As part of the ReLEAF project, partner AERIS has recently installed a pilot bioreactor at the project’s technical demonstration site in Vienna, the Kleine Stadtfarm. The installation marks an important step in testing how locally generated food waste can be transformed into bio-based fertilisers directly where it is produced.
The bioreactor, developed by AERIS, will be used to test a process based on solid-state fermentation that converts food scraps into bio-based fertiliser products. In this process, food waste collected from the restaurant at Kleine Stadtfarm is mixed with wood chips and inoculated with the beneficial fungus Trichoderma harzianum, known for its plant growth-promoting properties.
Inside the bioreactor, the mixture undergoes solid-state aerobic fermentation with a constant oxygen supply for approximately six days. During this time, the fungus uses organic material as a substrate to grow and develop biostimulant properties. The resulting fermented solids can then be used as a locally produced bio-based fertiliser.
When applied to plants, Trichoderma can colonise plant roots, help them grow stronger, expand their root systems, and improve their ability to access water and nutrients. The fungus can also contribute to improved resilience against harmful fungi.
A key feature of this demonstration is its closed-loop approach. The food scraps used in the process originate from the same location where the bioreactor operates, creating a local cycle in which food waste is converted into a resource that supports plant growth and soil health.
Through this pilot, ReLEAF aims to demonstrate how locally produced bio-waste can be recycled into innovative, accessible bio-based fertilisers, contributing to circular bioeconomy solutions that can be implemented in real-world settings. Initial fermentation batches are now being prepared, and further results from the pilot will be shared as the trials progress.