, required limit values for heavy metals and is also safe with respect to their hygienic parameters. The following European fertilizer product function categories are available for international trade of digestate: "organic soil improver", "growing medium", and "organic, non-microbial plant biostimulant". Establishing legal criteria determining End-of-Waste and subsequently the product status for digestate is another important step in the European circular economy.