Vienna relies on the circular economy: gain phosphorus from sewage sludge

Von WOM

In a significant step in waste management, Vienna Energie in Vienna Simmering built a new system that enables you to win phosphorus from sewage sludge. This innovative solution aims to reduce the dependence on imported phosphorus that is used as a fertilizer in agriculture. Every year, thousands of tons of this element could be recycled from the sewage sludge instead of obtaining it from far away.

The process in the new system begins with the drying of the sewage sludge, which consists of 96 percent of water. In a large centrifuge, the starting material is transformed into a fine -grained sand. Heat is added, which not only supports drying, but also uses waste heat for feeding into the district heating network.

double benefits of the sewage sludge

After the drying process, the sewage sludge is burned. With this combustion, ashes remain from which the phosphorus is to be obtained in a further phase. This procedure is currently being tested in pilot -like cooperation. Vienna Energie plans to build its own phosphorus separation system in the future. At the moment, however, drying already brings significant advantages.

In the past, additional oil, such as cooking oil, had to be used when the sewage sludge burned due to the high water content. With the new drying technology, however, you can get out without auxiliary substances, which leads to a saving of thousands of tons annually.

pioneering work in Europe

"Vienna is one of the first cities in Europe with such a system," said Vienna's City Councilor Peter Hanke at the opening. Only in Hamburg does a comparable facility exist that has already successfully recovered phosphorus from the ashes. This practice will be standard throughout Europe in the future, since the EU will make the recovery of phosphorus due to the amended waste incineration regulation from 2033.

"Phosphorus is a central raw material for agriculture that we currently import from distant countries, such as Morocco," explained the environmental city councilor Jürgen Czernohorszky. Karl Gruber, Managing Director of Vienna Energie, sees the project in Simmering as an exemplary example of the circular economy: "We have to go back to a circular company to ensure that we do not end the raw materials."

The new system will not only process sewage sludge from Vienna, but also from municipalities from all over Eastern Austria. Currently, municipalities have to pay for the disposal of the sewage sludge; In the future, this could possibly be the opposite, since the sewage sludge is considered a valuable resource. It is even conceivable that ashs that were previously stored on landfills are recycled as a waste.