On the second day of the DBU-Sommerakademie, three workshops offered the opportunity to delve deeper into individual topics. The main results are as follows.
Workshop 1: Fertilizer innovations
In Germany, large parts of agricultural areas are well supplied with phosphorus (P). In regions with a high animal population, the soils have reached a level of phosphorus supply which leads to environmental pollution. In Austria, a multi-year material flow balance was used to determine the parameter adjustments required to optimize P management. On the basis of this holistic approach, it can be shown, for example, that lower meat consumption and increased P recycling from sewage sludge would contribute to an improved P balance in Austria. Holistic and systemic considerations are also recommended for other countries and should be routinely included in the statistics. The previous figures for soil phosphorus content available to plants could be reduced by one third in almost all soils in Germany without any loss in quantity or quality of the harvested products. In the future, demand and plant availability must be determined in order to operate efficiently. For example, new digital analysis methods could help to determine the P requirement directly for each plant. Basically, it was argued that the disparity between scientific knowledge and implementation in practice has grown. Therefore, it is recommended to improve transformation processes in dialogue with science and practitioners.
Workshop 2: Spin straw into gold? "Dry" topics in communications, journalism and education
Phosphorus, nitrogen, and planetary boundaries: How can complex sustainability issues which at first glance appear to be far removed from everyday life be made "palatable" so that they arouse curiosity, are recognized, and promote systemic thinking? Creative examples of this were provided by the communications workshop of the DBU-Sommerakademie - starting with a service learning project from the University of Siegen, in which pupils advise agricultural businesses on the subject of area-differentiated fertilization; continuing with a project from the University of Bremen which involves trying out various phosphate recovery methods in school laboratories; a target group-oriented communication strategy of the German Phosphor Platform (Deutsche-Phosphor-Plattform e. V., Frankfurt) and the topical comic "Die Anthropozän-Küche" produced by the agency MINT WISSEN of Berlin; and finally the DBU's own exhibition "MenschenWelt".
The workshop participants agreed that even supposedly "dry" topics can be communicated in an interesting manner when everyday references are established, the relevance of the topics is pointed out, and good, target-group-oriented explanations are used. It is also important to tell success stories in order to avoid so-called reactance - the response of turning away because of the feeling that "nothing can be done anyway". At the end of the workshop, the participants worked on two tasks in the form of "design sprints" and thus quickly developed the bases for two target-group-oriented communication concepts.
Workshop 3: Strategies for recycling phosphorus
In recent years, a number of new and promising technologies for the removal and recovery of phosphorus (P) from wastewater, sewage sludge and sewage ash have been developed and, in some cases, already tested in practice. Some of these - such as the ExtraPhos process and the TetraPhos process - were presented in the workshop as examples. However, it became apparent that there is often still a lack of operating experience and information on costs and reliability, which are needed to promote the establishment of suitable technologies.
In view of the new sewage sludge regulations, many operators, especially large ones, are currently relying on sludge mono-combustion. Nevertheless, according to some participants in the discussion, the use of existing co-incineration options, for example in cement plants, should also continue to be pursued.
Against the background of the current disposal bottleneck for sewage sludge, it is important to achieve short-term solutions such as interim storage, explained Ralf Hilmer and Ralf Schüler of the Deutsche Vereinigung für Wasserwirtschaft, Abwasser und Abfall e.V., DWA. The reasons for this are the restrictions on application due to the new fertilizer law, and the sewage sludge ordinance as well as significantly reduced (co-)combustion capacities.
Above all, the workshop participants agreed on one point: The goal of finding intelligent regional solutions together and establishing the resulting sewage sludge as a raw material source for phosphorus should not be lost sight of.
