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Recycling Facility for Contents from Dry Separation Toilets to Continue Operations

The IGZ remains involved in the flagship project in Eberswalde

19.12.2024
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Humus rack in the recycling plant © Torsten Stapel
Humus rack in the recycling plant © Torsten Stapel

The recycling facility for humus and urine-based fertilisers is the first of its kind in Germany. Established as part of the IGZ-coordinated research project zirkulierBAR since 2019, with support from German and European funding, it has achieved a significant milestone: the facility will continue to operate even after the project ends. Its operations will be managed by the practical partners Finizio Future Sanitation and Kreiswerke Barnim. The facility transforms waste from dry toilets into high-quality recycled fertilisers. Its aim is to develop decentralised, scalable solutions for a circular economy in sanitation and nutrient management while providing municipalities with a water-saving alternative to conventional sewage systems. At the same time, it supports resource-efficient and environmentally friendly agriculture.

The facility produces two main types of recycled fertilisers: the liquid mineral fertiliser Aurin® and the organic humus fertiliser derived from dry toilet contents (German: Humusdünger aus Inhalten von Trockentoiletten, H.I.T.), which is rich in carbon and phosphorus. Both products enable nutrient recycling, protect water bodies from nutrient and pollutant inputs, and contribute to transitioning towards closed cycles in agricultural and food production.

Between 2022 and 2024, the facility produced approximately 400 cubic metres of humus fertiliser (H.I.T.) through controlled, oxygen-supplied composting. This amounts to 270 tonnes, equivalent to the weight of two blue whales or 45 elephants. The process has been further optimised with the installation of a humus rack, which has been operational since September 2024 and has an annual capacity of 200 cubic metres of solids.

The urine treatment facility, developed by the Swiss company VunaNexus, converts human urine into liquid mineral fertiliser. In 2024, the facility built under zirkulierBAR was upgraded with an evaporator as part of the Horizon Europe project P2GreeN, completing the process. To date, 15,000 litres of urine have been stabilised and purified. The development and testing of the urine treatment facility at the pilot site operated by Kreiswerke Barnim will continue under P2GreeN until November 2026.

Fertiliser trials conducted during the zirkulierBAR project used both products in combination. They demonstrated fertilisation efficacy comparable to that of chemical-synthetic fertilisers. As part of P2GreeN, the IGZ continues to sample recycled fertilisers—i.e., Aurin® from the pilot facility in Eberswalde and a similar humus fertiliser from the container-based composting facility of the practical partner Goldeimer gGmbH in Hanstedt-Ollsen—and apply them to fields in combination. This ensures ongoing data collection on safety and fertilisation effectiveness.

The recycling facility in Eberswalde serves as a flagship project for the bioeconomy. It demonstrates how waste can be transformed into a valuable contribution to food security and soil health. The model is not only scalable but also offers a blueprint for other regions seeking sustainable alternatives to linear wastewater management.

For more information on technical implementation and project results:

Correction from 12.01.2025: The original version of the post incorrectly stated that P2GreeN was responsible for the scientific monitoring of the recycling plant. It is correct that the urine treatment plant is part of one of three pilot regions of an Innovative Action of the Horizon Europe project P2GreeN, which is pursuing the scaling of the innovation.

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