SUSKULT: Agricultural system of the future

The efficient use of nutrients and water in plant production is a decisive factor in meeting the growing global demand for food while minimizing the environmental impact of agriculture. The provision of nitrogen, phosphorus and potassium - the three main nutrients for plant growth - plays a central role here.

As part of the joint research project SUSKULT, a transdisciplinary project consortium - including universities and research institutions as well as institutions from industry, business and public administrative staff - aims to harness the resources of municipal sewage treatment plants in metropolitan regions for food production, including in hydroponic cultivation systems. The aim is to create a nationwide network in Germany that ensures plant cultivation based on local resources. Among other things, Fraunhofer UMSICHT has developed a process for recovering nutrients from sludge water in the form of liquid fertilizer and tested its process performance.

The demand for agricultural products is growing continuously. At the same time, the need for fertilizers is also increasing. Between 2010 and 2020, global demand for nitrogen, phosphorus and potassium increased by more than 18 Percent^{(1) .}However, their industrial production is heavily dependent on fossil fuels and limited mineral resources. Phosphorus fertilizer, for example, is extracted from phosphorus-bearing rocks or marine sediments, which are mainly available in Morocco, Western Sahara, China and the USA. And nitrogen fertilizer production using the Haber-Bosch process accounts for 1 to 2 Percent of global energy consumption each year². Due to persistently high gas prices in 2025, nitrogen fertilizer production in Germany and Europe is under high pressure.

A promising alternative that addresses a more sustainable food supply is the recovery of nutrients from sources such as municipal wastewater. This approach is not only receiving a great deal of attention in research and in the first annexes, but also in political measures. For example, the German Sewage Sludge Ordinance³ stipulates a legal obligation for sewage treatment plant operators to recover phosphorus from 2029.

Wastewater treatment plant provides resources for plant production

The SUSKULT project partners have laid the scientific foundations for metropolitan, cycle-based agricultural production and developed individual modules. These building blocks have now been combined into a process chain in a demonstration plant at a wastewater treatment plant and are being tested in practice. In the SUSKULT vision, wastewater treatment plants become so-called NEWtrient^® centers that supply all the resources – nutrients, CO₂, water and energy – required for the cultivation of horticultural products. With short distances to the consumer. The resource wastewater is converted into NPK-containing liquid fertilizer (NPK: nitrogen, phosphorus and potassium), which in turn can be used to cultivate vegetables and lettuce or health-promoting foods such as sweet potatoes and moringa. SUSKULT is also looking at the production of duckweed, which has a high vitamin content and can serve as a regional soy substitute. They are grown vertically and indoors - protected from environmental influences, space-saving and season-independent.

NEWtrient^®-transformation

Following the successful completion of the first funding phase, the second phase of SUSKULT will start at the beginning of 2025. The NEWtrient^®-Center approach will be expanded into a NEWtrient^® transformation, whereby other resources such as fermentation residues will be used in addition to the resource potential from wastewater treatment plants. Mixed together, they will be used as liquid fertilizer for vertical farms in urban centers and for field cultivation.

_{[1] https://www.ifastat.org/databases/graph/1_1
[2] https://www.iea.org/reports/ammonia-technology-roadmap/executive-summary
[3] https://www.bgbl.de/xaver/bgbl/start.xav?startbk=Bundesanzeiger_BGBl&jumpTo=bgbl117s3465.pdf#/text/bgbl117s3465.pdf?_ts=1747141809200}