Thurgau and Schaffhausen test quagga mussels in cement production

Thurgau and Schaffhausen are funding industrial trials to determine whether quagga mussel remains can be used to produce cement or fertiliser, SRF reported on Tuesday.

Dead quagga mussels are causing problems for shipping on the Upper Rhine. When water levels are low, vessels can no longer travel between Diessenhofen and Stein am Rhein. Last year, the Untersee and Rhein shipping company had to suspend services there for about a month.

Dredging and disposing of the mussel remains is expensive, said Martin Eugster, head of Thurgau’s environmental office. Because it was unclear how the shells could be disposed of or recycled, the two cantons had refrained from further large-scale dredging.

This summer, an excavator stirred up the mussels in the hope that the remains would be carried away by the current. The method provided short-term relief, but the cantons are seeking a lasting solution. They are now pursuing a plan to recycle the mussels into cement or fertiliser.

The cantons are investing several tens of thousands of francs in a trial with a cement plant. Around 100 cubic metres of mussel sediment will be removed from the Upper Rhine near Stein am Rhein in the coming days. The plant will examine the material’s quality and whether lime from the shells can replace natural limestone.

Industrial trials will show whether the process remains stable when mussel lime is used, said Schaffhausen’s cantonal engineer, Dino Giuliani. The material itself is not a problem, he said, adding that the shells consist of 90 per cent limestone. Use in the fertiliser industry will also be examined.

The cantons expect the results by the end of the year. A similar trial is also under way in western Switzerland.