Dr. Ralf Kaegi
Eawag AG


Analytical Challenges and Possible Strategies to Quantify Engineered Nanoparticles in Managed Waste Facilities


Engineered nanoparticles (ENP) are used in many consumer products, such as cosmetics and textiles, and also in building and construction materials promising applications of ENP have been suggested (e.g. self-cleaning paints). During the use cycle of these materials, ENP can be release either directly into surface waters (e.g. via façade runoff) or they are discharge to the wastewater and reach the wastewater treatment plant after transport in the sewer system. ENP that remain in the products during their use phase are likely deposited in landfills. Depending on the type of landfills and on the quality of the landfill leachates, landfills may directly discharge their leachates into receiving streams. An assessment of the risks associated with the increased use of ENP in consumer products and other materials, therefore requires the quantification of ENP in complex matrices, including for example façade runoff, sewage sludge and landfill leachates. Depending on the chemistry of the ENP, different transformations occur in various managed water facilities. For examples, silver (Ag) and Copper (Cu)-NP will be sulfidized during the transport in sewer systems and during the following wastewater treatment. Other, more ‘conservative’ materials, such as TiO2-NP, do not change their chemical form but may heteroaggreate with natural colloids, which changes their transport behavior in surface waters. Based on selected case studies, including TiO2 in façade runoff, Ag-NP transformation in wastewater systems and TiO2 in landfill leachates, major challenges and possible strategies to detect and quantify ENP in complex , environmental matrices will be discussed.


Dr. Ralf Kaegi is leading the particle laboratory at Eawag since 2006. He studied earth sciences at the University of Basel and holds a Ph.D. in magmatic petrology from the ETH Zürich. He spent 5 years at Empa focusing on aerosol science before moving to Eawag. His main research interests include the fate of engineered nanoparticles in engineered systems, with a special focus on the transformation of silver nanoparticles in urban wastewater.