“We are closing regional cycles”

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Publication day2nd May 2023

The American biochemist and science-fiction writer Isaac Asimov once described phosphorus as “life’s bottleneck.” In my view, this sums up the properties of the element. It is the precondition for all life on earth, because phosphorus compounds play a crucial role in biological growth and energy metabolism. That’s why phosphorus is important for the food and feed industry. The element is one of the most abundant on earth, but it is unevenly distributed. Major deposits can be found in Morocco, China, and Russia. Because significant deposits are lacking within the European Union, the European Commission has classified phosphorus as a critical raw material. Beginning in 2029, Germany will legally require phosphorus to be recovered from sewage sludge at municipal wastewater treatment plants. For this purpose, the sewage sludge is first thermally treated, i.e. dried and incinerated. The phosphorus is then found concentrated in the ash. In the future, this ash will be further treated by the Gelsenwasser Group in one of the world’s first phosphorus recovery plants. In our favored process, hydrochloric acid is used to separate the ash into its harmful and valuable portions. This removes heavy metals from the material cycle and generates high-quality products. Our main product—calcium phosphate—is something like the mother of all phosphates. It is highly pure and can be used instead of imported phosphorus as a starting material for a variety of products, such as particularly clean fertilizers. Our recycling concept requires little transportation and helps to reduce pollutant emissions and close regional nutrient cycles. This is an important step toward circular value creation. In this way, we can obtain clean phosphorus and conserve natural resources, thus significantly reducing the environmental impact.

Tim Bunthoff is a project engineer at the Gelsenkirchen-based infrastructure company Gelsenwasser, where he is head of the department responsible for sewage sludge recovery.

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