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Top down bottom up: Out and about

A Swiss collaboration has found that many more nanoparticles can leave an experimental sewage works than was previously thought.

Wendelin Stark of ETH Zürich and Reto Müller of BMG Engineering had known each other from their days in the Swiss army. And it was through Müller that Stark heard about collaborations between BMG Engineering and Rolf Krebs' group at the Zürich University of Applied Sciences on various wastewater projects. Stark and Krebs then talked on the phone and decided to get their teams together to study how engineered nanoparticles are removed from a model water-treatment plant.

Stark is a chemical engineer who works on the synthesis and manufacture of inorganic oxides. He and his student Ludwig Limbach wanted to know if the nanoparticles they were making presented a risk to human health or the environment. Krebs and his colleagues at BMG contributed know-how on water-treatment plants and together they discovered that the bacteria found in sewage sludge can secrete surfactants that prevent the aggregation of cerium oxide nanoparticles. Previously it had been thought that the nanoparticles might form clumps that would precipitate, thus preventing them from entering the environment. However, the results of the Swiss team — which also included researchers from BMG and electron microscopists from ETH — show that further research is needed to develop ways to remove these nanoparticles from waste water (Environ. Sci. Technol. 42, 5828–5833; 2008).

“Collaborations mostly depend on the people involved. If you have great people, you will always find creative ways to realize and finance a project,” says Stark. “Long-term collaborations depend on trust; there are no contracts and if you are known to stick to your word, others will trust you more easily. It also helps if you learn a bit about other people's culture and their language — I spent months reading the medical literature, visiting hospitals and getting to know the problems and it was worth every single minute.”

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Top down bottom up: Out and about. Nature Nanotech 3, 581 (2008).

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